Output control circuit, flyback converter, chip and electronic device

Abstract

This application provides an output control circuit, a flyback converter, a chip, and an electronic device. The output control circuit can obtain a first output voltage from a first output circuit and a second output voltage from a second output circuit, and control the first and second output circuits to conduct sequentially based on the first and second output voltages in each switching cycle. Therefore, the output control circuit can determine a first freewheeling circuit and a second freewheeling circuit in the first and second output circuits, so that the magnetizing inductance of the transformer in the flyback converter transfers energy to the first and second freewheeling circuits respectively during the secondary freewheeling phase. That is, the magnetizing inductance transfers energy using high-frequency chopping in each switching cycle, making the high-frequency chopping frequency of the first and second output circuits equal to the switching frequency. Since the switching frequency is usually higher than the range of human hearing, the problem of audio noise can be solved, and the performance of the flyback converter can be improved.

Description

Technical Field

[0001] This application relates to the field of power management chip technology, and in particular to an output control circuit, a flyback converter, a chip, and an electronic device. Background Technology

[0002] A flyback converter (or flyback) is a type of DC-DC converter widely used in AC / DC and DC / DC conversion. It provides isolation between the input and output stages and is a type of switching power supply. Due to its simple structure and versatile functionality, flyback converters are widely used in electronic devices such as medical equipment, laptops, USB chargers, and high-voltage power supplies for cathode ray tubes.

[0003] In related technologies, the power of the two outputs of a flyback converter differs significantly, causing the flyback converter to switch back and forth between two different operating points. These different operating points refer to the different switching frequencies of the flyback converter. The switching frequency is determined by the loads on the two outputs.

[0004] Thus, when the switching frequency enters the range of human hearing (20Hz–20kHz), audio noise occurs in the flyback converter. Therefore, when a flyback converter is installed in noise-sensitive electronic devices, it generates additional noise interference, thereby affecting the performance of the flyback converter. Summary of the Invention

[0005] This application provides an output control circuit, a flyback converter, a chip, and an electronic device that can solve the problem of audio noise and improve the performance of the flyback converter.

[0006] In a first aspect, this application provides an output control circuit applied in a flyback converter, the flyback converter comprising: a first output circuit and a second output circuit; a first input terminal of the output control circuit is electrically connected to the output terminal of the first output circuit, a second input terminal of the output control circuit is electrically connected to the output terminal of the second output circuit, and the output terminal of the output control circuit is electrically connected to the control terminals of the first output circuit and the second output circuit, respectively.

[0007] The output control circuit is configured to obtain a first output voltage from the first output circuit and a second output voltage from the second output circuit, and determine a first freewheeling circuit and a second freewheeling circuit in the first output circuit and the second output circuit according to the first output voltage and the second output voltage in each switching cycle.

[0008] The output control circuit provided in the first aspect can obtain a first output voltage from the first output circuit and a second output voltage from the second output circuit. Within each switching cycle, the first and second output circuits are controlled to conduct sequentially based on the first and second output voltages. Therefore, the output control circuit can determine the first and second freewheeling circuits in the first and second output circuits, ensuring that the magnetizing inductance of the transformer in the flyback converter transfers energy to the first and second freewheeling circuits respectively during the secondary freewheeling phase. In other words, the magnetizing inductance transfers energy using high-frequency chopping within each switching cycle, making the high-frequency chopping frequency of the first and second output circuits equal to the switching frequency. Since the switching frequency is typically higher than the range of human hearing, this solves the problem of audio noise and improves the performance of the flyback converter.

[0009] In one possible design, the output control circuit includes: a freewheeling sequence determination circuit and a first comparator;

[0010] The first input terminal of the first comparator is electrically connected to the output terminal of the first output circuit, the second input terminal of the first comparator is electrically connected to the output terminal of the second output circuit, the output terminal of the first comparator is electrically connected to the input terminal of the freewheeling sequence determination circuit, and the output terminal of the freewheeling sequence determination circuit is electrically connected to the control terminal of the first output circuit and the control terminal of the second output circuit, respectively.

[0011] The first comparator is used to compare the magnitudes of the first output voltage and the second output voltage, obtain a first comparison result, and transmit the first comparison result to the freewheeling sequence determination circuit;

[0012] The freewheeling sequence determination circuit is used to determine the first freewheeling circuit and the second freewheeling circuit in the first output circuit and the second output circuit according to the first comparison result.

[0013] In one possible design, the freewheeling sequence determination circuit is used to determine, when the first comparison result indicates that the first output voltage is less than the second output voltage, that the first output circuit is the first freewheeling circuit and the second output circuit is the second freewheeling circuit, or to determine that the second output circuit is the first freewheeling circuit and the first output circuit is the second freewheeling circuit.

[0014] or,

[0015] The freewheeling sequence determination circuit is used to determine, when the first comparison result indicates that the first output voltage is greater than the second output voltage, that the second output circuit is the first freewheeling circuit and the first output circuit is the second freewheeling circuit, or to determine that the first output circuit is the first freewheeling circuit and the second output circuit is the second freewheeling circuit.

[0016] In one possible design, the output control circuit includes: a freewheeling sequence determination circuit, a power determination circuit, and a first comparator;

[0017] The first input terminal of the first comparator and the first input terminal of the power determination circuit are both electrically connected to the output terminal of the first output circuit. The second input terminal of the first comparator and the second input terminal of the power determination circuit are both electrically connected to the output terminal of the second output circuit. The output terminal of the first comparator is electrically connected to the first input terminal of the freewheeling sequence determination circuit. The output terminal of the power determination circuit is electrically connected to the second input terminal of the freewheeling sequence determination circuit. The output terminal of the freewheeling sequence determination circuit is electrically connected to the control terminal of the first output circuit and the control terminal of the second output circuit, respectively.

[0018] The first comparator is used to compare the magnitudes of the first output voltage and the second output voltage, obtain a first comparison result, and transmit the first comparison result to the freewheeling sequence determination circuit;

[0019] The power determination circuit is used to obtain a power determination result based on the first output voltage and the second output voltage, and to transmit the power determination result to the freewheeling sequence determination circuit.

[0020] The freewheeling sequence determination circuit is used to determine the first freewheeling loop and the second freewheeling loop in the first output circuit and the second output circuit based on the first comparison result and the power determination result.

[0021] In one possible design, the power determination circuit includes: a first power determination circuit and a second power determination circuit;

[0022] The input terminal of the first power determination circuit is electrically connected to the output terminal of the first output circuit, the input terminal of the second power determination circuit is electrically connected to the output terminal of the second output circuit, the output terminals of the first power determination circuit and the second power determination circuit are both electrically connected to the second input terminal of the freewheeling sequence determination circuit, the first terminal of the first power determination circuit is electrically connected to the first terminal of the second power determination circuit, and the second terminal of the first power determination circuit is electrically connected to the second terminal of the second power determination circuit.

[0023] The first power determination circuit is used to obtain a first feedback voltage based on the first output voltage, and the first feedback voltage is used to characterize the power of the first output circuit.

[0024] The second power determination circuit is used to obtain a second feedback voltage based on the second output voltage, and the second feedback voltage is used to characterize the power of the second output circuit.

[0025] The first power determination circuit is further configured to compare the magnitude of the first feedback voltage and the first preset voltage when the first output voltage is greater than the second output voltage, and obtain a second comparison result. The power determination result includes the second comparison result and a third comparison result. The first preset voltage is used to determine whether the load of the first output circuit or the load of the second output circuit is a heavy load.

[0026] The second power determination circuit is further used to compare the magnitude of the second feedback voltage and the second preset voltage when the first output voltage is greater than the second output voltage, and obtain the third comparison result. The second preset voltage is used to determine whether the load of the first output circuit or the load of the second output circuit is a light load.

[0027] or,

[0028] The first power determination circuit is further configured to, when the first output voltage is less than the second output voltage, obtain the second feedback voltage from the second power determination circuit, compare the magnitude of the second feedback voltage with the first preset voltage, and obtain the second comparison result;

[0029] The second power determination circuit is further configured to obtain the first feedback voltage from the first power determination circuit when the first output voltage is less than the second output voltage, and compare the magnitude of the first feedback voltage and the second preset voltage to obtain the third comparison result.

[0030] In one possible design, the freewheeling sequence determination circuit is specifically used to determine whether the second comparison result and the third comparison result satisfy the second preset condition when the first comparison result satisfies the first preset condition.

[0031] If the second preset condition is met, then the second output circuit is determined as the first freewheeling circuit, and the first output circuit is determined as the second freewheeling circuit.

[0032] If the second preset condition is not met, then the first output circuit is determined as the first freewheeling circuit, and the second output circuit is determined as the second freewheeling circuit.

[0033] or,

[0034] The freewheeling sequence determination circuit is specifically used to determine whether the second comparison result and the third comparison result satisfy the third preset condition when the first comparison result does not meet the first preset condition.

[0035] If the third preset condition is met, then the first output circuit is determined as the first freewheeling circuit, and the second output circuit is determined as the second freewheeling circuit.

[0036] If the third preset condition is not met, then the second output circuit is determined as the first freewheeling circuit, and the first output circuit is determined as the second freewheeling circuit.

[0037] In one possible design, the first power determination circuit includes: a first operational amplifier, a second comparator, a first capacitor, a first resistor, a first switching transistor, and a second switching transistor;

[0038] The non-inverting input terminal of the first operational amplifier is used to connect to a first reference voltage. The negative-inverting input terminal of the first operational amplifier and the first plate of the first capacitor are both electrically connected to the output terminal of the first output circuit. The second plate of the first capacitor is electrically connected to the first terminal of the first resistor. The output terminal of the first operational amplifier is electrically connected to the first terminal of the first switch, the first terminal of the second switch, and the second terminal of the first resistor. The second terminal of the first switch is electrically connected to the non-inverting input terminal of the second comparator and the first terminal of the second power determination circuit. The negative-inverting input terminal of the second comparator is used to connect to the first preset voltage. The output terminal of the second comparator is electrically connected to the second input terminal of the freewheeling sequence determination circuit. The second terminal of the second switch is electrically connected to the second terminal of the second power determination circuit. The control terminals of the first and second switches are used to connect to a first control signal. The first control signal is used to control the first and second switches to be turned on or off according to the first comparison result.

[0039] The first operational amplifier is used to amplify the voltage difference between the first output voltage and the first reference voltage, and to obtain the first feedback voltage with the compensation of the first resistor and the first capacitor, and to transmit the first feedback voltage to the second comparator;

[0040] The second comparator is used to compare the magnitude of the first feedback voltage and the first preset voltage to obtain the second comparison result, or to obtain the second feedback voltage from the second power determination circuit and compare the magnitude of the second feedback voltage with the first preset voltage to obtain the second comparison result.

[0041] In one possible design, the second power determination circuit includes: a second operational amplifier, a third comparator, a second capacitor, a second resistor, a third switch, and a fourth switch;

[0042] The non-inverting input of the second operational amplifier is used to connect to the second reference voltage. The negative-inverting input of the second operational amplifier and the first plate of the second capacitor are both electrically connected to the output of the second output circuit. The second plate of the second capacitor is electrically connected to the first end of the second resistor. The output of the second operational amplifier is electrically connected to the first end of the third switch, the first end of the fourth switch, and the second end of the second resistor, respectively. The second end of the third switch is electrically connected to the first end of the first power determination circuit. The second end of the fourth switch is electrically connected to the negative-inverting input of the third comparator and the second end of the first power determination circuit, respectively. The negative-inverting input of the third comparator is used to connect to the second preset voltage. The output of the second comparator is electrically connected to the third input of the freewheeling sequence determination circuit. The control terminals of the third and fourth switches are used to connect to the second control signal. The second control signal is used to control the conduction or cutoff of the third and fourth switches according to the first comparison result.

