Zero-voltage switching and its control method for single-tube quasi-resonant wireless charging

Abstract

This invention provides a zero-voltage switch and its control method for single-transistor quasi-resonant wireless charging. It includes: a control circuit for outputting a control signal; a drive circuit connected to the output of the control circuit for receiving and amplifying the control signal to drive a field-effect transistor (FET); a transmitter resonant network connected to the output of the drive circuit for generating a resonant voltage signal under the drive of the FET; and a voltage trigger circuit connected between the output of the transmitter resonant network and the input of the control circuit for outputting a trigger signal to the control circuit when the resonant voltage signal drops to a threshold voltage. The control circuit adjusts the control signal according to the falling edge of the received trigger signal to achieve cycle-by-cycle zero-voltage switching of the FET. This invention uses a voltage trigger circuit in conjunction with a control circuit to achieve a purely hardware-controlled zero-voltage switch. Due to its fast response speed, it can achieve cycle-by-cycle zero-voltage switching control, improving the efficiency of wireless charging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless charging, in particular to a zero-voltage switch for single-tube quasi-resonant wireless charging and a control method thereof. BACKGROUND

[0002] With the continuous progress and popularization of wireless charging technology, its application range has been extended from consumer electronics products to industrial equipment, electric vehicles and other fields. In order to meet the market demand for low-cost and high-efficiency wireless charging systems, single-tube quasi-resonant wireless charging topology has attracted widespread attention due to its simple structure and low cost. However, in actual application, such topology faces challenges in achieving high-efficiency charging in the full operating range, especially when facing different load conditions, maintaining high efficiency becomes more difficult. Therefore, developing a technical solution that can effectively improve the efficiency of single-tube quasi-resonant wireless charging systems has become a research hotspot in this field.

[0003] In the process of pursuing high-efficiency wireless charging, zero-voltage switch (ZVS) technology has been proven to be an effective means, which can improve the overall performance of the system by reducing switching losses. One existing method to achieve ZVS is to combine a zero-voltage sampling circuit with a single-chip microcomputer control to adjust the duty cycle of the drive signal to ensure that the switch tube can be turned on at the voltage zero-crossing point. This method relies on accurate detection of the zero-crossing time of the switch tube voltage and adjusts the operating state of the switch tube accordingly to achieve soft switching effect. This method provides a feasible path for the optimization of wireless charging systems, allowing higher operating efficiency even under varying load conditions.

[0004] Although the above method improves the efficiency of single-tube quasi-resonant wireless charging systems to some extent, it still has some shortcomings. First of all, since it needs to frequently enter the single-chip microcomputer interrupt program for zero-voltage switch control, it not only consumes a large amount of single-chip microcomputer resources, but also may affect the normal operation of other functions. Secondly, since zero-voltage switching cannot be achieved cycle by cycle, when the system load changes rapidly, the response speed is relatively slow, which may lead to problems such as system efficiency decline and energy transmission instability. These problems limit the popularization and use of this technology in wider applications, especially in application scenarios with high requirements for real-time performance and stability. SUMMARY

[0005] In order to solve the above problems existing in the prior art, the present application provides a zero-voltage switch for single-tube quasi-resonant wireless charging and a control method thereof.

[0006] The technical problem to be solved by the present application is solved by the following technical solutions:

[0007] In a first aspect, the present application provides a zero-voltage switch for single-tube quasi-resonant wireless charging, comprising:

[0008] Control circuit, used to output control signals;

[0009] The driving circuit is connected to the output of the control circuit and is used to receive and amplify the control signal to drive the field-effect transistor.

[0010] The transmitter resonant network is connected to the output of the driver circuit and is used to generate a resonant voltage signal under the drive of the field-effect transistor.

[0011] A voltage trigger circuit is connected between the output of the resonant network at the transmitting end and the input of the control circuit. It is used to output a trigger signal to the control circuit when the resonant voltage signal drops to the threshold voltage.

[0012] The control circuit adjusts the control signal based on the falling edge of the received trigger signal to achieve zero-voltage turn-on of the field-effect transistor cycle by cycle.

