A multi-output flyback converter and power supply system
By using closed-loop coordinated control of the control module and the synchronous rectification module, the duty cycle of the primary and secondary switches in the flyback converter is adjusted, thus solving the cross-regulation problem in the multi-output flyback converter and achieving high-performance voltage stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BEIJING WEIKE NENGCHUANG TECH CO LTD
- Filing Date
- 2026-04-07
- Publication Date
- 2026-07-10
Smart Images
Figure CN122371641A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of power supply technology, and more specifically, to a multi-output flyback converter and power supply system. Background Technology
[0002] In isolated power supply systems, it is often necessary to provide multiple outputs of different voltages simultaneously, requiring high output voltage accuracy and small size. Therefore, multi-output flyback converters are a common choice. However, because their secondary side contains multiple independent output windings, they are prone to cross-regulation issues. Cross-regulation refers to the degree of impact on the stability of the output voltages of other non-actively regulated outputs when the load current of one output (usually the main output) changes in a multi-output switching power supply. It reflects the degree of coupling and interference between the output voltages in a multi-output power supply. The smaller the cross-regulation, the less mutual influence between the outputs, and the more stable the overall performance of the power supply.
[0003] Solving the cross-regulation problem has always been a hot topic and a challenge in the industry. Traditional methods for improving cross-regulation often involve reducing transformer leakage inductance, optimizing transformer manufacturing processes, rigorously selecting rectifier diodes with good consistency, or adding auxiliary circuits. However, in practical applications, these traditional approaches cannot completely eliminate cross-regulation; they can only reduce it to a certain extent. Typically, reducing the cross-regulation to around 1.5% is considered a relatively ideal result in the industry, but this is still insufficient for applications with stringent performance requirements.
[0004] In summary, how to eliminate the cross-regulation in multi-output flyback converters to meet the needs of higher performance applications is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] The purpose of this application is to provide a multi-output flyback converter and power supply system to eliminate the cross-regulation in the multi-output flyback converter and meet the needs of higher performance applications.
[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: On the one hand, this application provides a multi-output flyback converter, including: a control module, a transformer, a primary-side switching module, and multiple synchronous rectification modules; The primary-side switching module is connected to the primary winding of the transformer, and each synchronous rectification module is connected to each secondary winding of the transformer in a one-to-one correspondence. Each synchronous rectification module includes two back-to-back connected switching transistors. The control module is connected to the control terminal of the primary-side switch module, the control terminals of the two switching transistors in each synchronous rectification module, and the output terminal of each synchronous rectification module; one of the synchronous rectification modules serves as the active regulation output path, and the rest serve as the non-active regulation output paths. The control module is used to adjust the duty cycle of the primary-side switch module according to the actual output voltage of the active-adjustment output path; and to adjust the duty cycle of at least one switch in the corresponding non-active-adjustment output path according to the actual output voltage of each non-active-adjustment output path, so as to eliminate the cross-regulation rate between the outputs.
[0007] Furthermore, the primary-side switching module includes a primary-side MOSFET, and each of the synchronous rectification modules includes a synchronous rectification MOSFET and a regulating MOSFET; The drain of the primary-side MOS transistor is connected to the second end of the primary-side winding, and the source of the primary-side MOS transistor and the first end of the primary-side winding are used to connect the two ends of the DC power supply. In each of the synchronous rectification modules, the drain of the regulating MOSFET is connected to the first end of the corresponding secondary winding, the source of the regulating MOSFET is connected to the source of the synchronous rectification MOSFET, and the drain of the synchronous rectification MOSFET and the second end of the secondary winding are used to connect the two ends of the corresponding load. The input terminal of the control module is connected to both ends of the load corresponding to each synchronous rectification module to collect the actual output voltage of each output; the output terminal of the control module is connected to the gate of the primary side MOS transistor, the gate of the synchronous rectification MOS transistor in each synchronous rectification module and the gate of the adjustment MOS transistor to adjust the duty cycle of the PWM signal of each MOS transistor.
