Isolated switching power supply, control method and storage medium

Abstract

The invention provides an isolated switching power supply, a control method and a computer readable storage medium. The isolated switching power supply comprises: at least two primary circuits, each of which comprises a power switch; each secondary side circuit comprises a synchronous rectifier tube; primary windings of the at least two transformers are connected in series with the power switches in the corresponding primary circuits, and secondary windings of the at least two transformers are connected in series with the synchronous rectifier tubes in the corresponding secondary circuits; the number of the primary side circuits, the number of the secondary side circuits and the number of the transformers are equal; the isolation controller is used for receiving an output voltage signal at the output end and at least two winding voltage signals on a secondary winding of the transformer; according to the output voltage signal and the winding voltage signal, generating at least two pulse width modulation signals with the same number as the primary side circuits, wherein the phases of the at least two pulse width modulation signals are mutually staggered; and the pulse width modulation signal is transmitted to the control end of the power switch.

Description

Technical Field

[0001] The present application relates to the field of electronic circuits, and in particular to an isolated switching power supply, a control method and a storage medium. Background Art

[0002] An isolated switching power converter, also known as a switching power supply or a switching power supply, is a high-frequency power conversion device and a type of power supply. The input of an isolated switching power converter generally receives an AC power supply (such as a mains power supply), and its output generally provides DC power to devices that require a DC power supply, such as mobile phones and laptops. The switching power converter is used to achieve the conversion of voltage and current between AC and DC.

[0003] Isolated switching power supplies in chargers and adapters usually use flyback switching power supplies. In order to improve user experience, the output power of current chargers and adapters is getting higher and higher. As the output power increases, flyback switching power supplies often require larger transformers, higher switching frequencies, smaller on-resistance switches, larger capacitance capacitors, and sometimes even need to enter current continuous mode (CCM). These usually make the power supply circuit less EMI-resistant, increase the system size, and increase costs.

[0004] In addition, in the actual operation of existing isolated switching power supplies, in the discontinuous current mode (DCM), due to reasons such as transformer leakage inductance, there is a possibility that the rapid change in the voltage signal caused by the free resonance of the inductor is judged as a signal that requires the operation of the secondary synchronous rectifier. That is, when the secondary synchronous rectifier is turned on, the power switch is mis-turned on, which may cause the primary circuit and the secondary circuit to be connected together for a period of time. Therefore, it is necessary to limit the current during the operation of the isolated power supply to avoid machine explosion, and such operation will also reduce the conversion efficiency of the isolated power supply. Summary of the invention

[0005] In view of this, it is necessary to provide an improved isolated switching power supply and a control method thereof to at least partially solve the above-mentioned technical problems, thereby optimizing electromagnetic interference, balancing heat distribution, reducing output ripple and the capacitance of output capacitors, and improving the overall conversion efficiency and safety of the isolated switching power supply.

[0006] In one aspect of the present disclosure, an isolated switching power supply is provided, comprising: at least two primary circuits, each of which comprises a power switch; at least two secondary circuits, each of which comprises a synchronous rectifier; at least two transformers, wherein the primary winding of each transformer is connected in series with the power switch in the corresponding primary circuit and then connected between the input end of the isolated switching power supply and the primary reference ground, and the secondary winding of each transformer is connected in series with the synchronous rectifier in the corresponding secondary circuit and then connected between the output end of the isolated switching power supply and the secondary reference ground, wherein the number of the at least two primary circuits, the at least two secondary circuits and the at least two transformers is equal; and an isolation controller, the isolation controller is used to: receive an output voltage signal at the output end of the isolated switching power supply and at least two winding voltage signals on the secondary windings of the at least two transformers; generate at least two pulse width modulation signals according to the output voltage signal and the at least two winding voltage signals, wherein the number of the at least two pulse width modulation signals is equal to the number of the at least two primary circuits, and the phases of the at least two pulse width modulation signals are staggered; and transmit each generated pulse width modulation signal to the control end of the power switch of the corresponding primary circuit in the at least two primary circuits to control the staggered operation between the power switches in the at least two primary circuits.

[0007] In one possible embodiment, the isolation controller includes: a secondary side controller, which is used to receive the output voltage signal and the at least two winding voltage signals, and generate and send a request signal based on the output voltage signal and the at least two winding voltage signals; a primary side controller, which is used to receive the request signal, generate the at least two pulse width modulation signals based on the request signal, and transmit each of the at least two pulse width modulation signals to the control end of the power switch of the corresponding primary circuit; and an isolator, which is connected between the secondary side controller and the primary side controller, and is used to transmit the request signal from the secondary side controller to the primary side controller in an isolated manner.

[0008] In a possible implementation manner, the secondary-side controller is configured to send the request signal only after the output voltage signal is lower than an output voltage threshold and the synchronous rectifiers in the at least two secondary-side circuits are turned off.

[0009] In one possible embodiment, the request signal is a common request signal for the at least two primary circuits, the secondary controller is configured to generate the common request signal based on the output voltage signal and the at least two winding voltage signals, the isolator is configured to transmit the common request signal generated by the secondary controller to the primary controller, and the primary controller is configured to generate the at least two pulse width modulation signals based on the common request signal.

[0010] In one possible implementation, the secondary side controller is configured to alternately generate at least two request signals based on the output voltage signal and the at least two winding voltage signals, the number of the request signals is the same as the number of the primary side circuits, and each request signal is used for a corresponding primary side circuit.

[0011] In a possible implementation manner, the isolator includes at least two isolation units, the number of the isolation units is the same as the number of the primary circuits, and each isolation unit is used to transmit a corresponding request signal.

[0012] In one possible implementation, the primary side controller includes at least two primary side control units, the number of the primary side control units is the same as the number of the primary side circuits, and the isolator transmits at least two request signals alternately generated by the secondary side controller to the corresponding primary side control units respectively, and the primary side control unit generates a corresponding pulse width modulation signal according to the corresponding request signal.

[0013] In a possible implementation, the primary control unit includes: a receiving module, which is used to receive a corresponding request signal; and a primary logic control module, which is used to receive the request signal from the receiving module and generate the pulse width modulation signal according to the request signal.

[0014] In one possible implementation, the primary side controller includes a primary side control unit, and the isolator transmits at least two request signals alternately generated by the secondary side controller to the primary side control unit, and the primary side control unit generates pulse width modulation signals for each of the at least two primary side circuits according to the at least two request signals.

