Switching power supply circuit

Abstract

The invention discloses a switching power supply circuit. The switching power supply circuit comprises an input loop, an output loop, a primary side auxiliary winding loop, a secondary side auxiliary winding loop, a current sampling circuit, a current loop circuit, a voltage loop circuit, a first optocoupler circuit, a second optocoupler circuit and a driving circuit. Wherein a primary side auxiliary winding in the primary side auxiliary winding loop is coupled with a transformer main winding in the input loop and is used for providing a power supply for a control circuit and a driving circuit on the primary side of a transformer; and a secondary side auxiliary winding in the secondary side auxiliary winding loop is also coupled with the transformer main winding and is used for providing a power supply for the input side of a second optocoupler circuit on the secondary side of the transformer. The current sampling circuit and the second optocoupler circuit can feed current and voltage in the output loop back to the primary side of the transformer respectively, and the current and the voltage are controlled through a control circuit of the primary side of the transformer. According to the circuit, the power supply stability and independence of the control circuit can be improved, and the control efficiency of the power supply is improved.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a switching power supply circuit. Background Technology

[0002] As a core device in modern electronic equipment for power conversion and management, the performance of switching power supplies directly affects the reliability, efficiency, and accuracy of end devices. With technological advancements, end devices place higher demands on the integration, conversion efficiency, and control precision of switching power supplies. In existing technologies, switching power supplies typically employ flyback or forward topologies, using transformers to achieve energy transfer between the primary and secondary sides. Furthermore, current designs primarily rely on optocouplers to construct voltage feedback loops, combined with single-loop control circuits (voltage or current loops) to regulate current or voltage output.

[0003] However, in existing designs, the primary-side control circuit and the secondary-side load circuit are usually powered by the same transformer winding. When an anomaly such as a short circuit or overload occurs at the secondary-side output, the abnormal energy may affect the stability of the primary-side control circuit through the winding, making it difficult to quickly locate the source of the problem. Furthermore, to meet the independent power supply requirements of the primary and secondary controllers, existing designs require additional buck converters or flyback auxiliary power modules. This not only increases circuit complexity and the number of components but also reduces overall efficiency due to multi-stage energy conversion. In addition, limited by a single voltage loop or single current loop control architecture, existing designs struggle to simultaneously achieve both dynamic response speed and steady-state accuracy. Voltage overshoot or current runaway is prone to occur during sudden load changes or input voltage fluctuations, resulting in low control accuracy and large errors. Summary of the Invention

[0004] In view of this, the present application provides a switching power supply circuit, the main purpose of which is to solve the technical problems of low positioning accuracy, low power conversion efficiency and low control precision caused by the non-independent power supply of the primary and secondary sides of the transformer in the existing switching power supply circuit design.

[0005] This application provides a switching power supply circuit, which includes an input circuit, an output circuit, a primary auxiliary winding circuit, a secondary auxiliary winding circuit, a current sampling circuit, a current loop circuit, a voltage loop circuit, a first optocoupler circuit, a second optocoupler circuit, and a drive circuit.

[0006] The primary auxiliary winding in the primary auxiliary winding circuit is coupled to the transformer main winding in the input circuit, and is used to provide power to the input side of the current loop circuit, the voltage loop circuit, the drive circuit and the first optocoupler circuit on the primary side of the transformer.

[0007] The secondary auxiliary winding in the secondary auxiliary winding circuit is coupled to the transformer main winding in the input circuit to provide power to the input side of the second optocoupler circuit on the secondary side of the transformer.

[0008] The current sampling circuit feeds back the current in the output circuit to the primary side of the transformer through a current transformer, and controls the current in the output circuit through the current loop circuit, the first optocoupler circuit and the drive circuit.

[0009] The second optocoupler circuit feeds back the output voltage of the output circuit to the primary side of the transformer through the voltage input signal on the input side, and controls the output voltage of the output circuit through the second optocoupler circuit and the driving circuit.

[0010] Optionally, the input circuit includes a switching device and a transformer main winding, wherein the switching device is connected between the input source and the transformer main winding, the gate of the switching device is connected to the output terminal of the drive circuit, and the switching device is used to receive the PWM signal sent by the drive circuit to control the on / off state of the input circuit.