[0008] Furthermore, the control module is used to increase the PWM duty cycle of the primary-side MOSFET when the actual output voltage of the actively regulated output path is less than its corresponding target output voltage, so as to maintain the voltage stability of the actively regulated output path; and to decrease the PWM duty cycle of the regulating MOSFET in each non-actively regulated output path until the actual output voltage of each non-actively regulated output path is restored to the corresponding target output voltage.
[0009] Furthermore, the control module is used to reduce the PWM duty cycle of the primary-side MOS transistor when the actual output voltage of the actively regulated output circuit is greater than its corresponding target output voltage, so as to maintain the voltage stability of the actively regulated output circuit; and to increase the PWM duty cycle of the regulating MOS transistor in each non-actively regulated output circuit until the actual output voltage of each non-actively regulated output circuit is restored to the corresponding target output voltage.
[0010] Furthermore, the PWM signal of each of the synchronous rectifier MOSFETs is phase-complementary to the PWM signal of the primary-side MOSFET, and each of the synchronous rectifier MOSFETs is used to provide a current path for the corresponding load during the turn-off period of the primary-side MOSFET.
[0011] Furthermore, each of the synchronous rectification modules also includes a capacitor; In each of the synchronous rectification modules, one end of the capacitor is connected to the drain of the synchronous rectification MOSFET, the other end of the capacitor is connected to the second end of the corresponding secondary winding, and the capacitor is connected in parallel with a corresponding load.
[0012] Furthermore, the control module includes a control chip and a PWM generator; The input terminal of the control chip is connected to the output terminal of each of the synchronous rectification modules, the output terminal of the control chip is connected to the input terminal of the PWM generator, and the output terminal of the PWM generator is connected to the control terminal of the primary-side switching module and the control terminals of the two switching transistors in each of the synchronous rectification modules. The control chip is used to perform calculations based on preset input parameters and the actual output voltage of each synchronous rectification module to generate duty cycle control signals for each switching transistor. The PWM generator is used to generate PWM signals with corresponding duty cycles according to the duty cycle control signal and output them to the control terminals of each switching transistor.
[0013] Furthermore, the preset input parameters include: input voltage, transformer inductance, turns ratio of each secondary winding of the transformer, and target output voltage of each synchronous rectification module.
[0014] Furthermore, the multi-output flyback converter also includes multiple sampling modules; The input terminal of each sampling module is connected to the output terminal of each synchronous rectification module in a one-to-one correspondence, and the output terminal of each sampling module is connected to the input terminal of the control module. The sampling module is used to collect the actual voltage at the output terminal of the corresponding synchronous rectifier module and send the collected actual output voltage to the control module.
[0015] On the other hand, this application also provides a power supply system including a multi-output flyback converter as described in any of the foregoing embodiments.
[0016] Compared with the prior art, this application has the following advantages: The multi-output flyback converter provided in this application includes a control module, a transformer, a primary-side switching module, and multiple synchronous rectifier modules. The primary-side switching module is connected to the primary winding of the transformer, and each synchronous rectifier module is connected to each secondary winding of the transformer. Each synchronous rectifier module includes two back-to-back connected switching transistors. The control module is connected to the control terminals of the primary-side switching module, the control terminals of the two switching transistors in each synchronous rectifier module, and the output terminal of each synchronous rectifier module. One of the synchronous rectifier modules serves as the actively regulated output path, while the others serve as non-actively regulated output paths. The control module adjusts the duty cycle of the primary-side switching module based on the actual output voltage of the actively regulated output path; and adjusts the duty cycle of the switching transistors in each non-actively regulated output path based on the actual output voltage of each non-actively regulated output path, thereby eliminating cross-regulation between the outputs. This application employs a closed-loop collaborative control mechanism that combines primary-side switch duty cycle adjustment and secondary-side switch duty cycle adjustment, enabling each output voltage to have closed-loop regulation capability. This solves the problem of large cross-regulation rate in multi-output flyback converters, effectively avoids output voltage disturbances in non-actively regulated output paths, and ensures the high performance requirements of each output. Attached Figure Description
[0017] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0018] Figure 1 One of the circuit diagrams of a multi-output flyback converter provided in this application embodiment; Figure 2 A second circuit diagram of a multi-output flyback converter provided in this application embodiment; Figure 3 A circuit diagram of a control module provided in an embodiment of this application; Figure 4 A circuit diagram of a 3-output flyback converter with the first output channel as the active adjustment output channel is provided for an embodiment of this application; Figure 5This is a waveform diagram of the output voltage of each output path when the load of the output path is actively adjusted, as provided in an embodiment of this application.
