Voltage conversion circuit, chip, electronic device and voltage conversion method

Abstract

The embodiment of the invention provides a voltage conversion circuit, a chip, electronic equipment and a voltage conversion method. The voltage conversion circuit comprises a switch module used for outputting an AC voltage according to an input first DC voltage; the switch module comprises a first switch, a second switch, a third switch and a fourth switch, the first switch and the second switch are connected in series to form a first midpoint, the third switch and the fourth switch are connected in series to form a second midpoint, and the four switches are respectively provided with parasitic capacitors; the conversion module is used for carrying out conversion processing on the AC voltage to obtain a second DC voltage; and the transfer circuit is respectively connected with the first midpoint and the second midpoint, and the transfer circuit is used for realizing electric energy transfer among the four parasitic capacitors when the switch module is in the dead zone period. According to the voltage conversion circuit, the chip, the electronic equipment and the voltage conversion method, zero voltage switching (ZVS) of the switch module can be ensured, and the working efficiency of the voltage conversion circuit is improved.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to a voltage conversion circuit, a chip, an electronic device and a voltage conversion method. Background Art

[0002] LLC resonant converter is based on the traditional LC resonant circuit. By adding excitation inductance to the transformer, the excitation current is increased, which can achieve ZVS (Zero Voltage Switch) and ZCS (Zero Current Switch), and there will be no reverse problem and low switching loss. LLC resonant converter has many advantages and is very suitable for high-frequency and high-power density design. It has been widely used in electronic products.

[0003] At present, in order to ensure that the LLC resonant converter can achieve ZVS, it is usually achieved by adjusting the dead time of the switch and the excitation inductance. For example, the excitation current is increased by increasing the dead time of the switch or reducing the excitation inductance. These methods will lead to a decrease in the working efficiency of the LLC resonant converter. Summary of the invention

[0004] The embodiments of the present application provide a voltage conversion circuit, a chip, an electronic device and a voltage conversion method, which can not only ensure that the switch module achieves zero voltage switching, but also improve the working efficiency of the voltage conversion circuit.

[0005] The embodiment of the present application discloses a voltage conversion circuit, comprising:

[0006] A switch module, configured to output an AC voltage according to an input first DC voltage; the switch module comprises a first switch, a second switch, a third switch and a fourth switch, the first switch and the second switch are connected in series to form a first midpoint, the third switch and the fourth switch are connected in series to form a second midpoint, the first switch comprises a first parasitic capacitor, the second switch comprises a second parasitic capacitor, the third switch comprises a third parasitic capacitor, and the fourth switch comprises a fourth parasitic capacitor;

[0007] A conversion module, used for converting the AC voltage to obtain a second DC voltage;

[0008] A transfer circuit is connected to the first midpoint and the second midpoint respectively, and is used to transfer the electric energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor, or to transfer the electric energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor when the switch module is in a dead zone.

[0009] An embodiment of the present application discloses a chip, comprising the voltage conversion circuit as described above.

[0010] An embodiment of the present application discloses an electronic device, including the voltage conversion circuit as described above, or including the chip as described above.

[0011] The present application discloses a voltage conversion method, including:

[0012] Outputting an AC voltage through a switch module according to an input first DC voltage; the switch module includes a first switch, a second switch, a third switch and a fourth switch, the first switch and the second switch are connected in series to form a first midpoint, the third switch and the fourth switch are connected in series to form a second midpoint, the first switch includes a first parasitic capacitor, the second switch includes a second parasitic capacitor, the third switch includes a third parasitic capacitor, and the fourth switch includes a fourth parasitic capacitor;

[0013] The AC voltage is transformed by a transformation module to obtain a second DC voltage;

[0014] When the switch module is in the dead zone, the electric energy of the first parasitic capacitor and the fourth parasitic capacitor is transferred to the second parasitic capacitor and the third parasitic capacitor, or the electric energy of the second parasitic capacitor and the third parasitic capacitor is transferred to the first parasitic capacitor and the fourth parasitic capacitor through a transfer circuit, and the transfer circuit is connected to the first midpoint and the second midpoint, respectively.

[0015] The voltage conversion circuit, chip, electronic device and voltage conversion method disclosed in the embodiments of the present application, the voltage conversion module includes a switch module, a conversion module and a transfer circuit, the switch module is used to output an AC voltage according to an input first DC voltage, the conversion module is used to convert the AC voltage to obtain a second DC voltage, the switch module includes a first switch, a second switch, a third switch and a fourth switch, the first switch is connected in series with the second switch to form a first midpoint, the third switch is connected in series with the fourth switch to form a second midpoint, the first switch includes a first parasitic capacitor, the second switch includes a second parasitic capacitor, the third switch includes a third parasitic capacitor, the fourth switch includes a fourth parasitic capacitor, and the transfer circuit is respectively connected to the first midpoint and the second midpoint. The transfer circuit is connected at two points, and is used to transfer the electric energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor, or to transfer the electric energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor when the switch module is in a dead zone. The newly added transfer circuit between the first midpoint and the second midpoint helps to realize the electric energy transfer between the four parasitic capacitors during the dead zone, so that the four switches in the switch module can achieve zero voltage switching, and the zero voltage switching demand of the switch module can be separated from the conversion module, thereby reducing the limitation of the switch module to achieve zero voltage switching, which can not only ensure that the switch module achieves zero voltage switching, but also improve the working efficiency of the voltage conversion circuit. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0017] Figure 1 It is a circuit diagram of a full-bridge LLC resonant converter in the related art;

[0018] Figure 2 is a structural block diagram of a voltage conversion circuit in one embodiment;

[0019] Figure 3 is a circuit diagram of a voltage conversion circuit in one embodiment;

[0020] Figure 4A A schematic diagram of an electric energy transmission path in an embodiment;

[0021] Figure 4B A schematic diagram of an electric energy transmission path in another embodiment;

[0022] Figure 4C A schematic diagram of an electric energy transmission path in another embodiment;

[0023] Figure 4D A schematic diagram of an electric energy transmission path in another embodiment;

[0024] Figure 5 is a structural block diagram of a voltage conversion circuit in another embodiment;

[0025] Fig. 6A is an equivalent circuit diagram of a switch module and a transfer circuit in one embodiment;

[0026] Figure 6B is an equivalent circuit diagram of a switch module and a transfer circuit in another embodiment;

[0027] Fig. 7A is a schematic diagram of a current variation waveform of a first inductor in an embodiment;

[0028] Figure 7B is a schematic diagram of a current variation waveform of a first inductor in another embodiment;

[0029] Figure 8 is a structural block diagram of a voltage conversion circuit in another embodiment;

[0030] Fig.9A is a circuit diagram of a voltage conversion circuit in another embodiment;

[0031] Fig. 9B is a circuit diagram of a voltage conversion circuit in another embodiment;

[0032] Fig.10 is a structural block diagram of a voltage conversion circuit in another embodiment;

[0033] Fig.11A is a circuit diagram of a voltage conversion circuit in another embodiment;

[0034] Fig. 11B is a circuit diagram of a voltage conversion circuit in another embodiment;

[0035] Fig.12 is a structural block diagram of a voltage conversion circuit in another embodiment;

[0036] Fig.13 is a circuit diagram of a voltage conversion circuit in another embodiment;

[0037] Fig.14A In one embodiment, Figure 1 Schematic diagram of simulation results of the LLC resonant converter shown;

[0038] Fig. 14B A schematic diagram of simulation results of a voltage conversion circuit in one embodiment;

[0039] Fig.15 A structural block diagram of a chip in an embodiment;

[0040] Fig.16 FIG. 4 is a flow chart of a voltage conversion method in one embodiment. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0042] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present application and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0043] It is understood that the terms "first", "second", etc. used in this application can be used in this article to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from another element. For example, without departing from the scope of this application, the first switch can be called the second switch, and similarly, the second switch can be called the first switch. Both the first switch and the second switch are switches, but they are not the same switch. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the schemes, or any combination of multiple schemes. The term "connection" used in this application should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0044] LLC resonant converter can realize zero voltage turn-on (i.e. ZVS turn-on) of the primary switch tube (i.e. primary switch tube) and ZCS turn-off of the secondary output switch tube (i.e. secondary switch tube), with low switching loss. LLC adopts soft switching technology, which has many advantages and is very suitable for high-frequency and high-power density design. It has been widely used in electronic products. DCX (Direct Current Transformer) is a special case of LLC resonant converter. It is a special working condition of LLC resonant converter working at the system resonant frequency. It has the advantages of extremely high efficiency, extremely low control complexity and cost.