[0011] Optionally, the output circuit includes a rectifier circuit, a filter circuit, and a transformer output winding. The two ends of the transformer output winding are connected to the input terminal of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the filter circuit, and the output terminal of the filter circuit is connected to the load. The primary winding of the current transformer in the current sampling circuit is connected in series between the transformer output winding and the rectifier circuit, and is used to collect the current in the output circuit.

[0012] Optionally, the primary-side auxiliary winding circuit includes a primary-side auxiliary winding, a first filter capacitor, and a first linear voltage regulator module. The primary-side auxiliary winding is coupled to the main winding of the transformer. The two ends of the primary-side auxiliary winding are connected to the two ends of the first filter capacitor and then connected to the input terminal of the first linear voltage regulator module. The output terminal of the first linear voltage regulator module is connected to the power supply terminal of the input side of the first optocoupler circuit and the power supply terminal of the drive circuit.

[0013] Optionally, the secondary auxiliary winding circuit includes a secondary auxiliary winding, a second filter capacitor, and a second linear voltage regulator module. The secondary auxiliary winding is coupled to the main winding of the transformer. The two ends of the secondary auxiliary winding are connected to the two ends of the second filter capacitor and then connected to the input terminal of the second linear voltage regulator module. The output terminal of the second linear voltage regulator module is connected to the power supply terminal on the input side of the second optocoupler circuit.

[0014] Optionally, the current sampling circuit includes a current transformer, a rectifier filter circuit, and a voltage conversion circuit. The voltage conversion circuit includes at least one load resistor connected in parallel. The primary winding of the current transformer is connected in series between the transformer output winding and the rectifier circuit in the output circuit. The two ends of the secondary winding of the current transformer are connected to the input terminal of the rectifier filter circuit. The output terminal of the rectifier filter circuit is connected to the input terminal of the voltage conversion circuit. The output terminal of the voltage conversion circuit is connected to the input terminal of the current loop circuit.

[0015] Optionally, the current loop circuit includes a first operational amplifier and a first compensation circuit, wherein the non-inverting input terminal of the first operational amplifier is connected to a first reference voltage, the inverting input terminal of the first operational amplifier is connected to the output terminal of the current sampling circuit, the output terminal of the first operational amplifier is connected to the first signal input terminal of the first optocoupler circuit, and the first compensation circuit is connected between the non-inverting input terminal and the output terminal of the first operational amplifier.

[0016] Optionally, the voltage loop circuit includes a second operational amplifier and a second compensation circuit, wherein the non-inverting input terminal of the second operational amplifier is connected to a second reference voltage, the inverting input terminal of the second operational amplifier is connected to the output terminal of the primary auxiliary winding circuit, the output terminal of the second operational amplifier is connected to the second signal input terminal of the first optocoupler circuit, and the second compensation circuit is connected between the non-inverting input terminal and the output terminal of the second operational amplifier.

[0017] Optionally, the power supply terminal on the input side of the first optocoupler circuit is connected to the output terminal of the primary auxiliary winding circuit, the first signal input terminal of the first optocoupler circuit is connected to the output terminal of the current loop circuit, the second signal input terminal of the first optocoupler circuit is connected to the output terminal of the voltage loop circuit, and the signal output terminal of the first optocoupler circuit is connected to the control terminal of the drive circuit; the power supply terminal on the input side of the second optocoupler circuit is connected to the output terminal of the secondary auxiliary winding circuit, the signal input terminal of the second optocoupler circuit is connected to the output terminal of the output loop, and the signal output terminal of the second optocoupler circuit is connected to the control terminal of the drive circuit.

[0018] Optionally, the driving circuit includes a driving chip, wherein the power supply terminal of the driving chip is connected to the output terminal of the primary-side auxiliary winding circuit, the input terminal of the driving chip is connected to the signal output terminal of the first optocoupler circuit and the signal output terminal of the second optocoupler circuit, and the output terminal of the driving chip is connected to the gate of the switching device in the input circuit.

