Flyback conversion circuit and electronic equipment

Abstract

The utility model provides a flyback conversion circuit and electronic equipment. The flyback conversion circuit comprises a primary winding; the switch control module is connected with the primary winding and is used for controlling the input voltage and outputting first voltage; the secondary winding is used for being coupled with the primary winding and outputting first coupling voltage; the first output module is connected with the secondary winding and is used for outputting a first output voltage according to the input first coupling voltage; the auxiliary winding is used for being coupled with the primary winding and outputting second coupling voltage; the second output module comprises a first power supply unit, a second power supply unit, a first load unit, a first diode, a first filtering unit and a second filtering unit; through the first filtering unit and the second filtering unit, the influence of leakage inductance peak voltage generated by primary winding side leakage inductance is reduced, and through the second filtering unit, the first load unit outputs power supply voltage to meet the power supply requirement.

Description

Technical Field

[0001] The utility model relates to the field of power supplies, in particular to a flyback conversion circuit and an electronic device. Background Art

[0002] In a flyback conversion circuit, due to the existence of leakage inductance on the primary winding side, and the magnitude of the leakage inductance spike voltage is positively correlated with the output power of the output circuit on the secondary winding side. Therefore, the greater the output power of the output circuit, the higher the leakage inductance spike voltage across the switching tube on the primary winding side. And the generated leakage inductance spike voltage will be input to the power supply circuit through the coupling between the primary winding and the auxiliary winding. Since the output power of the power supply circuit is small, the leakage inductance spike voltage will act on the output end of the power supply circuit for a long time, causing the supply voltage output by the power supply circuit to be in a state of excessive stress for a long time, thus resulting in circuit damage.

[0003] To address the above problems, a general solution is to improve the withstand voltage process of the power supply circuit or add a stage of linear voltage regulation circuit, but this will greatly increase the circuit cost and is not conducive to the small-size design of the flyback conversion circuit. Therefore, the prior art usually chooses to connect a resistor or an inductor in series with the diode in the power supply circuit to reduce the influence of the leakage inductance spike voltage. However, the problem with this solution is that when the main output circuit is in a light load or no-load state, the supply voltage output by the power supply circuit will not be able to meet the power supply requirements of the flyback conversion circuit.

[0004] Therefore, providing a flyback conversion circuit that can both eliminate the influence of the leakage inductance spike voltage and enable the supply voltage to always meet the power supply requirements has become a technical problem that the industry urgently needs to solve. Summary of the Utility Model

[0005] The technical problem solved by the utility model is to provide a flyback conversion circuit and an electronic device, which solve the problem of being able to both eliminate the influence of the leakage inductance spike voltage and enable the supply voltage to always meet the power supply requirements.

[0006] To solve the above technical problem, an embodiment of the utility model provides a flyback conversion circuit, including:

[0007] A primary winding;

[0008] A switch control module, the switch control module is connected to the primary winding, and the switch control module is used to control the input voltage and output a first voltage;

[0009] A secondary winding, the secondary winding is used to be coupled with the primary winding and output a first coupled voltage;

[0010] A first output module, the first output module is connected to the secondary winding, and the first output module is used to output a first output voltage according to the input first coupled voltage;

[0011] An auxiliary winding for coupling with the primary winding and outputting a second coupled voltage;

[0012] A second output module, which includes: a first power supply unit, a second power supply unit, a first load unit, a first diode, a first filtering unit, and a second filtering unit; the first diode is used to rectify the second coupled voltage and output a voltage to be filtered; the first power supply unit and the first filtering unit are jointly used to perform primary filtering on the voltage to be filtered and output a first filtered voltage; the second power supply unit and the second filtering unit are jointly used to perform secondary filtering on the second filtered voltage and output a second filtered voltage, and the second filtering unit is also used to isolate the first power supply unit and the second power supply unit; the first load unit is used to output a power supply voltage according to the second filtered voltage.

[0013] Optionally, the first power supply unit includes a first capacitor; the second power supply unit includes a second capacitor; the capacitance value of the first capacitor is greater than that of the second capacitor.