[0045] The LLC resonant converter may include a full-bridge LLC resonant converter. For example, Figure 1 FIG. 1 is a circuit diagram of a full-bridge LLC resonant converter in the related art. Figure 1 As shown, the full-bridge LLC resonant converter may include switch tube Q1, switch tube Q2, switch tube Q3, switch tube Q4, resonant inductor Lr, resonant capacitor Cr, excitation inductor Lm, transformer T, diode D1, diode D2, etc., wherein switch tube Q1 has parasitic capacitance Coss1, switch tube Q2 has parasitic capacitance Coss2, switch tube Q3 has parasitic capacitance Coss3, and switch tube Q4 has parasitic capacitance Coss4. The full-bridge LLC resonant converter can realize zero voltage turn-on of the primary switch tube (switch tube Q1 to switch tube Q4), that is, the voltage across the primary switch tube is 0 when it is turned on, and can also realize ZCS turn-off of the secondary switch tube (diode D1, diode D2), that is, the current of the secondary switch tube is 0 when it is turned off.

[0046] LLC resonant converters usually have gain requirements, so the resonant inductor Lr is required to be relatively large and the resonant capacitor Cr is required to be relatively small. However, since DCX operates at the resonant frequency and the gain is in the state of 1, DCX has no special restrictions on the resonant inductor Lr and the resonant capacitor Cr, and even requires the resonant inductor Lr to be smaller, which is more conducive to the integration of the resonant inductor on the transformer T. When DCX operates at the resonant frequency, the resonant cavity composed of the resonant inductor Lr and the resonant capacitor Cr is in a resonant short-circuit state. At this time, the system efficiency is the highest. High efficiency is one of the biggest advantages of DCX.

[0047] In the related art, in order to ensure that the switch tubes Q1 to Q4 of the full-bridge LLC resonant converter (such as DCX, etc.) achieve zero voltage switching, it is necessary to balance the dead time of the switch tubes Q1 / Q4, the switch tubes Q2 / Q3 and the excitation inductance Lm of the transformer (the excitation inductance Lm will affect the excitation current Im) during system debugging, so that the switch tubes Q1 to Q4 of the full-bridge LLC resonant converter achieve zero voltage switching. When the operating frequency of the full-bridge LLC resonant converter is increased, the corresponding working cycle duration of the full-bridge LLC resonant converter is reduced, so the excitation current Im of the transformer will also decrease. In order to meet the zero voltage switching of the switch tubes Q1 to Q4, it is necessary to increase the dead time, or reduce the excitation inductance Lm, thereby increasing the excitation current Im of the transformer.

[0048] Both of the above methods will lead to a decrease in the working efficiency of the full-bridge LLC resonant converter. For the method of increasing the dead time, when the operating frequency of the full-bridge LLC resonant converter is increased, the working cycle length of the switch tube itself will decrease. If the dead time is further increased, the effective conduction time of the switch tube will be greatly reduced, and the effective value of the resonant current of the full-bridge LLC resonant converter will increase significantly, thereby increasing the loss of the full-bridge LLC resonant converter and reducing the working efficiency of the full-bridge LLC resonant converter. For the method of reducing the excitation inductance Lm, although the dead time can be guaranteed to remain unchanged or even reduced, it will cause the excitation current Im to increase significantly, so the effective value of the resonant current of the full-bridge LLC resonant converter will also increase significantly, and the reactive power of the full-bridge LLC resonant converter will also increase, thereby increasing the loss of the full-bridge LLC resonant converter and reducing the working efficiency of the full-bridge LLC resonant converter. Therefore, the current full-bridge LLC resonant converter is subject to greater restrictions on the increase of the operating frequency.

[0049] In addition, when the full-bridge LLC resonant converter is in a certain working condition, it can achieve a better working state, such as the switch tube of the full-bridge LLC resonant converter just realizes zero voltage switching, the excitation current Im of the converter is also more appropriate, and the working efficiency of the full-bridge LLC resonant converter is higher. However, when the input voltage of the full-bridge LLC resonant converter changes, the full-bridge LLC resonant converter may be in a state where ZVS cannot be achieved or over ZVS, where the over ZVS state means that the full-bridge LLC resonant converter can realize zero voltage switching of the switch tube, but there are additional losses, such as the switch tube is turned on after the voltage at both ends of the switch tube drops to 0 for a period of time, which will bring additional losses. Therefore, the working efficiency of the full-bridge LLC resonant converter is seriously affected, resulting in a narrow voltage range of the input voltage of the full-bridge LLC resonant converter.

[0050] The embodiments of the present application provide a voltage conversion circuit, chip, electronic device and voltage conversion method, which can not only ensure that the switch module achieves zero voltage switching, but also improve the working efficiency of the voltage conversion circuit, and can effectively increase the operating frequency of the voltage conversion circuit and increase the voltage range of the input voltage.

[0051] like Figure 2 As shown, in one embodiment, a voltage conversion circuit 200 is provided, and the voltage conversion circuit 200 may include a switch module 210, a conversion module 220, and a transfer circuit 230. The switch module 210 may be connected to the transfer circuit 230 and the conversion module 220, respectively.

[0052] The switch module 210 is used to output an AC voltage according to an input first DC voltage.

[0053] The conversion module 220 is used to convert the AC voltage to obtain a second DC voltage.

[0054] A DC voltage may refer to a voltage whose direction does not change with time. Optionally, the first DC voltage and the second DC voltage may be a pulsating DC voltage or a constant DC voltage, wherein the pulsating DC voltage may refer to a DC voltage whose voltage magnitude changes with time, and the constant DC voltage may refer to a DC voltage whose voltage magnitude does not change with time (or changes very little).

[0055] AC voltage may refer to a voltage whose direction changes over time. The switch module 210 may invert the input first DC voltage and convert the first DC voltage into an AC voltage. In one working cycle of the switch module 210, a voltage in a positive direction and a voltage in a negative direction may be output. Taking the example that the switch module 210 outputs a positive direction voltage and a negative direction voltage in one working cycle, the switch module 210 may output a positive direction voltage in the first half of the working cycle and may output a negative direction voltage in the second half of the working cycle. It should be noted that the positive direction voltage and the negative direction voltage are only used to illustrate that the switch module 210 outputs a voltage in the opposite direction, and is not used to limit the specific voltage direction.

[0056] In the embodiment of the present application, the switch module 210 may be a full-bridge switch circuit, and the switch module 210 may include a first switch 212, a second switch 214, a third switch 216 and a fourth switch 218, wherein the first switch 212 and the second switch 214 may be connected in series to form a first midpoint SW1, and the third switch 216 and the fourth switch 218 may be connected in series to form a second midpoint SW2.

[0057] It should be noted that the first midpoint SW1 may be any node on the connection circuit between the first switch 212 and the second switch 214, and may be used to connect to other circuits or electronic devices. The second midpoint SW2 may be any node on the connection circuit between the third switch 216 and the fourth switch 218, and may be used to connect to other circuits or electronic devices. The first midpoint SW1 is not necessarily the center point of the connection circuit between the first switch 212 and the second switch 214, and the second midpoint SW2 is not necessarily the center point of the connection circuit between the third switch 216 and the fourth switch 218.

[0058] Further, the first switch 212 and the second switch 214 may form a first bridge arm, the first switch 212 may be an upper switch of the first bridge arm, and the second switch 214 may be a lower switch of the first bridge arm; the third switch 216 and the fourth switch 218 may form a second bridge arm, the third switch 216 may be an upper switch of the second bridge arm, and the fourth switch 218 may be a lower switch of the second bridge arm. The upper switch of the first bridge arm and the upper switch of the second bridge arm may be connected to the input terminal (i.e., Vin terminal), and the lower switch of the first bridge arm and the lower switch of the second bridge arm may be grounded.