[0019] By employing the above technical solution, the switching power supply circuit provided in this application embodiment, through the separate auxiliary winding circuits on the primary and secondary sides of the transformer, can directly couple energy from the primary and secondary sides of the transformer and provide a stable and isolated power supply to the control circuits on both sides. This avoids the need for additional auxiliary power supplies on both sides of the transformer, thereby reducing power supply losses and improving power supply efficiency. Furthermore, independent power supply to the primary and secondary sides of the transformer improves problem location efficiency and simplifies the overall circuit structure of the switching power supply. Simultaneously, a stable auxiliary power supply ensures that the controller and driver can still operate normally when the input voltage fluctuates or the load changes, thereby improving the accuracy and noise immunity of the output voltage feedback, and thus enhancing the stability of the output voltage. In addition, the current signal fed back from the current transformer and the voltage signal fed back from the optocoupler can be combined for control through a dual-loop system, thereby improving the regulation accuracy of the output current and output voltage, as well as the overall stability of the power supply system, thus enhancing the reliability, conversion efficiency, and control accuracy of the entire switching power supply.

[0020] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0022] Figure 1 A schematic diagram of the circuit structure of a switching power supply circuit provided in an embodiment of this application is shown;

[0023] Figure 2 A schematic diagram of the circuit structure of another switching power supply circuit provided in an embodiment of this application is shown. Detailed Implementation

[0024] The present application will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present application can be combined with each other.

[0025] In one embodiment, a switching power supply circuit is provided. For example... Figure 1As shown, the aforementioned switching power supply circuit includes an input circuit, an output circuit, a primary-side auxiliary winding circuit, a secondary-side auxiliary winding circuit, a current sampling circuit, a current loop circuit, a voltage loop circuit, a first optocoupler circuit, a second optocoupler circuit, and a drive circuit. Specifically, the primary-side auxiliary winding in the primary-side auxiliary winding circuit is coupled to the transformer's main winding in the input circuit, providing power to the input side of the current loop circuit, voltage loop circuit, drive circuit, and the first optocoupler circuit on the primary side of the transformer. The secondary-side auxiliary winding in the secondary-side auxiliary winding circuit is also coupled to the transformer's main winding in the input circuit, providing power to the input side of the second optocoupler circuit on the secondary side of the transformer. The current sampling circuit feeds back the current in the output circuit to the primary side of the transformer via a current transformer and controls the current in the output circuit through the current loop circuit, the first optocoupler circuit, and the drive circuit. The second optocoupler circuit feeds back the output voltage of the output circuit to the primary side of the transformer via the voltage input signal on the input side and controls the output voltage of the output circuit through the second optocoupler circuit and the drive circuit.

[0026] Specifically, in the switching power supply circuit provided in this embodiment, the input circuit and output circuit can be connected via a transformer. The main winding of the transformer is connected to the input circuit, and the output winding is connected to the output circuit. On the primary side of the transformer, a primary auxiliary winding circuit is provided. The primary auxiliary winding in this circuit is coupled to the main winding of the transformer. The primary auxiliary winding can directly couple energy from the primary side of the transformer and provide a stable and isolated power supply to the input side of the current loop circuit, voltage loop circuit, drive circuit, and the first optocoupler circuit on the primary side. Simultaneously, on the secondary side of the transformer, a secondary auxiliary winding circuit is provided. The secondary auxiliary winding in this circuit is also coupled to the main winding of the transformer in the input circuit. The secondary auxiliary winding can directly couple energy from the secondary side of the transformer and provide a stable power supply to the input side (receiver) of the second optocoupler circuit on the secondary side, ensuring the accuracy and stability of the feedback loop.

[0027] In this embodiment, the auxiliary windings on both sides provide necessary safety isolation to meet safety regulations. For example, the auxiliary windings on both the primary and secondary sides are reinforced with insulation to prevent ground loop noise from interfering with the control signal, especially the feedback signal. Even when the input voltage fluctuates significantly or the load changes abruptly, the auxiliary windings can still provide a relatively stable voltage, especially the secondary auxiliary winding, whose voltage is proportional to the main output, preventing damage to the controller or driver due to undervoltage reset or overvoltage. Furthermore, the secondary auxiliary winding can provide a stable power supply to the input side of the second optocoupler circuit, thereby improving the accuracy and noise immunity of the output voltage feedback, and ultimately enhancing the stability of the output voltage.