[0013] Optionally, the control circuit includes:

[0014] Clock signal input module, used to provide clock signal;

[0015] A counter is used to receive a clock signal and increment its own count value by 1 in each clock cycle.

[0016] Comparator 1 is used to compare the counter value with a preset first time threshold. When the counter value is less than the first time threshold, it outputs a high-level control signal.

[0017] Comparator 2 is used to compare the counter value with a preset second time threshold. When the counter value is greater than the second time threshold, it outputs a reset signal to reset the counter.

[0018] The falling edge capture module is used to capture the falling edge of the trigger signal output by the voltage trigger circuit and generate a reset signal to reset the counter.

[0019] Optionally, the control circuit also includes:

[0020] The drive signal output module is used to output a control signal to the drive circuit based on the output signal of comparator one after the counter is cleared.

[0021] Optionally, the driving circuit includes: a field-effect transistor Q1 and a gate driver U1; the field-effect transistor Q1 is an N-channel insulated-gate field-effect transistor;

[0022] The source of the field-effect transistor Q1 is grounded, the gate of the field-effect transistor Q1 is connected to the output terminal of the gate driver U1, and the drain of the field-effect transistor Q1 is connected to the input terminal of the emitter resonant network; the input terminal of the gate driver U1 is connected to the output terminal of the control circuit.

[0023] Optionally, the transmitter resonant network consists of a transmitter coil L1 and a capacitor C1;

[0024] The transmitting coil L1 and capacitor C1 are connected in parallel; one end of both the transmitting coil L1 and capacitor C1 is connected to the positive terminal V_IN of the power supply, and the other end of both the transmitting coil L1 and capacitor C1 is connected to the input terminal of the transmitting resonant network.

[0025] Optionally, the voltage triggering circuit includes: resistor R1, resistor R2, resistor R3, comparator U2, diode D1, and capacitor C2;

[0026] The non-inverting input of comparator U2 is connected to one end of resistor R1 and the anode of diode D1; the other end of resistor R1 and the positive power supply pin of comparator U2 are both connected to the positive power supply; the negative power supply pin of comparator U2 is grounded; the cathode of diode D1 is connected to the output of the emitter resonant network; the inverting input of comparator U2 is connected to one end of resistor R2, one end of resistor R3, and one end of capacitor C2; the other ends of resistor R2 and capacitor C2 are connected to each other and grounded; the other end of resistor R3 is connected to the positive power supply; the output of comparator U2 is connected to the input of the control circuit.

[0027] Optionally, the first time threshold is dynamically adjusted based on the load of the single-tube quasi-resonant wireless charging system; the second time threshold is set based on the operating frequency of the single-tube quasi-resonant wireless charging system and the switching characteristics of the field-effect transistor.

[0028] Secondly, the present invention provides a control method for a zero-voltage switch in single-tube quasi-resonant wireless charging, comprising:

[0029] The control circuit outputs a high-level control signal to turn on the field-effect transistor;

[0030] After the field-effect transistor is kept on for a preset time, the control circuit outputs a low-level control signal to turn off the field-effect transistor, and the transmitter resonant network enters a free resonance state and generates a resonant voltage signal.

[0031] When the voltage trigger circuit detects that the resonant voltage signal has dropped to the threshold voltage, it outputs a trigger signal to the control circuit.

[0032] The control circuit enables the field-effect transistor to turn on with zero voltage cycle by cycle based on the falling edge of the received trigger signal.

[0033] Optionally, the control circuit enables the field-effect transistor to turn on zero-voltage cycle by cycle based on the falling edge of the received trigger signal, including:

[0034] The counter increments by one count per clock cycle;

[0035] The counter's count value is compared with a preset first time threshold. When the count value is less than the first time threshold, a high-level control signal is output. When the count value is greater than a preset second time threshold, a reset signal is output to reset the counter's count value.

[0036] The zeroing signal is generated by capturing the falling edge of the trigger signal.