[0019] Icons: 10 - Multi-output flyback converter; 100 - Primary-side switching module; 200 - Synchronous rectification module; 300 - Control module; 310 - Control chip; 320 - PWM generator; 400 - Sampling module; T - Magnetic core; N1 - Primary winding; M1 - Primary MOSFET. Detailed Implementation
[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.
[0021] In the description of this application, it should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The term "connection" should be interpreted broadly, for example, it can refer to a direct connection or an indirect connection through an intermediate medium. The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.
[0022] As described in the background section, traditional methods for improving cross-regulation often involve reducing transformer leakage inductance, optimizing transformer manufacturing processes, rigorously selecting rectifier diodes with good consistency, or adding auxiliary circuitry. However, in practical applications, traditional methods can only reduce the cross-regulation to a certain extent. Typically, reducing the cross-regulation to around 1.5% is considered a relatively ideal result in the industry, but it is still difficult to meet the needs of applications with more demanding performance requirements. Therefore, how to eliminate the cross-regulation in multi-output flyback converters to meet the needs of higher-performance applications is a technical problem that urgently needs to be solved by those skilled in the art.
[0023] To resolve the above technical issues, please refer to Figure 1This application provides a multi-output flyback converter 10, including: a control module 300, a transformer, a primary-side switching module 100, and multiple synchronous rectification modules 200.
[0024] The primary-side switching module 100 is connected to the primary winding N1 of the transformer. The input terminal of each synchronous rectifier module 200 is connected to each secondary winding of the transformer, and the output terminal of each synchronous rectifier module 200 is used to connect to the corresponding load. The control module 300 is connected to the control terminal of the primary-side switching module 100, the control terminals of the two switching transistors in each synchronous rectifier module 200, and the output terminal of each synchronous rectifier module 200.
[0025] Among them, one of the multiple synchronous rectification modules 200 serves as the active regulation output path (i.e., the main power output path), while the remaining synchronous rectification modules 200 serve as the non-active regulation output path (i.e., the slave power output path).
[0026] The control module 300 is used to adjust the duty cycle of the primary-side switching module 100 according to the actual output voltage of the active-adjustment output path; and to adjust the duty cycle of at least one switching transistor in each non-active-adjustment output path according to the actual output voltage of each non-active-adjustment output path, so as to eliminate the cross-regulation rate between the outputs.
[0027] Understandably, this application achieves adaptive adjustment of each output voltage by introducing a controllable synchronous rectification module 200 on the secondary side of the transformer and incorporating the primary-side switching module 100 and each synchronous rectification module 200 into a closed-loop control system. Specifically, when the load of the actively regulated output path changes, causing fluctuations in the actual output voltage of the main path, the control module 300 adjusts the duty cycle of the primary-side switching module 100 to maintain the stability of the main path voltage. This adjustment process causes changes in the power transmitted by the transformer, which in turn causes fluctuations in the output voltage of the non-actively regulated output path. At this time, the control module 300 can quickly adjust the duty cycle of the switching transistor in the corresponding non-actively regulated output path based on the real-time acquired actual output voltage of each non-actively regulated output path to dynamically block excess energy transmission or compensate for energy loss, thereby offsetting the interference caused by the primary-side power adjustment and eliminating the cross-regulation rate between the outputs.