[0059] The first switch 212 and the fourth switch 218 can be turned on and off simultaneously as a group of switches, and the second switch 214 and the third switch 216 can be turned on and off simultaneously as another group of switches. The two groups of switches are not turned on at the same time. By switching between the two groups of switches, the output of AC voltage can be achieved.

[0060] Optionally, the first switch 212, the second switch 214, the third switch 216 and the fourth switch 218 may include but are not limited to any one of a MOS tube (Metal-Oxide-Semiconductor Field-Effect Transistor), a GaN (Gallium Nitride) switch, a SiC (Silicon Carbide) switch, etc.

[0061] The first end of the conversion module 220 can be connected to the first midpoint SW1, and the second end of the conversion module 220 can be connected to the second midpoint SW2. The conversion module 220 can transform the AC voltage output by the switch module 210 to obtain a second DC voltage. Further, the conversion module 220 can transform and rectify the AC voltage output by the switch module 210 to obtain a second DC voltage.

[0062] Optionally, when the first switch 212 and the fourth switch 218 are turned on and the second switch 214 and the third switch 216 are turned off, the switch module 210 may output a positive voltage according to the input first DC voltage, and the voltage direction may be from the first end of the conversion module 220 to the second end of the conversion module 220. When the second switch 214 and the third switch 216 are turned on and the first switch 212 and the fourth switch 218 are turned off, the switch module 210 may output a negative voltage according to the input first DC voltage, and the voltage direction may be from the second end of the conversion module 220 to the first end of the conversion module 220, thereby realizing the output of an AC voltage.

[0063] It should be noted that the voltage flowing from the first end of the conversion module 220 to the second end of the conversion module 220 can also be used as a negative direction voltage, and the voltage flowing from the second end of the conversion module 220 to the first end of the conversion module 220 can be used as a positive direction voltage, which is not limited here.

[0064] A working cycle of the switch module 210 may include a dead time period in addition to the stage when the first switch 212 and the fourth switch 218 are turned on and the stage when the second switch 214 and the third switch 216 are turned on. The dead time period may refer to the period when all switches of the switch module 210 are in the off state. The duration corresponding to the dead time period may be called the dead time. In order to avoid the switches on the bridge arm being turned on directly, the dead time may be added in the middle of the switching on of the two groups of switches, so as to avoid the first switch 212 and the second switch 214 being turned on at the same time or the third switch 216 and the fourth switch 218 being turned on at the same time.

[0065] Exemplarily, a working cycle of the switch module 210 may mainly include the following stages:

[0066] Phase 1: the first switch 212 and the fourth switch 218 are turned on, and the second switch 214 and the third switch 216 are turned off;

[0067] Phase 2: the first switch 212 and the fourth switch 218 are disconnected, the second switch 214 and the third switch 216 are disconnected, and the switch module 210 is in a dead zone;

[0068] Stage 3: the first switch 212 and the fourth switch 218 are disconnected, and the second switch 214 and the third switch 216 are connected;

[0069] In stage 4, the first switch 212 and the fourth switch 218 are disconnected, the second switch 214 and the third switch 216 are disconnected, and the switch module 210 is in a dead zone.

[0070] The switch module 210 can cycle through the above-mentioned stages 1 to 4 to work.

[0071] Each switch in the switch module 210 may include a parasitic capacitor, which may be connected in parallel with the switch tube of the switch. In order to achieve zero voltage switching of the switch, it is necessary to ensure that the voltage of the parasitic capacitor of the switch is 0V (volt) when the switch is switched on, that is, the voltage across the switch is 0V. For example, Figure 3 FIG. 1 is a circuit diagram of a voltage conversion circuit in one embodiment. Figure 3 As shown, the switch module 210 includes a first switch Q1, a second switch Q2, a third switch Q3 and a fourth switch Q4, wherein the first switch Q1 includes a first parasitic capacitor Coss1, the second switch Q2 includes a second parasitic capacitor Coss2, the third switch Q3 includes a third parasitic capacitor Coss3, and the fourth switch Q4 includes a fourth parasitic capacitor Coss4, wherein the first parasitic capacitor Coss1 is connected to the switch tube of the first switch Q1, the second parasitic capacitor Coss2 is connected to the switch tube of the second switch Q2, the third parasitic capacitor Coss3 is connected to the switch tube of the third switch Q3, and the fourth parasitic capacitor Coss4 is connected to the switch tube of the fourth switch Q4.

[0072] Optionally, the first switch Q1 , the second switch Q2 , the third switch Q3 and the fourth switch Q4 may be MOS tubes, and the parasitic capacitance of each switch may be connected to the drain (D electrode) and the source (S electrode) of the MOS tube respectively.

[0073] The transfer circuit 230 can be connected to the first midpoint SW1 and the second midpoint SW2 respectively. The transfer circuit 230 is used to transfer the electrical energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, or to transfer the electrical energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 when the switch module 210 is in the dead zone.

[0074] In an embodiment of the present application, a transfer circuit 230 may be added between the first midpoint SW1 of the first bridge arm and the second midpoint SW2 of the second bridge arm. When the switch module 210 is in a dead zone, the transfer circuit 230 may transfer the electrical energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, or transfer the electrical energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4.

[0075] For example, in the next stage when the first switch Q1 and the fourth switch Q4 are turned on (i.e., the current dead zone period is the dead zone period before the first switch Q1 and the fourth switch Q4 are turned on), the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be transferred to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, so that the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 becomes 0V, and the zero-voltage turn-on of the first switch Q1 and the fourth switch Q4 can be achieved.

[0076] For another example, in the next stage when the second switch Q2 and the third switch Q3 are turned on (i.e., the current dead zone period is the dead zone period before the second switch Q2 and the third switch Q3 are turned on), the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be transferred to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4, so that the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 becomes 0V, and the zero voltage turn-on of the second switch Q2 and the third switch Q3 can be achieved.

[0077] In some embodiments, the transfer circuit 230 is also used to transfer the electrical energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 if the voltage of the first midpoint SW1 is less than the voltage of the second midpoint SW2 when the switch module 210 enters the dead zone.

[0078] When the switch module 210 enters the dead zone, since the first switch Q1 is the upper switch tube of the first bridge arm, the first switch Q1 is connected to the input end, the fourth switch Q4 is the lower switch tube of the second bridge arm, and the fourth switch Q4 is grounded, if the voltage of the first midpoint SW1 is less than the voltage of the second midpoint SW2, it means that the voltage difference across the first switch Q1 and the voltage difference across the fourth switch Q4 are large. In order to achieve zero voltage turning on of the first switch Q1 and the fourth switch Q4, the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be transferred to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3.

[0079] The transfer circuit 230 is further used to transfer the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 if the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2 when the switch module 210 enters the dead zone.

[0080] When the switch module 210 enters the dead zone, since the second switch Q2 is the lower switch tube of the first bridge arm, the second switch Q2 is grounded, the third switch Q3 is the upper switch tube of the second bridge arm, and the third switch Q3 is connected to the input end, if the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2, it means that the voltage difference across the second switch Q2 and the voltage difference across the third switch Q3 are large. In order to achieve zero voltage turning on of the second switch Q2 and the third switch Q3, the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be transferred to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4.

[0081] By connecting the transfer circuit 230 between the first midpoint SW1 and the second midpoint SW2 , the transfer circuit 230 can realize power transfer according to the voltage between the first midpoint SW1 and the second midpoint SW2 , thereby realizing the zero voltage switching function of the switch module 210 .

[0082] In some embodiments, in the above-mentioned phase 1, the first switch Q1 and the fourth switch Q4 are turned on, and the second switch Q2 and the third switch Q3 are turned off. Figure 4A As shown, in stage 1, the flow direction of the input first DC voltage (i.e., Vin) may be as shown in path ①: input end-first switch Q1-first end of conversion module 220-second end of conversion module 220-fourth switch Q4-ground end. Since the first switch Q1 and the fourth switch Q4 are turned on, the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 may be 0V, the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 may be equal to the input first DC voltage (i.e., equal to Vin), the voltage of the first midpoint SW1 may be equal to the input first DC voltage (ignoring the voltage drop caused by the switch), and the voltage of the second midpoint SW2 may be equal to 0V.

