Multi-output switching power supply and control method thereof

Abstract

The invention discloses a multi-output switching power supply and a control method thereof, the multi-output switching power supply comprises a power conversion circuit and a plurality of output control switch tubes, the plurality of output control switch tubes are connected to the output end of the power conversion circuit, the power conversion circuit converts an input voltage into a first output voltage, and the first output voltage is connected to the output end of the power conversion circuit. A plurality of output control switch tubes adjust the first output voltage into a plurality of voltage outputs; and controlling the switching state of a main switching tube in the power conversion circuit according to the output feedback signal of one path of the multiplexed output as a first feedback signal, and controlling the switching states of a plurality of output control switching tubes according to the output feedback signals of other paths of the multiplexed output. According to the multi-output control scheme, a two-stage power conversion circuit is not needed, the cost is low, the control is simple, and the system efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of switch power supply control, and more particularly to a multi-output switch power supply and a control method thereof. Background Art

[0002] In multi-load applications, a switching power supply needs to supply power to multiple loads. In this case, the switching power supply is required to output multiple different DC powers to supply different loads. Existing multi-output switching power supplies usually design a two-stage power conversion scheme. The front-stage power converter, such as a flyback converter, converts high-voltage power into low-voltage power, and the rear-stage power converter, such as a buck converter, converts the output voltage of the front-stage power converter into the required power size. Usually, in order to meet the needs of multiple loads and system optimization, one front-stage power converter is generally set, and multiple rear-stage power converters are set.

[0003] like Figure 1 As shown, an existing multi-output solution is shown. The rear-stage power converter includes two parallel buck converters, which respectively receive the output electrical power of the front-stage power converter and convert it into different power outputs. This multi-stage solution not only increases the system cost, but also reduces the system efficiency.

[0004] Therefore, it is necessary to provide an improved technical solution to overcome the above technical problems existing in the prior art. Summary of the invention

[0005] In view of this, an object of the present invention is to provide a multi-output switching power supply and a control method thereof, so as to solve the technical problems of high cost and low efficiency of the multi-output switching power supply in the prior art.

[0006] A multi-output switching power supply is provided for providing multiple output powers, wherein the multi-output switching power supply comprises a power conversion circuit, a multi-channel output control switch tube, a first control module and a second control module, wherein the power conversion circuit converts an input voltage of the multi-output switching power supply into a first output voltage, and the multiple output control switch tubes are respectively connected to multiple output terminals of the power conversion circuit to adjust the first output voltage to multiple output voltage outputs; a first feedback signal is obtained according to an output feedback signal of a first channel in the multiple outputs and transmitted to the first control module to control the switch state of the main switch tube in the power conversion circuit; a second feedback signal is obtained according to output feedback signals of other channels in the multiple outputs and transmitted to the second control module to control the switch state of the multiple output control switch tube.

[0007] Preferably, the power conversion circuit comprises a main switch tube and a plurality of freewheeling tubes, and the plurality of freewheeling tubes are connected to the same power circuit in a one-to-one correspondence with the multi-channel output control switch tubes.

[0008] Each freewheeling tube is connected in series with the output control switch tube in the same branch.

[0009] Preferably, the plurality of freewheeling transistors are N-type transistors or P-type transistors.

[0010] Preferably, the plurality of freewheeling tubes are freewheeling diodes.

[0011] Preferably, the power conversion circuit includes a transformer, the main switch tube is connected to the primary winding of the transformer, and the multiple freewheeling tubes are connected to the secondary winding of the transformer, wherein the multiple freewheeling tubes are all connected to the same-name end or the opposite-name end of the secondary winding of the transformer.

[0012] Preferably, the multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes, and the two output control switch tubes respectively control the output terminal voltages of the two outputs; a first feedback signal is obtained according to an output feedback signal of a first one of the two outputs and transmitted to the first control module to control the switching state of the main switch tube in the power conversion circuit; a second feedback signal is obtained according to an output feedback signal of a second one of the two outputs and transmitted to the second control module to control the switching state of the two output control switch tubes.

[0013] Preferably, the switching states of the two output control switch tubes are complementary conduction.

[0014] Preferably, the first feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the first path and the output feedback signal of the second path; and the second feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the second path.