[0037] This invention provides a zero-voltage switch and its control method for single-transistor quasi-resonant wireless charging. The zero-voltage switch for single-transistor quasi-resonant wireless charging includes: a control circuit for outputting a control signal; a drive circuit connected to the output of the control circuit for receiving and amplifying the control signal to drive a field-effect transistor (FET); a transmitter resonant network connected to the output of the drive circuit for generating a resonant voltage signal under the drive of the FET; and a voltage trigger circuit connected between the output of the transmitter resonant network and the input of the control circuit for outputting a trigger signal to the control circuit when the resonant voltage signal drops to a threshold voltage. The control circuit adjusts the control signal according to the falling edge of the received trigger signal to achieve cycle-by-cycle zero-voltage turn-on of the FET. In this invention, a voltage trigger circuit combined with a control circuit achieves a purely hardware-controlled zero-voltage switch. Due to its fast response speed, cycle-by-cycle zero-voltage switch control can be achieved, improving the efficiency of wireless charging. Furthermore, the zero-voltage switch of this invention can quickly adjust to respond to load changes, improving the stability of the wireless charging system. Finally, compared with existing technologies, the zero-voltage switch provided by this invention reduces application costs and increases practical application value.

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0039] Figure 1 A schematic diagram of the structure of a zero-voltage switch for single-tube quasi-resonant wireless charging provided in an embodiment of the present invention;

[0040] Figure 2 An exemplary schematic diagram of the control circuit is shown;

[0041] Figure 3 An exemplary schematic diagram of the driving circuit and the transmitter resonant network is shown;

[0042] Figure 4 An exemplary schematic diagram of a voltage trigger circuit is shown.

[0043] Figure 5 This is a flowchart illustrating a control method for a zero-voltage switch in a single-tube quasi-resonant wireless charging system, as provided in an embodiment of the present invention. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0045] To improve the efficiency and stability of wireless charging, this invention provides a zero-voltage switch for single-tube quasi-resonant wireless charging. Figure 1 This is a schematic diagram of a zero-voltage switch for single-tube quasi-resonant wireless charging, provided as an embodiment of the present invention. Figure 1 As shown,

[0046] Control circuit, used to output control signals;

[0047] The driving circuit is connected to the output of the control circuit and is used to receive and amplify the control signal to drive the field-effect transistor.

[0048] The transmitter resonant network is connected to the output of the driver circuit and is used to generate a resonant voltage signal under the drive of the field-effect transistor.

[0049] A voltage trigger circuit is connected between the output of the resonant network at the transmitting end and the input of the control circuit. It is used to output a trigger signal to the control circuit when the resonant voltage signal drops to the threshold voltage.

[0050] The control circuit adjusts the control signal based on the falling edge of the received trigger signal to achieve zero-voltage turn-on of the field-effect transistor cycle by cycle.

[0051] The zero-voltage switch for single-tube quasi-resonant wireless charging provided in this invention uses a voltage triggering circuit in conjunction with a control circuit to achieve a purely hardware-controlled zero-voltage switch. Due to its fast response speed, it can achieve cycle-by-cycle zero-voltage switch control, improving the efficiency of wireless charging. Furthermore, the zero-voltage switch of this invention can also adjust rapidly under load changes, responding to load changes and improving the stability of the wireless charging system. Finally, compared with existing technologies, the zero-voltage switch provided by this invention reduces application costs and practical application value.

[0052] Figure 2 An exemplary schematic diagram of the control circuit is shown. For example... Figure 2 As shown, the control circuit includes:

[0053] Clock signal input module, used to provide clock signal;

[0054] A counter is used to receive a clock signal and increment its own count value by 1 in each clock cycle.

[0055] Comparator 1 is used to compare the counter value with a preset first time threshold. When the counter value is less than the first time threshold, it outputs a high-level control signal.

[0056] Comparator 2 is used to compare the counter value with a preset second time threshold. When the counter value is greater than the second time threshold, it outputs a reset signal to reset the counter.

[0057] The falling edge capture module is used to capture the falling edge of the trigger signal output by the voltage trigger circuit and generate a reset signal to reset the counter.