[0083] In the above-mentioned stage 2, the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 are all turned off, entering the dead zone period. Since the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 is 0V, the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss4 is equal to the first DC voltage, and the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2, the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be discharged. For example, Figure 4BAs shown in the paths ② and ③, the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be transferred to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 through the transfer circuit 230, so as to charge the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4. Thus, the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be reduced to 0V, and the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be increased to the first DC voltage (i.e., equal to Vin). At this time, the voltage of the first midpoint SW1 can be equal to 0V, and the voltage of the second midpoint SW2 can be equal to the first DC voltage, satisfying the condition that the second switch Q2 and the third switch Q4 can achieve zero voltage turn-on.

[0084] In the third stage, the first switch Q1 and the fourth switch Q4 are disconnected, and the second switch Q2 and the third switch Q3 are turned on. Figure 4C As shown, in stage three, the flow direction of the input first DC voltage (i.e., Vin) may be as shown in path ④: input terminal-third switch Q3-second terminal of conversion module 220-first terminal of conversion module 220-second switch Q2-ground terminal. Since the second switch Q2 and the third switch Q3 are turned on, the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 may be 0V, the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 may be equal to the input first DC voltage (i.e., equal to Vin), the voltage of the first midpoint SW1 may be equal to 0V, and the voltage of the second midpoint SW2 may be equal to the first DC voltage.

[0085] In phase 4, the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 are all turned off, entering the dead zone period. Since the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 is 0V, the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 is equal to the first DC voltage, and the voltage of the second midpoint SW2 is greater than the voltage of the first midpoint SW1, the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be discharged. For example, Figure 4DAs shown in the path ⑤ and the path ⑥, the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be transferred to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 through the transfer circuit 230, so as to charge the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3. Thus, the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can be reduced to 0V, and the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be increased to the first DC voltage (i.e., equal to Vin). At this time, the voltage of the second midpoint SW2 can be equal to 0V, and the voltage of the first midpoint SW1 can be equal to the first DC voltage, satisfying the condition that the first switch Q1 and the fourth switch Q4 can achieve zero voltage turn-on.

[0086] Before the above-mentioned stage one and stage three, that is, before turning on the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4, the parasitic capacitors corresponding to the switches to be turned on have completed discharging, and the voltage of the parasitic capacitors has dropped to 0V, that is, the voltage across the switches has dropped to 0V, thereby achieving zero-voltage turning-on of the switches, that is, achieving the soft switching function of the switch module 210.

[0087] Moreover, through the transfer circuit 230, the energy transfer of the parasitic capacitance can be separated from the conversion module 220, and the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 can realize the zero voltage switching function without being restricted by the conversion module 220 (such as not being restricted by the excitation inductance in the conversion module 220), nor by other factors such as dead time, the voltage level of the input first DC voltage, etc. When the operating frequency of the voltage conversion circuit 200 is increased, there is no need to increase the dead time or reduce the excitation inductance to realize the zero voltage opening of the switch module 210, thereby improving the working efficiency of the voltage conversion circuit 200.

[0088] In the embodiment of the present application, by adding a transfer circuit 230 between the first midpoint SW1 and the second midpoint SW2, the electric energy transfer between the four parasitic capacitors (Coss1~Coss4) is helped to be realized during the dead zone, so that the four switches (Q1~Q4) in the switch module 210 can be turned on with zero voltage, and the zero voltage switching requirement of the switch module 210 can be separated from the conversion module 220, thereby reducing the restrictions on the switch module 210 to achieve zero voltage switching, which can not only ensure that the switch module 210 achieves zero voltage switching, but also improve the working efficiency of the voltage conversion circuit.

[0089] In some embodiments, Figure 5 As shown, the transfer circuit 230 may include a first inductor 232 , and the first inductor 232 may be connected to the first midpoint SW1 and the second midpoint SW2 , respectively.

[0090] The first inductor 232 is used to form a resonant circuit with the first parasitic capacitor Coss1 , the second parasitic capacitor Coss2 , the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4 when the switch module 210 is in the dead zone.

[0091] When the switch module 210 is in the dead zone, the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 needs to be transferred to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, or the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 needs to be transferred to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4. During the electric energy transfer process, the first inductor 232 connected in series between the first midpoint SW1 and the second midpoint SW2 can form a resonant circuit with the first parasitic capacitor Coss1, the second parasitic capacitor Coss2, the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4, thereby realizing the transfer of electric energy between the four parasitic capacitors, and avoiding the sudden change of current during the electric energy transfer process, thereby ensuring the stability of the circuit.

[0092] Furthermore, in the above-mentioned stage 2, the electric energy released by the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 can be charged to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 through the first inductor 232. For example, Fig. 6A FIG. 1 is an equivalent circuit diagram of a switch module and a transfer circuit in one embodiment. Fig. 6A As shown, in stage two, when entering the dead zone, the voltage of the first midpoint SW1 is equal to the first DC voltage, the voltage of the second midpoint SW2 is equal to 0V, and the first inductor L1 can form an RLC resonant circuit with the first parasitic capacitor Coss1, the second parasitic capacitor Coss2, the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4 to help transfer the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4, so that the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 drops to 0V (i.e., discharge is completed), and the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 rises to the first DC voltage (i.e., charging is completed).

[0093] In the above-mentioned stage 4, the electric energy released by the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 can charge the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 through the first inductor 232. For example, Figure 6B FIG. 1 is an equivalent circuit diagram of a switch module and a transfer circuit in another embodiment. Figure 6BAs shown, in stage four, when entering the dead zone, the voltage of the second midpoint SW2 is equal to the first DC voltage, the voltage of the first midpoint SW1 is equal to 0V, and the first inductor L1 can form an RLC resonant circuit with the first parasitic capacitor Coss1, the second parasitic capacitor Coss2, the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4 to help transfer the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, so that the voltage of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 drops to 0V (i.e., discharge is completed), and the voltage of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 is boosted to the first DC voltage (i.e., charging is completed).

[0094] It should be noted that the R in the above-mentioned RLC resonant circuit may refer to the first inductor L1 in the circuit, the resistance of each switch, etc.

[0095] In some embodiments, during the process of power transfer, the current of the first inductor 232 may change. The current waveform of the first inductor 232 during the dead time period may include a half-wave waveform of a sine wave.

[0096] It should be noted that the current change waveform of the first inductor 232 during the dead zone is a half-wave waveform of a sine wave, which means that the current change waveform of the first inductor 232 during the dead zone is similar to a half-wave waveform of a sine wave. It does not strictly mean that the current change waveform of the first inductor 232 must be a standard half-wave waveform of a sine wave. The current change waveform may also have a small deformation or burrs.

[0097] Further, when the switch module 210 enters the dead zone, if the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2, the current change waveform of the first inductor during the dead zone includes a positive half-wave waveform of a sine wave. When the switch module 210 enters the dead zone, if the voltage of the first midpoint SW1 is less than the voltage of the second midpoint SW2, the current change waveform of the first inductor 232 during the dead zone includes a negative half-wave waveform of a sine wave.

[0098] In some embodiments, in the above-mentioned stage 2, when entering the dead zone, the voltage of the first midpoint SW1 is equal to the first DC voltage, and the voltage of the second midpoint SW2 is equal to 0V. During the process of electric energy transfer, the voltage of the first midpoint SW1 will continue to decrease until it drops to 0V, and the voltage of the second midpoint SW2 will continue to increase until it rises to the first DC voltage. In the case where the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2, the current of the first inductor 232 may gradually increase; the voltage of the first midpoint SW1 gradually decreases, and the voltage of the second midpoint SW2 gradually increases. Optionally, when the voltage of the first midpoint SW1 is equal to the voltage of the second midpoint SW2, the current of the first inductor 232 may reach a peak value; in the case where the voltage of the first midpoint SW1 is less than the voltage of the second midpoint SW2, the current of the first inductor 232 may gradually decrease until the voltage of the first midpoint SW1 drops to 0V, and the current of the first inductor 232 may also drop to 0A (ampere).

