Transformer circuit, voltage conversion circuit, electronic device, and circuit starting method

Abstract

The application relates to a voltage conversion circuit, a voltage conversion circuit, an electronic device and a circuit starting method. A switching unit is arranged between a half-bridge circuit and a resonant circuit. A control unit controls the switching unit to switch from a first switching state to a second switching state, so as to start the voltage conversion circuit. When the switching unit is in the first switching state, a first switch tube in the half-bridge circuit is complementary on. When the switching unit is in the second switching state, the switching unit is always on. It can be seen that, during the starting process of the voltage conversion circuit, the control unit controls the switching unit to gradually switch from the first switching state to the second switching state, so that the time length during which the first switch tube and the switching unit are simultaneously in the on state in a switching period gradually increases from zero, so that the current flowing to the resonant circuit during the starting process of the voltage conversion circuit can be controlled, and the current impact in the resonant circuit can be effectively inhibited, thereby the safe starting of the voltage conversion circuit is ensured.

Description

Technical Field

[0001] This application relates to the field of circuit technology, and in particular to a transformer circuit, voltage conversion circuit, electronic device, and circuit startup method. Background Technology

[0002] LLC circuit topology and LLC-DC transformer (DCX) circuit topology (hereinafter referred to as DCX circuit topology) are common voltage conversion topologies in high voltage DC to DC (direct current-direct current, DCDC) circuits.

[0003] Typically, LLC and DCX circuit topologies include half-bridge circuits (or full-bridge circuits), resonant circuits, and synchronous rectifier circuits. Among them, the resonant circuit includes: independent resonant inductors, resonant capacitors, and leakage inductance of the transformer.

[0004] Due to limitations in circuit space or cost, LLC and DCX circuit topologies often use the leakage inductance of a transformer as the resonant inductor in the resonant circuit, saving the need for a separate inductor. However, because the leakage inductance of a transformer is limited, it cannot suppress sudden current surges like a separate inductor. Therefore, during the startup process of LLC and DCX circuit topologies, there is a risk of excessive inrush current damaging the switching transistor. Summary of the Invention

[0005] Therefore, it is necessary to provide a transformer circuit, a voltage conversion circuit, an electronic device, and a circuit startup method to address the aforementioned technical problems.

[0006] In a first aspect, this application provides a transformer circuit, which includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded.

[0007] The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

[0008] Secondly, this application also provides a voltage conversion circuit, which includes a transformer circuit, wherein the transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit, wherein a first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and a second terminal of the resonant circuit is grounded through the switching unit; the first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded;

[0009] The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

[0010] Thirdly, this application also provides an electronic device, the electronic device including a voltage conversion circuit, the voltage conversion circuit including a transformer circuit, wherein the transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit, wherein a first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and a second terminal of the resonant circuit is grounded through the switching unit; the first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded;

[0011] The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

[0012] Fourthly, this application also provides a circuit startup method applied to a transformer circuit, the transformer circuit including a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit, wherein a first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and a second terminal of the resonant circuit is grounded through the switching unit; the first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded, the method comprising:

[0013] The control unit controls the switching unit to switch from a first switching state to a second switching state in order to start the transformer circuit;

[0014] Specifically, when the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor; when the switching unit is in the second switching state, the switching unit is normally open.

[0015] The aforementioned transformer circuit, voltage conversion circuit, electronic equipment, and circuit startup method utilize a switching unit placed between the half-bridge circuit and the resonant circuit. The control unit switches the switching unit from a first switching state to a second switching state to start the transformer circuit. Specifically, when the switching unit is in the first switching state, it is complementary to the first switching transistor in the half-bridge circuit; when the switching transistor is in the second switching state, it is normally open. Therefore, during the transformer circuit startup process, the control unit gradually increases the duration of the simultaneous conducting state of the first switching transistor and the switching unit within the switching cycle from zero. This allows for control of the current flowing to the resonant circuit during startup, effectively suppressing current surges within the resonant circuit and ensuring safe startup of the transformer circuit. Attached Figure Description

[0016] Figure 1 A schematic diagram of an LLC circuit topology provided in related technologies;