[0014] Optionally, the first filtering unit includes a first resistor, the first end of the first resistor is connected to the negative electrode of the first diode, and the second end of the first resistor is connected to the first end of the first power supply voltage;

[0015] The second filtering unit includes a second resistor, the first end of the second resistor is connected to the negative electrode of the first diode, and the second end of the second resistor is respectively connected to the first end of the second power supply voltage and the first end of the first load unit.

[0016] Optionally, the first filtering unit includes a third resistor, the first end of the third resistor is connected to the negative electrode of the first diode, and the second end of the third resistor is connected to the first end of the first power supply voltage;

[0017] The second filtering unit includes a first inductor, the first end of the first inductor is connected to the negative electrode of the first diode, and the second end of the first inductor is respectively connected to the first end of the second power supply voltage and the first end of the first load unit.

[0018] Optionally, the second output module further includes a third filtering unit, the first end of the third filtering unit is connected to the negative electrode of the first diode, and the second end of the third filtering unit is connected to the first end of the first filtering unit.

[0019] Optionally, the third filtering unit includes a fourth resistor, the first end of the fourth resistor serves as the first end of the third filtering unit, and the second end of the fourth resistor serves as the second end of the third filtering unit.

[0020] Optionally, the third filtering unit includes a second inductor. The first end of the second inductor serves as the first end of the third filtering unit, and the second end of the second inductor serves as the second end of the third filtering unit.

[0021] Optionally, the second output module further includes a second diode. The negative electrode of the second diode is connected to the second end of the second filtering unit, and the positive electrode of the second diode is connected to the first end of the second power supply unit.

[0022] Optionally, the switch control module includes a first filtering capacitor, an absorption unit, a signal control unit, a switching transistor, and a fifth resistor;

[0023] The first end of the first filtering capacitor is connected to the first end of the primary winding. The first filtering capacitor is used for filtering the input voltage. The first end of the switching transistor is connected to the second end of the primary winding. The second end of the switching transistor is connected to the first end of the fifth resistor. The second end of the fifth resistor and the second end of the first filtering capacitor are both connected to the ground terminal;

[0024] The first end of the absorption unit is connected to the first end of the primary winding, and the second end of the absorption unit is connected to the second end of the primary winding;

[0025] The signal control unit is powered by the supply voltage. The signal control unit is configured to output a control signal to the control end of the switching transistor to control the on / off of the switching transistor;

[0026] The absorption unit is used for absorbing the leakage inductance spike voltage generated when the switching transistor is turned off.

[0027] Optionally, the absorption unit includes: a fifth resistor, a third capacitor, and a third diode. The first end of the fifth resistor and the first end of the third capacitor are both connected to the first end of the primary winding. The first end of the fifth resistor and the second end of the third capacitor are both connected to the negative electrode of the third diode. The positive electrode of the third diode is connected to the second end of the primary winding.

[0028] Optionally, the first output module includes a fourth diode, a fourth capacitor, and a second load unit. The positive electrode of the fourth diode is connected to the first end of the secondary winding. The negative electrode of the fourth diode is respectively connected to the first end of the fourth capacitor and the first end of the second load unit. The second end of the fourth capacitor and the second end of the second load unit are both connected to the second end of the secondary winding. The second load unit is configured to output the first output voltage.

[0029] Correspondingly, the present invention further provides an electronic device, including the flyback conversion circuit provided by the present invention.

[0030] Compared with the prior art, the technical solution of the embodiment of the present utility model has the following beneficial effects:

[0031] In the flyback conversion circuit of the technical solution of the present utility model, when the output power of the first output module is large, resulting in a large leakage inductance spike voltage in the first voltage, the first power supply unit and the first filtering unit jointly perform primary filtering on the voltage to be filtered, and the second power supply unit and the second filtering unit jointly perform secondary filtering on the first filtered voltage, so as to greatly reduce the influence of the leakage inductance spike voltage on the power supply voltage. When the output power of the first output module is small, resulting in a small first voltage and the second coupled voltage being insufficient to charge the first power supply unit and the second power supply unit simultaneously, since the second filtering unit isolates the first power supply unit and the second power supply unit, the second coupled voltage can charge the second power supply unit alone, so that the second filtered voltage output by the second power supply unit meets the power supply requirements for the power supply voltage.

