Flyback-based inverter circuit and control method thereof, switching power supply and photovoltaic system
By dividing the secondary winding of the flyback converter into two groups and controlling the corresponding switch tube group, the problems of flyback converter inverter circuit loss and heat dissipation in the prior art are solved, and more efficient energy output and lower loss are achieved.
Patent Information
- Application Number
- CN202411659454.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-19
- Publication Date
- 2025-02-25
AI Technical Summary
When the inverter circuit of existing flyback converters reduces losses, it fails to effectively deal with diode rectification and thyristor rectification circuits, resulting in machine losses and heat dissipation problems.
By dividing the secondary windings of the transformer into two groups, each group is controlled by the corresponding switch tube group, which is cut off during the transformer energy storage stage. During the transformer energy release stage, the two secondary windings work in the positive half cycle and the negative half cycle respectively, and output AC power.
It reduces the use of power devices such as SBD in traditional inverter circuits, reduces the loss and temperature rise of the entire machine, and improves the efficiency of the inverter.
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Figure CN119519440A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of electronic technology, and in particular to a Flyback inverter circuit and a control method thereof, a switching power supply and a photovoltaic system. Background Art
[0002] Flyback Converter, also known as flyback converter or flyback converter, is a power electronic converter that controls the energy storage and release of the transformer through a switch tube. When the switch tube connected to the primary winding is turned on, the transformer stores energy; when the switch tube connected to the primary winding is turned off, the transformer releases energy to the load. Since the transformer has the characteristic of reverse current when releasing energy, it is called flyback.
[0003] The inverter circuit of the existing flyback converter often adopts a quasi-resonant control method to reduce losses, but the subsequent diode rectification and the rectification circuit composed of thyristors are not processed, which easily causes losses to the whole machine and also brings challenges to the heat dissipation of the whole machine. Summary of the invention
[0004] In view of this, the present application provides a Flyback inverter circuit and its control method, a switching power supply and a photovoltaic system, aiming to reduce the overall machine loss and heat dissipation through settings.
[0005] In a first aspect, the present application provides a Flyback inverter circuit, comprising a transformer, a first switch tube group and a second switch tube group, wherein the secondary winding of the transformer comprises a first secondary winding and a second secondary winding;
[0006] The second end of the first secondary winding and the first end of the second secondary winding are connected to the first node, the first end of the first secondary winding is connected to the first end of the first switch tube group, the second end of the second secondary winding is connected to the first end of the second switch tube group, the second end of the first switch tube group and the second end of the second switch tube group are connected to the second node, and the first end of the first secondary winding and the first end of the second secondary winding are the same end;
[0007] The first switch tube group and the second switch tube group are turned off in the transformer energy storage stage, and in the transformer energy release stage, the corresponding secondary windings are controlled to work in the positive half cycle and the negative half cycle respectively to output alternating current.
[0008] Optionally, the first switch tube group includes a switch tube 1 and a switch tube 2, and the second switch tube group includes a switch tube 3 and a switch tube 4;
[0009] Switch tube 2 and switch tube 4 are turned off during the transformer energy storage stage and turned on during the transformer energy release stage;
[0010] The switch tube 1 and the switch tube 3 are alternately turned on during the energy release stage of the transformer, so that AC power is output between the first node and the second node.
[0011] Optionally, switch tube 2 is a common source MOSFET, and when its body diode is turned on and the voltage across the switch tube 2 drops to the forward voltage drop Vf value of the body diode, the drive end of switch tube 2 is at a high level; when the current of switch tube 2 drops to a first preset value, the drive end of switch tube 2 is at a low level.
[0012] Optionally, switch tube four is a common source MOSFET. When the body diode of switch tube four is turned on and the voltage across the two ends of switch tube four drops to the forward voltage drop Vf value of its body diode, the driving end of switch tube four is at a high level; when the current of switch tube four drops to a second preset value, the driving end of switch tube two is at a low level.
[0013] Optionally, the switch tube 2 is a diode, and / or the switch tube 4 is a diode.
[0014] Optionally, the switch tube one and the switch tube three are MOSFETs of a common source stage.
[0015] Optionally, the first node and the second node are further connected to a filtering module.