[0015] Preferably, the one of the two outputs with a larger output power is used as the first output, and the first feedback signal is obtained according to its output feedback signal; the one of the two outputs with a smaller output power is used as the second output, and the second feedback signal is obtained according to its output feedback signal.

[0016] Preferably, the first control module includes a first feedback unit, an isolation transmission unit and a primary main control unit, the first feedback unit is connected to the output end of the first of the two outputs to obtain the first feedback signal; the isolation transmission unit isolates and transmits the first feedback signal to the primary control unit; the primary control unit generates a PWM control signal according to the signal transmitted by the isolation transmission unit to control the switching state of the main switch tube.

[0017] Preferably, the second control module includes a second feedback unit, a PWM control unit and a switch driving module, the second feedback unit is connected to the output end of the second of the two outputs to obtain the second feedback signal; the PWM control unit obtains a PWM control signal for controlling the switch duty cycle according to the second feedback signal, and the switch driving module generates a driving signal for controlling the switch tubes of the two outputs according to the PWM control signal.

[0018] Preferably, when the multiple freewheeling tubes are N-type transistors or P-type transistors, the multi-output switching power supply also includes a synchronous rectification control module, which is used to provide a switching control signal of the freewheeling tube to control the switching action of the freewheeling tube; the synchronous rectification control module is connected to the second control module to adjust the switching state of the freewheeling tube according to the switching control signal of the output control switch tube.

[0019] Preferably, the synchronous rectification control module controls the freewheeling tube of one of the two paths to be turned off before the output control switch tube of the other path is turned on.

[0020] Preferably, the multi-output switching power supply includes three outputs, the multi-output control switch tube includes three output control switch tubes, and the three output control switch tubes respectively control the output terminal voltages of the three outputs; a first feedback signal is obtained according to the output feedback signal of the first of the three outputs and transmitted to the first control module to control the switching state of the main switch tube in the power conversion circuit; the second control module includes a second control submodule 1 and a second control submodule 2, a second feedback signal is obtained according to the output feedback signal of the second of the three outputs and transmitted to the second control module 1, and a third feedback signal is obtained according to the output feedback signal of the third of the three outputs and transmitted to the second control module 2, and the second control module 1 and the second control module 2 control the switching state of the three output control switch tubes through logical operations.

[0021] Preferably, the sum of the duty cycles of the three output control switch tubes is 1.

[0022] In a second aspect, a control method for a multi-output switching power supply is provided, wherein the multi-output switching power supply includes a power conversion circuit and a multi-channel output control switch tube, and includes the following steps:

[0023] The power conversion circuit converts the input voltage of the multi-output switching power supply into a first output voltage, and the multiple output control switch tubes are respectively connected to the multiple output terminals of the power conversion circuit to adjust the first output voltage to multiple different output voltage outputs; a first feedback signal is obtained according to the output feedback signal of the first one of the multiple outputs to control the switching state of the main switch tube in the power conversion circuit; a second feedback signal is obtained according to the output feedback signals of other ones of the multiple outputs to control the switching state of the multiple output control switch tubes.

[0024] Preferably, the multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The first feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the first path and the output feedback signal of the second path; and the second feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the second path.

[0025] Preferably, the multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The output with larger output power among the two outputs is used as the first output, and a first feedback signal is obtained according to its output feedback signal; the output with smaller output power among the two outputs is used as the second output, and a second feedback signal is obtained according to its output feedback signal.

[0026] Preferably, the sum of the duty cycles of the two output control switch tubes is 1.

[0027] Preferably, the multi-output control switch tube includes a three-way output control switch tube, and the three-way output control switch tubes respectively control the output terminal voltages of the three outputs; a first feedback signal is obtained according to an output feedback signal of a first one of the three outputs to control the switching state of the main switch tube in the power conversion circuit; the second control module controls the switching state of the three-way output control switch tube according to an output feedback signal of a second one of the three outputs and an output feedback signal of a third one of the three outputs, wherein the sum of the duty cycles of the three-way output control switch tubes is 1.