[0017] Figure 2 This is a schematic diagram of the structure of a transformer circuit provided in one embodiment of this application;

[0018] Figure 3 This is a schematic diagram of the structure of a transformer circuit provided in another embodiment of this application;

[0019] Figure 4 A schematic diagram of the driving signals provided in the embodiments of this application;

[0020] Figure 5 This is a schematic diagram of the voltage conversion circuit provided in an embodiment of this application. Detailed Implementation

[0021] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0022] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0023] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0024] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” or “having,” etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0025] LLC circuit topology and LLC-DCX circuit (hereinafter referred to as DCX circuit topology) are common voltage conversion topologies in DC-DC circuits. Among them, LLC circuit can output a stable voltage by controlling the frequency change, while the main difference between DCX circuit and LLC circuit is that DCX circuit has a constant frequency during normal operation.

[0026] Figure 1 This is a schematic diagram of the LLC circuit topology provided in related technologies, such as... Figure 1 As shown, the LLC circuit topology may include a half-bridge circuit 1 (or a full-bridge circuit, Figure 1 The example shown is a half-bridge circuit (or a resonant circuit 2). The resonant circuit 2 can include: an independent resonant inductor Ls, a resonant capacitor Cs, and a transformer leakage inductance Lm. It should be noted that the DCX circuit topology can be referenced as follows: Figure 1 The LLC circuit topology shown is advantageous because it enables zero-voltage switching (ZVS) of the switching transistors in either the LLC or DCX circuit topology, thereby improving voltage conversion efficiency.

[0027] Due to limitations in circuit space or cost, LLC and DCX circuit topologies often use the leakage inductance of a transformer as the resonant inductor in the resonant circuit, saving the need for a separate inductor. However, because the leakage inductance of a transformer is limited, it cannot suppress sudden current surges like a separate inductor. Therefore, during the startup process of LLC and DCX circuit topologies, there is a risk of excessive inrush current damaging the switching transistor.

[0028] For example, during the startup process of a DCX circuit topology, the inrush current to the resonant circuit in the DCX circuit topology is not significant because the capacitive load of the DCX circuit topology is relatively small. However, when the switching transistor connected to the voltage input terminal in the half-bridge circuit of the DCX circuit topology is turned on, it will charge the resonant capacitor in the resonant circuit, resulting in a large inrush current.

[0029] The transformer circuit, voltage conversion circuit, electronic device, and circuit startup method provided in this application embodiment start the transformer circuit by setting a switching unit between the half-bridge circuit and the transformer circuit. The control unit controls the switching unit to switch from a first switching state to a second switching state. Specifically, when the switching unit is in the first switching state, it is complementary to the first switching transistor in the half-bridge circuit, meaning the duration for which the switching unit and the first switching transistor are simultaneously in the conducting state during the switching cycle is zero. When the switching transistor is in the second switching state, it is normally open, meaning the duration for which the switching unit and the first switching transistor are simultaneously in the conducting state during the switching cycle is equal to the conduction duration of the first switching transistor. Therefore, during the transformer circuit startup process, the control unit gradually switches the switching unit from the first switching state to the second switching state, gradually increasing the duration for which the first switching transistor and the switching unit are simultaneously in the conducting state during the switching cycle. This allows for control of the current flowing into the transformer circuit during startup, effectively suppressing current surges within the transformer circuit and ensuring safe startup.

[0030] Figure 2 This is a schematic diagram of the transformer circuit provided in one embodiment of this application, as shown below. Figure 2 As shown, the transformer circuit of this application embodiment may include a half-bridge circuit 101, a resonant circuit 102, a switching unit 103, and a control unit 104 connected to the switching unit 103.

[0031] For example, the first end of the resonant circuit 102 is connected between the first switch transistor 101A and the second switch transistor 101B in the half-bridge circuit 101. The first switch transistor 101A is connected to the voltage input terminal of the transformer circuit, and the second switch transistor 101B is grounded. The second end of the resonant circuit 102 can be grounded through the switching unit 103.