[0015] In a possible implementation, the secondary controller includes at least two secondary control units, the number of the secondary control units is the same as the number of the secondary circuits, and the at least two secondary control units each generate a corresponding request signal based on the output voltage signal and the corresponding winding voltage signal.

[0016] In one possible embodiment, one of the at least two secondary side control units is configured to generate a corresponding request signal and a first flag signal based on the output voltage signal and the corresponding winding voltage signal; and the other secondary side control units among the at least two secondary side control units are configured to generate a corresponding request signal based on the first flag signal, the output voltage signal and the corresponding winding voltage signal.

[0017] In one possible implementation, the primary controller includes at least two primary control units, the number of the primary control units is the same as the number of the primary circuits, and the isolator transmits the common request signal to one of the at least two primary control units, and the at least two primary control units each generate a corresponding pulse width modulation signal.

[0018] In a possible implementation manner, the primary control unit that receives the common request signal is configured to send a second flag signal to other primary control units, and the other primary control units are configured to each generate a corresponding pulse width modulation signal based on the second flag signal.

[0019] In one possible embodiment, the primary side control unit that receives the common request signal includes: a receiving module, which is used to receive the common request signal; and a first primary side logic control module, which is used to receive the common request signal from the receiving module, and generate a corresponding pulse width modulation signal and the second flag signal according to the common request signal; the other primary side control units include: a second primary side logic control module, which is used to receive the second flag signal, and generate a corresponding pulse width modulation signal according to the second flag signal.

[0020] In one possible embodiment, the secondary side controller includes a secondary side control unit, and the secondary side control unit includes: a secondary side logic control module, which is used to receive the output voltage signal and the at least two winding voltage signals and generate the request signal based on the output voltage signal and the at least two winding voltage signals; and a sending module, which is used to send the request signal generated by the secondary side logic control module to the isolator.

[0021] In a possible implementation manner, the secondary-side logic control module is further used to generate a secondary-side control signal for controlling the on or off of a synchronous rectifier tube in a corresponding secondary-side circuit according to the winding voltage signal.

[0022] In one possible embodiment, the primary side controller includes a primary side control unit, which includes: a receiving module, which is used to receive the common request signal from the isolator; and a primary side logic control module, which is used to receive the common request signal from the receiving module and generate the at least two pulse width modulation signals according to the common request signal.

[0023] In a possible implementation manner, the isolator includes at least one of the following: a transformer isolator, a capacitor isolator, and a digital isolator.

[0024] In another aspect of the present disclosure, a control method for an isolated switching power supply is provided, wherein the isolated switching power supply comprises: at least two primary circuits, each of which comprises a power switch; at least two secondary circuits, each of which comprises a synchronous rectifier; at least two transformers, wherein the primary winding of each transformer is connected in series with the power switch in the corresponding primary circuit and then connected between the input end of the isolated switching power supply and the primary reference ground, and the secondary winding of each transformer is connected in series with the synchronous rectifier in the corresponding secondary circuit and then connected between the output end of the isolated switching power supply and the secondary reference ground, wherein the number of the at least two primary circuits, the at least two secondary circuits and the at least two transformers is equal; and A controller is used to execute the method to control the power switch in the primary circuit, the method comprising: receiving an output voltage signal at the output end of the isolated switching power supply and at least two winding voltage signals on the secondary windings of the at least two transformers; generating at least two pulse width modulation signals according to the output voltage signal and the at least two winding voltage signals, wherein the number of the at least two pulse width modulation signals is equal to the number of the at least two primary circuits, and the phases of the at least two pulse width modulation signals are staggered; and transmitting each generated pulse width modulation signal to the control end of the power switch of the corresponding primary circuit in the at least two primary circuits to control the staggered operation between the power switches in the at least two primary circuits.

[0025] In another aspect of the present disclosure, a computer-readable storage medium is provided, which stores instructions, which, when executed by a controller, cause the controller to perform the method described above.

[0026] The present disclosure provides an isolated switching power supply, a control method and a storage medium, which can realize the phase-shifting control between the power switches in at least two primary circuits, and then realize the energy transmission from the power supply to the load through the phase-shifting control. This can, for example, reduce the volume and cost of a single circuit, optimize electromagnetic interference (EMI), balance heat distribution, reduce output ripple and the capacitance of the output capacitor, and thus improve the system cost performance. Furthermore, by controlling the timing relationship between the request signal and the synchronous rectifier tube of the secondary circuit, it is possible to avoid the situation where the power switch in the primary circuit and the synchronous rectifier tube in the secondary circuit are turned on at the same time, thereby avoiding the risk of explosion.

[0027] Further features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments, features, and aspects of the invention and, together with the description, serve to explain the principles of the invention.

[0029] Figure 1 A schematic diagram of the architecture of an isolated switching power supply according to an embodiment of the present invention is shown.

[0030] Figure 2 A schematic diagram showing an isolation controller according to a first embodiment of the present invention is shown.

[0031] Figure 3 A schematic diagram of operating waveforms of an isolated switching power supply according to a first embodiment of the present invention is shown.

[0032] Figure 4 A schematic diagram showing an isolation controller according to a second embodiment of the present invention is shown.

[0033] Figure 5 A schematic diagram showing an isolation controller according to a third embodiment of the present invention is shown.

[0034] Figure 6 A schematic diagram of operating waveforms of an isolated switching power supply according to a third embodiment of the present invention is shown.

[0035] Figure 7 A schematic diagram showing an isolation controller according to a fourth embodiment of the present invention is shown.

[0036] Figure 8 A schematic diagram showing an isolation controller according to a fifth embodiment of the present invention is shown.

[0037] Fig. 9 A flow chart showing a control method for an isolated switching power supply according to the present invention is shown. DETAILED DESCRIPTION

[0038] Various exemplary embodiments, features and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise specified.