[0028] The multi-output switching power supply and control method of the present application, the multi-output switching power supply includes a power conversion circuit and a plurality of output control switch tubes, the plurality of output control switch tubes are connected to the output end of the power conversion circuit, the power conversion circuit converts the input voltage into a first output voltage, and the plurality of output control switch tubes adjust the first output voltage to a plurality of different voltage outputs; the output feedback signal of one of the multi-channel outputs is transmitted to the first control module as a first feedback signal to control the switch state of the main switch tube in the first-level power conversion circuit, and the output feedback signal of the other channels of the multi-channel output is transmitted to the second control module as a second feedback signal to control the switch state of the plurality of output control switch tubes. The multi-output control scheme of the present application does not require a two-stage power conversion circuit, has low cost, simple control, and greatly improves system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A circuit block diagram of a multi-output switching power supply in the prior art;

[0030] Figure 2 A circuit block diagram of a first embodiment of a multi-output switching power supply according to the present invention;

[0031] Figure 3 According to the present invention Figure 2 An implementation circuit diagram of the second control module in;

[0032] Figure 4 Based on Figure 2 The working waveform diagram of the circuit in;

[0033] Figure 5 A circuit block diagram of a second embodiment of a multi-output switching power supply according to the present invention;

[0034] Figure 6 Based on Figure 5 A circuit diagram for realizing a synchronous rectification control module;

[0035] Figure 7 According to the present invention Figure 5 An implementation circuit diagram of the second control module in;

[0036] Figure 8 Based on Figure 5 The first working waveform diagram of the circuit in;

[0037] Fig. 9 Based on Figure 5 The second working waveform diagram of the circuit in;

[0038] Fig.10 A circuit block diagram of a third embodiment of a multi-output switching power supply according to the present invention;

[0039] Fig.11 According to the present invention Figure 5 An implementation circuit diagram of the second control module in;

[0040] Fig.12 A circuit diagram of a fourth embodiment of a multi-output switching power supply according to the present invention;

[0041] Fig.13 FIG. 4 is a circuit diagram of a fourth embodiment of a multi-output switching power supply according to the present invention. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any substitution, modification, equivalent method and scheme made within the spirit and scope of the present invention.

[0043] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without these detailed descriptions.

[0044] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all simplified and not in exact proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.

[0045] refer to Figure 2 FIG. 1 is a circuit block diagram of a first embodiment of a multi-output switching power supply according to the present invention. In this embodiment, two outputs are taken as an example. Figure 3 According to the present invention Figure 2 An implementation circuit diagram of the second control module in; Figure 4 Based on Figure 2 The working waveform diagram of the circuit in the embodiment. The multi-output switching power supply in this embodiment includes a power conversion circuit, two output control switch tubes (such as switch tube Q1 and switch tube Q2), a first control module and a second control module. The power conversion circuit converts the input voltage of the multi-output switching power supply into a first output voltage. The two output control switch tubes are respectively connected to the two output ends of the power conversion circuit to adjust the first output voltage to two output voltage outputs. Here, the two output voltages can be the same voltage value or different voltage values. Reference Figure 2Here, the power conversion circuit takes the flyback switch topology as an example, which includes a main switch tube Qp and two freewheeling tubes such as diode D1 and diode D2. The freewheeling tubes and the multi-channel output control switch tubes are connected one-to-one in the same power circuit, which is the power circuit connected on the output side. Here, each of the freewheeling tubes is connected in series with the output control switch tube on the same branch of the power circuit, which can prevent the problem of energy backflow when the voltages of the multi-channel outputs are unequal or have large differences. The flyback switch topology also includes a transformer, the main switch tube is connected to the primary winding of the transformer, and the multiple freewheeling tubes are connected to the secondary winding of the transformer, wherein the multiple freewheeling tubes are all connected to the same-name end or the opposite-name end of the secondary winding of the transformer. Figure 2 In the example, the freewheeling tubes are connected to the opposite-name terminals.

[0046] Specifically, refer to Figure 2 and Figure 3 , the first control module includes a first feedback unit, an isolation transmission unit and a primary main control unit, the first feedback unit is connected to the output end of the first of the two outputs to obtain the first feedback signal, the isolation transmission unit isolates and transmits the first feedback signal to the primary control unit; the primary control unit generates a PWM control signal according to the signal transmitted by the isolation transmission unit to control the switching state of the main switch tube. Here, the isolation transmission unit can be an optical coupling device, which couples the first feedback signal to the primary receiver, and the receiver transmits it to the primary control unit. The primary control unit generally includes a primary PWM control signal generator and a switch driver, which controls the switching action of the main switch tube Qp according to the feedback signal to adjust the output voltage of the power conversion circuit. The first feedback unit can be a sampling circuit composed of resistors, and the primary control unit can be a control and drive unit in the prior art.