[0032] Further, by setting the third filtering unit as a fourth resistor, the power loss of the first filtering unit is shared.

[0033] Further, by setting the third filtering unit as a second inductor, the influence of the leakage inductance spike voltage on the power supply voltage is further reduced.

[0034] Further, by setting the second diode, the charging start time of the first power supply unit and the second power supply unit is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic circuit structure diagram of the flyback conversion circuit provided by the embodiment of the present utility model Figure 1 ;

[0036] Figure 2 is a schematic circuit structure diagram of the flyback conversion circuit provided by the embodiment of the present utility model Figure 2 ;

[0037] Figure 3 is a waveform diagram of each parameter of the flyback conversion circuit provided by the embodiment of the present utility model;

[0038] Figure 4 is a schematic circuit structure diagram of the flyback conversion circuit provided by the embodiment of the present utility model Figure 4 ;

[0039] Figure 5 is a schematic circuit structure diagram of the flyback conversion circuit provided by the embodiment of the present utility model Figure 5 ;

[0040] Figure 6 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present utility model Figure 6 ;

[0041] Figure 7 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present utility model Figure 7 ;

[0042] Figure 8 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present utility model Figure 8 。

[0043] Reference numerals:

[0044] 10 - Switch control module;

[0045] 11 - Signal control unit;

[0046] 12 - Absorption unit;

[0047] 20 - First output module;

[0048] 21 - Second load unit;

[0049] 30 - Second output module;

[0050] 31 - First power supply unit;

[0051] 32 - Second power supply unit;

[0052] 33 - First load unit;

[0053] 34 - First filtering unit;

[0054] 35 - Second filtering unit;

[0055] 36 - Third filtering unit;

[0056] Vbulk - Input voltage;

[0057] Vo - First output voltage;

[0058] Vcc - Power supply voltage;

[0059] Va - Voltage to be filtered;

[0060] Vgs - Control signal;

[0061] Vds - Drain - source voltage;

[0062] Va - Voltage to be filtered;

[0063] Vcvcc1 - First filtered voltage;

[0064] Np - Primary winding;

[0065] Ns - Secondary winding;

[0066] Naux - Auxiliary winding;

[0067] C1 - First capacitor;

[0068] C2 - Second capacitor;

[0069] C3 - Third capacitor;

[0070] C4 - Fourth capacitor;

[0071] C5 - First filter capacitor;

[0072] R1 - First resistor;

[0073] R2 - Second resistor;

[0074] R3 - Third resistor;

[0075] R4 - Fourth resistor;

[0076] R5 - Fifth resistor;

[0077] D1 - First diode;

[0078] D2 - Second diode;

[0079] D3 - Third diode;

[0080] D4 - Fourth diode;

[0081] L1 - First inductor;

[0082] L2 - Second inductor;

[0083] Q1 - Switching transistor. Detailed implementation manners

[0084] As described in the background art, when the main output circuit is in a light - load or no - load state, although the influence of the leakage inductance spike voltage will be greatly reduced, the supply voltage output by the power supply circuit will not be able to meet the power supply requirements of the flyback conversion circuit. If the power supply requirements of the flyback conversion circuit when the main output circuit is in a light - load or no - load state are to be met, it is necessary to reduce the resistance value of the resistor in series with the diode or the inductance value in the power supply circuit. However, this will also cause the power supply circuit to be unable to offset the influence of the leakage inductance spike voltage when the main output circuit is in a heavy - load state. Therefore, the prior art cannot simultaneously take into account eliminating the influence of the leakage inductance spike voltage and meeting the power supply requirements of the circuit when the main output circuit is in any load state.

[0085] In view of this, an embodiment of the present utility model provides a new flyback conversion circuit.

[0086] Figure 1 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 1 .