[0032] It should be understood that the control unit 104 is also connected to the half-bridge circuit 101. Figure 2 (Not shown in the diagram) to control the on / off state of the first switch 101A and the second switch 101B in the half-bridge circuit 101. Optionally, the switching unit 103 involved in the embodiments of this application can be a controllable switch.

[0033] Optionally, the switching transistors or switching units involved in the embodiments of this application may include, but are not limited to, metal-oxide-semiconductor field-effect transistors (MOS transistors) or switching transistors made of gallium nitride (GaN) material, such as metal-semiconductor field-effect transistors (MESFETs), heterojunction field-effect transistors (HFETs), or modulation-doped field-effect transistors (MODFETs).

[0034] For example, the control unit 104 involved in the embodiments of this application may include, but is not limited to, a controller, wherein the controller may have a driving function. For another example, the control unit 104 involved in the embodiments of this application may include, but is not limited to, a controller and a driver, wherein the controller sends a control signal to the driver, so that the driver outputs a corresponding driving signal to the corresponding switching transistor according to the control signal.

[0035] In this embodiment, the control unit 104 is used to control the switching unit 103 to switch from a first switching state to a second switching state to start the transformer circuit. It should be noted that the transformer circuit startup process may include, but is not limited to, the process of increasing the output voltage of the transformer circuit from zero to a target voltage. This increase typically requires multiple switching cycles of the switching transistor in the transformer circuit, where the switching cycle refers to the sum of the on-time and off-time of the switching transistor within that cycle.

[0036] In one possible implementation, when the switching unit 103 is in the first switching state, the switching unit 103 is synchronously turned on with the second switching transistor 101B in the half-bridge circuit 101, and is complementaryly turned on with the first switching transistor 101A. The complementary turning on of the switching unit 103 and the first switching transistor means that during the switching cycle, when the first switching transistor 101A is in the on state, the switching unit 103 is in the off state, and when the first switching transistor 101A is in the off state, the switching unit 103 is in the on state.

[0037] It should be noted that the first switching transistor 101A is connected to the voltage input terminal of the transformer circuit. When the first switching transistor 101A and the switching unit 103 are both in the conducting state, the front-end circuit of the transformer circuit applies voltage to the transformer circuit through the voltage input terminal, so that the current flows to the resonant circuit 102 of the transformer circuit.

[0038] In another possible implementation, when the switching unit 103 is in the second switching state, the switching unit 103 is normally open, that is, the switching unit 103 is always in the conducting state during the switching cycle. At this time, the duration for which the switching unit 103 and the first switching transistor 101A are simultaneously in the conducting state during the switching cycle is the conducting duration of the first switching transistor 101A.

[0039] It should be understood that when the transformer circuit is first started, the switching unit 103 is in the first switching state, that is, the duration for which the switching unit 103 and the first switching transistor 101A are simultaneously in the conducting state within one switching cycle is zero. Therefore, there is no inrush current in the resonant circuit of the transformer circuit at this time.

[0040] In this embodiment, during the startup of the transformer circuit, the control unit 104 controls the switching unit 103 to gradually switch from the first switching state to the second switching state through multiple switching cycles. That is, the duration during which the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state during the switching cycle gradually increases from zero to the conduction duration of the first switching transistor 101A. This allows control over the current flowing to the resonant circuit during the startup of the transformer circuit, thereby effectively suppressing current surges in the resonant circuit and preventing damage to the switching transistors due to excessive surge current.

[0041] It should be noted that the longer the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state during the switching cycle, the greater the current flowing to the resonant circuit will be. In other words, the shorter the time that the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state during the switching cycle, the smaller the current flowing to the resonant circuit will be.

[0042] For example, suppose the transformer circuit startup process includes 20 switching cycles. Switching unit 103 is in the first switching state from the 1st to the 5th switching cycle, in the third switching state from the 6th to the 10th switching cycle, in the fourth switching state from the 11th to the 15th switching cycle, and in the second switching state from the 16th to the 20th switching cycle. The duration for which switching unit 103 and the first switching transistor 101A are simultaneously in the conducting state during the switching cycle when switching unit 103 is in the third switching state is duration 1. The duration for which switching unit 103 and the first switching transistor 101A are simultaneously in the conducting state during the switching cycle when switching unit 103 is in the fourth switching state is duration 2. Duration 1 is greater than zero and less than duration 2. Duration 2 is less than the conducting duration of the first switching transistor 101A during the switching cycle.