[0058] Optionally, the control circuit also includes:

[0059] The drive signal output module is used to output a control signal to the drive circuit based on the output signal of comparator one after the counter is cleared.

[0060] Figure 3 A schematic diagram of the driving circuit and the transmitter resonant network is shown as an example. Figure 3 As shown, the driving circuit includes: a field-effect transistor Q1 and a gate driver U1; the field-effect transistor Q1 is an N-channel insulated-gate field-effect transistor;

[0061] The source of the field-effect transistor Q1 is grounded, the gate of the field-effect transistor Q1 is connected to the output terminal of the gate driver U1, and the drain of the field-effect transistor Q1 is connected to the input terminal of the emitter resonant network; the input terminal of the gate driver U1 is connected to the output terminal of the control circuit.

[0062] like Figure 3 As shown, the transmitter resonant network consists of a transmitter coil L1 and a capacitor C1;

[0063] The transmitting coil L1 and capacitor C1 are connected in parallel; one end of both the transmitting coil L1 and capacitor C1 is connected to the positive terminal V_IN of the power supply, and the other end of both the transmitting coil L1 and capacitor C1 is connected to the input terminal of the transmitting resonant network.

[0064] Figure 4 An exemplary schematic diagram of a voltage-triggered circuit is shown. For example... Figure 4 As shown, the voltage triggering circuit includes: resistor R1, resistor R2, resistor R3, comparator U2, diode D1, and capacitor C2;

[0065] The non-inverting input of comparator U2 is connected to one end of resistor R1 and the anode of diode D1; the other end of resistor R1 and the positive power supply pin of comparator U2 are both connected to the positive power supply; the negative power supply pin of comparator U2 is grounded; the cathode of diode D1 is connected to the output of the emitter resonant network; the inverting input of comparator U2 is connected to one end of resistor R2, one end of resistor R3, and one end of capacitor C2; the other ends of resistor R2 and capacitor C2 are connected to each other and grounded; the other end of resistor R3 is connected to the positive power supply; the output of comparator U2 is connected to the input of the control circuit.

[0066] In this embodiment of the invention, the positive power supply can specifically be a 3.3V voltage signal.

[0067] Specifically, in this embodiment of the invention, the operation of the zero-voltage switch can be mainly divided into two stages. Stage one is that the control circuit outputs a high level, turning on the field-effect transistor (FET). After stage one is maintained for a period of time T1, stage one ends, the control circuit outputs a low level, the FET is turned off, and stage two begins. In stage two, the transmitter resonant network enters a free resonance state, and the waveform of the resonant voltage signal is approximately a sine wave. When the resonant voltage signal drops to the threshold voltage for the first time, the output of the voltage trigger circuit changes from a high level to a low level. The control circuit captures this falling edge and outputs a high level, driving the FET to turn on through the driving circuit, entering the first stage and realizing the function of the zero-voltage switch.

[0068] Optionally, the first time threshold is dynamically adjusted based on the load of the single-tube quasi-resonant wireless charging system; the second time threshold is set based on the operating frequency of the single-tube quasi-resonant wireless charging system and the switching characteristics of the field-effect transistor.

[0069] In summary, the zero-voltage switch for single-tube quasi-resonant wireless charging provided by this invention has the following technical advantages:

[0070] 1. Reduced microcontroller resource consumption: Specifically, traditional solutions rely on the microcontroller for zero-crossing detection and duty cycle adjustment, which consumes a significant amount of processing time and resources. In contrast, this invention uses pure hardware circuitry to perform these functions, freeing up the microcontroller for other tasks or reducing its performance requirements, thereby lowering cost and power consumption.

[0071] 2. Rapid Response to Load Changes: Specifically, the pure hardware circuit design provides a faster response time because it does not need to wait for the microcontroller to process interrupt requests. Within each cycle, the voltage-triggered circuit can immediately respond to voltage changes, ensuring that each switching operation occurs at the ideal zero-voltage point. This precise cycle-by-cycle control helps maintain system stability and efficiency, even under rapidly changing load conditions.