[0043] The second operational amplifier is used to amplify the voltage difference between the second output voltage and the second reference voltage, and to obtain the second feedback voltage with the compensation of the second resistor and the second capacitor, and to transmit the second feedback voltage to the third comparator;

[0044] The third comparator is used to compare the magnitude of the second feedback voltage and the second preset voltage to obtain the third comparison result, or to obtain the first feedback voltage from the first power determination circuit and compare the magnitude of the first feedback voltage with the second preset voltage to obtain the third comparison result.

[0045] In one possible design, the first preset condition is that the first output voltage is less than the second output voltage; the second preset condition is that the first feedback voltage is less than the second preset voltage and the second feedback voltage is greater than the first preset voltage; the third preset condition is that the first feedback voltage is greater than the first preset voltage and the second feedback voltage is less than the second preset voltage.

[0046] In one possible design, the flyback converter further includes: a first-stage switch, a transformer, and a primary switch;

[0047] The output control circuit is also used to control the second freewheeling circuit to reverse excite the transformer within a preset time during which the primary switch is turned on after the excitation inductor current in the transformer crosses zero and before the primary switch changes from off to on.

[0048] In a second aspect, this application provides a flyback converter, which includes: a primary switch, an inductor, an absorption circuit, a primary controller, a secondary controller, a transformer, a first primary switch, a first output circuit, a second output circuit, an isolation communication circuit, and an output control circuit in the first aspect and various possible designs of the first aspect.

[0049] The first terminal of the inductor and the first terminal of the snubber circuit are both used to connect to the input voltage. The second terminal of the inductor is electrically connected to the opposite terminal of the primary winding of the transformer. The first terminal of the primary switch and the second terminal of the snubber circuit are both electrically connected to the same terminal of the primary winding. The control terminal of the primary switch is electrically connected to the first terminal of the primary controller. The second terminal of the primary controller is electrically connected to the first terminal of the isolation communication circuit. The second terminal of the isolation communication circuit is electrically connected to the first terminal of the secondary controller. The second terminal of the secondary controller is electrically connected to the control terminal of the primary switch. The first terminal of the primary switch is electrically connected to the opposite terminal of the secondary winding of the transformer. The corresponding terminals are electrically connected to the input terminals of the first output circuit and the second output circuit, respectively. The output terminal of the first output circuit is electrically connected to the first input terminal of the output control circuit, and the output terminal of the second output circuit is electrically connected to the second input terminal of the output control circuit. The output terminal of the output control circuit is electrically connected to the control terminals of the first output circuit and the second output circuit, respectively. The third terminal of the secondary controller is electrically connected to the first terminal of the output control circuit. The second terminals of the first primary switching transistor and the second primary switching transistor are both grounded. The output terminal of the first output circuit is also used to output a first output voltage, and the output terminal of the second output circuit is also used to output a second output voltage.

[0050] The beneficial effects of the flyback converter provided in the second aspect and the various possible designs of the second aspect can be found in the first aspect and the various possible implementations of the first aspect, and will not be repeated here.

[0051] Thirdly, this application provides a chip comprising: the output control circuit of the first aspect and various possible designs of the first aspect, and / or the flyback converter of the second aspect.

[0052] Fourthly, this application provides an electronic device that includes the chip described in the third aspect above.

[0053] The above description is merely an overview of the technical solutions of the embodiments of this application. In order to better understand the technical means of the embodiments of this application and to implement them in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the embodiments of this application more obvious and understandable, specific implementation methods of this application are described below. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A schematic diagram of the output control circuit in a flyback converter provided for related technologies;

[0056] Figure 2 This is a schematic diagram of the working waveform of a flyback converter in related technologies.

[0057] Figure 3 This is a schematic diagram of the structure of a flyback converter provided in an embodiment of this application;

[0058] Figure 4 This is a schematic diagram of the structure of an output control circuit in a flyback converter provided in an embodiment of this application;

[0059] Figure 5 for Figure 4 A schematic diagram of the control flow of the output control circuit;

[0060] Figure 6 for Figure 4 A schematic diagram of the working waveform of a flyback converter;

[0061] Figure 7 for Figure 4 Another working waveform diagram of the flyback converter;

[0062] Figure 8 for Figure 4 Another working waveform diagram of a flyback converter;

[0063] Figure 9 A schematic diagram of another output control circuit in a flyback converter provided in the embodiments of this application;

[0064] Figure 10 for Figure 9A schematic diagram of the control flow of the output control circuit;

[0065] Figure 11 for Figure 9 A flowchart illustrating how the freewheeling sequence determination circuit determines the first and second freewheeling loops.

[0066] Figure 12 for Figure 9 A schematic diagram of the working waveform of a flyback converter;

[0067] Figure 13 for Figure 9 Another working waveform diagram of the flyback converter;

[0068] Figure 14 for Figure 9 A schematic diagram of another working waveform of a flyback converter. Detailed Implementation

[0069] In this application, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c alone can mean: a alone, b alone, c alone, a combination of a and b, a combination of a and c, a combination of b and c, or a, b, and c, where a, b, and c can be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0070] The terms “center,” “longitudinal,” “lateral,” “up,” “down,” “left,” “right,” “front,” and “rear,” etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0071] The terms "connected" and "connected" should be interpreted broadly. For example, in circuit structures, "connected" or "connected" can refer not only to physical connections but also to electrical or signal connections. This could be a direct connection (physical connection) or an indirect connection via at least one intermediate component, as long as the circuit is connected. It could also refer to the internal connection between two components. Similarly, a signal connection can refer to a connection via a circuit or a medium, such as radio waves. Those skilled in the art will understand the specific meaning of these terms in this application based on the specific circumstances.

[0072] First, the technical terms involved in the embodiments of this application will be explained.

[0073] Discontinuous conduction mode (DCM) refers to a situation where, in certain application scenarios, the inductor current in a flyback converter drops to zero during certain switching cycles. In this mode, the flyback converter experiences a light load.

[0074] Continuous conduction mode (CCM) refers to a flyback converter where the inductor current remains continuous and does not drop to zero in each switching cycle. In this mode, the flyback converter experiences heavy load.

[0075] The free resonance state refers to the resonant circuit formed by the magnetizing inductor, the parasitic diode of the primary switch, and the parasitic diode of the synchronous rectifier in the flyback converter, which allows the flyback converter to operate in a free resonance mode.

[0076] Among them, the magnetizing inductance refers to the inductance of the transformer in the flyback converter.

[0077] The secondary freewheeling stage refers to the process of demagnetizing the magnetizing inductor of the transformer, that is, the process of the magnetizing inductor current Imag decreasing from the peak current.

[0078] Then combine Figure 1 and Figure 2 The problems existing in flyback converters in related technologies are analyzed as follows:

[0079] Reference Figure 1 , Figure 1 A schematic diagram of the output control circuit in a flyback converter, provided for related technologies. (Example) Figure 1As shown, the flyback converter has two outputs: one output voltage VO1' and the other output voltage VO2'. After loop compensation, output voltages VO1' and VO2' are obtained as voltages VFB1' and VFB2', respectively. The diode array can then transmit the larger of VFB1' and VFB2' to the primary control unit via an isolated communication unit. Simultaneously, comparator Compa' compares VFB1' and VFB2' to obtain the comparison result. Therefore, within a single switching cycle, the transformer's magnetizing inductance can transfer energy to only one of the two outputs based on the comparison result.

[0080] These two outputs draw energy from the magnetizing inductor in a time-division multiplexing manner. For example, in the first switching cycle, only one output draws energy from the magnetizing inductor. Similarly, in the third switching cycle, only the other output draws energy from the magnetizing inductor.

[0081] Reference Figure 2 , Figure 2 This is a schematic diagram of the operating waveform of a flyback converter in related technologies. For example... Figure 2 As shown, in the first two switching cycles T1+T2, during the secondary freewheeling phase, the magnetizing inductor transfers energy to the output path where the output voltage VO1' is located. In the third switching cycle T3, since voltage VFB1' < voltage VFB2', during the secondary freewheeling phase, the magnetizing inductor transfers energy to the other output path where the output voltage VO2' is located. In the fourth switching cycle T4, since voltage VFB1' > voltage VFB2', during the secondary freewheeling phase, the magnetizing inductor again transfers energy to the output path where the output voltage VO1' is located.

[0082] However, due to the significant difference in power between the two outputs, the flyback converter switches back and forth between two different operating points. When the switching frequency enters the range of human hearing, this causes audio noise in the flyback converter. Therefore, when a flyback converter is installed in noise-sensitive electronic equipment, it generates additional noise interference, thus affecting the performance of the flyback converter.

[0083] Therefore, this application provides an output control circuit, a flyback converter, a chip, and an electronic device.

[0084] The output control circuit and flyback converter can be chips or circuit modules, and this application does not specifically limit them.

[0085] Furthermore, the output control circuit and the flyback converter can be integrated into one chip or into different chips; this application does not specifically limit this.

[0086] In this application, electronic devices may include, but are not limited to: power adapters, power tools, household appliances, and electric vehicle chargers.

[0087] Furthermore, the flyback converter can be a full-bridge flyback converter or a half-bridge flyback converter. Among them, the half-bridge flyback converter can be a symmetrical half-bridge flyback converter or an asymmetrical half-bridge flyback converter, and the embodiments of this application do not specifically limit it.

[0088] Reference Figure 3 , Figure 3 This is a schematic diagram of a flyback converter provided in an embodiment of this application. Figure 3 As shown, the flyback converter 1000 may include: a primary switch Q1, an inductor Lk, an absorption circuit 700, a primary controller 400, a secondary controller 200, a transformer T, a primary switch Q2, a first output circuit 500, a second output circuit 600, an isolation communication circuit 300, and an output control circuit 100.

[0089] The first terminal of inductor Lk and the first terminal of snubber circuit 700 are both used to connect to the input voltage Vin. The second terminal of inductor Lk is electrically connected to the opposite terminal of the primary winding of transformer T. The first terminal of primary switch Q1 and the second terminal of snubber circuit 700 are both electrically connected to the same terminal of the primary winding. The control terminal of primary switch Q1 is electrically connected to the first terminal of primary controller 400. The second terminal of primary controller 400 is electrically connected to the first terminal of isolation communication circuit 300. The second terminal of isolation communication circuit 300 is electrically connected to the first terminal of secondary controller 200. The second terminal of secondary controller 200 is electrically connected to the control terminal of primary switch Q2. The first terminal of primary switch Q2 is electrically connected to the opposite terminal of the secondary winding of transformer T. The secondary winding's corresponding terminals are electrically connected to the input terminals of the first output circuit 500 and the second output circuit 600, respectively. The output terminal of the first output circuit 500 is electrically connected to the first input terminal of the output control circuit 100. The output terminal of the second output circuit 600 is electrically connected to the second input terminal of the output control circuit 100. The output terminal of the output control circuit 100 is electrically connected to the control terminals of the first output circuit 500 and the second output circuit 600, respectively. The third terminal of the secondary controller 200 is electrically connected to the first terminal of the output control circuit 100. The second terminals of the first primary switching transistor Q2 and the primary switching transistor Q1 are both grounded. The output terminal of the first output circuit 500 is also used to output the first output voltage V. O1 The output terminal of the second output circuit 600 is also used to output the second output voltage V. O2 .