[0028] As can be seen, this application adopts a closed-loop collaborative control mechanism of primary-side switch duty cycle adjustment and secondary-side switch duty cycle adjustment, which enables each output voltage to have closed-loop regulation capability. This solves the problem of large cross-regulation rate in the multi-output flyback converter 10, effectively avoids output voltage disturbances in non-actively regulated output paths, and ensures the high performance requirements of each output. It is especially suitable for multi-power supply scenarios with extremely high voltage stability requirements.
[0029] In one optional implementation, the primary-side switching module 100 includes a primary-side MOSFET M1, and each synchronous rectification module 200 includes a synchronous rectification MOSFET (i.e., Figure 1 M3, M5, or M7) and a regulating MOSFET (i.e. Figure 1 (M2, M4, or M6 in the text).
[0030] The drain of the primary MOSFET M1 is connected to the second end of the primary winding N1, and the source of the primary MOSFET M1 and the first end of the primary winding N1 are used to connect the two ends of the DC power supply.
[0031] In each synchronous rectification module 200, the drain of the regulating MOSFET is connected to the first end of the corresponding secondary winding, the source of the regulating MOSFET is connected to the source of the synchronous rectification MOSFET, and the drain of the synchronous rectification MOSFET and the second end of the secondary winding are used to connect the two ends of the corresponding load.
[0032] Furthermore, each synchronous rectification module 200 also includes a capacitor. In each synchronous rectification module 200, one end of the capacitor is connected to the drain of the synchronous rectification MOSFET, the other end of the capacitor is connected to the second end of the corresponding secondary winding, and the capacitor is connected in parallel with a corresponding load.
[0033] The input terminals of the control module 300 are connected to the two ends of the corresponding load of each synchronous rectification module 200 to acquire the actual output voltage of each output. The output terminals of the control module 300 are connected to the gate of the primary-side MOSFET M1, the gate of the synchronous rectification MOSFET in each synchronous rectification module 200, and the gate of the regulating MOSFET to adjust the duty cycle of the PWM signal of each MOSFET.
[0034] Understandably, the multi-output flyback converter 10 provided in this application embodiment adopts a novel topology. On each secondary winding side of the transformer, the traditional rectifier diodes are replaced with synchronous rectifier MOSFETs to reduce conduction losses. In addition, a regulating MOSFET is connected in series with the synchronous rectifier MOSFET of each output, forming two back-to-back connected MOSFET structures. The control module 300 coordinates the control of multiple MOSFETs to eliminate cross-regulation between multiple outputs.
[0035] Based on the above design, the specific principle for eliminating the cross-adjustment rate is as follows: When the load on the actively regulated output path increases, the control module 300 detects that the actual output voltage of the actively regulated output path will momentarily drop below its corresponding target output voltage. At this time, the control module 300 increases the PWM duty cycle of the primary-side MOSFET M1, causing more power to be transferred from the primary side to the secondary side to maintain the voltage stability of the actively regulated output path. However, since the load on the non-actively regulated output paths remains unchanged, the increase in power transferred from the primary side will cause the output voltage of each non-actively regulated output path to rise. At this time, the control module 300 decreases the PWM duty cycle of the regulating MOSFET in each non-actively regulated output path to dynamically block the transfer of excess energy until the actual output voltage of each non-actively regulated output path recovers to its corresponding target output voltage.
[0036] When the load on the actively regulated output path decreases, the control module 300 detects that the actual output voltage of the actively regulated output path will rise instantaneously, exceeding its corresponding target output voltage. At this time, the control module 300 reduces the PWM duty cycle of the primary-side MOSFET M1, decreasing the power transferred from the primary side to the secondary side to maintain voltage stability in the actively regulated output path. However, since the load on the non-actively regulated output paths remains unchanged, the reduction in power transferred from the primary side will cause the output voltage of each non-actively regulated output path to drop. At this time, the control module 300 increases the PWM duty cycle of the regulating MOSFET in each non-actively regulated output path to dynamically compensate for the lost energy until the actual output voltage of each non-actively regulated output path recovers to its corresponding target output voltage.