[0028] Furthermore, a current transformer is incorporated into the current sampling circuit. This current transformer is connected to the output circuit, sampling the current in the output circuit and feeding it back to the primary side of the transformer. The acquired current signal is conditioned by the current loop circuit, isolated by the first optocoupler circuit, and then transmitted. The drive circuit then controls the current in the output circuit based on the feedback signal. Simultaneously, the output voltage of the output circuit can be received at the input side of the second optocoupler circuit and converted into an optical signal. After optocoupler isolation, this signal is fed back to the primary side of the transformer. Subsequently, the drive circuit can combine the current control signal transmitted by the first optocoupler circuit and the voltage control signal transmitted by the second optocoupler circuit to perform composite control on the output voltage of the primary auxiliary winding and the output voltage of the output circuit, thereby achieving coordinated regulation of the current loop and voltage loop.

[0029] The above embodiments, by setting independent auxiliary winding circuits on the primary and secondary sides of the transformer in the switching power supply, can directly couple energy from the primary and secondary sides of the transformer and provide a stable and isolated power supply to the control circuits on both sides. This avoids the need for additional auxiliary power supplies on both sides of the transformer, thereby reducing power supply losses and improving power supply efficiency. Furthermore, independent power supply to the primary and secondary sides of the transformer improves problem location efficiency and simplifies the overall circuit structure of the switching power supply. Simultaneously, a stable auxiliary power supply ensures that the controller and driver can still operate normally when the input voltage fluctuates or the load changes, thereby improving the accuracy and noise immunity of the output voltage feedback, and ultimately enhancing the stability of the output voltage. In addition, the current signal fed back from the current transformer and the voltage signal fed back from the optocoupler can be combined for control through a dual-loop system, thereby improving the regulation accuracy of the output current and output voltage, as well as the overall stability of the power supply system, thus enhancing the reliability, conversion efficiency, and control accuracy of the entire switching power supply.

[0030] In one embodiment, such as Figure 2 As shown, the input circuit includes a switching device and a transformer main winding. The switching device is connected between the input source and the transformer main winding, and its gate is connected to the output terminal of the drive circuit. The switching device receives the PWM signal sent by the drive circuit to control the on / off state of the input circuit.

[0031] Specifically, in the input circuit, the switching device and the transformer main winding can form a closed input circuit. Simultaneously, the output terminal of the drive circuit is connected to the gate of the switching device. The drive circuit can control the on / off state of the switching device by sending a PWM signal, thereby regulating the energy transfer of the transformer main winding in the input circuit. Under the control of the drive circuit, the switching device switches on and off at high frequency, converting the voltage of the input source into a pulse voltage and coupling it to the transformer main winding, thus achieving the initial conversion and transfer of energy on the input side.

[0032] This embodiment provides a stable input source for subsequent energy conversion by converting voltage properties. Furthermore, by coordinating the switching devices with the PWM signal of the drive circuit, the energy conversion efficiency on the input side can be effectively improved, and the control accuracy of the input circuit can be enhanced.

[0033] In one embodiment, such as Figure 2 As shown, the output circuit includes a rectifier circuit, a filter circuit, and a transformer output winding. The two ends of the transformer output winding are connected to the input terminals of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the filter circuit, and the output terminal of the filter circuit is connected to the load. The primary winding of the current transformer in the current sampling circuit is connected in series between the transformer output winding and the rectifier circuit, and is used to collect the current in the output circuit.

[0034] Specifically, in the output circuit, the two ends of the transformer output winding are connected to the input terminal of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the filter circuit, and the output terminal of the filter circuit is connected to the load, thus forming a complete output channel. Simultaneously, the primary winding of a current transformer in the current sampling circuit is connected in series in the line between the transformer output winding and the rectifier circuit. This primary winding can collect the current signal in the output circuit through the principle of electromagnetic induction. Subsequently, this signal can be output to the current sampling circuit through the secondary winding of the current transformer, thereby completing the real-time monitoring and feedback of the output current.

[0035] This embodiment converts the AC voltage of the transformer output winding into a pulsating DC voltage, and then filters out high-frequency ripple through a filter circuit, providing a stable DC output to the load. Alternatively, it can convert the DC voltage into a stable AC voltage for output. Furthermore, by connecting a current transformer in series at a key node in the output circuit, the current signal can be accurately acquired and transmitted to the primary-side control circuit in an isolated manner. This avoids signal distortion and interference during the current sampling process, thereby improving the adjustment accuracy of the output current.