[0047] refer to Figure 3 The second control module includes a second feedback unit, a PWM control unit and a switch driving module. The second feedback unit is connected to the output end of the second of the two outputs to obtain the second feedback signal, such as the error compensation signal Vcomp, which is obtained by performing error amplification and compensation processing on the output signal and the reference signal; the PWM control unit obtains a PWM control signal for controlling the switch duty cycle according to the second feedback signal comp, and the switch driving module generates a drive signal for controlling the two output switch tubes according to the PWM control signal. Here, the switch driving module includes a Q2 turn-on & Q1 turn-off drive module and a Q2 turn-off & Q1 turn-on drive module. By driving the switch tubes Q1 and Q2, preferably, for the convenience of control, the switch states of the two output control switch tubes Q1 and Q2 are complementary conduction, and the sum of their duty cycles is 1.

[0048] refer to Figure 4 Based on Figure 2 The working waveform diagram shows that at time t1, the switch control signal Vgsp of the main power tube is low, the main power tube is turned off, the switch control signal Vgs1 of Q1 becomes high, the switch tube Q1 is turned on, the switch control signal Vgs2 of Q2 is low, Q2 is turned off, the first output power loop is turned on, and Is1 decreases; then at time t2, the switch tube Q1 is turned off, Q2 is turned on, Is2 continues to decrease, and the second output power loop is turned on; then, at time t3, the current of the second output power loop drops to zero, and at time t4, the primary main power tube is turned on again, and the excitation inductance current Ip rises, and at time t5, the first output power loop is turned on, and the second output power loop is disconnected, and so on. Preferably, in the interval directly from t3 to t5, Q2 can be turned off and Q1 can be turned on, which does not affect the control effect. It is known to those skilled in the art that in the switching process of the switch tubes Q1 and Q2, there can be set a conduction time interval in which two switch tubes are turned on and overlap, so as to ensure that the path of the excitation current is unobstructed.

[0049] Through the above-mentioned embodiments, the two-way output switching power supply of the present invention does not need a two-stage circuit. By controlling the switch tube Q1 and the switch tube Q2, according to the feedback of the feedback signal, the switching power supply can realize separate control of the two output voltages in a simple control circuit.

[0050] refer to Figure 5 This is a circuit block diagram of a second embodiment of a multi-output switching power supply according to the present invention. In this embodiment, the freewheeling tube is a synchronous rectifier tube. In this embodiment, the synchronous rectifier tube and the output control switch tube are connected in series, both are connected to the high side of the output power loop, and are connected in the same branch. Of course, the two can also be connected in series on the low side of the output power loop. Figure 6 Based on Figure 5 A circuit diagram of a synchronous rectification control module in the embodiment of the present invention, wherein the synchronous rectification control module is used to drive the synchronous rectification tube. Figure 7 According to the present invention Figure 5 A circuit diagram of an implementation of the second control module in FIG. Figure 6As shown, the synchronous rectification control module is used to provide the switch control signal of the freewheeling tube to control the switch action of the freewheeling tube; the synchronous rectification control module is connected to the second control module to adjust the switch state of the freewheeling tube according to the switch control signal of the output control switch tube. The synchronous rectification control module includes a first SR1 synchronous rectification control module and a second SR2 synchronous rectification control module. The SR1 synchronous rectification control module includes a synchronous rectification sampling module, which samples the drain-source voltage of the switch tube SR2. The SR2 opening drive module and the closing drive module open and close the SR2 according to the sampled signal. At the same time, the SR2 closing drive module transmits the signal driving SR2 to shut down to the second control module. The SR2 synchronous rectification control module has the same structure as the SR1 synchronous rectification control module, except that the SR2 closing drive module receives the signal transmitted by the second control module. Both the SR1 synchronous rectification control module and the SR2 synchronous rectification control module can be control and drive schemes for synchronous rectification switch tubes in the prior art, such as turning on the SR by comparing the drain-source voltage flowing through the SR with the threshold voltage, and turning off the SR by detecting the current and drain-source voltage of the SR and comparing them with the threshold.