[0016] Optionally, the filtering module includes a capacitor, a first inductor and a second inductor, the first node is connected to the first end of the capacitor, the second node is connected to the second end of the capacitor, the first end of the capacitor is connected to the first end of the first inductor, the second end of the capacitor is connected to the first end of the second inductor, and the second end of the first inductor and the second end of the second inductor are output ends.
[0017] In a second aspect, the present application further provides a control method based on a Flyback inverter circuit, which is applied to a Flyback inverter circuit described in any one of the above, and the method includes:
[0018] During the transformer energy storage stage, the first switch tube group and the second switch tube group are both turned off;
[0019] During the energy release stage of the transformer, the first switch tube group and the second switch tube group are controlled to be turned on alternately, so that the first secondary winding and the second secondary winding work alternately to form alternating current.
[0020] Optionally, the switch tube 1 included in the first switch tube group and the switch tube 3 included in the second switch tube group are both common-source MOSFETs, and controlling the first switch tube group and the second switch tube group to be alternately turned on includes:
[0021] In the transformer energy release stage, driving signals are sent alternately to the driving end of the switch tube 1 and the driving end of the switch tube 2, so that the first switch tube group and the second switch tube group are alternately turned on.
[0022] Optionally, the switch tube 2 included in the first switch tube group is a common-source MOSFET, and the controlling the first switch tube group and the second switch tube group to be alternately turned on includes:
[0023] When the body diode of the switch tube 2 is turned on and the voltage across the two ends of the switch tube 2 drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube 2; when the current of the switch tube 2 drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube 2.
[0024] Optionally, the switch tube 4 included in the second switch tube group is a common-source MOSFET, and the controlling the first switch tube group and the second switch tube group to be alternately turned on includes:
[0025] When the body diode of the switch tube four is turned on and the voltage across the two ends of the switch tube four drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube four; when the current of the switch tube four drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube four.
[0026] In a third aspect, the present application provides a switching power supply, comprising a Flyback inverter circuit as described in any one of the above.
[0027] In a fourth aspect, the present application provides a photovoltaic system, comprising a Flyback inverter circuit as described in any one of the above.
[0028] The present application provides a Flyback inverter circuit and its control method, a switching power supply and a photovoltaic system, including a transformer, a first switch tube group and a second switch tube group, wherein the secondary winding of the transformer includes a first secondary winding and a second secondary winding; the second end of the first secondary winding and the first end of the second secondary winding are connected to a first node, the first end of the first secondary winding is connected to the first end of the first switch tube group, the second end of the second secondary winding is connected to the first end of the second switch tube group, the second end of the first switch tube group is connected to the second node, and the first end of the first secondary winding and the first end of the second secondary winding are the same-named ends. The secondary winding of the flyback converter is divided into two groups, and each secondary winding is controlled by a corresponding switch tube group to achieve cutoff in the energy storage stage of the transformer, and the two secondary windings work in the positive half cycle and the negative half cycle respectively in the energy release stage of the transformer to output AC power. In this way, the two secondary windings are controlled to output alternately by the first switch tube group and the second switch tube group, thereby reducing power devices, reducing losses, and improving the temperature rise of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] In order to more clearly illustrate the technical solutions in this embodiment or the prior art, the drawings required for use in the embodiments or the description of the prior art 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 paying creative work.
[0030] Figure 1 A schematic diagram of an inverter circuit of a flyback converter provided in an embodiment of the present application;
[0031] Figure 2 A schematic diagram of a circuit structure based on a Flyback inverter circuit provided in an embodiment of the present application;
[0032] Figure 3 A schematic diagram of another circuit structure based on a Flyback inverter circuit provided in an embodiment of the present application;
[0033] Figure 4 A schematic diagram of controlling driving signals of a switch tube 1 and a switch tube 3 provided in an embodiment of the present application;
[0034] Figure 5 A schematic diagram of a circuit structure based on a Flyback inverter circuit provided in an embodiment of the present application;
[0035] Figure 6 A schematic diagram of driving signal control for a first switch tube group and a second switch tube group based on a mains frequency provided in an embodiment of the present application;
[0036] Figure 7 A control schematic diagram of a switch tube 2 using a MOSFET tube provided in an embodiment of the present application;
[0037] Figure 8 A flow chart of a control method based on a Flyback inverter circuit provided in an embodiment of the present application. DETAILED DESCRIPTION
[0038] The inverter circuit of the existing flyback converter often adopts quasi-resonant control to reduce losses, but the subsequent diode rectification and the rectification circuit composed of thyristors are not processed, which easily causes losses to the whole machine and also brings challenges to the heat dissipation of the whole machine. For details, see Figure 1 The inverter circuit diagram of a flyback converter shown in the figure, the output part uses a Schottky barrier diode SBD as a rectifier diode, which has a large loss in the rectifier stage of the flyback converter. The rectifier part uses a bridge circuit composed of a thyristor and a MOS tube, and the thyristor has a large forward conduction voltage drop and a large thyristor loss.