[0090] The primary switch Q1 and the second-stage switch Q2 may include, but are not limited to, gallium nitride transistors, bipolar junction transistors, insulated gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, field-controlled thyristors, gate turn-off thyristors, and transmission gates.

[0091] For example, when the primary switch Q1 and the second primary switch Q2 are gallium nitride transistors, the control terminal of the primary switch Q1 and the second primary switch Q2 refers to the gate of the gallium nitride transistor, and the first terminal of the primary switch Q1 and the second primary switch Q2 can be the drain or source of the gallium nitride transistor. Correspondingly, the second terminal of the primary switch Q1 and the second primary switch Q2 can be the source or drain of the gallium nitride transistor.

[0092] For example, when the primary switch Q1 and the secondary switch Q2 are bipolar junction transistors (BJTs), the control terminals of the primary switch Q1 and the secondary switch Q2 refer to the base of the BJT. The first terminals of the primary switch Q1 and the secondary switch Q2 can be the collector or emitter of the BJT. Correspondingly, the second terminals of the primary switch Q1 and the secondary switch Q2 can be the emitter or collector of the BJT.

[0093] For example, when the primary switch Q1 and the secondary switch Q2 are insulated-gate bipolar transistors (IGBTs), the control terminals of the primary switch Q1 and the secondary switch Q2 refer to the gate of the IGBT. The first terminals of the primary switch Q1 and the secondary switch Q2 can be the collector or emitter of the IGBT. Correspondingly, the second terminals of the primary switch Q1 and the secondary switch Q2 can be the emitter or collector of the IGBT.

[0094] For example, when the primary switch Q1 and the secondary switch Q2 are metal-oxide-semiconductor field-effect transistors (MOSFETs), the control terminals of the primary switch Q1 and the secondary switch Q2 refer to the gates of the MOSFETs. The first terminals of the primary switch Q1 and the secondary switch Q2 can be the drain or source of the MOSFET. Correspondingly, the second terminals of the primary switch Q1 and the secondary switch Q2 can be the source or drain of the MOSFET.

[0095] For example, when the primary switch Q1 and the second primary switch Q2 are field-controlled thyristors, the control terminals of the primary switch Q1 and the second primary switch Q2 refer to the gate of the field-controlled thyristor. The first terminals of the primary switch Q1 and the second primary switch Q2 can be the drain or source of the field-controlled thyristor. Correspondingly, the second terminals of the primary switch Q1 and the second primary switch Q2 can be the source or drain of the field-controlled thyristor.

[0096] For example, when the primary switch Q1 and the first-stage switch Q2 are gate turn-off thyristors, the control terminals of the primary switch Q1 and the first-stage switch Q2 refer to the gate of the gate turn-off thyristor. The first terminal of the primary switch Q1 and the first-stage switch Q2 can be the cathode or anode of the gate turn-off thyristor. Correspondingly, the second terminal of the primary switch Q1 and the first-stage switch Q2 can be the cathode or anode of the gate turn-off thyristor.

[0097] For example, when the primary switch Q1 and the first secondary switch Q2 are transmission gates, the control terminals of the primary switch Q1 and the first secondary switch Q2 refer to the ports of the transmission gate used to receive the gate control signal. The first terminals of the primary switch Q1 and the first secondary switch Q2 can be the input or output terminals of the transmission gate. Correspondingly, the second terminals of the primary switch Q1 and the first secondary switch Q2 can be the input or output terminals of the transmission gate.

[0098] When the primary controller 400 controls the primary switch Q1 to turn on, the magnetizing inductance Lm of the transformer T is in the magnetizing process, causing the magnetizing inductance Lm to increase linearly. When the primary controller 400 controls the primary switch Q1 to turn off, the magnetizing inductance Lm is transferred to the secondary winding of the flyback converter 1000 for freewheeling, putting the flyback converter 1000 in the secondary freewheeling stage.

[0099] The output control circuit 100 can obtain the first output voltage V from the first output circuit 500. O1 and obtain the second output voltage V from the second output circuit 600. O2 Furthermore, the output control circuit 100 can adjust the output voltage V according to the first output voltage V during each switching cycle. O1 Second output voltage V O2 The first output circuit 500 and the second output circuit 600 are turned on sequentially. In this way, the output control circuit 100 can determine the output circuit that is turned on first as the first freewheeling circuit and the output circuit that is turned on later as the second freewheeling circuit.

[0100] Therefore, the output control circuit 100 can determine the first freewheeling circuit and the second freewheeling circuit in the first output circuit 500 and the second output circuit 600, so that the magnetizing inductance Lm of the transformer T transfers energy to the first freewheeling circuit and the second freewheeling circuit respectively during the secondary freewheeling phase of each switching cycle. That is, the magnetizing inductance Lm of the transformer T transfers energy using high-frequency chopping in each switching cycle, so that the high-frequency chopping frequency of the first output circuit 500 and the second output circuit 600 is equal to the switching frequency. Since the switching frequency is usually higher than the range of human hearing, the problem of audio noise can be solved, and the performance of the flyback converter 1000 can be improved.

[0101] Specifically, when the first output circuit 500 is turned on first and the second output circuit 600 is turned on later, the first output circuit 500 is the first freewheeling circuit and the second output circuit 600 is the second freewheeling circuit. When the second output circuit 600 is turned on first and the first output circuit 500 is turned on later, the second output circuit 600 is the first freewheeling circuit and the first output circuit 500 is the second freewheeling circuit.

[0102] Here, the switching frequency refers to the reciprocal of the switching cycle.

[0103] The output control circuit, flyback converter, chip, and electronic device provided in this application can obtain a first output voltage from a first output circuit and a second output voltage from a second output circuit through the output control circuit. In each switching cycle, the first and second output circuits are controlled to conduct sequentially based on the first and second output voltages. Therefore, the output control circuit can determine a first freewheeling circuit and a second freewheeling circuit in the first and second output circuits, allowing the magnetizing inductance of the transformer in the flyback converter to transfer energy to the first and second freewheeling circuits respectively during the secondary freewheeling phase. In other words, the magnetizing inductance transfers energy using high-frequency chopping in each switching cycle, making the high-frequency chopping frequency of the first and second output circuits equal to the switching frequency. Since the switching frequency is usually higher than the range of human hearing, the problem of audio noise can be solved, improving the performance of the flyback converter.

[0104] Based on the description of the above embodiments, the output control circuit 100 can be implemented in two feasible ways. These two feasible implementations can include: one feasible implementation of the output control circuit 100 and another feasible implementation of the output control circuit 100. The one feasible implementation of the output control circuit 100 and the other feasible implementation of the output control circuit 100 are related as either options. That is, either the one feasible implementation of the output control circuit 100 achieves the purpose of determining the first freewheeling circuit and the second freewheeling circuit in the first output circuit 500 and the second output circuit 600, or the other feasible implementation of the output control circuit 100 achieves the purpose of determining the first freewheeling circuit and the second freewheeling circuit in the first output circuit 500 and the second output circuit 600.

[0105] As a feasible implementation of the output control circuit 100, refer to Figure 4 , Figure 4 This is a schematic diagram of the structure of an output control circuit in a flyback converter provided in an embodiment of this application. Figure 4 As shown, the output control circuit 100 may include: a freewheeling sequence determination circuit 110 and a first comparator Compa1.

[0106] The first input terminal of the first comparator Compa1 is electrically connected to the output terminal of the first output circuit 500, the second input terminal of the first comparator Compa1 is electrically connected to the output terminal of the second output circuit 600, the output terminal of the first comparator Compa1 is electrically connected to the input terminal of the freewheeling sequence determination circuit 110, and the output terminal of the freewheeling sequence determination circuit 110 is electrically connected to the control terminal of the first output circuit 500 and the control terminal of the second output circuit 600, respectively.

[0107] The freewheeling sequence determination circuit 110 and the first comparator Compa1 can be set separately or integrated. This application embodiment does not specifically limit this.

[0108] Wherein, the first input terminal of the first comparator Compa1 is the first input terminal of the output control circuit 100, the second input terminal of the first comparator Compa1 is the second input terminal of the output control circuit 100, and the output terminal of the freewheeling sequence determination circuit 110 is the output terminal of the output control circuit 100.

[0109] In this embodiment, the first input terminal of the first comparator Compa1 can be either a positive or negative input terminal, and this application does not specifically limit this. Correspondingly, the second input terminal of the first comparator Compa1 can be either a negative or positive input terminal, and this application does not specifically limit this.

[0110] The following is combined with Figure 5 , Figure 5 for Figure 4 A schematic diagram of the control flow of the output control circuit is shown. The working principle of the output control circuit 100 is explained in detail below:

[0111] The first comparator Compa1 can compare the first output voltage V. O1 Second output voltage V O2 The first comparison result is obtained by determining the magnitude of the first comparison result. Furthermore, the first comparator Compa1 can transmit the first comparison result to the freewheeling sequence determination circuit 110, so that the freewheeling sequence determination circuit 110 can obtain the first comparison result.

[0112] Thus, the freewheeling sequence determination circuit 110 can determine the first freewheeling loop and the second freewheeling loop in the first output circuit 500 and the second output circuit 600 based on the first comparison result.

[0113] In some examples, the first comparison result characterizes the first output voltage V. O1 Less than the second output voltage V O2In this case, the freewheeling sequence determination circuit 110 can control the first output circuit 500 to turn on first, and the second output circuit 600 to turn on later. In this way, the freewheeling sequence determination circuit 110 can determine that the first output circuit 500 is the first freewheeling loop and the second output circuit 600 is the second freewheeling loop.

[0114] Due to the first output voltage V O1 Less than the second output voltage V O2 Therefore, the first output circuit 500 is a low-voltage circuit, and the second output circuit 600 is a high-voltage circuit. Thus, the freewheeling sequence determination circuit 110 determines that the low-voltage circuit is the first freewheeling circuit and the high-voltage circuit is the second freewheeling circuit, ensuring that the voltage Vds across the primary switch Q1 does not trigger the detection threshold. This prevents the flyback converter 1000 from entering an abnormal operating state and improves its anti-interference performance.

[0115] The freewheeling sequence determination circuit 110 can control the second output circuit 600 to turn on first, followed by the first output circuit 500. Therefore, the freewheeling sequence determination circuit 110 can determine that the second output circuit 600 is the first freewheeling circuit and the first output circuit 500 is the second freewheeling circuit.

[0116] The freewheeling sequence determination circuit 110 can characterize the first output voltage V by the first comparison result. O1 Greater than the second output voltage V O2 In this case, the freewheeling sequence determination circuit 110 can control the second output circuit 600 to turn on first, followed by the first output circuit 500. Thus, the freewheeling sequence determination circuit 110 can determine that the second output circuit 600 is the first freewheeling circuit and the first output circuit 500 is the second freewheeling circuit. Because the first output voltage V... O1 Greater than the second output voltage V O2 Therefore, the first output circuit 500 is a high-voltage circuit, and the second output circuit 600 is a low-voltage circuit. Thus, the freewheeling sequence determination circuit 110 determines that the low-voltage circuit is the first freewheeling circuit and the high-voltage circuit is the second freewheeling circuit, ensuring that the voltage Vds across the primary switch Q1 does not trigger the detection threshold. This prevents the flyback converter 1000 from entering an abnormal operating state and improves its anti-interference performance.