[0099] For example, Fig. 7A FIG. 1 is a schematic diagram of a current variation waveform of a first inductor in an embodiment. Fig. 7A As shown, in stage 2, the current change waveform of the first inductor 232 can be a positive half-wave waveform of a sine wave. The current change of the first inductor 232 during the dead zone is relatively gentle, and the first inductor 232 can prevent the current from changing suddenly during the power transfer process.

[0100] In some embodiments, in the above-mentioned stage 4, when entering the dead zone, the voltage of the second midpoint SW2 is equal to the first DC voltage, and the voltage of the first midpoint SW1 is equal to 0V. During the process of electric energy transfer, the voltage of the second midpoint SW2 will continue to decrease until it drops to 0V, and the voltage of the first midpoint SW1 will continue to increase until it rises to the first DC voltage. In the case where the voltage of the second midpoint SW2 is greater than the voltage of the first midpoint SW1, the current of the first inductor 232 may gradually increase; the voltage of the second midpoint SW2 gradually decreases, and the voltage of the first midpoint SW1 gradually increases. Optionally, when the voltage of the first midpoint SW1 is equal to the voltage of the second midpoint SW2, the current of the first inductor 232 may reach a peak value; in the case where the voltage of the second midpoint SW2 is less than the voltage of the first midpoint SW1, the current of the first inductor 232 may gradually decrease until the voltage of the second midpoint SW2 drops to 0V, and the current of the first inductor 232 may also drop to 0A (ampere).

[0101] For example, Figure 7B FIG. 1 is a schematic diagram of a current variation waveform of the first inductor in another embodiment. Figure 7BAs shown, in stage 4, the current change waveform of the first inductor 232 can be a negative half-wave waveform of a sine wave. The current change of the first inductor 232 during the dead zone is relatively gentle, and the first inductor 232 can prevent the current from changing suddenly during the power transfer process.

[0102] Furthermore, the current variation waveform of the first inductor 232 in the second stage and the current variation waveform in the fourth stage may be symmetrical half-sine wave waveforms.

[0103] It should be noted that the positive and negative values ​​of the current change waveform are only used to illustrate the direction of the current flow and are not used to represent the current magnitude.

[0104] In an embodiment of the present application, the first inductor 232 connected in series between the first midpoint SW1 and the second midpoint SW2 can form a resonant circuit with the first parasitic capacitor Coss1, the second parasitic capacitor Coss2, the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4, thereby realizing the transfer of electrical energy between the four parasitic capacitors and avoiding sudden changes in current during the energy transfer process, thereby ensuring the stability of the circuit.

[0105] In some embodiments, the transfer circuit 230 is also used to be in an on state when the switch module 210 is in a dead zone, so as to transfer the electrical energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, or to transfer the electrical energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4; and to be in an off state when the switch module is not in a dead zone.

[0106] When the switch module 210 is in the dead zone, the transfer circuit 230 can work, the transfer circuit 230 can be turned on, and help to achieve the power transfer between the four parasitic capacitors. When the switch module 210 is not in the dead zone, such as when the first switch 212 and the fourth switch 218 are turned on, or when the transfer circuit 230 of the second switch 214 and the third switch 216 is not working, the transfer circuit 230 can be disconnected, and the voltage conversion processing can be performed by the conversion module 220, so that the transfer circuit 230 can be separated from the conversion module 220, reducing the restriction of the conversion module 220 on the switch module 210 to achieve the zero voltage switching function.

[0107] In some embodiments, Figure 8 As shown, the transfer circuit 230 may include a switch unit 234, which may be connected in series between the first midpoint SW1 and the second midpoint SW2. Further, one end of the switch unit 234 may be connected to the first midpoint SW1, and the other end of the switch unit 234 may be connected to the first inductor 232.

[0108] The switch unit 234 is used to be in the on state when the switch module 210 is in the dead zone, so that the electric energy of the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 is transferred to the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3, or the electric energy of the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 is transferred to the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4; and is used to be in the off state when the switch module 210 is not in the dead zone.

[0109] When the switch module 210 is in the dead zone, the switch unit 234 may be in the on state, thereby conducting the paths between the four parasitic capacitors, so that the electric quantity between the four parasitic capacitors can be transferred through the transfer circuit 230 .

[0110] Further, the first inductor 232 may be connected to the switch unit 234 and the second midpoint SW2 respectively, and the first inductor 232 is used to form a resonant circuit with the first parasitic capacitor Coss1, the second parasitic capacitor Coss2, the third parasitic capacitor Coss3 and the fourth parasitic capacitor Coss4 when the switch unit 234 is in the on state. When the switch module 210 is in the dead zone, the switch unit 234 may be in the on state, thereby conducting the path between the first midpoint SW1 and the first inductor 232, so that the first inductor 232 can form a resonant circuit with the four parasitic capacitors, and realize the energy transfer between the four parasitic capacitors through the first inductor 232.

[0111] When the switch module 210 is not in the dead zone, the switch unit 234 can be in an off state, thereby disconnecting the path between the four parasitic capacitors and the transfer circuit 230, and the voltage input to the switch module 210 can be transmitted to the conversion module 220 for conversion processing, thereby obtaining a second DC voltage.

[0112] Furthermore, when the switch module 210 is not in the dead zone, the switch unit 234 can be in an off state, thereby disconnecting the path between the first midpoint SW1 and the first inductor 232, and no electric energy is transferred between the four parasitic capacitors, and the voltages of the four parasitic capacitors remain unchanged.

[0113] In the embodiment of the present application, the on / off control of the transfer circuit 230 can be realized by the switch unit 234, thereby realizing the controllable transfer of the electric energy of the four parasitic capacitors in the switch module 210, thereby realizing the zero voltage switching function of the switch module 210, and when the switch module 210 is not in the dead zone, the transfer circuit 230 is disconnected, which can reduce unnecessary power consumption loss.

[0114] In some embodiments, the switch unit 234 may include a bidirectional switch, a first end of the bidirectional switch may be connected to the first midpoint SW1 , and a second end of the bidirectional switch may be connected to the first inductor 232 .

[0115] The bidirectional switch is used to be in a first conduction state if the voltage of the first midpoint SW1 is less than the voltage of the second midpoint SW2 when the switch module 210 enters the dead zone, so that the electric energy output by the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4 charges the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3.

[0116] The bidirectional switch is also used to be in the second conduction state if the voltage of the first midpoint SW1 is greater than the voltage of the second midpoint SW2 when the switch module 210 enters the dead zone, so that the electric energy output by the second parasitic capacitor Coss2 and the third parasitic capacitor Coss3 charges the first parasitic capacitor Coss1 and the fourth parasitic capacitor Coss4.

[0117] The bidirectional switch can realize power transmission in two opposite directions. When the bidirectional switch is in the first on state, the power transmission direction can be from the second midpoint SW2 to the first midpoint SW1 via the first inductor 232; when the bidirectional switch is in the second on state, the power transmission direction can be from the first midpoint SW1 to the second midpoint SW2 via the first inductor 232.

[0118] Optionally, the first conduction state and the second conduction state may be the same conduction state or different conduction states.

[0119] In some embodiments, the bidirectional switch may include two MOS transistors connected back to back. Fig.9A As shown, the bidirectional switch may include a first MOS transistor Q5 and a second MOS transistor Q6, wherein the source of the first MOS transistor Q5 may be connected to the source of the second MOS transistor Q6, the drain of the first MOS transistor Q5 may be connected to the first midpoint SW1, and the drain of the second MOS transistor Q6 may be connected to the first inductor L1.

[0120] As another embodiment, Fig. 9B As shown, the bidirectional switch may include a first MOS transistor Q5 and a second MOS transistor Q6, the drain of the first MOS transistor Q5 may be connected to the drain of the second MOS transistor Q6, the source of the first MOS transistor may be connected to the first midpoint SW1, and the source of the second MOS transistor Q6 may be connected to the first inductor L1.