[0037] In addition, the PWM signal of each synchronous rectifier MOSFET is phase-complementary to the PWM signal of the primary MOSFET M1 (i.e., the synchronous rectifier MOSFET is turned off when the primary MOSFET M1 is turned on, and the synchronous rectifier MOSFET is turned on when the primary MOSFET M1 is turned off). Each synchronous rectifier MOSFET is used to provide a current path for the corresponding load during the period when the primary MOSFET M1 is turned off.
[0038] Therefore, this application constructs a complete closed-loop feedback regulation mechanism by using the control module 300 to coordinate the control of the primary-side MOSFET M1, the synchronous rectifier MOSFET, and the regulating MOSFET. When the load change of the actively regulated output path causes voltage fluctuations, the control module 300 adjusts the primary-side duty cycle to maintain the main power balance, and dynamically adjusts the PWM duty cycle of the regulating MOSFET in each non-actively regulated output path. By precisely blocking excess energy or compensating for energy loss, the output voltage of each path can be quickly restored to the target output voltage. The multiple outputs do not interfere with each other and have excellent performance with no cross-regulation.
[0039] In one alternative implementation, please refer to Figure 2 The multi-output flyback converter 10 also includes multiple sampling modules 400.
[0040] In this configuration, the input terminal of each sampling module 400 is connected to the output terminal of each synchronous rectification module 200 in a one-to-one correspondence, and the output terminal of each sampling module 400 is connected to the input terminal of the control module 300.
[0041] The sampling module 400 is used to collect the actual voltage at the output terminal of the corresponding synchronous rectifier module 200 and send the collected actual output voltage to the control module 300.
[0042] Optionally, the sampling module 400 can be a filter to filter the acquired output voltage signal to remove high-frequency noise interference, ensuring that the voltage signal input to the control module 300 is smooth and accurate, thereby improving control accuracy and system stability.
[0043] In another alternative implementation, please refer to Figure 3 The control module 300 includes a control chip 310 and a PWM generator 320. Optionally, the control chip 310 can be an MCU, a DSP, or an FPGA.
[0044] The input terminal of the control chip 310 is connected to the output terminal of each synchronous rectification module 200, the output terminal of the control chip 310 is connected to the input terminal of the PWM generator 320, and the output terminal of the PWM generator 320 is connected to the control terminal of the primary-side switching module 100 and the control terminals of the two switching transistors in each synchronous rectification module 200. The control chip 310 is used to perform calculations based on preset input parameters and the actual output voltages (such as Vo1, Vo2, and Vo3) of each synchronous rectification module 200 to generate duty cycle control signals corresponding to each switching transistor. Optionally, the preset input parameters include: input voltage Vin, transformer inductance Lp, turns ratio of each secondary winding of the transformer (such as n1, n2, and n3), and target output voltages (such as Vos1, Vos2, and Vos3) of each synchronous rectification module 200.
[0045] The PWM generator 320 is used to generate PWM signals with corresponding duty cycles based on the duty cycle control signal and output them to the control terminals of each switching transistor.
[0046] Understandably, the multi-output flyback converter 10 provided in this application embodiment adopts a digital control method. After acquiring relevant input parameters on an embedded real-time control chip platform, it uses an internally designed software algorithm to coordinately control the duty cycle of each switch in PWM form. This application only requires one embedded control chip to coordinately drive multiple switches, achieving crossover-free regulation for multiple flyback outputs.
[0047] It should be noted that the embodiments of this application do not limit the specific number of output paths, but in order to better understand the technical solution of this application, the following uses... Figure 4 The following explanation uses a 3-output flyback converter as an example.
[0048] like Figure 4 As shown, this application adopts a flyback topology. The transformer includes a magnetic core T and one primary winding N1 coupled to the magnetic core T, and three secondary windings (N2, N3, and N4). Multiple output voltages are achieved through a single magnetic core T, significantly reducing PCB layout space. This flyback topology has a total of seven MOSFETs: one primary MOSFET M1 on the primary side; a first secondary winding with a back-to-back regulating MOSFET M2 and a synchronous rectifier MOSFET M3; a second secondary winding with a back-to-back regulating MOSFET M4 and a synchronous rectifier MOSFET M5; and a third secondary winding with a back-to-back regulating MOSFET M6 and a synchronous rectifier MOSFET M7. The actual output voltage of the first winding is Vo1, the second winding is Vo2, and the third winding is Vo3.