[0043] In summary, the transformer circuit provided in this application starts the transformer circuit by setting a switching unit between the half-bridge circuit and the resonant circuit. The control unit controls the switching unit to switch from a first switching state to a second switching state. Specifically, when the switching unit is in the first switching state, it is complementary to the first switching transistor in the half-bridge circuit; when the switching transistor is in the second switching state, it is normally open. Therefore, during the startup process of the transformer circuit in this application, the control unit gradually switches the switching unit from the first switching state to the second switching state, causing the duration for which the first switching transistor and the switching unit are simultaneously in the conducting state within the switching cycle to gradually increase from zero. This allows for control of the current flowing to the resonant circuit during the transformer circuit startup process, effectively suppressing current surges within the resonant circuit and ensuring the safe startup of the transformer circuit.

[0044] Based on the above embodiments, this application describes a possible way for the control unit 104 to control the switch unit 103 to switch from the first switch state to the second switch state.

[0045] It should be understood that the control unit 104 is also connected to the first switch 101A and the second switch 101B in the half-bridge circuit 101, respectively. Figure 2 (Not shown in the diagram) so that the control unit 104 can output drive signals to control the first switch 101A and the second switch 101B in the half-bridge circuit 101. For example, the control unit 104 can output a second drive signal to the first switch 101A to control the on / off state of the first switch 101A, and a third drive signal to the second switch 101B to control the on / off state of the second switch 101B.

[0046] For example, any driving signal involved in the embodiments of this application may include, but is not limited to, a pulse width modulation (PWM) signal.

[0047] In this embodiment, the control unit 104 is used to control the first driving signal output to the switching unit 103 to increase from a first pulse width to a second pulse width. Specifically, when the first driving signal has the first pulse width, its phase is complementary to the phase of the second driving signal output to the first switching transistor 101A, and has the same phase as the phase of the third driving signal output to the second switching transistor 101B. When the pulse width of the first driving signal of the switching unit 103 is the first pulse width, it corresponds to the aforementioned first switching state; when the pulse width of the first driving signal of the switching unit 103 is the second pulse width, it corresponds to the aforementioned second switching state.

[0048] For example, the first pulse width involved in the embodiments of this application may be less than or equal to 1 / 2 of the pulse period of the first driving signal. It should be understood that the pulse period involved in the embodiments of this application is equal to the aforementioned switching period.

[0049] It should be understood that when the switching unit 103 is in the second switching state, the switching unit 103 is normally open, that is, the switching unit 103 is always in the conducting state during the switching cycle. Therefore, the second pulse width involved in the embodiments of this application can be equal to the pulse period.

[0050] For example, in this embodiment of the application, the control unit 104 can control the first drive signal output to the switching unit 103 to gradually increase from the first pulse width to the second pulse width through multiple switching cycles during the start-up process of the transformer circuit. That is, the duration during which the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state during the switching cycle gradually increases from zero to the conduction duration of the first switching transistor 101A. This is so as to control the magnitude of the current flowing to the resonant circuit during the start-up process of the transformer circuit, thereby effectively suppressing the current surge in the resonant circuit.

[0051] For example, assuming the transformer circuit startup process includes 20 switching cycles, the pulse width of the first drive signal of the switching unit 103 in the 1st to 5th switching cycles is the first pulse width, the pulse width of the first drive signal of the switching unit 103 in the 6th to 10th switching cycles is the third pulse width, the pulse width of the first drive signal of the switching unit 103 in the 11th to 15th switching cycles is the fourth pulse width, and the pulse width of the first drive signal of the switching unit 103 in the 16th to 20th switching cycles is the second pulse width. The pulse width of the second drive signal of the first switch transistor 101A in the above 20 switching cycles can be equal to the first pulse width (complementary to the phase of the first drive signal). The overlapping pulse width between the third pulse width and the second drive signal pulse width is pulse width 1, and the overlapping pulse width between the fourth pulse width and the second drive signal pulse width is pulse width 2. Pulse width 1 is greater than zero and less than pulse width 2, and pulse width 2 is less than the pulse width of the second drive signal.