[0036] In one embodiment, such as Figure 2 As shown, the primary-side auxiliary winding circuit includes a primary-side auxiliary winding, a first filter capacitor, and a first linear voltage regulator module. The primary-side auxiliary winding is coupled to the transformer's main winding. The two ends of the primary-side auxiliary winding are connected to the two ends of the first filter capacitor, and then connected to the input terminal of the first linear voltage regulator module. The output terminal of the first linear voltage regulator module is connected to the power supply terminal on the input side of the first optocoupler circuit and the power supply terminal of the drive circuit.

[0037] Specifically, the primary-side auxiliary winding in the primary-side auxiliary winding circuit can couple energy on the primary side by coupling with the transformer's main winding. Simultaneously, a first filter capacitor is connected to both ends of the primary-side auxiliary winding to filter out high-frequency noise. The filtered voltage signal can be input to the first linear voltage regulator module, and after voltage regulation, a stable DC power supply is output. This DC power supply can power the input side (light-emitting side) of the first optocoupler circuit and the power supply terminal of the drive circuit, thus forming an independent power supply circuit for the primary-side control circuit.

[0038] This embodiment utilizes the primary-side auxiliary winding to couple power from the transformer's main winding. Combined with a filter capacitor and a linear voltage regulator module, it provides a stable and isolated power supply to the primary-side control circuit, thus avoiding the need for an additional auxiliary power supply and reducing power loss. Simultaneously, a stable power supply ensures the stability of optocoupler signal transmission and the reliability of the drive circuit, thereby improving system efficiency and anti-interference capabilities.

[0039] In one embodiment, such as Figure 2 As shown, the secondary auxiliary winding circuit includes a secondary auxiliary winding, a second filter capacitor, and a second linear regulator module. The secondary auxiliary winding is also coupled to the main winding of the transformer in the input circuit. The two ends of the secondary auxiliary winding are connected to the two ends of the second filter capacitor, and then connected to the input terminal of the second linear regulator module. The output terminal of the second linear regulator module is connected to the power supply terminal on the input side of the second optocoupler circuit.

[0040] Specifically, the secondary auxiliary winding in the secondary auxiliary winding circuit couples with the main winding of the transformer in the input circuit, enabling energy coupling on the secondary side. Simultaneously, a second filter capacitor is connected to both ends of the secondary auxiliary winding to filter out high-frequency noise. The filtered voltage signal is input to the second linear regulator module, where it is regulated to output a stable DC power supply. This DC power supply provides operating power to the input side (light-emitting side) of the second optocoupler circuit, ensuring stable transmission of the feedback signal on the secondary side.

[0041] This embodiment utilizes the secondary auxiliary winding to couple power from the transformer's secondary side, and combines this with a filter capacitor and a linear voltage regulator module to provide an independent and stable power supply to the input side of the second optocoupler circuit. This eliminates the need for an additional auxiliary power supply and reduces power loss. Simultaneously, a stable power supply ensures the accuracy and anti-interference capability of the output voltage feedback signal, thereby improving the overall system reliability and control performance.

[0042] In one embodiment, such as Figure 2As shown, the current sampling circuit includes a current transformer, a rectifier and filter circuit, and a voltage conversion circuit. The voltage conversion circuit includes at least one load resistor connected in parallel. The primary winding of the current transformer is connected in series between the transformer output winding and the rectifier circuit in the output circuit. The two ends of the secondary winding of the current transformer are connected to the input terminal of the rectifier and filter circuit. The output terminal of the rectifier and filter circuit is connected to the input terminal of the voltage conversion circuit. The output terminal of the voltage conversion circuit is connected to the input terminal of the current loop circuit.

[0043] Specifically, the primary winding of the current transformer in the current sampling circuit is connected in series on the line between the output winding of the transformer in the output circuit and the rectifier circuit in the output circuit. The two ends of its secondary winding are connected to the input terminal of the rectifier and filter circuit in the current sampling circuit. The collected current signal is rectified and filtered before being input to the voltage conversion circuit. The voltage conversion circuit can convert the current signal on the secondary side of the current transformer into a voltage signal through at least one load resistor connected in parallel. This voltage signal can finally be output to the input terminal of the current loop circuit, thereby completing the sampling and signal conditioning of the output loop current.