[0117] The freewheeling sequence determination circuit 110 can control the first output circuit 500 to turn on first, and the second output circuit 600 to turn on later. Thus, the freewheeling sequence determination circuit 110 can determine that the first output circuit 500 is the first freewheeling loop and the second output circuit 600 is the second freewheeling loop.

[0118] For example, such as Figure 5As shown, after the magnetizing inductor current Imag in transformer T crosses zero, that is, when the flyback converter 1000 is in DCM (Distributed Current Management), before the primary switch Q1 changes from off to on, the output control circuit 100 can control the second freewheeling circuit to reverse-energize the transformer T within a preset time during which the primary switch Q2 is on, so that the primary switch Q2 can achieve zero-voltage turn-on. This reduces the losses generated by the flyback converter 1000 and improves its efficiency.

[0119] In summary, the first comparator compares the magnitudes of the first output voltage and the second output voltage to obtain a first comparison result, which is then transmitted to the freewheeling sequence determination circuit, enabling the freewheeling sequence determination circuit to acquire the first comparison result. Thus, the freewheeling sequence determination circuit can determine the first freewheeling circuit and the second freewheeling circuit in the first output circuit and the second output circuit based on the first comparison result. Consequently, the output control circuit can determine the first freewheeling circuit and the second freewheeling circuit in the first output circuit and the second output circuit.

[0120] The following is combined with Figures 6-8 , Figures 6-8 All showed Figure 4 A schematic diagram of the working waveforms of the flyback converter. A detailed explanation of how the output control circuit 100 controls the operation of the flyback converter 1000 under DCM and CCM conditions.

[0121] like Figure 6 As shown, under DCM, due to the first output voltage V O1 Second output voltage V O2 Therefore, the output control circuit 100 can determine that the first output circuit 500 is the first freewheeling circuit and the second output circuit 600 is the second freewheeling circuit.

[0122] During the time periods t0-t1 and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During this period, i.e., when the primary switch Q1 is on, the second output circuit 600, which serves as the second freewheeling circuit, is turned off, and the first output circuit 500, which serves as the first freewheeling circuit, is turned on.

[0123] At times t1 and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0124] During the time periods t1-t2 and t7-t8, the magnetizing inductor current Imag provides energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns*V. O1Where Vin is the input voltage, Np is the number of turns in the primary winding of transformer T, Ns is the number of turns in the secondary winding of transformer T, and V... O1 This is the first output voltage.

[0125] At times t2 and t8, the first output circuit 500 is turned off, and the second output circuit 600 is turned on.

[0126] During the time periods t2-t3 and t8-t9, the magnetizing inductor current Imag continues to supply energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns * V. O2 .

[0127] At times t3 and t9, the magnetizing inductor current Imag crosses zero, and the primary switch Q2 is turned off.

[0128] During the t3-t4 time period, the flyback converter 1000 enters a free resonance state.

[0129] During the time period t4-t5, before the primary switch Q1 changes from off to on, i.e., before the primary switch Q1 turns on again, the primary switch Q2 is turned on for a preset duration. Since the second output circuit 600 remains on during this period, the output control circuit 100 can control the second output circuit 600 to reverse-energize the magnetizing inductor of the transformer T, enabling the primary switch Q1 to achieve zero-voltage turn-on. This preset duration is specified in the original text.

[0130] like Figure 7 As shown, under DCM, due to the first output voltage V O1 Second output voltage V O2 Therefore, the output control circuit 100 can determine that the second output circuit 600 is the first freewheeling circuit and the first output circuit 500 is the second freewheeling circuit.

[0131] During the time periods t0-t1 and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During this period, i.e., while the primary switch Q1 is on, the first output circuit 500, which serves as the second freewheeling circuit, is turned off, and the second output circuit 600, which serves as the first freewheeling circuit, is turned on.

[0132] At times t1 and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0133] During the time periods t1-t2 and t7-t8, the magnetizing inductor current Imag supplies energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns * V. O2 .

[0134] At times t2 and t8, the second output circuit 600 is turned off, and the first output circuit 500 is turned on.

[0135] During the time periods t2-t3 and t8-t9, the magnetizing inductor current Imag continues to supply energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns * V. O1 .

[0136] At times t3 and t9, the magnetizing inductor current Imag crosses zero, and the primary switch Q2 is turned off.

[0137] During the t3-t4 time period, the flyback converter 1000 enters a free resonance state.

[0138] During the time period t4-t5, before the primary switch Q1 changes from off to on, i.e., before the primary switch Q1 turns on again, the primary switch Q2 is turned on for a preset duration. Since the first output circuit 500 is still in the on state during this period, the output control circuit 100 can control the first output circuit 500 to reverse-energize the magnetizing inductor of the transformer T, enabling the primary switch Q1 to achieve zero-voltage turn-on. This time period is the preset duration.

[0139] like Figure 8 As shown, under CCM, due to the first output voltage V O1 Second output voltage V O2 Therefore, the output control circuit 100 determines that the first output circuit 500 is the first freewheeling circuit and the second output circuit 600 is the second freewheeling circuit.

[0140] During the time periods t0-t1, t3-t4, and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During these time periods, i.e., when the primary switch Q1 is on, the second output circuit 600, which serves as the second freewheeling circuit, is turned off, and the first output circuit 500, which serves as the first freewheeling circuit, is turned on.

[0141] At times t1, t4, and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0142] During the time periods t1-t2, t4-t5, and t7-t8, the magnetizing inductor current Imag provides energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns*V. O1 .

[0143] At times t2, t5, and t8, the first output circuit 500 is turned off, and the second output circuit 600 is turned on.

[0144] During the time periods t2-t3, t5-t6, and t8-t9, the magnetizing inductor current Imag continues to supply energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns*V. O2 .

[0145] At times t3, t6, and t9, the magnetizing inductor current Imag has not been demagnetized to zero, so the primary switch Q2 is turned off and the primary switch Q1 is turned on.

[0146] As another feasible implementation of the output control circuit 100, refer to Figure 9 , Figure 9 This is a schematic diagram of another output control circuit in a flyback converter provided in an embodiment of this application. Figure 9 As shown, the output control circuit 100 may include: a freewheeling sequence determination circuit 110, a power determination circuit 120, and a first comparator Compa1.

[0147] The first input terminal of the first comparator Compa1 and the first input terminal of the power determination circuit 120 are both electrically connected to the output terminal of the first output circuit 500. The second input terminal of the first comparator Compa1 and the second input terminal of the power determination circuit 120 are both electrically connected to the output terminal of the second output circuit 600. The output terminal of the first comparator Compa1 is electrically connected to the first input terminal of the freewheeling sequence determination circuit 110. The output terminal of the power determination circuit 120 is electrically connected to the second input terminal of the freewheeling sequence determination circuit 110. The output terminal of the freewheeling sequence determination circuit 110 is electrically connected to the control terminal of the first output circuit 500 and the control terminal of the second output circuit 600, respectively.

[0148] The freewheeling sequence determination circuit 110, the power determination circuit 120, and the first comparator Compa1 can be set separately or integrated. This application embodiment does not specifically limit this.

[0149] Wherein, the first input terminal of the first comparator Compa1 and the first input terminal of the power determination circuit 120 are both the first input terminals of the output control circuit 100, the second input terminal of the first comparator Compa1 and the second input terminal of the power determination circuit 120 are both the second input terminals of the output control circuit 100, and the output terminal of the freewheeling sequence determination circuit 110 is the output terminal of the output control circuit 100.

[0150] In this embodiment, the first input terminal of the first comparator Compa1 can be either a positive or negative input terminal, and this application does not specifically limit this. Correspondingly, the second input terminal of the first comparator Compa1 can be either a negative or positive input terminal, and this application does not specifically limit this.

[0151] The following is combined with Figure 10 , Figure 10 for Figure 9 A schematic diagram of the control flow of the output control circuit is shown. The working principle of the output control circuit 100 is explained in detail below:

[0152] The first comparator Compa1 can compare the first output voltage V. O1 Second output voltage V O2 The first comparison result is obtained by determining the magnitude of the first comparison result. Furthermore, the first comparator Compa1 can transmit the first comparison result to the freewheeling sequence determination circuit 110, so that the freewheeling sequence determination circuit 110 can obtain the first comparison result.

[0153] The power determination circuit 120 can determine the power based on the first output voltage V. O1 Second output voltage V O2 The power determination circuit 120 can transmit the power determination result to the freewheeling sequence determination circuit 110, so that the freewheeling sequence determination circuit 110 can obtain the power determination result.

[0154] Thus, the freewheeling sequence determination circuit 110 can determine the first freewheeling loop and the second freewheeling loop in the first output circuit 500 and the second output circuit 600 based on the first comparison result and the power determination result. Consequently, the output control circuit 100 can determine the first freewheeling loop and the second freewheeling loop.

[0155] Since the output circuit corresponding to the first freewheeling circuit has a heavy or medium load, while the output circuit corresponding to the second freewheeling circuit has a light load, the output voltage ripple caused by the magnetizing inductor current Imag supplying energy to the first freewheeling circuit is smaller when the magnetizing inductor current Imag is larger, and the output voltage ripple caused by the magnetizing inductor current Imag supplying energy to the second freewheeling circuit is smaller when the magnetizing inductor current Imag is smaller. Therefore, the output voltage ripple can be improved.

[0156] For example, such as Figure 10As shown, after the magnetizing inductor current Imag in transformer T crosses zero, that is, when the flyback converter 1000 is in DCM (Distributed Current Management), before the primary switch Q1 changes from off to on, the output control circuit 100 can control the second freewheeling circuit to reverse-energize the transformer T within a preset time during which the primary switch Q2 is on, so that the primary switch Q2 can achieve zero-voltage turn-on. This reduces the losses generated by the flyback converter 1000 and improves its efficiency.

[0157] In summary, the first comparator compares the magnitudes of the first and second output voltages to obtain a first comparison result, which is then transmitted to the freewheeling sequence determination circuit, enabling the freewheeling sequence determination circuit to acquire the first comparison result. The power determination circuit determines the power based on the first and second output voltages and transmits the power determination result to the freewheeling sequence determination circuit, enabling the freewheeling sequence determination circuit to acquire the power determination result. Furthermore, the freewheeling sequence determination circuit can determine the first and second freewheeling loops in the first and second output circuits based on the first comparison result and the power determination result. Therefore, the output control circuit can determine the first and second freewheeling loops in the first and second output circuits.

[0158] Based on the description of the above embodiments, an exemplary possible implementation of the power determination circuit 120 is provided. For example... Figure 9 As shown, the power determination circuit 120 may include: a first power determination circuit 121 and a second power determination circuit 122.

[0159] The input terminal of the first power determination circuit 121 is electrically connected to the output terminal of the first output circuit 500, the input terminal of the second power determination circuit 122 is electrically connected to the output terminal of the second output circuit 600, the output terminals of the first power determination circuit 121 and the second power determination circuit 122 are both electrically connected to the second input terminal of the freewheeling sequence determination circuit 110, the first terminal of the first power determination circuit 121 is electrically connected to the first terminal of the second power determination circuit 122, and the second terminal of the first power determination circuit 121 is electrically connected to the second terminal of the second power determination circuit 122.