[0039] The word "exemplary" is used herein to mean "serving as an example, embodiment or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as being superior or better than other embodiments. The terms "first", "second", "third", etc. (if any) in the specification and claims of the present invention and the drawings are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected", "connected" and "coupled" should be understood in a broad sense. For example, it can be an electrical connection or mutual communication, it can be a direct connection, it can also be an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can also be implemented without certain specific details. In some examples, methods, means, components and circuits well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0042] Figure 1 FIG. 1 is a schematic diagram showing an isolated switching power supply 100 according to an embodiment of the present invention. Figure 1 In the example of FIG. 1 , the isolated switching power supply 100 is a flyback isolated switching power supply, which includes at least two primary circuits 111 and 112, at least two secondary circuits 121 and 122, at least two transformers T1 and T2, and an isolation controller 130. The primary circuits 111 and 112 each include a power switch, such as Figure 1The power switches G1 and G2 shown, each of the primary windings of the transformer is connected in series with the power switch in the corresponding primary circuit and then connected between the input terminal 140 of the isolated switching power supply 100 and the primary reference ground PGND. Specifically, each power switch is connected in series between the primary winding of the corresponding transformer and the primary reference ground PGND, and is controlled by a corresponding pulse width modulation (PWM) signal from the isolation controller 130, and the primary winding of each transformer is connected in series between the input terminal 140 of the isolated switching power supply and the corresponding power switch; or, each power switch is connected in series between the primary winding of the corresponding transformer and the input terminal 140 of the isolated switching power supply 100, and the primary winding of each transformer is connected in series between the corresponding power switch and the primary reference ground PGND. The secondary circuits 121 and 122 each include a synchronous rectifier tube, such as Figure 1 The synchronous rectifiers SR1 and SR2 shown in the figure, each of the secondary windings of the transformer is connected in series with the synchronous rectifier in the corresponding secondary circuit and then connected between the output terminal 150 of the isolated switching power supply and the secondary reference ground SGND. Specifically, each synchronous rectifier is connected in series between the secondary winding of the corresponding transformer and the secondary reference ground SGND, and is controlled by the corresponding secondary control signal from the isolation controller 130, and the secondary winding of each transformer is connected in series between the output terminal 150 of the isolated switching power supply 100 and the corresponding synchronous rectifier; or, each synchronous rectifier is connected in series between the output terminal 150 of the isolated switching power supply 100 and the secondary winding of the corresponding transformer, and the secondary winding of each transformer is connected in series between the secondary reference ground SGND and the corresponding synchronous rectifier.

[0043] The isolated switching power supply may further include a primary capacitor Cbus and a secondary capacitor Cout, wherein the primary capacitor Cbus is connected between the input voltage terminal and the primary reference ground PGND; the secondary capacitor Cout is connected between the voltage output terminal 150 and the secondary reference ground SGND; wherein the primary and secondary sides of the transformer are not grounded in common.

[0044] In the example, the input voltage signal VBUS at the voltage input terminal 140 may have some noise, which may interfere with other components in the primary circuit, causing the primary circuit to work unstably. The primary capacitor Cbus can filter and store energy for the input voltage to ensure the stability of the input voltage. Similarly, the output voltage at the voltage output terminal 150 may also have some noise, which may interfere with other components in the secondary circuit, causing the secondary circuit to work unstably. The secondary capacitor Cout can filter and store energy for the output voltage. In addition, setting the secondary capacitor Cout can also smooth the fluctuation of the output voltage and ensure the stability of the output voltage.

[0045] The isolated switching power supply 100 further includes an isolation controller 130 for controlling the primary circuit and the secondary circuit. The isolation controller 130 is used to receive the output voltage signal VOUT at the voltage output terminal 150 and the winding voltage signals Forward1 and Forward2 on the secondary winding of each transformer, and generate at least two PWM signals PWM1 and PWM2 with phase staggered according to the output voltage signal VOUT and at least two winding voltage signals Forward1 and Forward2, that is, the signals PWM1 and PWM2 are generated sequentially at a certain interval in time, wherein the number of the at least two pulse width modulation signals is equal to the number of the at least two primary circuits. The isolation controller 130 is connected to the control terminal of each power switch G1 and G2 to output PWM1 and PWM2 to the corresponding power switch G1 and G2 respectively, thereby controlling the conduction and disconnection of the power switches G1 and G2. According to an embodiment of the present invention, the winding voltage signal on the secondary winding of the transformer refers to the voltage signal at the connection point between the secondary winding of the transformer and the synchronous rectifier. According to an embodiment of the present invention, the isolation controller 130 generates signals PWM1 and PWM2 in an interlaced manner, so that the power switches G1 and G2 are turned on in sequence at a certain interval in time, thereby realizing the interlaced operation between the power switches G1 and G2, and further realizing the interlaced operation of at least two primary circuits.

[0046] In addition, the isolation controller 130 is also used to generate a secondary control signal for controlling the conduction and disconnection of the synchronous rectifier in the corresponding secondary circuit according to the winding voltage signal, for example Figure 1 The isolation controller 130 is connected to the control end of each synchronous rectifier SR1 and SR2 to output SRC1 and SRC2 to the corresponding synchronous rectifier SR1 and SR2 for control. Specifically, when the isolation controller 130 determines that the winding voltage signal Forward1 or Forward2 reaches the first secondary winding voltage threshold for turning on the synchronous rectifier, such as a negative value, a high-level secondary control signal SRC1 or SRC2 is generated to turn on the corresponding synchronous rectifier SR1 or SR2.

[0047] Figure 2The isolating controller according to the first embodiment of the present invention is shown. The isolating controller 130 specifically includes a primary controller 210, a secondary controller 220 and an isolator 240. The secondary controller 220 is used to receive the output voltage signal VOUT from the voltage output terminal 150 and the winding voltage signals Forward1 and Forward2 from the secondary winding of each transformer, and to generate a request signal request according to the output voltage signal VOUT and the winding voltage signals Forward1 and Forward2, and to send the request signal request to the primary controller 210 through the isolator 240 to generate a PWM signal for each primary circuit 111 and 112. Specifically, the secondary control unit in the secondary controller 220 includes a secondary logic control module 221 and a sending module 223; wherein the secondary logic control module 221 receives the output voltage signal VOUT and the winding voltage signals Forward1 and Forward2 on the secondary winding of each transformer and generates a request signal request accordingly, and the generated request signal request is sent with the aid of the sending module 223. Additionally, the secondary logic control module 221 further generates secondary control signals SRC1 and SRC2 for controlling the synchronous rectifiers SR1 and SR2 in the corresponding secondary circuits 121 and 122 according to the winding voltage signals Forward1 and Forward2 .