[0044] This embodiment achieves accurate current sampling and electrical isolation by connecting a current transformer in series in the output circuit, thus avoiding signal distortion and interference caused by direct sampling. Furthermore, the rectifier and filter circuit removes high-frequency noise, and the voltage conversion circuit converts the current signal into a processable voltage signal, providing precise feedback input to the current loop and improving the adjustment accuracy of the output current.

[0045] In one embodiment, such as Figure 2 As shown, the current loop circuit includes a first operational amplifier and a first compensation circuit. The non-inverting input of the first operational amplifier is connected to a first reference voltage, the inverting input of the first operational amplifier is connected to the output of the current sampling circuit, the output of the first operational amplifier is connected to the first signal input of the first optocoupler circuit, and the first compensation circuit is connected between the non-inverting input and the output of the first operational amplifier.

[0046] Specifically, in the current loop circuit, the non-inverting input of the first operational amplifier is connected to the first reference voltage source to obtain the reference voltage, and its inverting input is connected to the output of the current sampling circuit to receive the converted voltage signal from the current sampling. Its output is connected to the first signal input of the first optocoupler circuit, thus forming the transmission path for the error signal. Simultaneously, a first compensation circuit is connected in parallel between the non-inverting input and output of the first operational amplifier. This compensation circuit can be composed of resistors, capacitors, and other components, and is used to adjust the frequency response characteristics of the current loop, suppressing high-frequency noise and the risk of oscillation caused by insufficient phase margin. This ultimately completes the construction of the current loop circuit and forms a closed-loop regulation with the subsequent control link.

[0047] In this embodiment, a current comparator is constructed using a first operational amplifier. This comparator amplifies the error between the current sampling signal and the reference voltage and outputs it to the optocoupler circuit, thereby achieving precise control of the output current.

[0048] In one embodiment, such as Figure 2 As shown, the voltage loop circuit includes a second operational amplifier and a second compensation circuit. The non-inverting input of the second operational amplifier is connected to a second reference voltage, the inverting input is connected to the output of the primary auxiliary winding circuit, the output is connected to the second signal input of the first optocoupler circuit, and the second compensation circuit is connected between the non-inverting input and the output of the second operational amplifier.

[0049] Specifically, in the voltage loop circuit, the non-inverting input of the second operational amplifier is connected to the second reference voltage source to obtain the reference voltage, and its inverting input is connected to the output of the primary-side auxiliary winding circuit to receive the supply voltage signal of the primary-side auxiliary winding. Its output is connected to the second signal input of the first optocoupler circuit, thus forming the transmission path for the voltage error signal. Simultaneously, a second compensation circuit is connected in parallel between the non-inverting input and output of the second operational amplifier. This compensation circuit, composed of resistors, capacitors, and other components, is used to adjust the frequency response characteristics of the voltage loop, suppressing high-frequency noise and the risk of oscillation caused by insufficient phase margin. This completes the construction of the voltage loop circuit and forms a closed-loop regulation with the subsequent control link.

[0050] In this embodiment, a voltage comparator is constructed using a second operational amplifier. This comparator amplifies the error between the supply voltage of the primary auxiliary winding and the reference voltage and outputs it to the first optocoupler circuit, thereby achieving precise control of the output voltage of the primary auxiliary winding.

[0051] In one embodiment, such as Figure 2 As shown, the power supply terminal on the input side of the first optocoupler circuit is connected to the output terminal of the primary auxiliary winding circuit. The first signal input terminal of the first optocoupler circuit is connected to the output terminal of the current loop circuit. The second signal input terminal of the first optocoupler circuit is connected to the output terminal of the voltage loop circuit. The signal output terminal of the first optocoupler circuit is connected to the control terminal of the drive circuit. The power supply terminal on the input side of the second optocoupler circuit is connected to the output terminal of the output loop. The signal output terminal of the second optocoupler circuit is connected to the control terminal of the drive circuit.