[0160] Wherein, the input terminal of the first power determination circuit 121 is the first input terminal of the power determination circuit 120, the input terminal of the second power determination circuit 122 is the second input terminal of the power determination circuit 120, and the output terminals of the first power determination circuit 121 and the second power determination circuit 122 are both output terminals of the power determination circuit 120.

[0161] The first power determination circuit 121 can determine the power based on the first output voltage V. O1 The first feedback voltage V is obtained. FB1.

[0162] Among them, the first feedback voltage V FB1 Used to characterize the power of the first output circuit 500.

[0163] The second power determination circuit 122 can determine the power based on the second output voltage V. O2 The second feedback voltage V is obtained. FB2 .

[0164] Among them, the second feedback voltage V FB2 Used to characterize the power of the second output circuit 600.

[0165] First output voltage V O1 Greater than the second output voltage V O2 In this case, the first power determination circuit 121 can compare the first feedback voltage V. FB1 and the first preset voltage V FBH The size of the two values ​​is used to obtain the second comparison result.

[0166] The power determination result may include: a second comparison result and a third comparison result. The first preset voltage V FBH Used to determine whether the load of the first output circuit 500 or the load of the second output circuit 600 is overloaded.

[0167] The second power determination circuit 122 can compare the second feedback voltage V. FB2 Second preset voltage V FBL The size of the values ​​is used to obtain the third comparison result.

[0168] Among them, the second preset voltage V FBL Used to determine whether the load of the first output circuit 500 or the load of the second output circuit 600 is lightly loaded.

[0169] Based on this, the power determination circuit 120 can determine the first output voltage V. O1 Second output voltage V O2 The power determination result is obtained.

[0170] First output voltage V O1 Less than the second output voltage V O2 In this case, the first power determination circuit 121 can obtain the second feedback voltage V from the second power determination circuit 122. FB2 Furthermore, the first power determination circuit 121 can compare the second feedback voltage V. FB2 and the first preset voltage V FBH The size of the two values ​​is used to obtain the second comparison result.

[0171] The second power determination circuit 122 can obtain the first feedback voltage V from the first power determination circuit 121.FB1 Furthermore, the second power determination circuit 122 can compare the first feedback voltage V. FB1 Second preset voltage V FBL The size of the values ​​is used to obtain the third comparison result.

[0172] Based on this, the power determination circuit 120 can determine the first output voltage V. O1 Second output voltage V O2 The power determination result is obtained.

[0173] In summary, the first power determination circuit can obtain a first feedback voltage characterizing the power of the first output circuit based on the first output voltage. The second power determination circuit can obtain a second feedback voltage characterizing the power of the second output circuit based on the second output voltage. Thus, when the first output voltage is greater than the second output voltage, the first power determination circuit can compare the first feedback voltage with a first preset voltage to obtain a second comparison result. The second power determination circuit can obtain a third comparison result based on the second feedback voltage and the second preset voltage. Alternatively, when the first output voltage is less than the second output voltage, the first power determination circuit can obtain the second feedback voltage from the second power determination circuit and compare the second feedback voltage with the first preset voltage to obtain the second comparison result. The second power determination circuit can obtain the first feedback voltage from the first power determination circuit and compare the first feedback voltage with the second preset voltage to obtain the third comparison result. Therefore, the power determination circuit can obtain a power determination result based on the first output voltage and the second output voltage.

[0174] The following is combined with Figure 11 , Figure 11 It shows Figure 9 A flowchart illustrating how the freewheeling sequence determination circuit 110 determines the first and second freewheeling loops is provided. The details of how the freewheeling sequence determination circuit 110 determines the first and second freewheeling loops are as follows:

[0175] The first comparison result satisfies the first output voltage V O1 Less than the second output voltage V O2 Under the first preset condition, the freewheeling sequence determination circuit 110 can determine whether the second comparison result and the third comparison result satisfy the first feedback voltage V. FB1 Less than the second preset voltage V FBL And the second feedback voltage V FB2 Greater than the first preset voltage V FBH That is, the second preset condition.

[0176] If the second comparison result and the third comparison result meet the second preset condition, the freewheeling sequence determination circuit 110 can determine the second output circuit 600 as the first freewheeling loop and the first output circuit 500 as the second freewheeling loop.

[0177] If the second comparison result and the third comparison result do not meet the second preset condition, the freewheeling sequence determination circuit 110 can determine the first output circuit 500 as the first freewheeling loop and the second output circuit 600 as the second freewheeling loop.

[0178] Where the second comparison result and the third comparison result do not meet the second preset condition, due to the first output voltage V O1 Less than the second output voltage V O2 Therefore, the first output circuit 500 is a low-voltage circuit, and the second output circuit 600 is a high-voltage circuit. Thus, the freewheeling sequence determination circuit 110 determines that the low-voltage circuit is the first freewheeling circuit and the high-voltage circuit is the second freewheeling circuit, ensuring that the voltage Vds across the primary switch Q1 does not trigger the detection threshold. This prevents the flyback converter 1000 from entering an abnormal operating state and improves its anti-interference performance.

[0179] If the first comparison result does not meet the first preset condition, the freewheeling sequence determination circuit 110 can determine whether the second comparison result and the third comparison result meet the first feedback voltage V. FB1 Greater than the first preset voltage V FBH And the second feedback voltage V FB2 Less than the second preset voltage V FBL That is, the third preset condition.

[0180] If the second comparison result and the third comparison result satisfy the third preset condition, the freewheeling sequence determination circuit 110 can determine the first output circuit 500 as the first freewheeling loop and the second output circuit 600 as the second freewheeling loop.

[0181] If the second comparison result and the third comparison result do not meet the third preset condition, the freewheeling sequence determination circuit 110 can determine the second output circuit 600 as the first freewheeling loop and the first output circuit 500 as the second freewheeling loop.

[0182] Among them, if the second comparison result and the third comparison result do not meet the third preset condition, the first output voltage V O1 Greater than the second output voltage V O2Therefore, the first output circuit 500 is a high-voltage circuit, and the second output circuit 600 is a low-voltage circuit. Thus, the freewheeling sequence determination circuit 110 determines that the low-voltage circuit is the first freewheeling circuit and the high-voltage circuit is the second freewheeling circuit, ensuring that the voltage Vds across the primary switch Q1 does not trigger the detection threshold. This prevents the flyback converter 1000 from entering an abnormal operating state and improves its anti-interference performance.

[0183] In some examples, the first preset condition is the first output voltage V. O1 Less than the second output voltage V O2 The second preset condition is the first feedback voltage V. FB1 Less than the second preset voltage V FBL And the second feedback voltage V FB2 Greater than the first preset voltage V FBH The third preset condition is the first feedback voltage V. FB1 Greater than the first preset voltage V FBH And the second feedback voltage V FB2 Less than the second preset voltage V FBL .

[0184] Based on the description of the above embodiments, an exemplary possible implementation of the first power determination circuit 121 is provided. For example... Figure 9 As shown, the first power determination circuit 121 may include: a first operational amplifier EA1, a second comparator Compa2, a first capacitor C1, a first resistor R1, a first switch S1, and a second switch S2.

[0185] The non-inverting input of the first operational amplifier EA1 is used to connect to the first reference voltage Vref1. The non-inverting input of the first operational amplifier EA1 and the first plate of the first capacitor C1 are both electrically connected to the output of the first output circuit 500. The second plate of the first capacitor C1 is electrically connected to the first end of the first resistor R1. The output of the first operational amplifier EA1 is electrically connected to the first end of the first switch S1, the first end of the second switch S2, and the second end of the first resistor R1. The second end of the first switch S1 is electrically connected to the non-inverting input of the second comparator Compa2 and the first end of the second power determination circuit 122. The non-inverting input of the second comparator Compa2 is used to connect to the first preset voltage V. FBH The output of the second comparator Compa2 is electrically connected to the second input of the freewheeling sequence determination circuit 110. The second terminal of the second switch S2 is electrically connected to the second terminal of the second power determination circuit 122. The control terminals of the first switch S1 and the second switch S2 are used to receive the first control signal. The first control signal is used to control the first switch S1 and the second switch S2 to turn on or off according to the first comparison result.

[0186] In this circuit, the negative input terminal of the first operational amplifier EA1 is the input terminal of the first power determination circuit 121, the output terminal of the second comparator Compa2 is the output terminal of the first power determination circuit 121, the second terminal of the first switch S1 is the first terminal of the first power determination circuit 121, and the second terminal of the second switch S2 is the second terminal of the first power determination circuit 121.

[0187] The first switch S1 and the second switch S2 may include, but are not limited to, gallium nitride transistors, bipolar junction transistors, insulated gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, field-controlled thyristors, gate turn-off thyristors, and transmission gates.

[0188] For example, when the first switch S1 and the second switch S2 are gallium nitride transistors, the control terminal of the first switch S1 and the second switch S2 refers to the gate of the gallium nitride transistor. The first terminal of the first switch S1 and the second switch S2 can be the drain or source of the gallium nitride transistor. Correspondingly, the second terminal of the first switch S1 and the second switch S2 can be the source or drain of the gallium nitride transistor.

[0189] For example, when the first switch S1 and the second switch S2 are bipolar junction transistors, the control terminal of the first switch S1 and the second switch S2 refers to the base of the bipolar junction transistor. The first terminal of the first switch S1 and the second switch S2 can be the collector or emitter of the bipolar junction transistor. Correspondingly, the second terminal of the first switch S1 and the second switch S2 can be the emitter or collector of the bipolar junction transistor.

[0190] For example, when the first switch S1 and the second switch S2 are insulated gate bipolar transistors (IGBTs), the control terminal of the first switch S1 and the second switch S2 refers to the gate of the IGBT. The first terminal of the first switch S1 and the second switch S2 can be the collector or emitter of the IGBT. Correspondingly, the second terminal of the first switch S1 and the second switch S2 can be the emitter or collector of the IGBT.

[0191] For example, when the first switch S1 and the second switch S2 are metal-oxide-semiconductor field-effect transistors, the control terminals of the first switch S1 and the second switch S2 refer to the gates of the metal-oxide-semiconductor field-effect transistors. The first terminals of the first switch S1 and the second switch S2 can be the drain or source of the metal-oxide-semiconductor field-effect transistors. Correspondingly, the second terminals of the first switch S1 and the second switch S2 can be the source or drain of the metal-oxide-semiconductor field-effect transistors.

[0192] For example, when the first switch S1 and the second switch S2 are field-controlled thyristors, the control terminal of the first switch S1 and the second switch S2 refers to the gate of the field-controlled thyristor. The first terminal of the first switch S1 and the second switch S2 can be the drain or source of the field-controlled thyristor. Correspondingly, the second terminal of the first switch S1 and the second switch S2 can be the source or drain of the field-controlled thyristor.

[0193] For example, when the first switch S1 and the second switch S2 are gate turn-off thyristors, the control terminals of the first switch S1 and the second switch S2 refer to the gate of the gate turn-off thyristor. The first terminals of the first switch S1 and the second switch S2 can be the cathode or anode of the gate turn-off thyristor. Correspondingly, the second terminals of the first switch S1 and the second switch S2 can be the cathode or anode of the gate turn-off thyristor.