[0048] The isolator 240 is used to transmit the request signal request from the secondary-side controller 220 to the primary-side controller 210 in an isolated manner. In a preferred embodiment, the isolator 240 can be at least one of a magnetic coupling isolator, a capacitive isolator and a digital isolator.

[0049] The primary side controller 210 is used to receive a request signal request from the isolator 240, wherein the request signal request may be a pulse signal, and generates signals PWM1 and PWM2 for controlling the power switches G1 and G2 according to the request signal request, and sends the signals PWM1 and PWM2 to the corresponding power switches G1 and G2 respectively. Specifically, the primary side control unit in the primary side controller 210 includes a primary side logic control module 211 and a receiving module 213; wherein the receiving module 213 receives the request signal request from the isolator 240 and forwards it to the primary side logic control module 211, and the primary side logic control module 211 generates signals PWM1 and PWM2 according to the request signal request and sends them to the corresponding power switches G1 and G2.

[0050] like Figure 2As shown, the isolation controller 130 includes a primary controller 210, a secondary controller 220 and an isolator 240. The secondary controller 220 is used to generate a common request signal request according to the output voltage signal VOUT and at least two winding voltage signals Forward1 and Forward2, and send the common request signal request to the primary controller 210 through the isolator 240. The primary controller 210 is used to receive the common request signal request from the isolator 240, alternately generate signals PWM1 and PWM2 for controlling the power switches G1 and G2 according to the common request signal request, and send the signals PWM1 and PWM2 to the corresponding power switches G1 and G2 respectively.

[0051] Figure 3 A schematic diagram of operating waveforms of an isolated switching power supply according to a first embodiment of the present invention is shown. Figure 3 The first row shows the current at each location in the primary circuit and the secondary circuit, where Ipril is the primary current of transformer T1. Figure 3 In red, Ipri2 is the primary current of transformer T2. Figure 3 It is shown in green in the figure; Isec1 is the secondary current of T1. Figure 3 In blue, Isec2 is the secondary current of transformer T2. Figure 3 Shown in purple.

[0052] At time t1, the secondary controller 220 generates a request signal request, for example, in response to the output voltage signal VOUT being lower than the output voltage threshold and the winding voltage signal Forward1 on the secondary winding of the transformer T1 reaching the second secondary winding voltage threshold (i.e., the synchronous rectifier SR1 is turned off). The primary controller 210 receives the request signal request from the isolator 240. At time t2, in response to the request signal request being received, the primary controller 210 changes the pulse width modulation signal PWM1 for the primary circuit 111 to a high level, controls the power switch G1 in the primary circuit 111 to turn on, and the primary current Ipri1 of the transformer T1 gradually increases from zero. At this time, the synchronous rectifier SR1 in the secondary circuit is turned off, the secondary current Isec1 of the transformer T1 is zero, and the transformer T1 stores energy in the form of a magnetic field. At time t3, the primary current Ipri1 of the transformer T1 reaches the current threshold, the pulse width modulation signal PWM1 output by the primary controller 210 becomes low, the power switch G1 in the primary circuit 111 is controlled to be turned off, and the primary current Ipri1 of the transformer T1 becomes zero. At this time, the winding voltage signal Forward1 of the secondary winding of the transformer T1 begins to drop sharply. When the winding voltage signal Forward1 reaches the first secondary winding voltage threshold, the secondary control signal SRC1 becomes high, the synchronous rectifier SR1 in the secondary circuit is turned on, the transformer T1 begins to release the stored energy, and the secondary current Isec1 of the transformer T1 begins to flow, thereby providing energy to the load through the voltage output terminal 150. The secondary current Isec1 of the transformer T1 gradually decreases until it becomes zero; at this time, when the secondary controller 220 detects that the winding voltage signal Forward1 reaches the second secondary winding voltage threshold for turning off the synchronous rectifier, the secondary control signal SRC1 is changed from high to low, and the synchronous rectifier SR1 is controlled to turn off.

[0053] At time t4, the secondary controller 220 generates a request signal request, for example, in response to the output voltage signal VOUT becoming lower than the output voltage threshold again and the winding voltage signal Forward2 on the secondary winding of the transformer T2 reaching the second secondary winding voltage threshold (i.e., the synchronous rectifier SR2 is turned off). The primary controller 210 receives the request signal request from the isolator 240 for the second time. At time t5, in response to the request signal request being received, the primary controller 210 changes the pulse width modulation signal PWM2 for the primary circuit 112 to a high level, controls the power switch G2 in the primary circuit 112 to turn on, and the primary current Ipri2 of the transformer T2 gradually increases from zero. At this time, the synchronous rectifier SR2 in the secondary circuit 122 is turned off, the secondary current Isec2 of the transformer T2 is zero, and the transformer T2 stores energy in the form of a magnetic field. At time t6, the primary current Ipri2 of transformer T2 reaches the current threshold, and the PWM2 output by the primary controller 210 becomes low level, controlling the power switch G2 in the primary circuit 112 to turn off, and the primary current Ipri2 of transformer T2 becomes zero. At this time, the voltage signal Forward2 of the secondary winding of transformer T2 begins to drop sharply. When the winding voltage signal Forward2 reaches the first secondary winding voltage threshold, the secondary control signal SRC2 becomes high level, the synchronous rectifier SR2 in the secondary circuit is turned on, the transformer T2 begins to release the stored energy, and the secondary current Isec2 of transformer T2 begins to flow; at this time, the energy is transferred to the voltage output terminal 150 through the second transformer T2 to provide to the load. At the same time, similar to the operation of the secondary circuit of transformer T1 above, the secondary current Isec2 of transformer T2 gradually decreases until it becomes zero; when the winding voltage signal Forward2 reaches the second secondary winding voltage threshold, the secondary control signal SRC2 changes from high level to low level, controlling the synchronous rectifier SR2 to turn off.