[0072] 3. Achieve Zero-Voltage Switching (ZVS) Across the Entire Operating Range: Specifically, thanks to a specially designed voltage-triggered circuit, zero-voltage switching can be achieved under a wider range of conditions, including light load, heavy load, and dynamic load scenarios. This means maintaining high conversion efficiency throughout the entire operating range, reducing switching losses, and thus improving the overall energy efficiency of the wireless charging system.

[0073] 4. Simplified System Complexity and Cost: Specifically, by integrating complex control logic into hardware circuitry, not only is the reliance on external microcontrollers reduced, but the cost and difficulty of software development are also lowered. Furthermore, since hardware circuitry is generally more reliable than software implementations with equivalent functionality, it can also improve the overall stability of the system.

[0074] 5. Enhanced Reliability: Specifically, hardware control typically offers higher reliability and a lower failure rate compared to software control. The elimination of timing errors or program crashes inherent in software allows wireless charging systems to operate stably in various environments.

[0075] In summary, the embodiments of the present invention solve the problems of high resource consumption and slow response in existing single-tube quasi-resonant wireless charging systems by introducing specially designed voltage triggering and control circuits. Furthermore, they enable efficient zero-voltage switching under all operating conditions, thereby significantly improving the efficiency and practicality of single-tube quasi-resonant wireless charging systems.

[0076] Corresponding to a zero-voltage switch for single-tube quasi-resonant wireless charging, this embodiment of the invention also provides a control method for the zero-voltage switch of single-tube quasi-resonant wireless charging. Figure 5 A flowchart illustrating a zero-voltage switch control method for single-tube quasi-resonant wireless charging provided by an embodiment of the present invention is shown below. Figure 5 As shown, it includes:

[0077] S501, the control circuit outputs a high-level control signal to turn on the field-effect transistor.

[0078] S502. After maintaining the MOSFET on for a preset time, the control circuit outputs a low-level control signal to turn off the MOSFET, causing the transmitter resonant network to enter a free resonance state and generate a resonant voltage signal.

[0079] S503. When the voltage trigger circuit detects that the resonant voltage signal drops to the threshold voltage, it outputs a trigger signal to the control circuit.

[0080] S504: The control circuit enables the field-effect transistor to turn on with zero voltage cycle by cycle based on the falling edge of the received trigger signal.

[0081] Optionally, S504 may specifically include:

[0082] The counter increments by one count per clock cycle;

[0083] The counter's count value is compared with a preset first time threshold. When the count value is less than the first time threshold, a high-level control signal is output. When the count value is greater than a preset second time threshold, a reset signal is output to reset the counter's count value.

[0084] The zeroing signal is generated by capturing the falling edge of the trigger signal.

[0085] It should be noted that the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the invention.

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Furthermore, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0087] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings and the disclosure, will understand and implement other variations of the disclosed embodiments in carrying out the claimed invention. In the description of the invention, the word "comprising" does not exclude other components or steps, "a" or "an" does not exclude a plurality, and "a plurality" means two or more, unless otherwise explicitly specified. Furthermore, while different embodiments may describe certain measures, this does not mean that these measures cannot be combined to produce good results.

[0088] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the inventive concept, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A zero voltage switching for single tube quasi-resonant wireless charging, characterized in that, include: Control circuit, used to output control signals; A driving circuit, connected to the output of the control circuit, is used to receive and amplify the control signal to drive the field-effect transistor. The transmitter resonant network is connected to the output of the driving circuit and is used to generate a resonant voltage signal under the drive of the field-effect transistor. A voltage trigger circuit is connected between the output terminal of the transmitting end resonant network and the input terminal of the control circuit, and is used to output a trigger signal to the control circuit when the resonant voltage signal drops to a threshold voltage; The control circuit adjusts the control signal according to the falling edge of the received trigger signal to achieve zero-voltage turn-on of the field-effect transistor cycle by cycle. The control circuit includes: Clock signal input module, used to provide clock signal; A counter is used to receive the clock signal and increment its own count value by 1 in each clock cycle; Comparator 1 is used to compare the count value of the counter with a preset first time threshold, and outputs a high-level control signal when the count value is less than the first time threshold; Comparator 2 is used to compare the count value of the counter with a preset second time threshold. When the count value is greater than the second time threshold, a clear signal is output to clear the counter. A falling edge capture module is used to capture the falling edge of the trigger signal output by the voltage trigger circuit and generate a reset signal to reset the counter.