[0039] Based on the above problems, the present application provides a Flyback inverter circuit and its control method, a switching power supply and a photovoltaic system, including a transformer, a first switch tube group and a second switch tube group, the secondary winding of the transformer includes a first secondary winding and a second secondary winding; the second end of the first secondary winding and the first end of the second secondary winding are connected to a first node, the first end of the first secondary winding is connected to the first end of the first switch tube group, the second end of the second secondary winding is connected to the first end of the second switch tube group, the second end of the first switch tube group and the second end of the second switch tube group are connected to a second node, and the first end of the first secondary winding and the first end of the second secondary winding are the same-named ends. The secondary winding of the flyback converter is divided into two groups, and each secondary winding is controlled by a corresponding switch tube group to achieve cutoff in the energy storage stage of the transformer. In the energy release stage of the transformer, the two secondary windings respectively work in the positive half cycle and the negative half cycle to output alternating current. In this way, the two secondary windings are controlled to output alternately by the first switch tube group and the second switch tube group, thereby reducing Figure 1 The SBD and other power devices in the inverter circuit of the traditional flyback converter reduce the loss and improve the temperature rise of the whole machine.
[0040] In order to be able to understand the features and technical contents of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The attached drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.
[0041] The terms "first", "second", etc. in the specification and claims of the embodiments of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way can be interchanged where appropriate, so that the embodiments of the embodiments of the present disclosure described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions.
[0042] Unless otherwise stated, the term "plurality" means two or more.
[0043] In the embodiment of the present disclosure, the character " / " indicates that the preceding and following objects are in an "or" relationship. For example, A / B indicates: A or B.
[0044] The term "and / or" is a description of the association relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or, A and B.
[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings 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.
[0046] See also Figure 2 , Figure 2 A schematic diagram of a circuit structure based on a Flyback inverter circuit provided in an embodiment of the present application, a Flyback inverter circuit based on the present application, including:
[0047] A transformer, a first switch tube group and a second switch tube group, wherein the secondary winding of the transformer comprises a first secondary winding and a second secondary winding;
[0048] The second end of the first secondary winding and the first end of the second secondary winding are connected to the first node, the first end of the first secondary winding is connected to the first end of the first switch tube group, the second end of the second secondary winding is connected to the first end of the second switch tube group, the second end of the first switch tube group and the second end of the second switch tube group are connected to the second node, and the first end of the first secondary winding and the first end of the second secondary winding are the same end;
[0049] The first switch tube group and the second switch tube group are turned off in the transformer energy storage stage, and in the transformer energy release stage, the corresponding secondary windings are controlled to work in the positive half cycle and the negative half cycle respectively to output alternating current.
[0050] The secondary windings in the above transformer are divided into two groups, namely the first secondary winding and the second secondary winding, and adopt a double high-voltage winding structure. Figure 2 The primary winding of the converter can use a traditional flyback converter circuit, and the secondary winding uses a transformer structure with a center tap. The number of turns of the primary winding of the transformer is Np, and the inductance is Lp. The number of turns of the two secondary windings is Ns, and the inductance of the secondary winding is Ls. It is divided into two secondary windings, namely the first secondary winding Ls1 and the second secondary winding Ls2.
[0051] Each secondary winding is rectified by a high-voltage switch tube group. During the transformer energy release stage, the two switch tube groups control the two secondary windings to alternately work in the positive half-cycle and the negative half-cycle of the power frequency. Figure 2 The AC terminal shown outputs alternating current. In this way, the reduction of Figure 1 The SBD and other power devices shown can reduce losses, reduce temperature rise and improve the efficiency of the inverter.