[0052] In one possible implementation, the control unit 104 can control the first drive signal to randomly increase a first preset pulse width every at least one pulse cycle until it increases to a second pulse width, wherein the first preset pulse width can be any random pulse width.

[0053] In another possible implementation, the control unit 104 can control the first drive signal to increase by a second preset pulse width every first preset pulse period until it reaches the second preset pulse width. The second preset pulse width can be a fixed value, or it can increase incrementally during the transformer circuit startup process. For example, the second preset pulse width can be increased by a third preset pulse width every second preset pulse period, and this third preset pulse width can be a fixed value.

[0054] In this implementation, by controlling the increase of the first pulse width to the second pulse width, the current flowing to the resonant circuit during the start-up process of the transformer circuit can be controlled more precisely, thereby further effectively suppressing the current surge in the resonant circuit.

[0055] Of course, during the start-up process of the transformer circuit, the control unit 104 can also control the first drive signal to increase from the first pulse width to the second pulse width in other ways, and this application embodiment does not limit this.

[0056] In summary, the transformer circuit provided in this application embodiment controls the first driving signal output to the switching unit 103 via the control unit 104 to gradually increase from a first pulse width to a second pulse width. When the first driving signal has the first pulse width, its phase is complementary to the phase of the second driving signal output to the first switching transistor. When the first driving signal has the second pulse width, the switching unit is normally open. This application embodiment allows the duration for which the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state within the pulse period to gradually increase from zero during the transformer circuit startup process. This facilitates control over the current flowing to the resonant circuit during startup, effectively suppressing current surges within the resonant circuit and ensuring safe startup of the transformer circuit.

[0057] In addition, during the start-up process of the transformer circuit in this embodiment, the pulse width of the first drive signal used to control the conduction of the switching unit and the pulse width of the drive signal used to control the conduction of each switch in the half-bridge circuit both have a certain width. It can be seen that the switch involved in this embodiment will conduct for a relatively long time during the pulse cycle. Therefore, there is no need to consider the minimum conduction time requirement of the controller or driver with drive function, so it can be adapted to various controllers or drivers with drive function.

[0058] For ease of understanding, the following embodiments of this application use NMOS transistors as an example to describe the transformer circuit of the embodiments of this application.

[0059] In one embodiment, Figure 3 This is a schematic diagram of a transformer circuit provided in another embodiment of this application. Based on the above embodiments, as follows... Figure 3As shown, the transformer circuit of this application embodiment may include a half-bridge circuit 101, a resonant circuit 102, a switching unit 103, and a control unit 104. Exemplarily, the half-bridge circuit 101 may include a first switching transistor 101A and a second switching transistor 101B, and the switching unit 103 may include a switching transistor; the resonant circuit 102 may include a resonant capacitor C and a resonant inductor L, where the resonant inductor L may be used to represent the leakage inductance of the transformer.

[0060] Of course, the resonant inductance L can also represent the leakage inductance and independent inductance of the transformer, where the inductance of the independent inductance can be relatively small. It should be noted that for transformer circuits that still use independent inductors but with relatively small inductance, the method provided in the embodiments of this application can also effectively suppress current surges within the resonant circuit, which is beneficial for ensuring the safe startup of the transformer circuit.

[0061] For example, the drain of the first switching transistor 101A is connected to the voltage input terminal of the transformer circuit, the source of the first switching transistor 101A and the drain of the second switching transistor 101B are connected to the resonant inductor L, the drain of the switching transistor 103 is connected to the resonant capacitor C, and the sources of the second switching transistor 101B and the switching transistor 103 are grounded. It should be understood that... Figure 3 The positions of the resonant capacitor C and the resonant inductor L in the resonant circuit 102 can be interchanged.