[0087] Please refer to Figure 1 , the flyback conversion circuit provided by the embodiment of the present invention includes:

[0088] Primary winding Np;

[0089] Switch control module 10, the switch control module 10 is connected to the primary winding Np, and the switch control module 10 is used to control the input voltage Vbulk and output a first voltage;

[0090] Secondary winding Ns, the secondary winding Ns is used to be coupled with the primary winding Np and output a first coupled voltage;

[0091] First output module 20, the first output module 20 is connected to the secondary winding Ns, and the first output module 20 is used to output a first output voltage Vo according to the input first coupled voltage;

[0092] Auxiliary winding Naux, the auxiliary winding Naux is used to be coupled with the primary winding Np and output a second coupled voltage;

[0093] Second output module 30, the second output module 30 includes: a first power supply unit 31, a second power supply unit 32, a first load unit 33, a first diode D1, a first filtering unit 34, a second filtering unit 35; the first diode D1 is used to rectify the second coupled voltage and output a voltage to be filtered Va; the first power supply unit 31 and the first filtering unit 34 are jointly used to perform primary filtering on the voltage to be filtered Va and output a first filtered voltage Vcvcc1; the second power supply unit 32 and the second filtering unit 35 are jointly used to perform secondary filtering on the second filtered voltage and output a second filtered voltage, and the second filtering unit 35 is also used to isolate the first power supply unit 31 and the second power supply unit 32; the first load unit 33 is used to output a power supply voltage Vcc according to the second filtered voltage.

[0094] By the above technical means, in the embodiment of the present invention, when the first output module 20 is in any load state, the second output module 30 can simultaneously take into account the influence of eliminating the leakage inductance spike voltage and meet the power supply requirements of the circuit. The specific reasons are as follows:

[0095] When the output power of the first output module 20 is relatively large, that is, the first output module 20 is in a heavy load state, resulting in a large leakage inductance spike voltage in the first voltage, the first power supply unit 31 and the first filtering unit 34 jointly perform primary filtering on the voltage Va to be filtered and output the first filtered voltage Vcvcc1. The second power supply unit 32 and the second filtering unit 35 jointly perform secondary filtering on the first filtered voltage Vcvcc1 and output the second filtered voltage, thereby greatly reducing the influence of the leakage inductance spike voltage on the supply voltage Vcc and enabling the supply voltage Vcc output by the first load unit 33 to be stabilized within a normal range.

[0096] When the output power of the first output module 20 is relatively small, that is, the first output module 20 is in a light load or no-load state, resulting in a relatively small first voltage, the second coupling voltage is not sufficient to charge the first power supply unit 31 and the second power supply unit 32 simultaneously. Since the second filtering unit 35 isolates the first power supply unit 31 and the second power supply unit 32, the second coupling voltage can charge the second power supply unit 32 alone, so that the second filtered voltage output by the second power supply unit 32 meets the power supply requirements for the supply voltage Vcc.

[0097] The flyback conversion circuit provided by the embodiment of the present invention will be described in detail through specific embodiments as follows:

[0098] Figure 2 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 2 。

[0099] Please refer to Figure 2 , as a specific embodiment, the switch control module 10 includes a first filter capacitor C5, a signal control unit 11, an absorption unit 12, a switching transistor Q1, and a fifth resistor R5;

[0100] The first end of the first filter capacitor C5 is connected to the first end of the primary winding Np, and the first filter capacitor C5 is used to filter the input voltage Vbulk; the first end of the switching transistor Q1 is connected to the second end of the primary winding Np, the second end of the switching transistor Q1 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 and the second end of the first filter capacitor C5 are both connected to the ground terminal;

[0101] The first end of the absorption unit 12 is connected to the first end of the primary winding Np, and the second end of the absorption unit 12 is connected to the second end of the primary winding Np; the absorption unit 12 is used to absorb the leakage inductance spike voltage generated when the switching transistor Q1 is turned off. The absorption unit 12 includes: a fifth resistor R5, a third capacitor C3, and a third diode D3; the first end of the fifth resistor R5 and the first end of the third capacitor C3 are both connected to the first end of the primary winding Np, the first end of the fifth resistor R5 and the second end of the third capacitor C3 are both connected to the cathode of the third diode D3, and the anode of the third diode D3 is connected to the second end of the primary winding Np.

[0102] The signal control unit 11 is powered by the supply voltage Vcc, and the signal control unit 11 is used to output a control signal Vgs to the control end of the switching transistor Q1 to control the on and off of the switching transistor Q1; the signal control unit 11 is specifically a PWM controller.