[0054] By analogy, when the output voltage signal VOUT becomes lower than the output voltage threshold again and the winding voltage signal on the secondary winding of the next transformer reaches the second secondary winding voltage threshold, the primary controller 210 generates a PWM signal for the next primary circuit in response to the request signal request being received, thereby transferring energy to the voltage output terminal 150 through the next transformer to provide it to the load. Figure 2In the first embodiment shown, the number of the primary circuit, the secondary circuit and the transformer is 2, so after time t6, when the output voltage signal VOUT becomes lower than the output voltage threshold again and the winding voltage signal Forward1 on the secondary winding of the transformer T1 reaches the second secondary winding voltage threshold, the primary controller 210 changes PWM1 to a high level, turning on the power switch G1, thereby transferring energy to the voltage output terminal 150 through the transformer T1. However Figure 2 The numbers in the illustrated embodiments are exemplary and non-restrictive. Those skilled in the art will appreciate that the number of primary circuits, secondary circuits, and transformers can be any number of two or more, as long as the number of primary circuits, secondary circuits, transformers, and generated PWMs is equal; the present invention does not limit the specific value of the number.

[0055] Through the isolated switching power supply of the first embodiment, phase-shifting control between power switches in at least two primary circuits can be achieved, thereby reducing the volume and cost of a single circuit, optimizing EMI, balancing heat distribution, reducing output ripple and output capacitance, and thus improving the system cost performance.

[0056] In a further preferred embodiment, the secondary controller 220 is configured to send the request signal request to the primary controller 210 only after the output voltage signal VOUT is lower than the voltage threshold and the synchronous rectifiers in each secondary circuit are turned off, that is, after the secondary control signals SRC1 and SRC2 both become low level. Thus, it is possible to avoid the situation where the power switch in the primary circuit and the synchronous rectifier in the secondary circuit are turned on at the same time, thereby avoiding the risk of explosion.

[0057] like Figure 2 As shown, the request signal request may be a common request signal for at least two primary circuits 111 and 112. The secondary controller 220 is configured to generate a common request signal request according to the output voltage signal VOUT and at least two winding voltage signals Forward1 and Forward2. The isolator 240 transmits the common request signal request generated by the secondary controller 220 to the primary controller 210, and the primary controller 210 generates at least two pulse width modulation signals PWM1 and PWM2 according to the common request signal request.

[0058] Figure 4FIG. 1 is a schematic diagram of an isolation controller according to a second embodiment of the present invention. The isolation controller 130 according to the second embodiment has a structure similar to that of the first embodiment, and the currents at various positions in the primary circuit and the secondary circuit, the pulse width modulation signals PWM1 and PWM2 of the primary circuit, and the operating timing of the request signal request are the same as those of the first embodiment (e.g. Figure 3 The difference is that the primary side controller includes two primary side control units 210a and 210b.

[0059] like Figure 4 As shown, in the second embodiment, the primary control unit 210a is used to generate a signal PWM1 for controlling the power switch G1 in the primary circuit 111, and the primary control unit 210b is used to generate a signal PWM2 for controlling the power switch G2 in the primary circuit 112, that is, each primary circuit has a dedicated primary control unit. One of the primary control units 210a and 210b, such as the primary control unit 210a, includes a receiving module 213 for receiving a common request signal request from the isolator 240, while the remaining primary control units, such as the primary control unit 210b, do not include a receiving module. The primary control unit 210a also includes a first primary logic control module 211a. The primary control unit 210b includes a second primary logic control module 211b. The first primary logic control module 211a receives the common request signal request from the receiving module 213, and generates a pulse width modulation signal PWM1 and a flag signal P-Flag according to the common request signal request. Specifically, the first primary logic control module 211a identifies and allocates the common request signal request, identifies the request signal request that belongs to its own processing, generates a pulse width modulation signal PWM1 according to the request signal request, and generates a flag signal P-Flag according to the remaining request signals for other primary control units. The flag signal P-Flag is sent to the second primary logic control module 211b, and the second primary logic control module 211b identifies the request signal request that belongs to its own processing from the flag signal P-Flag to generate a pulse width modulation signal PWM2.

[0060] Specifically, in order to implement the phase-shifting control of the primary circuit, the first primary logic control module 211a sends a flag signal P-Flag to the second primary logic control module 211b of the primary control unit 210b. Figure 3In the example shown, the request signal request at time t1 is assigned to the first primary logic control module 211a, and the request signal request at t4 is assigned to the second primary logic control module 211b of the primary control unit 210b through the flag signal P-Flag. By alternatingly assigning the request signal request, the phases of the pulse width modulation signals PWM1 and PWM2 are staggered.

[0061] In some embodiments, when there are more than two second primary logic control modules, the first primary logic control module 211a receives the common request signal request from the receiving module 213, and generates the pulse width modulation signal PWM1 and the flag signal P-Flag according to the common request signal request. Specifically, the first primary logic control module 211a identifies and allocates the common request signal request, identifies the request signal request that belongs to its own processing to generate the pulse width modulation signal PWM1, and generates the flag signal P-Flag according to the remaining request signals for other primary control units, and the flag signal P-Flag is sent to other second primary logic control modules. Other second primary logic control modules respectively identify the request signal request that belongs to their own processing from the flag signal to generate the pulse width modulation signal. In other embodiments, when there are more than two second primary logic control modules, the first primary logic control module 211a sends the flag signal P-Flag to the second primary logic control module connected to it, and the second primary logic control module identifies the request signal request that belongs to its own processing to generate a pulse width modulation signal, and sends the remaining request signal request to generate the flag signal to the second primary logic control module connected to it, and so on, until the last second primary logic control module identifies the request signal request that belongs to its own processing from the flag signal to generate a pulse width modulation signal.

[0062] Through the coordinated control between the independent primary control units 210a, 210b in the second embodiment, it is also possible to implement phase-shifting control between power switches in at least two primary circuits, and by providing an independent primary controller, the flexibility and robustness of the system are increased.

[0063] The above specific implementation method using the flag signal P-Flag is only exemplary. Those skilled in the art will appreciate that other methods are used to achieve coordination between primary side controllers. For example, a separate component may be used to record each request signal, and each primary side controller may cooperatively generate a pulse width modulation signal in sequence according to the recorded instructions. In addition, although the number of primary side controllers is 2 in the second embodiment, this is only exemplary and not restrictive. Those skilled in the art will appreciate that the number of primary side controllers may be any number of two or more, as long as it is equal to the number of primary side circuits, secondary side circuits and transformers; the present invention does not limit the specific value of this number.