2. The single inductor quasi-resonant wireless charging zero voltage switching of claim 1, wherein, The control circuit also includes: The drive signal output module is used to output a control signal to the drive circuit according to the output signal of the first comparator after the counter is cleared.

3. The single inductor quasi-resonant wireless charging zero voltage switching of claim 1, wherein, The driving circuit includes: a field-effect transistor Q1 and a gate driver U1; the field-effect transistor Q1 is an N-channel insulated-gate field-effect transistor. The source of the field-effect transistor Q1 is grounded, the gate of the field-effect transistor Q1 is connected to the output terminal of the gate driver U1, and the drain of the field-effect transistor Q1 is connected to the input terminal of the emitter resonant network; the input terminal of the gate driver U1 is connected to the output terminal of the control circuit.

4. The single inductor quasi-resonant wireless charging zero voltage switching of claim 3, wherein, The transmitting end resonant network consists of a transmitting coil L1 and a capacitor C1; The transmitting coil L1 and the capacitor C1 are connected in parallel; one end of the transmitting coil L1 and the capacitor C1 are both connected to the positive terminal V_IN of the power supply, and the other end of the transmitting coil L1 and the capacitor C1 are both connected to the input terminal of the transmitting resonant network.

5. The single inductor quasi-resonant wireless charging zero voltage switching of claim 1, wherein, The voltage triggering circuit includes: resistor R1, resistor R2, resistor R3, comparator U2, diode D1, and capacitor C2; An anode of a diode D1 is connected to one end of a resistor R1 and a non-inverting input of a comparator U2; the other end of the resistor R1 and a positive power supply pin of the comparator U2 are connected to a positive power supply; a negative power supply pin of the comparator U2 is grounded; a cathode of the diode D1 is connected to an output of a transmitting-end resonant network; an inverting input of the comparator U2 is connected to one end of a resistor R3, one end of a resistor R2 and one end of a capacitor C2; the other end of the resistor R2 and the other end of the capacitor C2 are connected to each other and grounded; the other end of the resistor R3 is connected to the positive power supply; an output of the comparator U2 is connected to an input of a control circuit.

6. The single inductor quasi-resonant wireless charging zero voltage switching of claim 1, wherein, The first time threshold is dynamically adjusted according to a load of the single-tube quasi-resonant wireless charging system; and the second time threshold is set according to a working frequency of the single-tube quasi-resonant wireless charging system and a switching characteristic of the field effect transistor.

7. A control method of a single-tube quasi-resonant wireless charging zero-voltage switching, characterized by, The method comprises: the control circuit outputs a high-level control signal to turn on the field effect transistor; after maintaining the field effect transistor on for a preset time length, the control circuit outputs a low-level control signal to turn off the field effect transistor, so that the transmitting-end resonant network enters a free resonant state and generates a resonant voltage signal; when the voltage trigger circuit detects that the resonant voltage signal drops to a threshold voltage, a trigger signal is output to the control circuit; the control circuit realizes zero-voltage turn-on of the field effect transistor cycle by cycle according to a falling edge of the received trigger signal; the control circuit realizes zero-voltage turn-on of the field effect transistor cycle by cycle according to a falling edge of the received trigger signal, comprising: a counter is incremented at each clock cycle; a count value of the counter is compared with a preset first time threshold; when the count value is less than the first time threshold, a high-level control signal is output; and when the count value is greater than a preset second time threshold, a clear signal is output to clear the count value of the counter; wherein, the clear signal is generated by capturing a falling edge of the trigger signal.

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