[0103] The first output module 20 includes a fourth diode D4, a fourth capacitor C4, and a second load unit 21; the anode of the fourth diode D4 is connected to the first end of the secondary winding Ns, the cathode of the fourth diode D4 is respectively connected to the first end of the fourth capacitor C4 and the first end of the second load unit 21, the second end of the fourth capacitor C4 and the second end of the second load unit 21 are both connected to the second end of the secondary winding Ns, and the second load unit 21 is used to output the first output voltage Vo.

[0104] The first power supply unit 31 includes a first capacitor C1; the second power supply unit 32 includes a second capacitor C2; the capacitance value of the first capacitor C1 is greater than the capacitance value of the second capacitor C2. The first capacitor C1 is specifically an electrolytic capacitor with a large capacitance value. The second capacitor C2 is specifically a chip capacitor with a small capacitance value.

[0105] The first filtering unit 34 includes a first resistor R1, the first end of the first resistor R1 is connected to the cathode of the first diode D1, and the second end of the first resistor R1 is connected to the first end of the first supply voltage Vcc;

[0106] The second filtering unit 35 includes a second resistor R2, the first end of the second resistor R2 is connected to the cathode of the first diode D1, and the second end of the second resistor R2 is respectively connected to the first end of the second supply voltage Vcc and the first end of the first load unit 33.

[0107] Among them, the resistance value range of the first resistor R1 can be set between 10Ω and 20Ω. The first resistor R1 is specifically used to form a high-frequency filtering circuit with the first capacitor C1 to filter and rectify the voltage Va to be filtered, so that the first filtered voltage Vcvcc1 is close to the normal theoretical voltage value.

[0108] The working principle of the high-frequency filtering circuit formed by the first resistor R1 and the first capacitor C1 is described below with a specific example:

[0109] Figure 3 It is the waveform diagram of each parameter of the flyback conversion circuit provided by the embodiment of the present invention.

[0110] Please refer to Figure 2 and Figure 3 , when the first output voltage Vo output by the first output module 20 is 15V, the number of turns of the auxiliary winding Naux is 40 turns, and the number of turns of the secondary winding Ns is 20 turns. If there is no leakage inductance on the primary winding Np side, when the first diode D1 conducts, the theoretical voltage value formula of the supply voltage Vcc is as follows:

[0111] VCC = Vo * Naux / Ns; Formula (1)

[0112] Among them, VCC is used to represent the supply voltage Vcc; Vo is used to represent the first output voltage Vo; Naux is used to represent the number of turns of the auxiliary winding Naux; Ns is used to represent the number of turns of the secondary winding Ns.

[0113] According to Formula (1), it can be known that the supply voltage Vcc should be 30V when the first diode D1 conducts. However, due to the existence of leakage inductance on the primary winding Np side, the additional leakage inductance spike voltage will increase the supply voltage Vcc to 50V - 60V. At the same time, since the second output module 30 is lightly loaded, the supply voltage Vcc will be maintained at 50V - 60V for a long time, thus greatly increasing the voltage stress burden of the second output module 30. The specific influence of the leakage inductance spike voltage is as follows:

[0114] From Figure 3As can be seen from the waveform diagram shown, after the gate-source voltage of the switching transistor Q1 jumps from a high level to a low level, the switching transistor Q1 will be turned off, causing the drain-source voltage Vds of the switching transistor Q1, which was originally zero, to start rising and enter the Miller plateau period. During the Miller plateau period, the leakage inductance spike voltage generated by the leakage inductance will act on the second coupling voltage through winding coupling, causing a high-frequency voltage to appear in the voltage Va to be filtered output after rectification by the first diode D1. In order to filter out the high-frequency voltage in the voltage Va to be filtered as much as possible, in this embodiment, the first resistor R1 is connected in series with the first capacitor C1 to form a high-frequency filter circuit, so that the first filtered voltage Vcvcc1 output by the first capacitor C1 becomes stable and approaches the theoretical voltage value of the supply voltage Vcc.