[0052] Based on the above embodiment, the first switch tube group may include a switch tube 1 and a switch tube 2, and the second switch tube group may include a switch tube 3 and a switch tube 4;
[0053] Among them, switch tube 2 and switch tube 4 are cut off in the energy storage stage of the transformer and turned on in the energy release stage of the transformer; switch tube 1 and switch tube 3 are alternately turned on in the energy release stage of the transformer, controlling the first secondary winding and the second secondary winding to alternately output between the first node and the second node to form alternating current.
[0054] The switch tube 1 and the switch tube 3 mentioned above can select common-source MOSFETs, such as silicon carbide MOSFETs, gallium nitride MOSFETs or ordinary high-voltage MOSFETs.
[0055] There are also many possible implementations for selecting the switch tube 2 and the switch tube 4, and specific examples are as follows:
[0056] In one possible implementation, see Figure 3 Another circuit structure diagram based on the Flyback inverter circuit is shown in FIG. 1 , where the switch tube 2 and the switch tube 4 can be diodes, such as Figure 3 , the second switch is a diode D 11 , switch tube 4 is diode D 21 .
[0057] Switch tube Q 11 With switch tube 2 (diode D 11 ) are combined to form a first switch tube group, switch tube Q 11 The source of the first switch tube group is connected to the first end of the first secondary winding, and the switch tube Q 11 The drain of the diode D 11 The positive pole of diode D 11 The negative electrode of is the second end of the first switch tube group, connected to the second node.
[0058] Switching tube three Q 21 With switch tube 4 (diode D 21 ) are combined to form the second switch tube group, and the diode D 21 The cathode of the diode D is the first end of the second switch tube group, connected to the second end of the second secondary winding. 21 The positive pole of the switch tube 3Q 21 The drain of the switch tube is Q 21 The source is the second end of the second switch tube group, connected to the second node.
[0059] During the transformer energy storage stage, the diode D 11 and diode D 21 Cut-off, during the transformer energy release stage, diode D 11and diode D 21 Conductivity.
[0060] Among them, the switch tube Q 11 The gate and switch tube three Q 21 The gate is the driving end, and the switching tube Q is alternately supplied to the switching tube during the transformer energy release phase. 11 And the switch tube three Q 21 A high level is input to the driving end to realize output of alternating current between the first node and the second node.
[0061] For example, in the transformer energy release stage, the switch tube Q is alternately 11 And the switch tube three Q 21 The frequency of the high level input to the driver end can correspond to the mains frequency, for example, see Figure 4 The control schematic diagram of the driving signal of the switch tube 1 and the switch tube 3 is shown in FIG. 11 The gate inputs a high-level drive signal. In the negative half cycle of the mains frequency, the switch tube Q 11 The gate of the switch stops inputting high-level drive signals, and the switch tube Q 21 The gate input high level drive signal.
[0062] In another possible implementation, see Figure 5 As shown in another circuit structure diagram based on the Flyback inverter circuit, the switch tube 2 and the switch tube 4 can use a common source MOSFET, such as a silicon carbide MOSFET, a gallium nitride MOSFET or a common high-voltage MOSFET. Figure 5 , the second switch tube is MOSFET tube Q 12 , switch tube 4 is MOSFET tube Q 22 .
[0063] Switch tube Q 11 With switch tube 2 (MOSFET tube Q 12 ) are combined to form a first switch tube group, switch tube Q 11 The source of the first switch tube group is connected to the first end of the first secondary winding, and the switch tube Q 11 The drain connection Q 12 The drain, Q 12 The source of is the second end of the first switch tube group, connected to the second node.
[0064] Switching tube three Q 21 With switch tube 4 (MOSFET tube Q 22 ) are combined to form the second switch tube group, Q 22 The source of is the first end of the second switch tube group, connected to the second end of the second secondary winding, Q 22 The drain of the switch tube is connected to the three Q21 The drain of the switch tube is Q 21 The source is the second end of the second switch tube group, connected to the second node.
[0065] For example, see Figure 6 The schematic diagram of the driving signal control of the first switch tube group and the second switch tube group based on the mains frequency is shown. 11 And the switch tube three Q 21 The frequency of the high level input to the driving end of the switch can correspond to the mains frequency to form an alternating current. 11 The gate inputs a high-level drive signal. In the negative half cycle of the mains frequency, the switch tube Q 21 The gate inputs a high-level drive signal. Among them, due to the high-frequency on-off of the switch tube Q3 of the primary winding in one mains cycle, the Q3 drive signal waveform is dense and displayed as a gray area.