[0194] For example, when the first switch S1 and the second switch S2 are transmission gates, the control terminals of the first switch S1 and the second switch S2 refer to the ports of the transmission gate used to receive gate control signals. The first terminals of the first switch S1 and the second switch S2 can be the input terminals or output terminals of the transmission gate. Correspondingly, the second terminals of the first switch S1 and the second switch S2 can be the input terminals or output terminals of the transmission gate.

[0195] Wherein, the first comparison result characterizes the first output voltage V O1 Greater than the second output voltage V O2 At that time, the first control signal controls the first switch S1 to turn on and the second switch S2 to turn off. The first comparison result characterizes the first output voltage V. O1 Less than the second output voltage V O2 At that time, the first control signal controls the first switch S1 to turn off and the second switch S2 to turn on.

[0196] The first operational amplifier EA1 can amplify the first output voltage V. O1 The voltage difference between the first reference voltage Vref1 and the first reference voltage Vref1, and with compensation from the first resistor R1 and the first capacitor C1, yields the first feedback voltage V. FB1 And transmits the first feedback voltage V to the second comparator Compa2. FB1 This allows the second comparator Compa2 to acquire the first feedback voltage V. FB1 .

[0197] Thus, the second comparator Compa2 can compare the first feedback voltage V. FB1 and the first preset voltage V FBH The magnitude of the voltage is used to obtain the second comparison result. Alternatively, the second comparator Compa2 can obtain the second feedback voltage V from the second power determination circuit 122. FB2Furthermore, the second comparator Compa2 can compare the second feedback voltage V. FB2 With the first preset voltage V FBH The size of the two values ​​is used to obtain the second comparison result.

[0198] Therefore, the first power determination circuit 121 can compare the first feedback voltage V FB1 and the first preset voltage V FBH The magnitude or comparison of the second feedback voltage V FB2 and the first preset voltage V FBH The size of the two values ​​is used to obtain the second comparison result.

[0199] In summary, the first operational amplifier amplifies the voltage difference between the first output voltage and the first reference voltage, and, with compensation from the first resistor and the first capacitor, obtains a first feedback voltage. This first feedback voltage is then transmitted to the second comparator, enabling the second comparator to acquire the first feedback voltage. The second comparator can compare the magnitude of the first feedback voltage with a first preset voltage to obtain a second comparison result, or it can obtain the second feedback voltage from the second power determination circuit and compare it with the first preset voltage to obtain a second comparison result. Therefore, the first power determination circuit can obtain the second comparison result.

[0200] Based on the description of the above embodiments, an exemplary possible implementation of the second power determination circuit 122 is provided. For example... Figure 9 As shown, the second power determination circuit 122 may include: a second operational amplifier EA2, a third comparator Compa3, a second capacitor C2, a second resistor R2, a third switch S3, and a fourth switch S4.

[0201] The non-inverting input of the second operational amplifier EA2 is used to connect to the second reference voltage Vref2. The negative-inverting input of the second operational amplifier EA2 and the first plate of the second capacitor C2 are both electrically connected to the output of the second output circuit 600. The second plate of the second capacitor C2 is electrically connected to the first end of the second resistor R2. The output of the second operational amplifier EA2 is electrically connected to the first ends of the third switch S3, the fourth switch S4, and the second end of the second resistor R2, respectively. The second end of the third switch S3 is electrically connected to the first end of the first power determination circuit 121. The second end of the fourth switch S4 is electrically connected to the negative-inverting input of the third comparator Compa3 and the second end of the first power determination circuit 121, respectively. The negative-inverting input of the third comparator Compa3 is used to connect to the second preset voltage V. FBLThe output of the second comparator Compa2 is electrically connected to the third input of the freewheeling sequence determination circuit 110. The control terminals of the third switch S3 and the fourth switch S4 are used to receive the second control signal. The second control signal is used to control the third switch S3 and the fourth switch S4 to turn on or off according to the first comparison result.

[0202] In this circuit, the negative input terminal of the second operational amplifier EA2 is the input terminal of the second power determination circuit 122, the output terminal of the second comparator Compa2 is the output terminal of the second power determination circuit 122, the second terminal of the third switch S3 is the first terminal of the second power determination circuit 122, and the second terminal of the fourth switch S4 is the second terminal of the second power determination circuit 122.

[0203] Among them, the third switch S3 and the fourth switch S4 may include, but are not limited to, gallium nitride transistors, bipolar junction transistors, insulated gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, field-controlled thyristors, gate turn-off thyristors, and transmission gates.

[0204] For example, when the third switch S3 and the fourth switch S4 are gallium nitride transistors, the control terminal of the third switch S3 and the fourth switch S4 refers to the gate of the gallium nitride transistor, the first terminal of the third switch S3 and the fourth switch S4 can be the drain or source of the gallium nitride transistor, and correspondingly, the second terminal of the third switch S3 and the fourth switch S4 can be the source or drain of the gallium nitride transistor.

[0205] For example, when the third switch S3 and the fourth switch S4 are bipolar junction transistors, the control terminal of the third switch S3 and the fourth switch S4 refers to the base of the bipolar junction transistor. The first terminal of the third switch S3 and the fourth switch S4 can be the collector or emitter of the bipolar junction transistor. Correspondingly, the second terminal of the third switch S3 and the fourth switch S4 can be the emitter or collector of the bipolar junction transistor.

[0206] For example, when the third switch S3 and the fourth switch S4 are insulated-gate bipolar transistors (IGBTs), the control terminals of the third switch S3 and the fourth switch S4 refer to the gate of the IGBT. The first terminals of the third switch S3 and the fourth switch S4 can be the collector or emitter of the IGBT. Correspondingly, the second terminals of the third switch S3 and the fourth switch S4 can be the emitter or collector of the IGBT.

[0207] For example, when the third switch S3 and the fourth switch S4 are metal-oxide-semiconductor field-effect transistors (MOSFETs), the control terminals of the third switch S3 and the fourth switch S4 refer to the gates of the MOSFETs. The first terminals of the third switch S3 and the fourth switch S4 can be the drain or source of the MOSFETs. Correspondingly, the second terminals of the third switch S3 and the fourth switch S4 can be the source or drain of the MOSFETs.

[0208] For example, when the third switch S3 and the fourth switch S4 are field-controlled thyristors, the control terminal of the third switch S3 and the fourth switch S4 refers to the gate of the field-controlled thyristor, and the first terminal of the third switch S3 and the fourth switch S4 can be the drain or source of the field-controlled thyristor. Correspondingly, the second terminal of the third switch S3 and the fourth switch S4 can be the source or drain of the field-controlled thyristor.

[0209] For example, when the third switch S3 and the fourth switch S4 are gate turn-off thyristors, the control terminals of the third switch S3 and the fourth switch S4 refer to the gate of the gate turn-off thyristor. The first terminal of the third switch S3 and the fourth switch S4 can be the cathode or anode of the gate turn-off thyristor. Correspondingly, the second terminal of the third switch S3 and the fourth switch S4 can be the cathode or anode of the gate turn-off thyristor.

[0210] For example, when the third switch S3 and the fourth switch S4 are transmission gates, the control terminals of the third switch S3 and the fourth switch S4 refer to the ports of the transmission gate used to receive gate control signals. The first terminals of the third switch S3 and the fourth switch S4 can be the input or output terminals of the transmission gate. Correspondingly, the second terminals of the third switch S3 and the fourth switch S4 can be the input or output terminals of the transmission gate.

[0211] Wherein, the first comparison result characterizes the first output voltage V O1 Greater than the second output voltage V O2 At that time, the second control signal controls the third switch S3 to turn off and the fourth switch S4 to turn on. The first comparison result characterizes the first output voltage V. O1 Less than the second output voltage V O2 At that time, the second control signal controls the third switch S3 to turn on and the fourth switch S4 to turn off.

[0212] The second operational amplifier EA2 can amplify the second output voltage V. O2 The voltage difference between the second reference voltage Vref2 and the second reference voltage V, and the compensation by the second resistor R2 and the second capacitor C2, yield the second feedback voltage V. FB2 And transmits the second feedback voltage V to the third comparator Compa3. FB2This allows the third comparator Compa3 to acquire the second feedback voltage V. FB2 .

[0213] Thus, the third comparator Compa3 can compare the second feedback voltage V. FB2 Second preset voltage V FBL The magnitude of the voltage is used to obtain the third comparison result. Alternatively, the third comparator Compa3 can obtain the first feedback voltage V from the first power determination circuit 121. FB1 Furthermore, the third comparator Compa3 can provide the first feedback voltage V. FB1 With the second preset voltage V FBL The size of the third comparison result.

[0214] Therefore, the second power determination circuit 122 can compare the second feedback voltage V. FB2 Second preset voltage V FBL The magnitude, or compared with the first feedback voltage V FB1 Second preset voltage V FBL The size of the values ​​is used to obtain the third comparison result.

[0215] In summary, the second operational amplifier amplifies the voltage difference between the second output voltage and the second reference voltage. With compensation from the second resistor and the second capacitor, a second feedback voltage is obtained, which is then transmitted to the third comparator, enabling the third comparator to acquire the second feedback voltage. The third comparator can compare the magnitude of the second feedback voltage with the second preset voltage to obtain a third comparison result, or it can obtain the first feedback voltage from the first power determination circuit and compare its magnitude with the second preset voltage to obtain a third comparison result. Therefore, the second power determination circuit can obtain the third comparison result.

[0216] The following is combined with Figures 12-14 , Figures 12-14 All showed Figure 9 A schematic diagram of the working waveforms of the flyback converter. A detailed explanation of how the output control circuit 100 controls the operation of the flyback converter 1000 under DCM and CCM conditions.

[0217] like Figure 12 As shown, under DCM, due to the first output voltage V O1 Second output voltage V O2 First feedback voltage V FB1 Second preset voltage V FBL Second feedback voltage V FB2 <First preset voltage V FBH Therefore, the output control circuit 100 can determine that the first output circuit 500 is the first freewheeling circuit and the second output circuit 600 is the second freewheeling circuit.

[0218] During the time periods t0-t1 and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During this period, i.e., when the primary switch Q1 is on, the second output circuit 600, which serves as the second freewheeling circuit, is turned off, and the first output circuit 500, which serves as the first freewheeling circuit, is turned on.

[0219] At times t1 and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0220] During the time periods t1-t2 and t7-t8, the magnetizing inductor current Imag supplies energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + NV. O1 Where N is Np / Ns.

[0221] At times t2 and t8, the first output circuit 500 is turned off, and the second output circuit 600 is turned on.

[0222] During the time periods t2-t3 and t8-t9, the magnetizing inductor current Imag continues to supply energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + NV. O2 .

[0223] At times t3 and t9, the magnetizing inductor current Imag crosses zero, and the primary switch Q2 is turned off.

[0224] During the t3-t4 time period, the flyback converter 1000 enters a free resonance state.

[0225] During the time period t4-t5, before the primary switch Q1 changes from off to on, i.e., before the primary switch Q1 turns on again, the primary switch Q2 is turned on for a preset duration. Since the second output circuit 600 remains on during this period, the output control circuit 100 can control the second output circuit 600 to reverse-energize the magnetizing inductor of the transformer T, enabling the primary switch Q1 to achieve zero-voltage turn-on. This time period is a preset duration.

[0226] like Figure 13 As shown, under DCM, due to the first output voltage V O1 Second output voltage V O2 First feedback voltage V FB1 Second preset voltage V FBL Second feedback voltage V FB2 First preset voltage V FBHTherefore, the output control circuit 100 can determine that the second output circuit 600 is the first freewheeling circuit and the first output circuit 500 is the second freewheeling circuit.