[0115] Among them, the resistance value range of the second resistor R2 can be set in the range of several hundred ohms. The second resistor R2 is specifically used to form another high-frequency filter circuit with the second capacitor C2 to further filter and rectify the first filtered voltage Vcvcc1, so that the second filtered voltage is closer to the normal theoretical voltage value and is also smoother and more stable. The working principle of the high-frequency filter circuit composed of the second resistor R2 and the second capacitor C2 is similar to that of the high-frequency filter circuit composed of the first resistor R1 and the first capacitor C1, and will not be elaborated here.

[0116] In addition to being used to form a high-frequency filter circuit with the second capacitor C2, the second resistor R2 is also used to isolate the first capacitor C1 and the second capacitor C2, so that when the second load unit 21 is in a light load state or an idle state, the supply voltage Vcc can also meet the power supply requirements of the circuit.

[0117] The specific principle is as follows:

[0118] When the second load unit 21 is in a light load state or an unloaded state, the first voltage will be greatly reduced, thereby reducing the voltage Va to be filtered. If the second resistor R2 is not provided to isolate the first capacitor C1 and the second capacitor C2, the voltage Va to be filtered will charge the first capacitor C1 and the second capacitor C2 simultaneously, resulting in that the first filtered voltage Vcvcc1 output by the first capacitor C1 and the second filtered voltage output by the second capacitor C2 do not meet the charging requirements of the circuit, and ultimately resulting in that the supply voltage Vcc output by the first load unit 33 cannot meet the charging requirements of the circuit. After the first capacitor C1 and the second capacitor C2 are isolated by the second resistor R2, the voltage Va to be filtered will charge the first capacitor C1 and the second capacitor C2 separately. Since the first capacitor C1 is a large capacitor and the second capacitor C2 is a small capacitor, after separate charging, regardless of whether the first capacitor C1 can be charged to the required voltage, the second capacitor C2 will be quickly charged to the required voltage, so that the supply voltage Vcc output by the first load unit 33 meets the charging requirements of the circuit.

[0119] It should be noted that it is necessary to ensure that the high-pass filter frequency of the filter circuit formed by the first capacitor C1 and the first resistor R1 and the high-pass filter frequency of the filter circuit formed by the second capacitor C2 and the second resistor R2 are both greater than the oscillation frequency of the leakage inductance spike voltage, so as to minimize the influence of the leakage inductance spike voltage on the supply voltage Vcc and make the supply voltage Vcc close to the theoretical voltage value.

[0120] Figure 4 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 4 。

[0121] Please refer to Figure 4 , the first filtering unit 34 includes a third resistor R3. The first end of the third resistor R3 is connected to the negative electrode of the first diode D1, and the second end of the third resistor R3 is connected to the first end of the first supply voltage Vcc. It should be noted that the first resistor R1 and the third resistor R3 can be set as the same resistor.

[0122] The second filtering unit 35 includes a first inductor L1. The first end of the first inductor L1 is connected to the negative electrode of the first diode D1, and the second end of the first inductor L1 is respectively connected to the first end of the second supply voltage Vcc and the first end of the first load unit 33.

[0123] It should be noted that the third resistor R3 and the first resistor R1 in the first filtering unit 34 can be set as the same resistor, and both the third resistor R3 and the first resistor R1 can also be replaced by inductors. However, for the stability of the circuit, when the third resistor R3 or the first resistor R1 is replaced by an inductor, the first inductor L1 needs to be replaced by the second resistor R2 again, that is, at least one resistor needs to be provided in the circuit.

[0124] Figure 5 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 5 。 Figure 6 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 6 。 Figure 7 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 7 。

[0125] Please refer to Figure 5 ,As a specific implementation manner, on the basis of the corresponding embodiment in Figure 2 or Figure 4 ,the second output module 30 further includes a third filtering unit 36. The first end of the third filtering unit 36 is connected to the negative electrode of the first diode D1, and the second end of the third filtering unit 36 is connected to the first end of the first filtering unit 34.