[0052] Specifically, the power supply terminal on the input side of the first optocoupler circuit is connected to the output terminal of the primary-side auxiliary winding circuit. The primary-side auxiliary winding circuit provides a stable power supply to the input side (light-emitting side) of the first optocoupler circuit. Simultaneously, the first signal input terminal of the first optocoupler circuit is connected to the output terminal of the current loop circuit, which can be used to receive current error amplification signals. The second signal input terminal is connected to the output terminal of the voltage loop circuit, which can be used to receive voltage error amplification signals. Its signal output terminal is connected to the control terminal of the drive circuit, which can transmit the integrated current control signal and voltage control signal to the drive circuit. Further, the power supply terminal on the input side of the second optocoupler circuit is connected to the output terminal of the secondary-side auxiliary winding circuit. The secondary-side auxiliary winding circuit provides a stable power supply to the input side (light-emitting side) of the second optocoupler circuit. Its signal input terminal is connected to the output terminal of the output loop, which can be used to receive the output voltage feedback signal. Its signal output terminal is connected to the control terminal of the drive circuit, which can transmit the secondary-side feedback voltage signal to the drive circuit. Finally, the drive circuit can regulate the on / off state of the switching devices based on the received multiple feedback signals, thereby forming a closed-loop system of primary and secondary-side coordinated control.

[0053] This embodiment integrates the error signals from the current loop and voltage loop using the first optocoupler circuit, enabling composite control of the primary-side current and voltage, thereby improving control accuracy and dynamic response. Simultaneously, by using the secondary-side auxiliary winding to power the second optocoupler circuit, it can stably transmit the output voltage feedback signal, thus avoiding signal distortion caused by instability in the secondary-side power supply. Furthermore, the dual optocoupler structure achieves electrical isolation between the primary and secondary sides, reducing ground loop interference and further improving the overall reliability, control accuracy, and anti-interference capability of the power supply system.

[0054] In one embodiment, such as Figure 2 As shown, the driving circuit includes a driving chip. The power supply terminal of the driving chip is connected to the output terminal of the primary-side auxiliary winding circuit, the input terminal of the driving chip is connected to the signal output terminals of the first optocoupler circuit and the second optocoupler circuit, and the output terminal of the driving chip is connected to the gate of the switching device in the input circuit.

[0055] Specifically, the power supply terminal of the driver chip is connected to the output terminal of the primary-side auxiliary winding circuit, providing a stable operating power supply for the driver chip. Simultaneously, the input terminal of the driver chip is connected to the signal output terminals of the first and second optocoupler circuits, allowing it to receive composite control signals from the primary-side current loop and voltage loop, as well as voltage signals from the secondary-side feedback. The output terminal of the driver chip is connected to the gate of the switching device in the input circuit, enabling the generation of a PWM drive waveform based on the integrated control signal. This allows for adjustment of the switching frequency and duty cycle of the switching device, ultimately achieving precise control of energy transfer in the input circuit.

[0056] This embodiment utilizes a driver chip to integrate multiple feedback signals from the primary and secondary sides, transforming the composite control logic of the current and voltage loops into driving waveforms for switching devices, thereby adjusting the efficiency of energy conversion on the input side. Simultaneously, the stable power supply provided by the primary-side auxiliary winding ensures reliable operation of the driver chip, preventing drive anomalies caused by power fluctuations. Furthermore, the integration of dual optocoupler signals improves the power supply's control precision and dynamic response speed, thus optimizing the overall efficiency and stability of the entire power supply system.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A switching power supply circuit, characterized in that, The switching power supply circuit includes an input circuit, an output circuit, a primary auxiliary winding circuit, a secondary auxiliary winding circuit, a current sampling circuit, a current loop circuit, a voltage loop circuit, a first optocoupler circuit, a second optocoupler circuit, and a drive circuit. The primary auxiliary winding in the primary auxiliary winding circuit is coupled to the transformer main winding in the input circuit, and is used to provide power to the input side of the current loop circuit, the voltage loop circuit, the drive circuit and the first optocoupler circuit on the primary side of the transformer. The secondary auxiliary winding in the secondary auxiliary winding circuit is coupled to the transformer main winding in the input circuit to provide power to the input side of the second optocoupler circuit on the secondary side of the transformer. The current sampling circuit feeds back the current in the output circuit to the primary side of the transformer through a current transformer, and controls the current in the output circuit through the current loop circuit, the first optocoupler circuit and the drive circuit. The second optocoupler circuit feeds back the output voltage of the output circuit to the primary side of the transformer through the voltage input signal on the input side, and controls the output voltage of the output circuit through the second optocoupler circuit and the driving circuit.