[0051] Figure 7 According to the present invention Figure 5 A circuit diagram of an implementation of a second control module in Figure 3 The second control module in the embodiment is generally the same in structure, except that the Q2 off & Q1 on drive module receives the SR2 off control signal transmitted by the SR2 synchronous rectification control module to control the switching actions of Q2 and Q1 according to their off timing. In addition, before SR2 is turned on, Figure 5 The SR1 early shutdown control signal is transmitted to the SR1 synchronous rectification module to control SR1 to shut down early.

[0052] for Figure 5 In the circuit diagram, when the output voltages of the two paths are not equal or even very different, when the switch tube Q1 continues to be turned on, the switch tube Q2 starts to be turned on. At this time, since the SR synchronous rectification can flow current in both directions, there will be a large discharge current from the Vo1 output capacitor to the V02 output capacitor, or from the Vo2 output capacitor to the V01 output capacitor. Therefore, preferably, the synchronous rectification control module controls the freewheeling tube of one of the two paths to be turned off before the output control switch tube of the other path is turned on, such as Figure 5 The SR1 early shutdown control signal is transmitted to the SR1 synchronous rectification module, so that the freewheeling tube can be turned off. Figure 8 Based on Figure 5In the first working waveform of the circuit in the figure, if the second output voltage is greater than the first output voltage, the driver of the SR1 synchronous rectifier tube is forced to be turned off at or before the switch tube Q2 is turned on, so as to prevent a large discharge current between the two paths during the overlapping stage of the drive of Q1 and Q2. Figure 8 The overlapping interval of t2 and t3 in . Fig. 9 Based on Figure 5 The second working waveform of the circuit in FIG. 1; if the first output voltage is greater than the second output voltage, at or before the switch tube Q2 is turned on, the drive of the SR1 synchronous rectifier tube is forced to be turned off, and Figure 8 The difference is that Q2 is turned on at time t2, but because the output voltage Vo2 of the second path is higher than the output voltage Vo1 of the first path, the excitation current does not flow to the output end of Vo2 until Q1 is turned off, such as at time t3. Figure 8 and Fig. 9 The symbols in Figure 4 They are the same and can be understood in the same way. Vgs_SR1 is the switch control signal of SR1, and Vgs_SR2 is the switch control signal of SR2, which are both provided by the synchronous rectification control module.

[0053] Preferably, Figure 5 The freewheeling tube in the embodiment is an N-type transistor, which can also be a P-type transistor. When the freewheeling tube is a P-type transistor, the P-type transistor can be connected to the low potential end of the secondary output loop, so that the driving of the P-type transistor is simpler.

[0054] refer to Fig.10 The third embodiment of the circuit diagram of the multi-output switching power supply according to the present invention is shown in FIG. Figure 5 The circuit architecture of the illustrated embodiment is the same, except that, in the present embodiment, the first feedback unit performs a preset weight calculation based on the output feedback signal of the first path and the output feedback signal of the second path to obtain the first feedback signal. For example, the first feedback unit receives the output feedback signal Vo1 of the first path and the output feedback signal Vo2 of the second path, and receives coefficients K1 and K2, performs a weight calculation on the two such as: Vo1*k1+Vo2*k2=Vref1, obtains the feedback signal Vref1 as the first feedback signal and transmits it to the isolation transmission unit; similarly, the second feedback unit receives the output feedback signal Vo2 of the second path and the coefficient K3, performs a weight calculation such as: Vo1*k3=Vref2, and transmits the feedback signal Vref2 as the second feedback signal to the PWM control unit, refer to Figure 5 A circuit diagram and a circuit diagram of the first control module in Fig.11 According to the present invention Figure 5The second control module in the circuit diagram is realized; the first feedback unit and the second feedback unit are added with coefficients, which can be set internally or externally and transmitted to the feedback unit. The above k1, k2, and k3 are set according to the needs of the system and the load conditions, and the size of the feedback signal can be accurately fed back, so as to more accurately control the size of the output voltages Vo1 and V02. This embodiment is more accurate and reliable for the feedback and control of the output voltage, and can also ensure that the output voltage or output power can be met under any circumstances.