[0121] Optionally, the first conduction state and the second conduction state may be states where both the first MOS transistor Q5 and the second MOS transistor Q6 are turned on. Optionally, the first conduction state may be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned off, and the second abnormal state may be that the first MOS transistor Q5 is turned off and the second MOS transistor Q6 is turned on. Alternatively, the first conduction state may be that the first MOS transistor Q5 is turned off and the second MOS transistor Q6 is turned on, and the second abnormal state may be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned off.

[0122] by Fig.9A For example, when the bidirectional switch is in the first conducting state, the direction of power transmission may be from the second midpoint SW2 to the first midpoint SW1 via the first inductor 232, then the second MOS transistor Q6 may be turned on, the first MOS transistor Q5 may be turned off, and the current is transmitted from the second midpoint SW2 to the first midpoint SW1 via the turned-on second MOS transistor Q6 and the parasitic diode of the first MOS transistor Q5. When the bidirectional switch is in the second conducting state, the direction of power transmission may be from the first midpoint SW1 to the second midpoint SW2 via the first inductor 232, then the first MOS transistor Q5 may be turned on, the second MOS transistor Q6 may be turned off, and the current is transmitted from the first midpoint SW1 to the second midpoint SW2 via the turned-on first MOS transistor Q5 and the parasitic diode of the second MOS transistor Q6.

[0123] by Fig. 9B For example, when the bidirectional switch is in the first conducting state, the direction of power transmission may be from the second midpoint SW2 to the first midpoint SW1 via the first inductor 232, then the first MOS transistor Q5 may be turned on, the second MOS transistor Q6 may be turned off, and the current is transmitted from the second midpoint SW2 to the first midpoint SW1 via the parasitic diode of the second MOS transistor Q6 and the turned-on first MOS transistor Q5. When the bidirectional switch is in the second conducting state, the direction of power transmission may be from the first midpoint SW1 to the second midpoint SW2 via the first inductor 232, then the second MOS transistor Q6 may be turned on, the first MOS transistor Q5 may be turned off, and the current is transmitted from the first midpoint SW1 to the second midpoint SW2 via the parasitic diode of the first MOS transistor Q5 and the turned-on second MOS transistor Q6.

[0124] It should be noted that the bidirectional switch may also adopt other device structures, and is not limited to the first MOS transistor and the second MOS transistor mentioned above.

[0125] In the embodiment of the present application, bidirectional power transmission can be achieved through a bidirectional switch, which can help four parasitic capacitors to transfer power, and when the transfer circuit 230 is not working, it can block the discharge of the parasitic capacitors to ensure circuit safety.

[0126] like Fig.10As shown, in one embodiment, the voltage conversion circuit 200 may further include a control module 240, which may be connected to the switch unit 234. The control module 240 may control the transfer circuit 230 to be turned on when the switch module 210 is in the dead zone, and control the transfer circuit 230 to be turned off when the switch module 210 is not in the dead zone.

[0127] Furthermore, the control module 240 is used to send a first control signal to the switch unit 234 when the switch module 210 is in the dead zone, and the first control signal is used to trigger the switch unit to be in the on state.

[0128] Optionally, the first control signal may be a pulse signal, for example, the first control signal may be a high level signal or a low level signal.

[0129] When the switch module 210 is in the dead zone, the control module 240 may send a first control signal to the switch unit 234 , and the switch unit 234 may be switched to the on state according to the first control signal.

[0130] As an implementation manner, the switch unit 234 may include a bidirectional switch composed of a first MOS transistor Q5 and a second MOS transistor Q6, and the control module 240 may be connected to the first MOS transistor Q5 and the second MOS transistor Q6, respectively. Further, the control module 240 may use one signal to simultaneously control the first MOS transistor Q5 and the second MOS transistor Q6, and the control module 240 may also use two signals to respectively control the first MOS transistor Q5 and the second MOS transistor Q6.

[0131] For example, Fig.11A As shown, the control module 240 can control the first MOS transistor Q5 and the second MOS transistor Q6 simultaneously through a signal G5, and the on-off state of the first MOS transistor Q5 and the second MOS transistor Q6 can be consistent, so the first conduction state and the second conduction state can be the same, which can be a state where both the first MOS transistor Q5 and the second MOS transistor Q6 are turned on. Using a signal to simultaneously control the first MOS transistor Q5 and the second MOS transistor Q6 makes the control method simpler.

[0132] For example, Fig. 11BAs shown, the control module 240 can control the first MOS transistor Q5 and the second MOS transistor Q6 respectively through two signals G6 and G7. Optionally, during the dead zone, the on-off states of the first MOS transistor Q5 and the second MOS transistor Q6 are different. When the first MOS transistor Q5 is turned on, the second MOS transistor Q6 can be turned off. When the second MOS transistor Q6 is turned on, the second MOS transistor Q6 can be turned off. The first on-state and the second on-state can be different. The first on-state can be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned off. The second abnormal state can be that the first MOS transistor Q5 is turned off and the second MOS transistor Q6 is turned on. Alternatively, the first on-state can be that the first MOS transistor Q5 is turned off and the second MOS transistor Q6 is turned on. The second abnormal state can be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned on. The first abnormal state can be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned on. The first abnormal state can be that the first MOS transistor Q5 is turned on and the second MOS transistor Q6 is turned off. The use of two signals to control the first MOS transistor Q5 and the second MOS transistor Q6 respectively can improve the accuracy of control.

[0133] In some embodiments, the control module 240 may also be used to control the on / off state of each switch in the switch module 210. For example, in stage 1, the control module 240 may control the first switch 212 and the fourth switch 218 to be turned on, and the second switch 214 and the third switch 216 to be turned off; in stage 2, the control module 240 may control the four switches to be turned off at the same time; in stage 3, the control module 240 may control the second switch 214 and the third switch 216 to be turned on, and the first switch 212 and the fourth switch 218 to be turned off; in stage 4, the control module 240 may control the four switches to be turned off at the same time.

[0134] For example, Fig.11A or Fig. 11B As shown, the control module 240 can be connected to the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 respectively, and can control the first switch Q1, the second switch Q2, the third switch Q3 and the fourth switch Q4 respectively through four signals G1-G4.

[0135] In the embodiment of the present application, the on-off state of the switch unit 234 can be accurately controlled by the control module 240 to achieve controllable transfer of electrical energy of the four parasitic capacitors in the switch module 210, thereby improving control accuracy and further reducing losses.

[0136] like Fig.12 As shown, in some embodiments, the transformation module 220 may include a resonant network 222 and a voltage transformation unit 224 , and the resonant network 222 may be connected to the first midpoint SW1 , the voltage transformation unit 224 , and the second midpoint SW2 , respectively.

[0137] The resonant network 222 is used to generate resonance and output an AC voltage to the transformer unit together with the switch module.

[0138] The voltage transformation unit 224 is used to transform and rectify the AC voltage to obtain a second DC voltage.

[0139] As an implementation method, Fig.13 As shown, the resonant network 222 may include a resonant inductor Lr, a resonant capacitor Cr, and an excitation inductor Lm, which may constitute a resonant cavity, and may generate resonance when there is voltage and / or current, thereby transferring electric energy to the transformer unit 224. The resonant capacitor Cr may play the role of a DC isolation capacitor and balance the magnetic flux of the transformer in the transformer unit 224.

[0140] As an implementation method, Fig.13 As shown, the transformer unit 224 may include a transformer T and a rectifier circuit 226 , the resonant network 222 may be connected to the first midpoint SW1 , the primary connection of the transformer T and the second midpoint SW2 , and the rectifier circuit 226 may be connected to the secondary side of the transformer.

[0141] Transformer T is used to transform the AC voltage.

[0142] The rectifier circuit 226 can be used to rectify the transformed AC voltage to obtain a second DC voltage.

[0143] Furthermore, if Fig.13 As shown, the rectifier circuit 226 may include a first diode D1 and a second diode D2, etc., and the AC voltage output by the transformer T may be rectified by the first diode D1 and the second diode D2.