[0062] It should be noted that the gate of the switching transistor 103 can be connected to the control unit 104 to receive the first drive signal sent by the control unit 104; the gate of the first switching transistor 101A can be connected to the control unit 104 to receive the second drive signal sent by the control unit 104; and the gate of the second switching transistor 101B can be connected to the control unit 104 to receive the third drive signal sent by the control unit 104.

[0063] Figure 4 A schematic diagram of the driving signals provided in the embodiments of this application, as shown below. Figure 4 As shown, in the first pulse cycle (or when the transformer circuit just starts), the control unit 104 can control the phase of the first drive signal to be complementary to the phase of the second drive signal and the phase of the third drive signal. The pulse widths of the first drive signal, the second drive signal and the third drive signal can all be the first pulse width, which can be equal to 1 / 2 of the pulse period T (ignoring the switching dead time), that is, the duty cycle of the first drive signal, the second drive signal and the third drive signal is 50%.

[0064] Furthermore, during the initial startup of the transformer circuit, the control unit can control the first drive signal to gradually increase from the first pulse width to the second pulse width. For example: 1) From the second pulse cycle to the i-th pulse cycle, the control unit can control the first drive signal to gradually increase from the first pulse width to the third pulse width, where the duty cycle of the first drive signal can be 60%, and i is an integer greater than 1. 2) From the (i+1)-th pulse cycle to the j-th pulse cycle, the control unit can control the first drive signal to gradually increase from the third pulse width to the fourth pulse width, where the duty cycle of the first drive signal can be 75%, and j is an integer greater than i. 3) From the (j+1)-th pulse cycle to the k-th pulse cycle, the control unit can control the first drive signal to gradually increase from the fourth pulse width to the second pulse width, where the duty cycle of the first drive signal can be 100%, and k is an integer greater than j.

[0065] It should be understood that for any of the above-mentioned switching transistors, when the corresponding drive signal is high, the switching transistor is in the on state; when the corresponding drive signal is low, the switching transistor is in the off state.

[0066] As can be seen, in this embodiment, during the start-up process of the transformer circuit, the control unit 104 controls the first drive signal output to the switching unit 103 to gradually increase from the first pulse width to the second pulse width. This allows the duration during which the first switching transistor 101A and the switching unit 103 are simultaneously in the conducting state within the pulse period to gradually increase from zero. This helps to control the magnitude of the current flowing to the resonant circuit during the start-up process of the transformer circuit, thereby effectively suppressing the current surge in the resonant circuit and ensuring the safe start-up of the transformer circuit.

[0067] In one embodiment, a voltage conversion circuit is provided, which may include the above-mentioned transformer circuit. The transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between the first and second switching transistors in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded.

[0068] The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit and the second switching transistor are synchronously turned on and complementary to each other. When the switching unit is in the second switching state, the switching unit is normally open.

[0069] In one embodiment, the control unit is also connected to the first switching transistor and the second switching transistor respectively;

[0070] The control unit is used to output drive signals to control the first and second switching transistors;

[0071] The control unit is also used to control the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width;

[0072] Specifically, when the first driving signal has a first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switching transistor, and has the same phase as the phase of the third driving signal output to the second switching transistor; when the first driving signal has a second pulse width, the switching unit is normally open.

[0073] In one embodiment, the control unit is configured to: control the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

[0074] In one embodiment, the preset pulse width is a fixed value, or the preset pulse width increases during the start-up of the transformer circuit.

[0075] In one embodiment, the first pulse width is less than or equal to half the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

[0076] The voltage conversion circuit provided in the embodiments of this application may include the transformer circuit provided in the above embodiments of this application. Its implementation principle and technical effect are similar, and will not be described again here.

[0077] In one embodiment, this application describes the possible implementation methods of the preceding and following stages of the transformer circuit in a voltage conversion circuit. Figure 5 This is a schematic diagram of the voltage conversion circuit provided in the embodiments of this application. Optionally, as shown... Figure 5 As shown, the front-end circuit of the transformer circuit may also include a rectifier bridge circuit and a power factor correction (PFC) circuit, and the back-end circuit of the transformer circuit may also include a synchronous rectification circuit and a voltage regulator circuit.