[0066] Above Figure 5 In the circuit shown, switch tube 2 and switch tube 4 use MOSFET tubes. By controlling the gate, zero voltage conduction of switch tube 2 and switch tube 4 can be achieved, further reducing the loss of switch tube 2 and switch tube 4. Specifically, when the mains voltage is in the positive half cycle, Figure 5 The switch tube 2 (Q 12 ) as an example to illustrate the drive control.
[0067] When the mains voltage is in the positive half cycle, Figure 6 , Q 11 Continuous conduction, see Figure 7 A control schematic diagram of a switch tube 2 using a MOSFET tube is shown.
[0068] At t0, the main switch Q3 connected to the primary winding is driven to open, the input voltage is across the winding, the primary inductor current of the transformer rises linearly, and the transformer stores energy until t1, Q 22 and Q 21 The drive is always in the off state, and the secondary winding does not transfer energy;
[0069] At time t1, the main switch tube Q3 is driven off, Q3 is turned off, and due to Q 11 In the on state, the first secondary winding Ls1 of the transformer is connected to the 11 and Q 12 The body diode transfers energy to the mains terminal;
[0070] At time t2 (Q 12 After the body diode is turned on, and Q 12The voltage across the two ends drops to the forward voltage drop Vf value of the body diode), Q 12 Driven high, Q 12 Zero voltage switching can be achieved.
[0071] At time t3 (after Q 12 The current drops to a first preset value, which is a manually set value and is smaller than the value at time t2 after Q 12 Current value), Q 12 The driver is turned off, and the current in the secondary winding of the transformer is naturally commutated to its body diode until time t4;
[0072] At t4, the current in the secondary winding of the transformer drops to zero, Q 12 The body diode current naturally goes to zero and there is no reverse recovery. 22 and Q 21 The drive is always in the off state, and the second secondary winding Ls2 does not transfer energy. At t4, the secondary winding current discharges to zero, and the low-voltage side Lp inductor participates in the resonance and continues until Ts. At Ts, the main switch Q3 is turned on and the next high-frequency cycle (t0-Ts) begins. In addition, during the time from t4 to Ts, due to the 22 and Q 21 The drive is always in the off state, and the second secondary winding Ls2 does not transfer energy.
[0073] The above t0-Ts is in the positive half cycle of the mains, and only Ls1 of the secondary high-voltage winding is working, and Ls2 does not participate in the energy transfer. Figure 5 When the AC voltage enters the negative half cycle, Q 11 and Q 12 The drive is in the off state, the secondary winding Ls1 does not transfer energy, and Q 21 In the on state, Q 22 Adopt Q 12 The same control method (at Q 22 The body diode conducts and Q 22 The voltage across the terminals drops to Q 22 When the forward voltage drop of the body diode is Vf, Q 22 The driving end is a high-level driving signal; 22 The current drops to the second preset value, Q 22 The driving end stops sending the driving signal), so that the second secondary winding Ls2 transfers energy, and the first secondary winding Ls1 does not transfer energy.
[0074] Therefore, based on the above Figure 5-7As an example, compared with the traditional flyback converter, in the micro-inverter of the high-voltage secondary winding freewheeling stage, the current needs to flow through the SBD and the thyristor switch tube, and the conduction of the two tubes brings a large voltage drop. In this application, during most of the time when the secondary winding of the transformer is freewheeling, the current of the secondary winding of the transformer flows through the high-voltage MOSFET tube, which reduces the voltage drop of the tube conduction, greatly reduces the loss, and then reduces the temperature rise, thereby improving the efficiency of the micro-inverter.
[0075] In addition, based on the above two possible implementation methods, of course, the switch tube 2 can be a diode, the switch tube 4 can be a MOSFET tube, or the switch tube 4 can be a diode, and the switch tube 2 can be a MOSFET tube, which will not be repeated here.
[0076] Based on the above embodiments, Figure 2 As shown, a filtering module may be connected between the first node and the second node, the filtering module including a capacitor C, a first inductor L1 and a second inductor L2, the first node is connected to the first end of the capacitor C, the second node is connected to the second end of the capacitor C, the first end of the capacitor C is connected to the first end of the first inductor L1, the second end of the capacitor C is connected to the first end of the second inductor L2, and the second end of the first inductor L1 and the second end of the second inductor L2 are output ends. In addition, Figure 2 An electromagnetic compatibility (EMC) circuit is set at the AC end.