[0126] Please refer to Figure 6 ,Specifically, the third filtering unit 36 includes a fourth resistor R4. The first end of the fourth resistor R4 serves as the first end of the third filtering unit 36, and the second end of the fourth resistor R4 serves as the second end of the third filtering unit 36. The beneficial effect of setting the fourth resistor R4 is that the fourth resistor R4 can share the power loss of the first resistor R1 or the third resistor R3.

[0127] Please refer to Figure 7 ,Specifically, in addition to including the fourth resistor R4, the third filtering unit 36 can also replace the fourth resistor R4 with a second inductor L2. The first end of the second inductor L2 serves as the first end of the third filtering unit 36, and the second end of the second inductor L2 serves as the second end of the third filtering unit 36. The beneficial effect of replacing the fourth resistor R4 with the second inductor L2 is that it can improve the filtering degree of the leakage inductance spike voltage and further reduce the influence of the leakage inductance spike voltage on the supply voltage Vcc.

[0128] Figure 8 Schematic diagram of the circuit structure of the flyback conversion circuit provided by the embodiment of the present invention Figure 8 。

[0129] Please refer to Figure 8 , as a specific implementation, in addition to Figure 3 , Figures 2 to 7 On the basis of any of the embodiments corresponding to the attached drawings, the second output module 30 further includes a second diode D2. The negative electrode of the second diode D2 is connected to the second end of the second filtering unit 35, and the positive electrode of the second diode D2 is connected to the first end of the second power supply unit 32. The beneficial effect of setting the second diode D2 is as follows: Through the second diode D2, the charging time of the first capacitor C1 can be reduced, and the startup speed of the supply voltage Vcc can be increased. The specific reasons are as follows:

[0130] The first load unit 33 needs to charge the first capacitor C1 and the second capacitor C2 first to output the supply voltage Vcc. After the charging of the first capacitor C1 is completed, the first filtered voltage Vcvcc1 output by the first capacitor C1 supplies power to the first load unit 33 to output the supply voltage Vcc. Since the first capacitor C1 is a large capacitor and the second capacitor C2 is a small capacitor, compared with charging the second capacitor C2 first and then charging the first capacitor C1, charging the first capacitor C1 and the second capacitor C2 simultaneously will increase the final charging time of the first capacitor C1. And setting the second diode D2 is to prevent the charging current from flowing through the first capacitor C1 when charging the second capacitor C2, so as to quickly complete the charging of the second capacitor C2, and finally increase the charging of the first capacitor C1 and the startup speed of the supply voltage Vcc.

[0131] In summary, for the flyback conversion circuit provided by the embodiment of the present invention, the first power supply unit and the first filtering unit jointly perform primary filtering on the voltage to be filtered, and the second power supply unit and the second filtering unit jointly perform secondary filtering on the first filtered voltage, and the second filtering unit isolates the first power supply unit and the second power supply unit, so as to greatly reduce the influence of the leakage inductance spike voltage on the supply voltage when the first output module is in a heavy load state, and when the first output module is in a light load or no-load state, the supply voltage meets the power supply requirements of the circuit.

[0132] Further, by setting the third filtering unit as a fourth resistor, the power loss of the first resistor or the third resistor can be shared.

[0133] Further, by setting the third filtering unit as a second inductor, the filtering degree of the leakage inductance spike voltage can be improved, and the influence of the leakage inductance spike voltage on the supply voltage can be further reduced.

[0134] Further, by providing the second diode, the charging time of the first capacitor can be reduced, and the startup speed of the supply voltage can be increased.

[0135] An embodiment of the present invention further provides an electronic device, including the flyback conversion circuit provided by the embodiment of the present invention.

[0136] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A flyback conversion circuit, characterized in that: include: Primary winding; A switch control module, the switch control module is connected to the primary winding, and the switch control module is used to control the input voltage and output a first voltage; A secondary winding, the secondary winding is used to couple with the primary winding and output a first coupling voltage; a first output module, the first output module is connected to the secondary winding, and the first output module is used to output a first output voltage according to the input first coupling voltage; an auxiliary winding, the auxiliary winding being used to couple with the primary winding and output a second coupling voltage; A second output module, the second output module comprising: a first power supply unit, a second power supply unit, a first load unit, a first diode, a first filtering unit, and a second filtering unit; The first diode is used to rectify the second coupling voltage and output the voltage to be filtered; the first power supply unit and the first filtering unit are used together to perform primary filtering on the voltage to be filtered and output the first filtered voltage; the second power supply unit and the second filtering unit are used together to perform secondary filtering on the first filtered voltage and output the second filtered voltage, and the second filtering unit is also used to isolate the first power supply unit and the second power supply unit; the first load unit is used to output the supply voltage according to the second filtered voltage.