[0144] For example, in phase 1, the first switch Q1 and the fourth switch Q4 are turned on, and the transmission path of electric energy (such as current, etc.) can be input end-first switch Q1-resonant inductor Lr-resonant capacitor Cr-excitation inductor Lm-fourth switch Q4-ground; in phase 3, the second switch Q2 and the third switch Q3 are turned on, and the transmission path of electric energy (such as current, etc.) can be input end-third switch Q3-excitation inductor Lm-resonant capacitor Cr-resonant inductor Lr-second switch Q2-ground. The resonant network 222 can generate resonance and transmit AC voltage to the transformer T.

[0145] In the embodiment of the present application, when the switch module 210 is in the dead zone, the energy transfer between the four parasitic capacitors of the switch module 210 does not depend on the resonant network 222, so that the zero voltage switching requirement of the switch module 210 can be separated from the resonant network 222. When the switching frequency of the switch module 210 is increased, it is not necessary to reduce the excitation inductance Lm or increase the dead zone time to ensure that the switch module 210 is turned on at zero voltage.

[0146] Furthermore, in the related art, Figure 1 The minimum condition formula for the primary switch in the LLC resonant converter shown to achieve zero voltage switching can be: Coss*Vin≤Im*Td, where Coss represents the total parasitic capacitance of the primary switch, Vin represents the first input DC voltage, Im represents the excitation current, and Td represents the dead time.

[0147] When the switching frequency of the primary switch is increased, if the power is increased, more switches are required to be connected in parallel or a switch with a smaller on-resistance is used, which will increase the total parasitic capacitance Coss of the primary switch. Based on the above minimum condition formula, in order to achieve zero voltage switching of the primary switch, the zero voltage switching function of the switch module 210 can be achieved by reducing the excitation inductance Lm to increase the excitation current Im, or by increasing the dead time Td. Both methods will reduce the working efficiency of the voltage conversion circuit 200.

[0148] For example, Fig.14A In one embodiment, Figure 1 The schematic diagram of the simulation results of the LLC resonant converter is shown in FIG. Fig.14A As shown, when the simulation parameters are dead time Td = 20ns (nanoseconds), excitation inductance Lm = 4uH (microhenry), excitation current Im = 2.4A, and operating frequency = 1MHz (megahertz), Figure 1 The LLC resonant converter shown is simulated. Assuming that the high-level signal G1 can trigger the first switch Q1 to turn on, the zero voltage switching function of the switch tube cannot be achieved. For example, when the first switch Q1 is turned on, the voltage across the switch Q1 has not dropped to 0V.

[0149] In the embodiment of the present application, by adding a bidirectional switch (such as Q5 and Q6) and a first inductor L1 between the first midpoint SW1 and the second midpoint SW2, the zero voltage switching function of the switch module 210 can be separated from the excitation inductance Lm and the dead time Td, and the zero voltage switching function of the switch module 210 is not limited by the excitation current Im, thereby solving the limitation caused by the increase in the operating frequency of the switch module 210 and improving the working efficiency of the voltage conversion circuit 200. In addition, the zero voltage switching function of the switch module 210 is separated from the input first DC voltage, and the zero voltage switching function of the switch module 210 is no longer related to the input first DC voltage, so that the input voltage range of the voltage conversion circuit 200 is greatly increased, and the application market range of the voltage conversion circuit 200 is further improved.

[0150] For example, Fig. 14B FIG. 1 is a schematic diagram showing the simulation results of a voltage conversion circuit in one embodiment. Fig. 14BAs shown, when the simulation parameters are dead time Td=3ns, excitation inductance Lm=40uH, excitation current Im=0.36A, and operating frequency=1MHz, the zero voltage switching function of the switch module 210 can be realized. When the first switch Q1 is turned on, the voltage drop across the first switch Q1 is 0V or approximately 0V, which can explain the limitations and difficulties encountered in further increasing the operating frequency of the switch module 210. The zero voltage switching function of the switch module 210 no longer depends on the excitation current Im and the dead time Td, thereby improving the working efficiency of the voltage conversion circuit 200.

[0151] It should be noted that Fig. 14B It is only used to illustrate the effect of the voltage conversion circuit 200 provided in the embodiment of the present application, and is not used to limit specific circuit parameters.

[0152] like Fig.15 As shown, in one embodiment, a chip 1500 is provided. The chip 1500 may include the voltage conversion circuit 200 described in any of the above embodiments.

[0153] In one embodiment, an electronic device is provided. The electronic device may include the voltage conversion circuit 200 described in any one of the above embodiments, or may include the chip 1500 in the above embodiments.

[0154] Electronic devices may include but are not limited to adapters, mobile power supplies, mobile phones, wearable devices (such as smart glasses, smart watches, etc.), tablets, vehicle-mounted terminals, laptops, PCs (Personal Computers), smart speakers, etc.

[0155] like Fig.16 As shown, in one embodiment, a voltage conversion method is provided, which can be applied to any one of the voltage conversion circuit 200, chip 1500 and electronic device in the above embodiments; the method may include the following steps:

[0156] Step 1610, the switch module outputs an AC voltage according to the input first DC voltage, and the switch module includes a first switch, a second switch, a third switch and a fourth switch, the first switch is connected in series with the second switch to form a first midpoint, the third switch is connected in series with the fourth switch to form a second midpoint, the first switch includes a first parasitic capacitor, the second switch includes a second parasitic capacitor, the third switch includes a third parasitic capacitor, and the fourth switch includes a fourth parasitic capacitor.

[0157] Step 1620: transform the AC voltage through a transformation module to obtain a second DC voltage.

[0158] Step 1630, when the switch module is in the dead zone, the electric energy of the first parasitic capacitor and the fourth parasitic capacitor is transferred to the second parasitic capacitor and the third parasitic capacitor through the transfer circuit, or the electric energy of the second parasitic capacitor and the third parasitic capacitor is transferred to the first parasitic capacitor and the fourth parasitic capacitor, and the transfer circuit is connected to the first midpoint and the second midpoint respectively.

[0159] In some embodiments, step 1630 may include: if the voltage of the first midpoint is less than the voltage of the second midpoint when the switch module enters the dead zone, the electric energy of the first parasitic capacitor and the fourth parasitic capacitor is transferred to the second parasitic capacitor and the third parasitic capacitor through the transfer circuit; if the voltage of the first midpoint is greater than the voltage of the second midpoint when the switch module enters the dead zone, the electric energy of the second parasitic capacitor and the third parasitic capacitor is transferred to the first parasitic capacitor and the fourth parasitic capacitor through the transfer circuit.

[0160] In some embodiments, the transfer circuit may include a first inductor, and step 1630 may include: when the switch module is in a dead zone, a resonant circuit is formed by the first inductor and the first parasitic capacitor, the second parasitic capacitor, the third parasitic capacitor and the fourth parasitic capacitor to transfer the electrical energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor, or to transfer the electrical energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor.

[0161] In some embodiments, the method further includes: when the switch module is in a dead zone, controlling the transfer circuit to be turned on; when the switch module is not in the dead zone, controlling the transfer circuit to be turned off.

[0162] In some embodiments, the transfer circuit includes a switch unit, and the step of controlling the transfer circuit to be turned on when the switch module is in a dead zone includes: when the switch module is in the dead zone, sending a first control signal to the switch unit, and the first control signal is used to trigger the switch unit to be in a conducting state.

[0163] In some embodiments, the conversion module includes a resonant network and a transformer unit, and the method also includes: generating resonance through the resonant network, and outputting an AC voltage to the transformer unit together with the switch module; step 1620 includes: transforming and rectifying the AC voltage through the transformer unit to obtain a second DC voltage.

[0164] It should be noted that the description of the voltage conversion method provided in the embodiment of the present application can refer to the relevant description of the voltage conversion circuit 200 provided in the above embodiments, and will not be repeated here.

[0165] In an embodiment of the present application, a new transfer circuit is added between the first midpoint and the second midpoint to help realize the energy transfer between the four parasitic capacitors during the dead zone, so that the four switches in the switch module can be turned on at zero voltage, and the zero voltage switching requirement of the switch module can be separated from the conversion module, thereby reducing the restrictions on the switch module to achieve zero voltage switching, which can not only ensure that the switch module achieves zero voltage switching (i.e., ZVS), but also improve the working efficiency of the voltage conversion circuit.