[0064] Figure 5 An isolation controller according to a third embodiment of the present invention is shown. The primary controller specifically includes at least two primary control units 210a and 210b, and the number of the primary control units is the same as the number of the primary circuits. The isolator includes at least two isolation units 240a and 240b, and the number of the isolation units is the same as the number of the primary circuits. The difference from the first embodiment or the second embodiment is that, based on the output voltage signal VOUT and at least two winding voltage signals Forward1 and Forward2, the secondary controller 220 does not generate a common request signal request, but alternately generates dedicated request signals request1 and request2 for the power switches G1 and G2 in each primary circuit 111 and 112, and the number of the request signals request1 and request2 is the same as the number of the primary circuits 111 and 112. The generated request signals request1 and request2 are respectively sent to the primary control units 210a and 210b through the corresponding isolation units 240a and 240b. The primary control units 210a and 210b receive corresponding request signals request1 and request2 through their respective receiving modules 213a and 213b, and generate pulse width modulation signals PWM1 and PWM2 for controlling the power switches G1 and G2 in the corresponding primary circuits 111 and 112 through their respective primary logic control modules 211a and 211b.

[0065] Figure 6 FIG. 1 is a schematic diagram showing the operating waveforms of an isolated switching power supply according to a third embodiment of the present invention, wherein the currents Ipril, Ipri2, Isec1 and Isec2 at each position in the primary circuit and the secondary circuit and the operating timing of the pulse width modulation signals PWM1 and PWM2 are the same as those in the first embodiment (eg, Figure 3 The difference is that the secondary side controller 220 sequentially provides two request signals requst1 and request2 which are dedicated to controlling the power switches G1 and G2 respectively.

[0066] At time t1, the secondary controller 220 generates a request signal request1 in response to the output voltage signal VOUT being lower than the output voltage threshold and the winding voltage signal Forward1 of the secondary winding of the first transformer T1 reaching the second secondary winding voltage threshold; in this example, the secondary controller 220 sends it to the primary control unit 210a through the corresponding isolation unit 240a. At time t2, the primary control unit 210a changes the pulse width modulation signal PWM1 to a high level according to the request signal request1, and combines Figure 3 The described sequence operates to transfer energy to the voltage output terminal 150 through the transformer T1 and provide it to the load.

[0067] At time t4, the secondary controller 220 generates a request signal request2 in response to the output voltage signal VOUT being lower than the output voltage threshold and the winding voltage signal Forward2 of the secondary winding of the second transformer T2 reaching the second secondary winding voltage threshold. The request signal request2 is sent to the primary control unit 210b through the corresponding isolation unit 240b. At time t5, the primary control unit 210b changes the pulse width modulation signal PWM2 to a high level according to the request signal request2, and combines Figure 3 The described sequence operates to transfer energy to the voltage output terminal 150 through the transformer T2 and provide it to the load.

[0068] By analogy, when the output voltage signal VOUT becomes lower than the output voltage threshold again and the winding voltage signal of the secondary winding of the next transformer reaches the second secondary winding voltage threshold, the secondary controller 220 generates a request signal request for the next primary circuit, so that energy is transferred to the voltage output terminal 150 through the next transformer and provided to the load in the form of the output voltage signal VOUT. Figure 5 In the third embodiment shown, the number of the primary circuit, the secondary circuit and the transformer is 2, so after time t6, a new cycle starts, that is, when the output voltage signal VOUT becomes lower than the output voltage threshold again and the winding voltage signal Forward1 of the secondary winding of the first transformer T1 reaches the second secondary voltage threshold, the secondary controller 220 generates and sends request1. Figure 5 The numbers in the illustrated embodiments are exemplary and non-restrictive. Those skilled in the art will appreciate that the number of primary circuits, secondary circuits, and transformers can be any number of two or more, as long as the number of primary circuits, secondary circuits, and transformers is equal; the present invention does not limit the specific value of the number.

[0069] In the isolated switching power supply according to the third embodiment, the secondary controller 220 determines the primary circuit to be operated, and the primary control units 210a and 210b simply receive the corresponding request signals request1 and request2 and generate pulse width modulation signals PWM1 and PWM2 for controlling the power switches G1 and G2 in the corresponding primary circuits 111 and 112. In this way, the phase-shifting control between the power switches in at least two primary circuits can be achieved, thereby reducing the volume and cost of a single circuit, optimizing EMI, balancing heat distribution, reducing output ripple and output capacitance, and thus improving the system cost performance.

[0070] Figure 7 1 is a schematic diagram of an isolation controller according to a fourth embodiment of the present invention. The isolation controller 130 according to the fourth embodiment has a structure similar to that of the third embodiment, and the currents at various positions in the primary circuit and the secondary circuit, the pulse width modulation signals PWM1 and PWM2 of the primary circuit, and the operating timings of the request signals request1 and request2 are similar to those of the third embodiment (e.g. Figure 6 The difference is that the primary side controller 210 includes a single primary side control unit.

[0071] like Figure 7 As shown, in the fourth embodiment, the primary control unit in the primary controller 210 has a primary logic control module 211 and a receiving module 213. The receiving module 213 is used to receive all request signals request1 and request2 from different isolation units 240a and 240b at different times; the primary logic control module 211 determines whether to change PWM1 or PWM2 to a high level according to the different request signals received, so as to turn on the corresponding power switch G1 or G2. For example, in Figure 6 At time t2 in FIG. 2 , the receiving module 213 completes receiving the request signal request1 from the isolation unit 240a, and the primary logic control module 211 changes the corresponding signal PWM1 to a high level according to the received request signal request1, so as to turn on the power switch G1; similarly, at Figure 6 At time t5, the receiving module 213 completes receiving the request signal request2 from the isolation unit 240b, and the primary logic control module 211 changes the corresponding signal PWM2 to a high level according to the received request signal request2, so as to turn on the power switch G2.

[0072] Therefore, through the fourth embodiment, no matter how many primary circuits, secondary circuits and transformers there are, a single primary control unit can be used to implement phase-shifting control between power switches in each primary circuit, which is convenient for system expansion. Although the number of primary circuits in the fourth embodiment is 2, this is only exemplary and not restrictive. Those skilled in the art can understand that the number of primary controllers can be any number of two or more; the present invention does not limit the specific value of this number.