[0055] refer to Fig.12 The circuit diagram of the fourth embodiment of the multi-output switching power supply according to the present invention is Figure 5 The circuit architecture of the embodiments shown is the same, except that the output with the larger output power of the two outputs is used as the first output, and the first feedback signal is obtained according to its output feedback signal; the output with the smaller output power of the two outputs is used as the second output, and the second feedback signal is obtained according to its output feedback signal. In some cases, due to the different load sizes of the two outputs, or when one of the outputs is unloaded, the feedback signal of the high-power output is selected as the feedback signal to control the main switch tube, so as to ensure that the output power supply of the normal load is not affected when the output is unloaded. Fig.12 As shown, the multi-output switching power supply includes a power selection module, which selects the one with higher power to be transmitted to the first feedback unit and the one with lower power to be transmitted to the second feedback unit according to the output voltage or output power Output1 and Output2 of the two paths, so that the switch control of the main power tube can meet the demand of the one with higher power.

[0056] Fig.13 This is a circuit diagram of the fourth embodiment of a multi-output switching power supply according to the present invention. The multi-output switching power supply includes three outputs, and the multi-output control switch tube includes a three-way output control switch tube, and the three-way output control switch tubes respectively control the output terminal voltages of the three outputs; a first feedback signal is obtained according to the output feedback signal of the first of the three outputs and transmitted to the first control module to control the switching state of the main switch tube in the power conversion circuit; the second control module includes a second control submodule 1 and a second control submodule 2, a second feedback signal is obtained according to the output feedback signal of the second of the three outputs and transmitted to the second control module 1, and a third feedback signal is obtained according to the output feedback signal of the third of the three outputs and transmitted to the second control module 2, and the second control module 1 and the second control module 2 control the switching state of the three-way output control switch tube through a logic operation module through a logic operation module. The sum of the duty cycles of the three-way output control switch tubes is 1. Here, the second control submodule 1 and the second control submodule 2 can both be connected with Figure 3 The structure of the second control module is the same or similar.

[0057] In the case of three outputs, the first control module can be connected with Figure 2 , Figure 5 , Fig.10 , Fig.11 The circuit of any embodiment is the same as that of the embodiment, except that the feedback signal is changed from two paths to three paths, such as the two-path weighted operation is changed to the three-path weighted operation or the one with the largest power among the three paths is selected as the feedback signal.

[0058] Those skilled in the art will appreciate that, inspired by the embodiments of the present invention, the multi-channel output power supply may also be four-channel, five-channel or other multi-channel situations, and the control ideas thereof are the same as or analogous to the present invention and are all within the protection scope of the present invention.

[0059] Finally, the present application provides a control method for a switching power supply, wherein the multi-output switching power supply includes a power conversion circuit and a multi-channel output control switch tube, and includes the following steps: the power conversion circuit converts the input voltage of the multi-output switching power supply into a first output voltage, and the multiple output control switch tubes are respectively connected to multiple output ends of the power conversion circuit to adjust the first output voltage to multiple different output voltage outputs;

[0060] Obtaining a first feedback signal according to an output feedback signal of a first path among the multiple output paths to control a switching state of a main switch tube in the power conversion circuit;

[0061] A second feedback signal is obtained according to output feedback signals of other output paths in the multi-path output to control the switching state of the multi-path output control switch tube.

[0062] Preferably, the multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The first feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the first path and the output feedback signal of the second path; and the second feedback signal is obtained by performing a preset weight calculation based on the output feedback signal of the second path.

[0063] Preferably, the multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The output with larger output power among the two outputs is used as the first output, and a first feedback signal is obtained according to its output feedback signal; the output with smaller output power among the two outputs is used as the second output, and a second feedback signal is obtained according to its output feedback signal.

[0064] Preferably, the sum of the duty cycles of the two output control switch tubes is 1.