[0166] An embodiment of the present application discloses an electronic device, including a memory and a power amplifier circuit. The power amplifier circuit includes a processor. A computer program is stored in the memory. When the computer program is executed by the processor, the power amplifier circuit implements the methods described in the above embodiments.

[0167] An embodiment of the present application discloses a computer-readable storage medium storing a computer program, wherein the computer program implements the methods described in the above embodiments when executed by a processor.

[0168] The embodiments of the present application disclose a computer program product, including a computer program, and the computer program can be executed by a processor to implement the methods described in the above embodiments.

[0169] It should be understood that the "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. Those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required for the present application.

[0170] In the various embodiments of the present application, it should be understood that the size of the serial numbers of the above-mentioned processes does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0171] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0172] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0173] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0174] The above is a detailed introduction to a voltage conversion circuit, chip, electronic device and voltage conversion method disclosed in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and core idea of ​​the present application. At the same time, for those of ordinary skill in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A voltage conversion circuit, characterized in that: include: A switch module, configured to output an AC voltage according to an input first DC voltage; the switch module comprises a first switch, a second switch, a third switch and a fourth switch, the first switch and the second switch are connected in series to form a first midpoint, the third switch and the fourth switch are connected in series to form a second midpoint, the first switch comprises a first parasitic capacitor, the second switch comprises a second parasitic capacitor, the third switch comprises a third parasitic capacitor, and the fourth switch comprises a fourth parasitic capacitor; A conversion module, used for converting the AC voltage to obtain a second DC voltage; A transfer circuit is connected to the first midpoint and the second midpoint respectively, and is used to transfer the electric energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor, or to transfer the electric energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor when the switch module is in a dead zone.

2. The voltage conversion circuit according to claim 1, characterized in that: The transfer circuit is further configured to transfer the electric energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor if the voltage of the first midpoint is less than the voltage of the second midpoint when the switch module enters the dead zone; The transfer circuit is further used to transfer the electrical energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor if the voltage of the first midpoint is greater than the voltage of the second midpoint when the switch module enters the dead zone.

3. The voltage conversion circuit according to claim 1, characterized in that: The transfer circuit comprises: The first inductor is used to form a resonant circuit with the first parasitic capacitor, the second parasitic capacitor, the third parasitic capacitor and the fourth parasitic capacitor when the switch module is in a dead zone.

4. The voltage conversion circuit according to claim 3, characterized in that: The current variation waveform of the first inductor during the dead zone includes a half-wave waveform of a sine wave.

5. The voltage conversion circuit according to claim 4, characterized in that: When the switch module enters the dead zone, if the voltage of the first midpoint is less than the voltage of the second midpoint, the current change waveform of the first inductor during the dead zone includes a negative half-wave waveform of a sine wave; When the switch module enters the dead zone, if the voltage of the first midpoint is greater than the voltage of the second midpoint, the current variation waveform of the first inductor during the dead zone includes a positive half-wave waveform of a sine wave.

6. The voltage conversion circuit according to any one of claims 1 to 5, characterized in that: The transfer circuit is further configured to be in a conducting state when the switch module is in a dead zone, so as to transfer the electric energy of the first parasitic capacitor and the fourth parasitic capacitor to the second parasitic capacitor and the third parasitic capacitor, or to transfer the electric energy of the second parasitic capacitor and the third parasitic capacitor to the first parasitic capacitor and the fourth parasitic capacitor; And used for being in an off state when the switch module is not in the dead zone.

7. The voltage conversion circuit according to claim 6, characterized in that: The transfer circuit comprises: The switch unit is used to be in an on state when the switch module is in a dead zone, so that the electric energy of the first parasitic capacitor and the fourth parasitic capacitor is transferred to the second parasitic capacitor and the third parasitic capacitor, or the electric energy of the second parasitic capacitor and the third parasitic capacitor is transferred to the first parasitic capacitor and the fourth parasitic capacitor; and is used to be in an off state when the switch module is not in the dead zone.

8. The voltage conversion circuit according to claim 7, characterized in that: The switch unit includes a bidirectional switch; The bidirectional switch is configured to be in a first on state if the voltage of the first midpoint is less than the voltage of the second midpoint when the switch module enters the dead zone, so that the electric energy output by the first parasitic capacitor and the fourth parasitic capacitor charges the second parasitic capacitor and the third parasitic capacitor; The bidirectional switch is also used to be in a second conduction state if the voltage of the first midpoint is greater than the voltage of the second midpoint when the switch module enters the dead zone, so that the electric energy output by the second parasitic capacitor and the third parasitic capacitor charges the first parasitic capacitor and the fourth parasitic capacitor.

9. The voltage conversion circuit according to claim 8, characterized in that: The bidirectional switch includes a first MOS tube and a second MOS tube, the source of the first MOS tube is connected to the source of the second MOS tube, or the drain of the first MOS tube is connected to the drain of the second MOS tube.

10. The voltage conversion circuit according to any one of claims 7 to 9, characterized in that: The transfer circuit further includes: The first inductor is connected to the switch unit and the second midpoint respectively, and the first inductor is used to form a resonant circuit with the first parasitic capacitor, the second parasitic capacitor, the third parasitic capacitor and the fourth parasitic capacitor when the switch unit is in an on state.

11. The voltage conversion circuit according to any one of claims 7 to 9, characterized in that: The voltage conversion circuit also includes: The control module is used to send a first control signal to the switch unit when the switch module is in a dead zone, wherein the first control signal is used to trigger the switch unit to be in a conducting state.

12. The voltage conversion circuit according to claim 1, characterized in that: The conversion module includes a resonant network and a transformer unit, and the resonant network is connected to the first midpoint, the transformer unit and the second midpoint respectively; The resonant network is used to generate resonance and output an AC voltage to the transformer unit together with the switch module; The transformer unit is used to transform and rectify the AC voltage to obtain a second DC voltage.

13. The voltage conversion circuit according to claim 12, characterized in that: The transformer unit includes a transformer and a rectifier circuit, the resonant network is connected to the first midpoint, the primary side of the transformer and the second midpoint, and the rectifier circuit is connected to the secondary side of the transformer; The transformer is used to transform the AC voltage; The rectifier circuit is used to rectify the transformed AC voltage to obtain a second DC voltage.

14. A chip, characterized in that: It comprises the voltage conversion circuit as claimed in any one of claims 1 to 13.

15. An electronic device, characterized in that: It comprises the voltage conversion circuit as claimed in any one of claims 1 to 13, or comprises the chip as claimed in claim 14.

16. A voltage conversion method, characterized in that: include: Outputting an AC voltage through a switch module according to an input first DC voltage; the switch module includes a first switch, a second switch, a third switch and a fourth switch, the first switch and the second switch are connected in series to form a first midpoint, the third switch and the fourth switch are connected in series to form a second midpoint, the first switch includes a first parasitic capacitor, the second switch includes a second parasitic capacitor, the third switch includes a third parasitic capacitor, and the fourth switch includes a fourth parasitic capacitor; The AC voltage is transformed by a transformation module to obtain a second DC voltage; When the switch module is in the dead zone, the electric energy of the first parasitic capacitor and the fourth parasitic capacitor is transferred to the second parasitic capacitor and the third parasitic capacitor, or the electric energy of the second parasitic capacitor and the third parasitic capacitor is transferred to the first parasitic capacitor and the fourth parasitic capacitor through a transfer circuit, and the transfer circuit is connected to the first midpoint and the second midpoint, respectively.

17. The method according to claim 16, characterized in that The method further comprises: When the switch module is in a dead zone, controlling the transfer circuit to be turned on; When the switch module is not in the dead zone, the transfer circuit is controlled to be disconnected.

18. The method according to claim 17, characterized in that The transfer circuit includes a switch unit, and when the switch module is in a dead zone, controlling the transfer circuit to be turned on includes: When the switch module is in the dead zone, a first control signal is sent to the switch unit, where the first control signal is used to trigger the switch unit to be in a conducting state.

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