[0049] Assuming the first output path is actively regulated, while the second and third are non-actively regulated, when the load R1 of the first path (actively regulated output) increases, its actual output voltage Vo1 will drop instantaneously. To ensure voltage stability in the first path, the control module 300 will increase the PWM duty cycle of the primary-side switch, transferring more power from the primary to the secondary side, thus ensuring the actual output voltage Vo1 of the first path stabilizes at its target output voltage Vos1. However, since the loads R2 and R3 of the second and third paths (non-actively regulated outputs) remain unchanged, the increase in power transferred from the primary side will cause both the actual output voltages Vo2 and Vo3 of the second and third paths to rise. At this point, the control module 300 will reduce the PWM duty cycle of the regulating MOSFET M4 in the second channel and the regulating MOSFET M6 in the third channel to block excess energy transfer until the actual output voltage Vo2 of the second channel stabilizes to its target output voltage Vos2, and the actual output voltage Vo3 of the third channel stabilizes to its target output voltage Vos3, ensuring that there is no static error between the actual output voltage and the target output voltage of each channel. When the load R1 of the first channel decreases, the adjustment process is reversed, thus constructing a complete cross-adjustment closed-loop feedback mechanism.
[0050] Based on the above adjustment mechanism, this application conducted experiments on the first channel (i.e., the active adjustment output channel) under three operating conditions: no load (0%), light load (≤20%), and heavy load (≥50%). The target output voltages for the first, second, and third channels were 6V, 5V, and 3V, respectively, and the maximum output current of the first channel was 8A. Table 1 and... Figure 5The data presented in the experiment all use the first path as the active adjustment output path, and the second and third paths as the non-active adjustment output paths.
[0051] Table 1. Experimental data of output voltage for each channel under different load conditions.
[0052] According to Table 1 and Figure 5 It can be seen that when the load of the actively regulated output path (i.e., the first path) increases, the output voltage of the non-actively regulated output path (i.e., the second and third paths) will rise instantaneously and then stabilize and converge to the target output voltage value; when the load of the actively regulated output path decreases, the output voltage of the non-actively regulated output path will drop instantaneously and then stabilize and converge to the target output voltage value.
[0053] In summary, the multi-output flyback converter provided in this application requires only one winding on the primary side of the transformer, while the secondary side can be expanded with multiple windings to form multiple outputs. Each output uses synchronous rectification, and a regulating MOSFET is connected in series on the synchronous rectification MOSFET link. Combined with digital control technology, this achieves non-interference between the multiple outputs and exhibits excellent performance with no cross-regulation. Furthermore, in terms of digital control, only one embedded control chip is needed to collaboratively drive multiple MOSFETs, achieving no cross-regulation for the flyback multi-output.
[0054] Optionally, embodiments of this application also provide a power supply system, which includes a multi-output flyback converter as described in any of the foregoing embodiments.
[0055] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.
[0056] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A multi-output flyback converter, characterized in that, include: Control module, transformer, primary-side switch module and multiple synchronous rectifier modules; The primary-side switching module is connected to the primary winding of the transformer, and each synchronous rectification module is connected to each secondary winding of the transformer in a one-to-one correspondence. Each synchronous rectification module includes two back-to-back connected switching transistors. The control module is connected to the control terminal of the primary-side switch module, the control terminals of the two switching transistors in each synchronous rectification module, and the output terminal of each synchronous rectification module; one of the synchronous rectification modules serves as the active regulation output path, and the rest serve as the non-active regulation output paths; The control module is used to adjust the duty cycle of the primary-side switch module according to the actual output voltage of the active adjustment output path. Based on the actual output voltage of each of the non-actively regulated output paths, the duty cycle of at least one switch in the corresponding non-actively regulated output path is adjusted to eliminate the cross-regulation rate between the outputs.