2. The flyback converter circuit according to claim 1, characterized in that: The first power supply unit includes a first capacitor; the second power supply unit includes a second capacitor; the capacitance of the first capacitor is greater than the capacitance of the second capacitor.

3. The flyback converter circuit according to claim 1, characterized in that: The first filtering unit comprises a first resistor, a first end of the first resistor is connected to the cathode of the first diode, and a second end of the first resistor is connected to the first end of the first power supply unit; The second filtering unit includes a second resistor, a first end of the second resistor is connected to the cathode of the first diode, and a second end of the second resistor is respectively connected to the first end of the second power supply unit and the first end of the first load unit.

4. The flyback converter circuit according to claim 1, characterized in that: The first filtering unit comprises a third resistor, a first end of the third resistor is connected to the cathode of the first diode, and a second end of the third resistor is connected to the first end of the first power supply unit; The second filtering unit includes a first inductor, a first end of the first inductor is connected to the cathode of the first diode, and a second end of the first inductor is respectively connected to a first end of the second power supply unit and a first end of the first load unit.

5. The flyback converter circuit according to claim 1, characterized in that: The second output module further includes a third filtering unit, a first end of the third filtering unit is connected to the cathode of the first diode, and a second end of the third filtering unit is connected to the first end of the first filtering unit.

6. The flyback converter circuit according to claim 5, characterized in that: The third filtering unit includes a fourth resistor, a first end of the fourth resistor serves as a first end of the third filtering unit, and a second end of the fourth resistor serves as a second end of the third filtering unit.

7. The flyback converter circuit according to claim 5, characterized in that: The third filtering unit includes a second inductor, a first end of the second inductor serves as a first end of the third filtering unit, and a second end of the second inductor serves as a second end of the third filtering unit.

8. The flyback converter circuit according to claim 1, characterized in that: The second output module further includes a second diode, a cathode of the second diode is connected to the second end of the second filtering unit, and an anode of the second diode is connected to the first end of the second power supply unit.

9. The flyback converter circuit according to claim 1, characterized in that: The switch control module includes a first filter capacitor, an absorption unit, a signal control unit, a switch tube and a fifth resistor; The first end of the first filter capacitor is connected to the first end of the primary winding, and the first filter capacitor is used to filter the input voltage; the first end of the switch tube is connected to the second end of the primary winding, the second end of the switch tube is connected to the first end of the fifth resistor, and the second end of the fifth resistor and the second end of the first filter capacitor are both grounded; The first end of the absorption unit is connected to the first end of the primary winding, and the second end of the absorption unit is connected to the second end of the primary winding; The signal control unit is powered by the power supply voltage, and is used to output a control signal to the control end of the switch tube to control the on and off of the switch tube; The absorption unit is used to absorb the leakage inductance peak voltage generated when the switch tube is turned off.

10. The flyback converter circuit according to claim 9, characterized in that: The absorption unit includes: a fifth resistor, a third capacitor and a third diode; the first end of the fifth resistor and the first end of the third capacitor are both connected to the first end of the primary winding, the first end of the fifth resistor and the second end of the third capacitor are both connected to the cathode of the third diode, and the anode of the third diode is connected to the second end of the primary winding.

11. The flyback converter circuit according to claim 1, characterized in that: The first output module includes a fourth diode, a fourth capacitor and a second load unit; the anode of the fourth diode is connected to the first end of the secondary winding, the cathode of the fourth diode is respectively connected to the first end of the fourth capacitor and the first end of the second load unit, the second end of the fourth capacitor and the second end of the second load unit are both connected to the second end of the secondary winding, and the second load unit is used to output the first output voltage.

12. An electronic device, characterized in that: A flyback converter circuit comprising any one of claims 1 to 11.

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