[0077] Based on the above example, see Figure 8 The present application also provides a control method based on a Flyback inverter circuit, the method comprising:
[0078] S801, during the transformer energy storage stage, the first switch tube group and the second switch tube group are both turned off.
[0079] For example, the first switch tube group and the second switch tube group can refer to Figure 3 The circuit shown uses a diode to achieve cutoff, and can also be seen in Figure 5 Q in the circuit shown 12 and Q 22 The body diode in the common source MOSFET is used to achieve cutoff. Of course, one of the first switch tube group and the second switch tube group can use a diode and the other can use a common source MOSFET to achieve cutoff.
[0080] S802, in the transformer energy release stage, controlling the first switch tube group and the second switch tube group to be turned on alternately, so that the first secondary winding and the second secondary winding work alternately to form alternating current.
[0081] For example, the first switch tube group and the second switch tube group can refer to Figure 3 and Figure 5 The circuit shown is based on Q 11 and Q 21 The first switch tube group and the second switch tube group are controlled to be alternately turned on.
[0082] Based on the above control method based on Flyback inverter circuit, during the transformer energy storage stage, the transformer secondary side has no output to realize transformer energy storage; during the transformer energy release stage, the two switch tube groups respectively control the two secondary windings to alternately work in the positive half cycle and the negative half cycle of the power frequency to output AC power. In this way, it can reduce, for example Figure 1 The SBD and other power devices shown can reduce losses, reduce temperature rise and improve the efficiency of the inverter.
[0083] Optional, see Figure 3 and Figure 5 In the circuit shown in FIG. 1 , the switch tube 1 included in the first switch tube group and the switch tube 3 included in the second switch tube group are both common-source MOSFETs, and the control of the first switch tube group and the second switch tube group being alternately turned on includes:
[0084] In the transformer energy release stage, a driving signal is alternately sent to the driving end of the switch tube 1 and the driving end of the switch tube 2, so that the first switch tube group and the second switch tube group are alternately turned on.
[0085] Optionally, control can be performed based on the mains frequency. Specifically, in the positive half cycle of the mains frequency, a drive signal is sent to the drive end of switch tube one, and in the negative half cycle of the mains frequency, a drive signal is sent to the drive end of switch tube two, thereby forming alternating current with the mains frequency.
[0086] Optional, see Figure 5 In the circuit shown in the figure, the switch tube 2 included in the first switch tube group is a common source MOSFET, and the control of the first switch tube group and the second switch tube group being alternately turned on also includes:
[0087] When the body diode of the switch tube 2 is turned on and the voltage across the two ends of the switch tube 2 drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube 2; when the current of the switch tube 2 drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube 2.
[0088] In this way, by controlling the driving end of the switch tube 2, the zero voltage conduction of the switch tube 2 can be achieved, thereby further reducing the loss of the switch tube 2.
[0089] Optional, see Figure 5In the circuit shown in FIG. 1 , the switch tube 4 included in the second switch tube group is a common-source MOSFET, and the control of the first switch tube group and the second switch tube group being alternately turned on further includes:
[0090] When the body diode of the switch tube four is turned on and the voltage across the two ends of the switch tube four drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube four; when the current of the switch tube four drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube four.
[0091] In this way, by controlling the driving end of the switch tube 4, the zero voltage conduction of the switch tube 4 can be achieved, thereby further reducing the loss of the switch tube 4.
[0092] The above are some specific implementations of a Flyback inverter circuit provided in the embodiments of the present application. Based on this, the present application also provides a switching power supply, which includes a Flyback inverter circuit based on any of the above embodiments. The present application also provides a photovoltaic system, which includes a Flyback inverter circuit based on any of the above embodiments.
[0093] The "first" and "second" in the names such as "first" and "second" (if any) mentioned in the embodiments of the present application are only used as name identifiers and do not represent the first or second in order.
[0094] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.
[0095] The above description is merely an exemplary embodiment of the present application and is not intended to limit the protection scope of the present application.