[0073] Figure 8 FIG. 1 is a schematic diagram of an isolation controller according to a fifth embodiment of the present invention. The isolation controller 130 according to the fifth embodiment has a structure similar to that of the third embodiment, and the currents at various positions in the primary circuit and the secondary circuit, the pulse width modulation signals PWM1 and PWM2 of the primary circuit, and the operating timings of the request signals request1 and request2 are similar to those of the third embodiment (e.g. Figure 6 The difference is that the secondary side controller includes two secondary side control units 220a and 220b.

[0074] like Figure 8 As shown, in the fifth embodiment, each primary circuit has a dedicated secondary control unit; the secondary control unit 220a is used to generate a request signal request1 for the primary circuit 111 through the secondary logic control module 221a and send it to the corresponding isolation unit 240a through the sending module 223a; and the secondary control unit 220b is used to generate a request signal request2 for the primary circuit 112 through the secondary logic control module 221b and send it to the corresponding isolation unit 240b through the sending module 223b. In addition, the secondary control units 220a and 220b respectively detect the winding voltage signals Forward1 and Forward2 in the corresponding secondary circuits to control the corresponding synchronous rectifiers SR1 and SR2.

[0075] Specifically, in order to achieve the phase-shifting control of the primary circuit, the secondary control units 220a and 220b perform coordinated control. Figure 6 Before the time t1 shown, for the secondary control unit 220a, since the request signal request2 (not shown) was generated last time, the secondary control unit 220a receives the flag signal S-Flag2 (described below) from the secondary control unit 220b. At the time t1, after the secondary controller 220a detects that the output voltage signal VOUT is lower than the output voltage threshold and the winding voltage signal Forward1 reaches the second secondary winding voltage threshold, it generates and sends request1; then, it sends the flag signal S-Flag1 to the secondary control unit 220b.

[0076] After time t1, the secondary-side control unit 220b receives the flag signal S-Flag1 from the secondary-side control unit 220a.

[0077] At time t4, the secondary controller 220a generates and sends request2 after detecting that the output voltage signal VOUT is lower than the output voltage threshold and the winding voltage signal Forward2 reaches the second secondary winding voltage threshold; and sends a flag signal S-Flag2 to the secondary control unit 220a.

[0078] After time t4, the secondary-side control unit 220a receives the flag signal S-Flag2 from the secondary-side control unit 220b, and is thus ready to generate and send the next round of request1.

[0079] Through the coordinated control between the independent secondary side controllers 220a, 220b in the fifth embodiment, it is also possible to implement phase-shifting control between the power switches in at least two primary side circuits, and by providing an independent secondary side controller, the flexibility and robustness of the system are increased.

[0080] The above specific implementation method using the flag signal S-Flag1 / S-Flag2 is only exemplary. Those skilled in the art will appreciate that other methods are used to achieve coordination between secondary control units. For example, a separate component may be used to record the request signal of each secondary control unit, and each secondary control unit may cooperatively generate a request signal in sequence according to the recorded instructions. In addition, although the number of secondary control units is 2 in the fifth embodiment, this is only exemplary and not restrictive. Those skilled in the art will appreciate that the number of secondary control units may be any number of two or more, as long as it is equal to the number of primary circuits, secondary circuits, and transformers; the present invention does not limit the specific value of this number.

[0081] Fig. 9 A flow chart of a control method for an isolated switching power supply according to the present invention is shown, and the method can be implemented by an isolation controller 130. In step 910, an output voltage signal of the isolated switching power supply and at least two winding voltage signals on the secondary windings of at least two transformers are received. In step 920, at least two pulse width modulation signals are generated according to the output voltage signal and the at least two winding voltage signals to generate at least two PWM signals with phases staggered. In step 930, each generated PWM signal is transmitted to the control end of the power switch in the corresponding primary circuit. Through method 900, it is possible to achieve phase-shifting control between the power switches of at least two primary circuits, and then achieve phase-shifting control between at least two transformers in the isolated switching power supply, thereby achieving the aforementioned technical effects.

[0082] In some implementations, a non-volatile computer-readable storage medium or program product is also provided, and the instructions included in the computer-readable storage medium or program product can be executed on a processor to complete the above control method. The processor includes but is not limited to an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a controller, a microcontroller, a microprocessor or other electronic components.

[0083] In summary, the present invention provides an improved isolated switching power supply, a control method and a storage medium, which can realize the staggered phase control between the power switches in at least two primary circuits, thereby reducing the volume and cost of a single circuit, optimizing EMI, balancing heat distribution, reducing output ripple and the capacitance of the output capacitor, thereby improving the overall conversion efficiency of the isolated switching power supply and avoiding the risk of explosion.

[0084] In the above-mentioned embodiments, the descriptions of different embodiments have different emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments. The above descriptions are only specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. An isolated switching power supply, characterized in that: include: at least two primary circuits, each of the primary circuits comprising a power switch; At least two secondary circuits, each of which includes a synchronous rectifier tube; At least two transformers, each of the primary windings of the transformer is connected in series with a power switch in a corresponding primary circuit and then connected between an input end of the isolated switching power supply and a primary reference ground, and each of the secondary windings of the transformer is connected in series with a synchronous rectifier in a corresponding secondary circuit and then connected between an output end of the isolated switching power supply and a secondary reference ground, wherein the number of the at least two primary circuits, the at least two secondary circuits and the at least two transformers is equal; and An isolation controller, the isolation controller being used for: Receiving an output voltage signal at an output end of the isolated switching power supply and at least two winding voltage signals on the secondary windings of the at least two transformers; generating at least two pulse width modulation signals according to the output voltage signal and the at least two winding voltage signals, wherein the number of the at least two pulse width modulation signals is equal to the number of the at least two primary circuits, and the phases of the at least two pulse width modulation signals are staggered; and The generated pulse width modulation signals are transmitted to the control end of the power switch of the corresponding primary circuit in the at least two primary circuits to control the power switches in the at least two primary circuits to work alternately.

2. The isolated switching power supply according to claim 1, characterized in that: The isolation controller comprises: a secondary side controller, configured to receive the output voltage signal and the at least two winding voltage signals, and generate and send a request signal according to the output voltage signal and the at least two winding voltage signals; a primary-side controller, configured to receive the request signal, generate the at least two pulse width modulation signals according to the request signal, and transmit each of the at least two pulse width modulation signals to a control terminal of a power switch of a corresponding primary-side circuit; and An isolator is connected between the secondary-side controller and the primary-side controller, and is used to transmit the request signal from the secondary-side controller to the primary-side controller in an isolated manner.