[0078] Of course, the voltage conversion circuit in this application embodiment may also include other circuit units, and this application embodiment does not limit this.

[0079] In one embodiment, an electronic device is provided, which may include the voltage conversion circuit provided in the above embodiments of this application. The voltage conversion circuit may include a transformer circuit, wherein the transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between the first and second switching transistors in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded.

[0080] The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit and the second switching transistor are synchronously turned on and complementary to each other. When the switching unit is in the second switching state, the switching unit is normally open.

[0081] In one embodiment, the control unit is also connected to the first switching transistor and the second switching transistor respectively;

[0082] The control unit is used to output drive signals to control the first and second switching transistors;

[0083] The control unit is also used to control the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width;

[0084] Specifically, when the first driving signal has a first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switching transistor, and has the same phase as the phase of the third driving signal output to the second switching transistor; when the first driving signal has a second pulse width, the switching unit is normally open.

[0085] In one embodiment, the control unit is configured to: control the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

[0086] In one embodiment, the preset pulse width is a fixed value, or the preset pulse width increases during the start-up of the transformer circuit.

[0087] In one embodiment, the first pulse width is less than or equal to half the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

[0088] The electronic device provided in this application embodiment may include the transformer circuit provided in the above embodiment of this application, and its implementation principle and technical effect are similar, so it will not be described again here.

[0089] For example, the electronic devices involved in the embodiments of this application may include, but are not limited to: power adapters, power banks, mobile phones, laptops, tablets, smartwatches, smart bracelets, robot vacuums, wireless headphones, electric toothbrushes, or desktop computers.

[0090] In one embodiment, a circuit startup method is provided for a transformer circuit provided in the above embodiments of this application. The transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. A first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and a second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded. The method includes:

[0091] The control unit controls the switching unit to switch from the first switching state to the second switching state in order to start the transformer circuit;

[0092] Specifically, when the switching unit is in the first switching state, the switching unit and the second switching transistor are synchronously turned on and complementary to each other; when the switching unit is in the second switching state, the switching unit is normally open.

[0093] In one embodiment, the control unit is further connected to the first switching transistor and the second switching transistor respectively, and the method further includes:

[0094] The control unit outputs a drive signal to control the first and second switching transistors;

[0095] Correspondingly, the control unit controls the switch unit to switch from the first switch state to the second switch state, including:

[0096] The control unit controls the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width;

[0097] Specifically, when the first driving signal has a first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switching transistor, and has the same phase as the phase of the third driving signal output to the second switching transistor; when the first driving signal has a second pulse width, the switching unit is normally open.

[0098] In one embodiment, the control unit controls the first drive signal output to the switching unit to increase from a first pulse width to a second pulse width, including:

[0099] The control unit controls the first drive signal to increase the preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

[0100] In one embodiment, the preset pulse width is a fixed value, or the preset pulse width increases during the start-up of the transformer circuit.

[0101] In one embodiment, the first pulse width is less than or equal to half the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

[0102] The circuit startup method provided in this application embodiment can be applied to the transformer circuit provided in the above embodiment of this application. Its implementation principle and technical effect are similar, and will not be described again here.

[0103] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0104] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A transformer circuit, characterized in that, The transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between the first and second switching transistors in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded. The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

2. The transformer circuit according to claim 1, characterized in that, The control unit is also connected to the first switching transistor and the second switching transistor respectively; The control unit is used to output drive signals to control the first switch and the second switch; The control unit is also used to control the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width; Wherein, when the first driving signal is the first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switch, and is the same as the phase of the third driving signal output to the second switch; when the first driving signal is the second pulse width, the switching unit is normally open.

3. The transformer circuit according to claim 2, characterized in that, The control unit is used to: control the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

4. The transformer circuit according to claim 3, characterized in that, The preset pulse width is a fixed value, or the preset pulse width increases during the startup of the transformer circuit.