[0227] During the time periods t0-t1 and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During this period, i.e., when the primary switch Q1 is on, the first output circuit 500, which serves as the second freewheeling circuit, is turned off, and the second output circuit 600, which serves as the first freewheeling circuit, is turned on.

[0228] At times t1 and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0229] During the time periods t1-t2 and t7-t8, the magnetizing inductor current Imag supplies energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + NV. O2 Where N is Np / Ns.

[0230] At times t2 and t8, the second output circuit 600 is turned off, and the first output circuit 500 is turned on.

[0231] During the time periods t2-t3 and t8-t9, the magnetizing inductor current Imag continues to supply energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + NV. O1 .

[0232] At times t3 and t9, the magnetizing inductor current Imag crosses zero, and the primary switch Q2 is turned off.

[0233] During the t3-t4 time period, the flyback converter 1000 enters a free resonance state.

[0234] During the time period t4-t5, before the primary switch Q1 changes from off to on, i.e., before the primary switch Q1 turns on again, the primary switch Q2 is turned on for a preset duration. Since the first output circuit 500 remains on during this period, the output control circuit 100 can control the first output circuit 500 to reverse-energize the magnetizing inductor of the transformer T, enabling the primary switch Q1 to achieve zero-voltage turn-on. This time period is the preset duration.

[0235] like Figure 14 As shown, under CCM, due to the first output voltage V O1 Second output voltage V O2 First feedback voltage V FB1 Second preset voltage V FBL Second feedback voltage V FB2 First preset voltage VFBH Therefore, the output control circuit 100 can determine that the first output circuit 500 is the first freewheeling circuit and the second output circuit 600 is the second freewheeling circuit.

[0236] During the time periods t0-t1, t3-t4, and t6-t7, the primary switch Q1 is in the on state, and the magnetizing inductor current Imag increases linearly. During these time periods, i.e., when the primary switch Q1 is on, the second output circuit 600, which serves as the second freewheeling circuit, is turned off, and the first output circuit 500, which serves as the first freewheeling circuit, is turned on.

[0237] At times t1, t4, and t7, primary switch Q1 is turned off, and primary switch Q2 is turned on.

[0238] During the time periods t1-t2, t4-t5, and t7-t8, the magnetizing inductor current Imag provides energy to the first output circuit 500. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns*V. O1 .

[0239] At times t2, t5, and t8, the first output circuit 500 is turned off, and the second output circuit 600 is turned on.

[0240] During the time periods t2-t3, t5-t6, and t8-t9, the magnetizing inductor current Imag continues to supply energy to the second output circuit 600. During these periods, the voltage Vds across the primary switch Q1 is Vin + Np / Ns*V. O2 .

[0241] At times t3, t6, and t9, the magnetizing inductor current Imag has not been demagnetized to zero, so the primary switch Q2 is turned off and the primary switch Q1 is turned on.

[0242] Based on the description of the above embodiments, an exemplary possible implementation of the first output circuit 500 is provided. Figure 3 , Figure 4 and Figure 9 As shown, the first output circuit 500 may include: a second-stage switch Q3, a third-stage switch Q4, a first load resistor Rload1, and a first output capacitor Cout1.

[0243] The first terminal of the second-stage switch Q3 is electrically connected to the corresponding terminal of the secondary winding. The second terminal of the second-stage switch Q3 is electrically connected to the first terminal of the third-stage switch Q4. The control terminals of the second-stage switch Q3 and the third-stage switch Q4 are both electrically connected to the output terminal of the output control circuit 100. The second terminal of the third-stage switch Q4 is electrically connected to the first plate of the first output capacitor Cout1, the first terminal of the first output capacitor Cout1, and the first input terminal of the output control circuit 100, respectively. The second plate of the first output capacitor Cout1 and the first terminal of the first output capacitor Cout1 are both grounded.

[0244] Among them, the second-stage switch Q3 and the third-stage switch Q4 can be, but are not limited to, gallium nitride transistors, bipolar junction transistors, insulated gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, field-controlled thyristors, gate turn-off thyristors, and transmission gates.

[0245] For example, when the second-stage switch Q3 and the third-stage switch Q4 are gallium nitride transistors, the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the gate of the gallium nitride transistor. The first terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the drain or source of the gallium nitride transistor. Correspondingly, the second terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the source or drain of the gallium nitride transistor.

[0246] For example, when the second-stage switch Q3 and the third-stage switch Q4 are bipolar junction transistors (BJTs), the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the base of the BJTs. The first terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the collector or emitter of the BJTs. Correspondingly, the second terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the emitter or collector of the BJTs.

[0247] For example, when the second-stage switch Q3 and the third-stage switch Q4 are insulated-gate bipolar transistors (IGBTs), the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the gate of the IGBT. The first terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the collector or emitter of the IGBT. Correspondingly, the second terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the emitter or collector of the IGBT.

[0248] For example, when the second-stage switch Q3 and the third-stage switch Q4 are metal-oxide-semiconductor field-effect transistors (MOSFETs), the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the gates of the MOSFETs. The first terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the drain or source of the MOSFET. Correspondingly, the second terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the source or drain of the MOSFET.

[0249] For example, when the second-stage switch Q3 and the third-stage switch Q4 are field-controlled thyristors, the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the gate of the field-controlled thyristor. The first terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the drain or source of the field-controlled thyristor. Correspondingly, the second terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the source or drain of the field-controlled thyristor.

[0250] For example, when the second-stage switch Q3 and the third-stage switch Q4 are gate turn-off thyristors, the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the gate of the gate turn-off thyristor. The first terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the cathode or anode of the gate turn-off thyristor. Correspondingly, the second terminal of the second-stage switch Q3 and the third-stage switch Q4 can be the cathode or anode of the gate turn-off thyristor.

[0251] For example, when the second-stage switch Q3 and the third-stage switch Q4 are transmission gates, the control terminals of the second-stage switch Q3 and the third-stage switch Q4 refer to the ports of the transmission gates used to receive gate control signals. The first terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the input or output terminals of the transmission gates. Correspondingly, the second terminals of the second-stage switch Q3 and the third-stage switch Q4 can be the input or output terminals of the transmission gates.

[0252] Furthermore, the second-stage switch Q3 and the third-stage switch Q4 can be replaced by a bidirectional gallium nitride (GaN) transistor.

[0253] Based on the description of the above embodiments, an exemplary possible implementation of the second output circuit 600 is provided. Figure 3 , Figure 4 and Figure 9 As shown, the first output circuit 600 may include: a fourth secondary switch Q5, a fifth secondary switch Q6, a second load resistor Rload2, and a second output capacitor Cout2.

[0254] The first terminal of the fourth secondary switch Q5 is electrically connected to the opposite terminal of the secondary winding. The second terminal of the fourth secondary switch Q5 is electrically connected to the first terminal of the fifth secondary switch Q6. The control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 are both electrically connected to the output terminal of the output control circuit 100. The fourth control signal is used to control the conduction or cutoff of the fourth secondary switch Q5 and the fifth secondary switch Q6. The second terminal of the fifth secondary switch Q6 is electrically connected to the first plate of the second output capacitor Cout2, the first terminal of the second output capacitor Cout2, and the second input terminal of the output control circuit 100, respectively. The second plate of the second output capacitor Cout2 and the first terminal of the second output capacitor Cout2 are both grounded.

[0255] The fourth secondary switch Q5 and the fifth secondary switch Q6 may include, but are not limited to, gallium nitride transistors, bipolar junction transistors, insulated gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, field-controlled thyristors, gate turn-off thyristors, and transmission gates.

[0256] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are gallium nitride transistors, the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the gate of the gallium nitride transistor, and the first terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the drain or source of the gallium nitride transistor. Correspondingly, the second terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the source or drain of the gallium nitride transistor.

[0257] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are bipolar junction transistors (BJTs), the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the base of the BJTs. The first terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the collector or emitter of the BJTs. Correspondingly, the second terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the emitter or collector of the BJTs.

[0258] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are insulated-gate bipolar transistors (IGBTs), the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the gate of the IGBT. The first terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the collector or emitter of the IGBT. Correspondingly, the second terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the emitter or collector of the IGBT.

[0259] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are metal-oxide-semiconductor field-effect transistors (MOSFETs), the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the gate of the MOSFET. The first terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the drain or source of the MOSFET. Correspondingly, the second terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the source or drain of the MOSFET.

[0260] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are field-controlled thyristors, the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the gate of the field-controlled thyristor, and the first terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the drain or source of the field-controlled thyristor. Correspondingly, the second terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the source or drain of the field-controlled thyristor.

[0261] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are gate turn-off thyristors, the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the gate of the gate turn-off thyristor. The first terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the cathode or anode of the gate turn-off thyristor. Correspondingly, the second terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the cathode or anode of the gate turn-off thyristor.

[0262] For example, when the fourth secondary switch Q5 and the fifth secondary switch Q6 are transmission gates, the control terminals of the fourth secondary switch Q5 and the fifth secondary switch Q6 refer to the ports of the transmission gate used to receive the gate control signal. The first terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the input terminal or the output terminal of the transmission gate. Correspondingly, the second terminal of the fourth secondary switch Q5 and the fifth secondary switch Q6 can be the input terminal or the output terminal of the transmission gate.

[0263] Furthermore, the fourth secondary switch Q5 and the fifth secondary switch Q6 can be replaced by a bidirectional gallium nitride (GaN) transistor.

[0264] Based on the description of the above embodiments, an exemplary possible implementation of the absorption circuit 700 is provided. For example... Figure 3 , Figure 4 and Figure 9 As shown, the absorption circuit 700 may include: a capacitor Cclamp, a resistor Rclamp, and a diode D.

[0265] The first plate of capacitor Cclamp and the first terminal of resistor Rclamp are both electrically connected to the first terminal of inductor Lk. The second plate of capacitor Cclamp and the second terminal of resistor Rclamp are both electrically connected to the negative terminal of diode D. The positive terminal of diode D is electrically connected to the same terminal of the primary winding.

[0266] The input voltage can be provided by the input capacitor Cin.

[0267] The primary switching transistor Q2 can be either a rectifier configured for low-end synchronous rectification or a rectifier configured for high-end synchronous rectification; however, this embodiment does not specifically limit its configuration.

[0268] The isolated communication circuit 300 may include, but is not limited to, optocouplers, capacitive isolation, and inductive isolation.

[0269] The secondary controller 200 can be a synchronous rectifier controller, a protocol controller, or a combination of a synchronous rectifier controller and a protocol controller. This application does not specifically limit this.