[0065] Preferably, the multi-output control switch tube includes a three-way output control switch tube, and the three-way output control switch tubes respectively control the output terminal voltages of the three outputs; a first feedback signal is obtained according to an output feedback signal of a first one of the three outputs to control the switching state of the main switch tube in the power conversion circuit; the second control module controls the switching state of the three-way output control switch tube according to an output feedback signal of a second one of the three outputs and an output feedback signal of a third one of the three outputs, wherein the sum of the duty cycles of the three-way output control switch tubes is 1.

[0066] It should be noted that the specific implementation and corresponding illustrations given are merely a way of describing the implementation method of the present invention, and do not limit the specific structure of the implementation scheme of the present invention. Various changes or modifications can be made to these implementation schemes without departing from the principle and essence of the present invention, but these changes and modifications fall within the scope of protection of the present invention.

[0067] Although the embodiments are described and illustrated separately above, some common technologies are involved. It is the opinion of ordinary technicians in this field that the embodiments can be replaced and integrated. If the content is not clearly recorded in one of the embodiments, reference can be made to another recorded embodiment.

[0068] The above-described implementation methods do not constitute a limitation on the protection scope of the technical solution. Any modification, equivalent replacement and improvement made within the spirit and principle of the above-described implementation methods shall be included in the protection scope of the technical solution.

Claims

1. A multi-output switching power supply for providing multiple output powers, wherein: The multi-output switching power supply includes a power conversion circuit, a multi-channel output control switch tube, a first control module and a second control module. The power conversion circuit converts the input voltage of the multi-output switching power supply into a first output voltage, and the multiple output control switch tubes are respectively connected to multiple output terminals of the power conversion circuit to adjust the first output voltage into multiple output voltage outputs; Obtaining a first feedback signal according to an output feedback signal of a first path among the multiple output paths and transmitting the first feedback signal to the first control module to control the switching state of the main switch tube in the power conversion circuit; A second feedback signal is obtained according to output feedback signals of other outputs in the multi-channel output and transmitted to the second control module to control the switching state of the multi-channel output control switch tube.

2. The multi-output switching power supply according to claim 1, wherein: The power conversion circuit includes a main switch tube and a plurality of freewheeling tubes. The multiple freewheeling tubes and the multi-channel output control switch tubes are connected in a same power circuit in a one-to-one correspondence.

3. The multi-output switching power supply according to claim 2, wherein: Each of the freewheeling tubes and the output control switch tube is connected in series on the same branch of the power circuit.

4. The multi-output switching power supply according to claim 2, wherein: The plurality of freewheeling transistors are N-type transistors or P-type transistors.

5. The multi-output switching power supply according to claim 2, wherein: The plurality of freewheeling tubes are freewheeling diodes.

6. The multi-output switching power supply according to claim 4, wherein: The power conversion circuit includes a transformer, The main switch tube is connected to the primary winding of the transformer, and the plurality of freewheeling tubes are connected to the secondary winding of the transformer. Wherein, the multiple freewheeling tubes are all connected to the same-name end or different-name end of the secondary winding of the transformer.

7. The multi-output switching power supply according to claim 1, wherein: The multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The two output control switch tubes respectively control the output terminal voltages of the two outputs; Obtaining a first feedback signal according to an output feedback signal of a first output of the two outputs and transmitting the first feedback signal to the first control module to control the switching state of the main switch tube in the power conversion circuit; A second feedback signal is obtained according to an output feedback signal of a second output of the two outputs and transmitted to the second control module to control the switching states of the two output control switch tubes.

8. The multi-output switching power supply according to claim 7, wherein: The switching states of the two output control switch tubes are complementary conduction.

9. The multi-output switching power supply according to claim 7, wherein: Performing preset weight calculation according to the output feedback signal of the first path and the output feedback signal of the second path to obtain the first feedback signal; The second feedback signal is obtained by performing a preset weight calculation according to the output feedback signal of the second path.

10. The multi-output switching power supply according to claim 7, wherein: The output path with the larger output power among the two output paths is used as the first path, and a first feedback signal is obtained according to the output feedback signal thereof; The output path with smaller output power among the two output paths is used as the second path, and a second feedback signal is obtained according to its output feedback signal.

11. The multi-output switching power supply according to claim 7, wherein: The first control module includes a first feedback unit, an isolation transmission unit and a primary side main control unit. The first feedback unit is connected to the output end of the first of the two outputs to obtain the first feedback signal; The isolation transmission unit isolates and transmits the first feedback signal to the primary side control unit; The primary control unit generates a PWM control signal according to the signal transmitted by the isolation transmission unit to control the switching state of the main switch tube.