5. The transformer circuit according to any one of claims 2 to 4, characterized in that, The first pulse width is less than or equal to 1 / 2 of the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

6. A voltage conversion circuit, characterized in that, The voltage conversion circuit includes a transformer circuit, wherein the transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between the first and second switching transistors in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded. The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

7. The voltage conversion circuit according to claim 6, characterized in that, The control unit is also connected to the first switching transistor and the second switching transistor respectively; The control unit is used to output drive signals to control the first switch and the second switch; The control unit is also used to control the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width; Wherein, when the first driving signal is the first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switch, and is the same as the phase of the third driving signal output to the second switch; when the first driving signal is the second pulse width, the switching unit is normally open.

8. The voltage conversion circuit according to claim 7, characterized in that, The control unit is used to: control the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

9. The voltage conversion circuit according to claim 8, characterized in that, The preset pulse width is a fixed value, or the preset pulse width increases during the startup of the transformer circuit.

10. The voltage conversion circuit according to any one of claims 7 to 9, characterized in that, The first pulse width is less than or equal to 1 / 2 of the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

11. An electronic device, characterized in that, The electronic device includes a voltage conversion circuit, which includes a transformer circuit. The transformer circuit includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. The first terminal of the resonant circuit is connected between a first switching transistor and a second switching transistor in the half-bridge circuit, and the second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded. The control unit is used to control the switching unit to switch from a first switching state to a second switching state to start the transformer circuit. When the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor. When the switching unit is in the second switching state, the switching unit is normally open.

12. The electronic device according to claim 11, characterized in that, The control unit is also connected to the first switching transistor and the second switching transistor respectively; The control unit is used to output drive signals to control the first switch and the second switch; The control unit is also used to control the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width; Wherein, when the first driving signal is the first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switch, and is the same as the phase of the third driving signal output to the second switch; when the first driving signal is the second pulse width, the switching unit is normally open.

13. The electronic device according to claim 12, characterized in that, The control unit is used to: control the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

14. The electronic device according to claim 13, characterized in that, The preset pulse width is a fixed value, or the preset pulse width increases during the startup of the transformer circuit.

15. The electronic device according to any one of claims 12 to 14, characterized in that, The first pulse width is less than or equal to 1 / 2 of the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

16. A circuit startup method, characterized in that, The method is applied to a transformer circuit, which includes a half-bridge circuit, a resonant circuit, a switching unit, and a control unit connected to the switching unit. A first terminal of the resonant circuit is connected between a first and a second switching transistor in the half-bridge circuit, and a second terminal of the resonant circuit is grounded through the switching unit. The first switching transistor is connected to the voltage input terminal of the transformer circuit, and the second switching transistor is grounded. The method includes: The control unit controls the switching unit to switch from a first switching state to a second switching state in order to start the transformer circuit; Specifically, when the switching unit is in the first switching state, the switching unit is synchronously turned on with the second switching transistor and is complementary to the first switching transistor; when the switching unit is in the second switching state, the switching unit is normally open.

17. The method according to claim 16, characterized in that, The control unit is also connected to the first switching transistor and the second switching transistor respectively, and the method further includes: The control unit outputs a drive signal to control the first switching transistor and the second switching transistor; Correspondingly, the control unit controls the switch unit to switch from a first switch state to a second switch state, including: The control unit controls the first drive signal output to the switching unit to increase from the first pulse width to the second pulse width; Wherein, when the first driving signal is the first pulse width, the phase of the first driving signal is complementary to the phase of the second driving signal output to the first switch, and is the same as the phase of the third driving signal output to the second switch; when the first driving signal is the second pulse width, the switching unit is normally open.

18. The method according to claim 17, characterized in that, The control unit controls the first drive signal output to the switching unit to increase from a first pulse width to a second pulse width, including: The control unit controls the first drive signal to increase by a preset pulse width every preset pulse period from the first pulse width until it increases to the second pulse width.

19. The method according to claim 18, characterized in that, The preset pulse width is a fixed value, or the preset pulse width increases during the startup of the transformer circuit.

20. The method according to any one of claims 17 to 19, characterized in that, The first pulse width is less than or equal to 1 / 2 of the pulse period of the first driving signal, and the second pulse width is equal to the pulse period.

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