[0270] Finally, it should be noted that the above embodiments are merely specific implementations of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. An output control circuit, characterized in that, The output control circuit is applied in a flyback converter, which includes a first output circuit and a second output circuit. The first input terminal of the output control circuit is electrically connected to the output terminal of the first output circuit, the second input terminal of the output control circuit is electrically connected to the output terminal of the second output circuit, and the output terminal of the output control circuit is electrically connected to the control terminals of the first output circuit and the second output circuit, respectively. The output control circuit is used to obtain a first output voltage from the first output circuit and a second output voltage from the second output circuit, and control the first output circuit and the second output circuit to be turned on sequentially according to the first output voltage and the second output voltage in each switching cycle, so as to determine a first freewheeling circuit and a second freewheeling circuit in the first output circuit and the second output circuit, so that the magnetizing inductance of the transformer in the flyback converter transfers energy in each switching cycle by high-frequency chopping, wherein the high-frequency chopping frequency of the first output circuit and the second output circuit is equal to the reciprocal of the switching cycle; The output control circuit includes: a freewheeling sequence determination circuit, a power determination circuit, and a first comparator; The first input terminal of the first comparator and the first input terminal of the power determination circuit are both electrically connected to the output terminal of the first output circuit. The second input terminal of the first comparator and the second input terminal of the power determination circuit are both electrically connected to the output terminal of the second output circuit. The output terminal of the first comparator is electrically connected to the first input terminal of the freewheeling sequence determination circuit. The output terminal of the power determination circuit is electrically connected to the second input terminal of the freewheeling sequence determination circuit. The output terminal of the freewheeling sequence determination circuit is electrically connected to the control terminal of the first output circuit and the control terminal of the second output circuit, respectively. The first comparator is used to compare the magnitudes of the first output voltage and the second output voltage, obtain a first comparison result, and transmit the first comparison result to the freewheeling sequence determination circuit; The power determination circuit is used to obtain a power determination result based on the first output voltage and the second output voltage, and to transmit the power determination result to the freewheeling sequence determination circuit. The freewheeling sequence determination circuit is used to determine the first freewheeling loop and the second freewheeling loop in the first output circuit and the second output circuit based on the first comparison result and the power determination result.

2. The output control circuit according to claim 1, characterized in that, The output control circuit includes: a freewheeling sequence determination circuit and a first comparator; The first input terminal of the first comparator is electrically connected to the output terminal of the first output circuit, the second input terminal of the first comparator is electrically connected to the output terminal of the second output circuit, the output terminal of the first comparator is electrically connected to the input terminal of the freewheeling sequence determination circuit, and the output terminal of the freewheeling sequence determination circuit is electrically connected to the control terminal of the first output circuit and the control terminal of the second output circuit, respectively. The first comparator is used to compare the magnitudes of the first output voltage and the second output voltage, obtain a first comparison result, and transmit the first comparison result to the freewheeling sequence determination circuit; The freewheeling sequence determination circuit is used to determine the first freewheeling circuit and the second freewheeling circuit in the first output circuit and the second output circuit according to the first comparison result.

3. The output control circuit according to claim 2, characterized in that, The freewheeling sequence determination circuit is used to determine, when the first comparison result indicates that the first output voltage is less than the second output voltage, that the first output circuit is the first freewheeling circuit and the second output circuit is the second freewheeling circuit, or to determine that the second output circuit is the first freewheeling circuit and the first output circuit is the second freewheeling circuit. or, The freewheeling sequence determination circuit is used to determine, when the first comparison result indicates that the first output voltage is greater than the second output voltage, that the second output circuit is the first freewheeling circuit and the first output circuit is the second freewheeling circuit, or to determine that the first output circuit is the first freewheeling circuit and the second output circuit is the second freewheeling circuit.

4. The output control circuit according to claim 1, characterized in that, The power determination circuit includes: a first power determination circuit and a second power determination circuit. The input terminal of the first power determination circuit is electrically connected to the output terminal of the first output circuit, the input terminal of the second power determination circuit is electrically connected to the output terminal of the second output circuit, the output terminals of the first power determination circuit and the second power determination circuit are both electrically connected to the second input terminal of the freewheeling sequence determination circuit, the first terminal of the first power determination circuit is electrically connected to the first terminal of the second power determination circuit, and the second terminal of the first power determination circuit is electrically connected to the second terminal of the second power determination circuit. The first power determination circuit is used to obtain a first feedback voltage based on the first output voltage, and the first feedback voltage is used to characterize the power of the first output circuit. The second power determination circuit is used to obtain a second feedback voltage based on the second output voltage, and the second feedback voltage is used to characterize the power of the second output circuit. The first power determination circuit is further configured to compare the magnitude of the first feedback voltage and the first preset voltage when the first output voltage is greater than the second output voltage, and obtain a second comparison result. The power determination result includes the second comparison result and a third comparison result. The first preset voltage is used to determine whether the load of the first output circuit or the load of the second output circuit is a heavy load. The second power determination circuit is further used to compare the magnitudes of the second feedback voltage and the second preset voltage when the first output voltage is greater than the second output voltage, and obtain the third comparison result. The second preset voltage is used to determine whether the load of the first output circuit or the load of the second output circuit is a light load. or, The first power determination circuit is further configured to, when the first output voltage is less than the second output voltage, obtain the second feedback voltage from the second power determination circuit, compare the magnitude of the second feedback voltage with the first preset voltage, and obtain the second comparison result; The second power determination circuit is further configured to obtain the first feedback voltage from the first power determination circuit when the first output voltage is less than the second output voltage, and compare the magnitude of the first feedback voltage and the second preset voltage to obtain the third comparison result.

5. The output control circuit according to claim 4, characterized in that, The freewheeling sequence determination circuit is specifically used to determine whether the second comparison result and the third comparison result satisfy the second preset condition when the first comparison result satisfies the first preset condition. If the second preset condition is met, then the second output circuit is determined as the first freewheeling circuit, and the first output circuit is determined as the second freewheeling circuit. If the second preset condition is not met, then the first output circuit is determined as the first freewheeling circuit, and the second output circuit is determined as the second freewheeling circuit. or, The freewheeling sequence determination circuit is specifically used to determine whether the second comparison result and the third comparison result satisfy the third preset condition when the first comparison result does not meet the first preset condition. If the third preset condition is met, then the first output circuit is determined as the first freewheeling circuit, and the second output circuit is determined as the second freewheeling circuit. If the third preset condition is not met, then the second output circuit is determined as the first freewheeling circuit, and the first output circuit is determined as the second freewheeling circuit.

6. The output control circuit according to claim 4, characterized in that, The first power determination circuit includes: a first operational amplifier, a second comparator, a first capacitor, a first resistor, a first switching transistor, and a second switching transistor; The non-inverting input terminal of the first operational amplifier is used to connect to a first reference voltage. The negative-inverting input terminal of the first operational amplifier and the first plate of the first capacitor are both electrically connected to the output terminal of the first output circuit. The second plate of the first capacitor is electrically connected to the first terminal of the first resistor. The output terminal of the first operational amplifier is electrically connected to the first terminal of the first switch, the first terminal of the second switch, and the second terminal of the first resistor. The second terminal of the first switch is electrically connected to the non-inverting input terminal of the second comparator and the first terminal of the second power determination circuit. The negative-inverting input terminal of the second comparator is used to connect to the first preset voltage. The output terminal of the second comparator is electrically connected to the second input terminal of the freewheeling sequence determination circuit. The second terminal of the second switch is electrically connected to the second terminal of the second power determination circuit. The control terminals of the first and second switches are used to connect to a first control signal. The first control signal is used to control the first and second switches to be turned on or off according to the first comparison result. The first operational amplifier is used to amplify the voltage difference between the first output voltage and the first reference voltage, and to obtain the first feedback voltage with the compensation of the first resistor and the first capacitor, and to transmit the first feedback voltage to the second comparator; The second comparator is used to compare the magnitude of the first feedback voltage and the first preset voltage to obtain the second comparison result, or to obtain the second feedback voltage from the second power determination circuit and compare the magnitude of the second feedback voltage with the first preset voltage to obtain the second comparison result.

7. The output control circuit according to claim 6, characterized in that, The second power determination circuit includes: a second operational amplifier, a third comparator, a second capacitor, a second resistor, a third switch, and a fourth switch; The non-inverting input of the second operational amplifier is used to connect to the second reference voltage. The negative-inverting input of the second operational amplifier and the first plate of the second capacitor are both electrically connected to the output of the second output circuit. The second plate of the second capacitor is electrically connected to the first end of the second resistor. The output of the second operational amplifier is electrically connected to the first end of the third switch, the first end of the fourth switch, and the second end of the second resistor, respectively. The second end of the third switch is electrically connected to the first end of the first power determination circuit. The second end of the fourth switch is electrically connected to the negative-inverting input of the third comparator and the second end of the first power determination circuit, respectively. The negative-inverting input of the third comparator is used to connect to the second preset voltage. The output of the second comparator is electrically connected to the third input of the freewheeling sequence determination circuit. The control terminals of the third and fourth switches are used to connect to the second control signal. The second control signal is used to control the conduction or cutoff of the third and fourth switches according to the first comparison result. The second operational amplifier is used to amplify the voltage difference between the second output voltage and the second reference voltage, and to obtain the second feedback voltage with the compensation of the second resistor and the second capacitor, and to transmit the second feedback voltage to the third comparator; The third comparator is used to compare the magnitude of the second feedback voltage and the second preset voltage to obtain the third comparison result, or to obtain the first feedback voltage from the first power determination circuit and compare the magnitude of the first feedback voltage with the second preset voltage to obtain the third comparison result.

8. The output control circuit according to claim 5, characterized in that, The first preset condition is that the first output voltage is less than the second output voltage; the second preset condition is that the first feedback voltage is less than the second preset voltage, and the second feedback voltage is greater than the first preset voltage. The third preset condition is that the first feedback voltage is greater than the first preset voltage, and the second feedback voltage is less than the second preset voltage.

9. The output control circuit according to any one of claims 1-8, characterized in that, The flyback converter also includes: a primary switch, a transformer, and a primary switch; The output control circuit is also used to control the second freewheeling circuit to reverse excite the transformer within a preset time during which the primary switch is turned on after the excitation inductor current in the transformer crosses zero and before the primary switch changes from off to on.

10. A flyback converter, characterized in that, The flyback converter includes: a primary switch, an inductor, a snubber circuit, a primary controller, a secondary controller, a transformer, a first primary switch, a first output circuit, a second output circuit, an isolation communication circuit, and an output control circuit as described in any one of claims 1-9; The first terminal of the inductor and the first terminal of the snubber circuit are both used to connect to the input voltage. The second terminal of the inductor is electrically connected to the opposite terminal of the primary winding of the transformer. The first terminal of the primary switch and the second terminal of the snubber circuit are both electrically connected to the same terminal of the primary winding. The control terminal of the primary switch is electrically connected to the first terminal of the primary controller. The second terminal of the primary controller is electrically connected to the first terminal of the isolation communication circuit. The second terminal of the isolation communication circuit is electrically connected to the first terminal of the secondary controller. The second terminal of the secondary controller is electrically connected to the control terminal of the primary switch. The first terminal of the primary switch is electrically connected to the opposite terminal of the secondary winding of the transformer. The corresponding terminals are electrically connected to the input terminals of the first output circuit and the second output circuit, respectively. The output terminal of the first output circuit is electrically connected to the first input terminal of the output control circuit, and the output terminal of the second output circuit is electrically connected to the second input terminal of the output control circuit. The output terminal of the output control circuit is electrically connected to the control terminals of the first output circuit and the second output circuit, respectively. The third terminal of the secondary controller is electrically connected to the first terminal of the output control circuit. The second terminals of the first primary switching transistor and the second primary switching transistor are both grounded. The output terminal of the first output circuit is also used to output a first output voltage, and the output terminal of the second output circuit is also used to output a second output voltage.

11. A chip, characterized in that, include: The output control circuit as described in any one of claims 1-9, and / or the flyback converter as described in claim 10.

12. An electronic device, characterized in that, include: The chip as described in claim 11.

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