Claims
1. A Flyback inverter circuit, characterized in that: It includes a transformer, a first switch tube group and a second switch tube group, wherein the secondary winding of the transformer includes a first secondary winding and a second secondary winding; The second end of the first secondary winding and the first end of the second secondary winding are connected to the first node, the first end of the first secondary winding is connected to the first end of the first switch tube group, the second end of the second secondary winding is connected to the first end of the second switch tube group, the second end of the first switch tube group and the second end of the second switch tube group are connected to the second node, and the first end of the first secondary winding and the first end of the second secondary winding are the same end; The first switch tube group and the second switch tube group are turned off in the transformer energy storage stage, and in the transformer energy release stage, the corresponding secondary windings are controlled to work in the positive half cycle and the negative half cycle respectively to output alternating current.
2. The inverter circuit according to claim 1, characterized in that: The first switch tube group includes a switch tube 1 and a switch tube 2, and the second switch tube group includes a switch tube 3 and a switch tube 4; Switch tube 2 and switch tube 4 are turned off during the transformer energy storage stage and turned on during the transformer energy release stage; The switch tube 1 and the switch tube 3 are alternately turned on during the energy release stage of the transformer, so that AC power is output between the first node and the second node.
3. The inverter circuit according to claim 2, characterized in that: The switch tube 2 is a common source MOSFET. When the body diode of the switch tube 2 is turned on and the voltage across the two ends of the switch tube 2 drops to the forward voltage drop Vf value of the body diode, the drive end of the switch tube 2 is at a high level; when the current of the switch tube 2 drops to a first preset value, the drive end of the switch tube 2 is at a low level.
4. The inverter circuit according to claim 2 or 3, characterized in that: Switch tube four is a common source MOSFET. When the body diode of switch tube four is turned on and the voltage across the two ends of switch tube four drops to the forward voltage drop Vf value of its body diode, the driving end of switch tube four is at a high level; when the current of switch tube four drops to a second preset value, the driving end of switch tube two is at a low level.
5. The inverter circuit according to claim 2, characterized in that: The second switch tube is a diode, and / or the fourth switch tube is a diode.
6. The inverter circuit according to claim 2, characterized in that: The switch tube 1 and the switch tube 3 are MOSFETs of a common source stage.
7. The inverter circuit according to claim 1, characterized in that: The first node and the second node are also connected to a filtering module.
8. The inverter circuit according to claim 7, characterized in that: The filtering module includes a capacitor, a first inductor and a second inductor, the first node is connected to the first end of the capacitor, the second node is connected to the second end of the capacitor, the first end of the capacitor is connected to the first end of the first inductor, the second end of the capacitor is connected to the first end of the second inductor, and the second end of the first inductor and the second end of the second inductor are output ends.
9. A control method based on a Flyback inverter circuit, characterized in that: The method according to any one of claims 1 to 8, based on a Flyback inverter circuit, comprises: During the transformer energy storage stage, the first switch tube group and the second switch tube group are both turned off; During the energy release stage of the transformer, the first switch tube group and the second switch tube group are controlled to be turned on alternately, so that the first secondary winding and the second secondary winding work alternately to form alternating current.
10. The method according to claim 9, characterized in that The switch tube 1 included in the first switch tube group and the switch tube 3 included in the second switch tube group are both common-source MOSFETs, and the controlling the first switch tube group and the second switch tube group to be alternately turned on includes: In the transformer energy release stage, driving signals are sent alternately to the driving end of the switch tube 1 and the driving end of the switch tube 2, so that the first switch tube group and the second switch tube group are alternately turned on.
11. The method according to claim 9, characterized in that The switch tube 2 included in the first switch tube group is a common source MOSFET, and the controlling the first switch tube group and the second switch tube group to be alternately turned on includes: When the body diode of the switch tube 2 is turned on and the voltage across the two ends of the switch tube 2 drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube 2; when the current of the switch tube 2 drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube 2.
12. The method according to any one of claims 9 to 11, characterized in that: The switch tube 4 included in the second switch tube group is a common source MOSFET, and the control of the first switch tube group and the second switch tube group being alternately turned on includes: When the body diode of the switch tube four is turned on and the voltage across the two ends of the switch tube four drops to the forward voltage drop Vf value of the body diode, a drive signal is sent to the driving end of the switch tube four; when the current of the switch tube four drops to a first preset value, the drive signal is stopped from being sent to the driving end of the switch tube four.
13. A switching power supply, characterized in that: A flyback inverter circuit comprising any one of claims 1 to 8.
14. A photovoltaic system, characterized in that: A flyback inverter circuit comprising any one of claims 1 to 8.