2. The multi-output flyback converter according to claim 1, characterized in that, The primary-side switching module includes a primary-side MOSFET, and each of the synchronous rectification modules includes a synchronous rectification MOSFET and a regulating MOSFET; The drain of the primary-side MOS transistor is connected to the second end of the primary-side winding, and the source of the primary-side MOS transistor and the first end of the primary-side winding are used to connect the two ends of the DC power supply. In each of the synchronous rectification modules, the drain of the regulating MOSFET is connected to the first end of the corresponding secondary winding, the source of the regulating MOSFET is connected to the source of the synchronous rectification MOSFET, and the drain of the synchronous rectification MOSFET and the second end of the secondary winding are used to connect the two ends of the corresponding load. The input terminal of the control module is connected to both ends of the load corresponding to each synchronous rectification module to collect the actual output voltage of each output; the output terminal of the control module is connected to the gate of the primary side MOS transistor, the gate of the synchronous rectification MOS transistor in each synchronous rectification module and the gate of the adjustment MOS transistor to adjust the duty cycle of the PWM signal of each MOS transistor.
3. The multi-output flyback converter according to claim 2, characterized in that, The control module is used to increase the PWM duty cycle of the primary-side MOS transistor when the actual output voltage of the active regulation output path is less than its corresponding target output voltage, so as to maintain the voltage stability of the active regulation output path. And reduce the PWM duty cycle of the regulating MOS transistor in each non-actively regulated output path until the actual output voltage of each non-actively regulated output path is restored to the corresponding target output voltage.
4. The multi-output flyback converter according to claim 2, characterized in that, The control module is used to reduce the PWM duty cycle of the primary-side MOSFET when the actual output voltage of the actively regulated output path is greater than its corresponding target output voltage, so as to maintain the voltage stability of the actively regulated output path; and to increase the PWM duty cycle of the regulating MOSFET in each non-actively regulated output path until the actual output voltage of each non-actively regulated output path is restored to the corresponding target output voltage.
5. The multi-output flyback converter according to claim 2, characterized in that, The PWM signal of each of the synchronous rectifier MOSFETs is phase-complementary to the PWM signal of the primary MOSFET, and each of the synchronous rectifier MOSFETs is used to provide a current path for the corresponding load during the turn-off period of the primary MOSFET.
6. The multi-output flyback converter according to claim 2, characterized in that, Each of the aforementioned synchronous rectification modules also includes a capacitor; In each of the synchronous rectification modules, one end of the capacitor is connected to the drain of the synchronous rectification MOSFET, the other end of the capacitor is connected to the second end of the corresponding secondary winding, and the capacitor is connected in parallel with a corresponding load.
7. The multi-output flyback converter according to claim 1, characterized in that, The control module includes a control chip and a PWM generator; The input terminal of the control chip is connected to the output terminal of each of the synchronous rectification modules, the output terminal of the control chip is connected to the input terminal of the PWM generator, and the output terminal of the PWM generator is connected to the control terminal of the primary-side switching module and the control terminals of the two switching transistors in each of the synchronous rectification modules. The control chip is used to perform calculations based on preset input parameters and the actual output voltage of each synchronous rectification module to generate duty cycle control signals for each switching transistor. The PWM generator is used to generate PWM signals with corresponding duty cycles according to the duty cycle control signal and output them to the control terminals of each switching transistor.
8. The multi-output flyback converter according to claim 7, characterized in that, The preset input parameters include: input voltage, transformer inductance, turns ratio of each secondary winding of the transformer, and target output voltage of each synchronous rectifier module.
9. The multi-output flyback converter according to claim 1, characterized in that, The multi-output flyback converter also includes multiple sampling modules; The input terminal of each sampling module is connected to the output terminal of each synchronous rectification module in a one-to-one correspondence, and the output terminal of each sampling module is connected to the input terminal of the control module. The sampling module is used to collect the actual voltage at the output terminal of the corresponding synchronous rectifier module and send the collected actual output voltage to the control module.
10. A power supply system, characterized in that, The power system includes a multi-output flyback converter as described in any one of claims 1-9.