12. The multi-output switching power supply according to claim 7, wherein: The second control module includes a second feedback unit, a PWM control unit and a switch driving module. The second feedback unit is connected to the output end of the second output of the two outputs to obtain the second feedback signal; The PWM control unit obtains a PWM control signal for controlling the switch duty cycle according to the second feedback signal, The switch driving module generates the two output control switch tube driving signals according to the PWM control signal.

13. The multi-output switching power supply according to claim 1 or 7, wherein: When the plurality of freewheeling transistors are N-type transistors or P-type transistors, the multi-output switching power supply further includes a synchronous rectification control module. The synchronous rectification control module is used to provide a switch control signal of the freewheeling tube to control the switch action of the freewheeling tube; The synchronous rectification control module is connected to the second control module to adjust the switching state of the freewheeling tube according to the switching control signal of the output control switch tube.

14. The multi-output switching power supply according to claim 13, wherein: The synchronous rectification control module controls the freewheeling tube of one of the two paths to be turned off before the output control switch tube of the other path is turned on.

15. The multi-output switching power supply according to claim 1, wherein: The multi-output switching power supply includes three outputs, and the multi-output control switch tube includes three output control switch tubes. The three-way output control switch tubes respectively control the output terminal voltages of the three-way outputs; Obtaining a first feedback signal according to an output feedback signal of a first output among the three outputs and transmitting the first feedback signal to the first control module to control the switching state of a main switch in the power conversion circuit; The second control module includes a second control submodule 1 and a second control submodule 2. A second feedback signal is obtained according to an output feedback signal of the second of the three outputs and transmitted to the second control module 1. A third feedback signal is obtained according to an output feedback signal of the third of the three outputs and transmitted to the second control module 2. The second control module 1 and the second control module 2 control the switching state of the three-way output control switch tube through logical operations.

16. The multi-output switching power supply according to claim 15, wherein: The sum of the duty cycles of the three output control switch tubes is 1.

17. A control method for a multi-output switching power supply, the multi-output switching power supply comprising a power conversion circuit and a multi-channel output control switch tube, wherein: The following steps are involved: The power conversion circuit converts the input voltage of the multi-output switching power supply into a first output voltage, and the multiple output control switch tubes are respectively connected to multiple output terminals of the power conversion circuit to adjust the first output voltage into multiple different output voltage outputs; Obtaining a first feedback signal according to an output feedback signal of a first path among the multiple output paths to control a switching state of a main switch tube in the power conversion circuit; A second feedback signal is obtained according to output feedback signals of other output paths in the multi-path output to control the switching state of the multi-path output control switch tube.

18. The control method of a multi-output switching power supply according to claim 17, wherein: The multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. Performing preset weight calculation according to the output feedback signal of the first path and the output feedback signal of the second path to obtain the first feedback signal; The second feedback signal is obtained by performing a preset weight calculation according to the output feedback signal of the second path.

19. The control method of a multi-output switching power supply according to claim 17, wherein: The multi-output switching power supply includes two outputs, and the multi-output control switch tube includes two output control switch tubes. The output path with the larger output power among the two output paths is used as the first path, and a first feedback signal is obtained according to the output feedback signal thereof; The output path with smaller output power among the two output paths is used as the second path, and a second feedback signal is obtained according to its output feedback signal.

20. The control method of a multi-output switching power supply according to claim 18 or 19, wherein: The sum of the duty cycles of the two output control switch tubes is 1.

21. The control method of a multi-output switching power supply according to claim 17, wherein: The multi-output switching power supply includes three outputs, and the multi-output control switch tube includes three output control switch tubes. The three-way output control switch tubes respectively control the output terminal voltages of the three-way outputs; Obtaining a first feedback signal according to an output feedback signal of a first output among the three outputs to control a switching state of a main switch tube in the power conversion circuit; The second control module controls the switch states of the three-way output control switch tubes according to the output feedback signal of the second way and the output feedback signal of the third way among the three-way outputs. The sum of the duty cycles of the three output control switch tubes is 1.

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