3. The isolated switching power supply according to claim 2, characterized in that: The secondary-side controller is configured to send the request signal only after the output voltage signal is lower than an output voltage threshold and the synchronous rectifiers in the at least two secondary-side circuits are turned off.

4. The isolated switching power supply according to claim 2, characterized in that: The request signal is a common request signal for the at least two primary circuits, The secondary side controller is configured to generate the common request signal according to the output voltage signal and the at least two winding voltage signals, The isolator is configured to transmit the common request signal generated by the secondary-side controller to the primary-side controller, and The primary-side controller is configured to generate the at least two pulse width modulation signals according to the common request signal.

5. The isolated switching power supply according to claim 2, characterized in that: The secondary controller is configured to alternately generate at least two request signals according to the output voltage signal and the at least two winding voltage signals, the number of the request signals is the same as the number of the primary circuits, and each request signal is used for a corresponding primary circuit.

6. The isolated switching power supply according to claim 5, characterized in that: The isolator includes at least two isolation units, the number of the isolation units is the same as the number of the primary circuits, and each isolation unit is used to transmit a corresponding request signal.

7. The isolated switching power supply according to claim 5, characterized in that: The primary controller comprises at least two primary control units, the number of the primary control units being the same as the number of the primary circuits, and The isolator transmits at least two request signals alternately generated by the secondary-side controller to the corresponding primary-side control unit respectively, and the primary-side control unit generates a corresponding pulse width modulation signal according to the corresponding request signal.

8. The isolated switching power supply according to claim 7, characterized in that: The primary control unit comprises: A receiving module, configured to receive a corresponding request signal; and The primary side logic control module is used to receive the request signal from the receiving module and generate the pulse width modulation signal according to the request signal.

9. The isolated switching power supply according to claim 5, characterized in that: The primary side controller includes a primary side control unit, and The isolator transmits at least two request signals alternately generated by the secondary-side controller to the primary-side control unit, and the primary-side control unit generates pulse width modulation signals of the at least two primary-side circuits respectively according to the at least two request signals.

10. The isolated switching power supply according to any one of claims 5 to 9, characterized in that: The secondary controller includes at least two secondary control units, the number of which is the same as the number of the secondary circuits, and each of the at least two secondary control units generates a corresponding request signal according to the output voltage signal and the corresponding winding voltage signal.

11. The isolated switching power supply according to claim 10, characterized in that: One of the at least two secondary control units is configured to generate a corresponding request signal and a first flag signal according to the output voltage signal and the corresponding winding voltage signal; and The other secondary control units of the at least two secondary control units are configured to generate corresponding request signals according to the first flag signal, the output voltage signal and the corresponding winding voltage signal.

12. The isolated switching power supply according to claim 4, characterized in that: The primary controller comprises at least two primary control units, the number of the primary control units being the same as the number of the primary circuits, and The isolator transmits the common request signal to one of the at least two primary control units, and the at least two primary control units each generate a corresponding pulse width modulation signal.

13. The isolated switching power supply according to claim 12, characterized in that: The primary control unit that receives the common request signal is configured to send a second flag signal to other primary control units, and the other primary control units are configured to each generate a corresponding pulse width modulation signal based on the second flag signal.

14. The isolated switching power supply according to claim 13, characterized in that: The primary side control unit that receives the common request signal includes: a receiving module, configured to receive the common request signal; and a first primary-side logic control module, configured to receive the common request signal from the receiving module, and generate a corresponding pulse width modulation signal and the second flag signal according to the common request signal; The other primary-side control unit includes: a second primary-side logic control module, which is used to receive the second flag signal and generate a corresponding pulse width modulation signal according to the second flag signal.

15. The isolated switching power supply according to claim 2, characterized in that: The secondary side controller includes a secondary side control unit, and the secondary side control unit includes: a secondary side logic control module, configured to receive the output voltage signal and the at least two winding voltage signals and generate the request signal according to the output voltage signal and the at least two winding voltage signals; and The sending module is used to send the request signal generated by the secondary side logic control module to the isolator.

16. The isolated switching power supply according to claim 15, characterized in that: The secondary logic control module is further used to generate a secondary control signal for controlling the conduction or disconnection of a synchronous rectifier tube in a corresponding secondary circuit according to the winding voltage signal.

17. The isolated switching power supply according to claim 4, characterized in that: The primary side controller includes a primary side control unit, and the primary side control unit includes: a receiving module, configured to receive the common request signal from the isolator; and The primary-side logic control module is configured to receive the common request signal from the receiving module and generate the at least two pulse width modulation signals according to the common request signal.

18. The isolated switching power supply according to claim 2, characterized in that: The isolator includes at least one of the following: a transformer isolator, a capacitor isolator and a digital isolator.

19. A control method for an isolated switching power supply, characterized in that: The isolated switching power supply comprises: at least two primary circuits, each of the primary circuits comprising a power switch; At least two secondary circuits, each of which includes a synchronous rectifier tube; At least two transformers, each of the primary windings of the transformer is connected in series with a power switch in a corresponding primary circuit and then connected between an input end of the isolated switching power supply and a primary reference ground, and each of the secondary windings of the transformer is connected in series with a synchronous rectifier in a corresponding secondary circuit and then connected between an output end of the isolated switching power supply and a secondary reference ground, wherein the number of the at least two primary circuits, the at least two secondary circuits and the at least two transformers is equal; and an isolation controller, configured to execute the method to control a power switch in the primary circuit, The method comprises: Receiving an output voltage signal at an output end of the isolated switching power supply and at least two winding voltage signals on the secondary windings of the at least two transformers; generating at least two pulse width modulation signals according to the output voltage signal and the at least two winding voltage signals, wherein the number of the at least two pulse width modulation signals is equal to the number of the at least two primary circuits, and the phases of the at least two pulse width modulation signals are staggered; and The generated pulse width modulation signals are transmitted to the control end of the power switch of the corresponding primary circuit in the at least two primary circuits to control the power switches in the at least two primary circuits to work alternately.

20. A computer-readable storage medium storing instructions, which when executed by a controller cause the controller to perform the method of claim 19.

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