2. The switching power supply circuit according to claim 1, characterized in that, The input circuit includes input switching devices and the main winding of a transformer, wherein, The switching device is connected between the input source and the main winding of the transformer. The gate of the switching device is connected to the output terminal of the driving circuit. The switching device is used to receive the PWM signal sent by the driving circuit to control the on / off state of the input circuit.

3. The switching power supply circuit according to claim 1, characterized in that, The output circuit includes a rectifier circuit, a filter circuit, and a transformer output winding, wherein, The two ends of the transformer output winding are connected to the input terminal of the rectifier circuit, the output terminal of the rectifier circuit is connected to the input terminal of the filter circuit, and the output terminal of the filter circuit is connected to the load. In the current sampling circuit, the primary winding of the current transformer is connected in series between the output winding of the transformer and the rectifier circuit, and is used to collect the current in the output circuit.

4. The switching power supply circuit according to claim 1, characterized in that, The primary-side auxiliary winding circuit includes a primary-side auxiliary winding, a first filter capacitor, and a first linear voltage regulator module, wherein... The primary auxiliary winding is coupled to the main winding of the transformer. The two ends of the primary auxiliary winding are connected to the two ends of the first filter capacitor and then connected to the input terminal of the first linear voltage regulator module. The output terminal of the first linear voltage regulator module is connected to the power supply terminal of the input side of the first optocoupler circuit and the power supply terminal of the drive circuit.

5. The switching power supply circuit according to claim 1, characterized in that, The secondary auxiliary winding circuit includes a secondary auxiliary winding, a second filter capacitor, and a second linear voltage regulator module, wherein... The secondary auxiliary winding is coupled to the main winding of the transformer. The two ends of the secondary auxiliary winding are connected to the two ends of the second filter capacitor and then connected to the input terminal of the second linear voltage regulator module. The output terminal of the second linear voltage regulator module is connected to the power supply terminal on the input side of the second optocoupler circuit.

6. The switching power supply circuit according to claim 1, characterized in that, The current sampling circuit includes a current transformer, a rectifier and filter circuit, and a voltage conversion circuit. The voltage conversion circuit includes at least one load resistor connected in parallel. The primary winding of the current transformer is connected in series between the output winding of the transformer and the rectifier circuit in the output circuit. The two ends of the secondary winding of the current transformer are connected to the input terminal of the rectifier and filter circuit. The output terminal of the rectifier and filter circuit is connected to the input terminal of the voltage conversion circuit. The output terminal of the voltage conversion circuit is connected to the input terminal of the current loop circuit.

7. The switching power supply circuit according to claim 1, characterized in that, The current loop circuit includes a first operational amplifier and a first compensation circuit, wherein... The non-inverting input of the first operational amplifier is connected to the first reference voltage, the inverting input of the first operational amplifier is connected to the output of the current sampling circuit, the output of the first operational amplifier is connected to the first signal input of the first optocoupler circuit, and the first compensation circuit is connected between the non-inverting input and the output of the first operational amplifier.

8. The switching power supply circuit according to claim 1, characterized in that, The voltage loop circuit includes a second operational amplifier and a second compensation circuit, wherein... The non-inverting input of the second operational amplifier is connected to the second reference voltage, the inverting input of the second operational amplifier is connected to the output of the primary auxiliary winding circuit, the output of the second operational amplifier is connected to the second signal input of the first optocoupler circuit, and the second compensation circuit is connected between the non-inverting input and the output of the second operational amplifier.

9. The switching power supply circuit according to any one of claims 1, 7, and 8, characterized in that, The power supply terminal on the input side of the first optocoupler circuit is connected to the output terminal of the primary auxiliary winding circuit, the first signal input terminal of the first optocoupler circuit is connected to the output terminal of the current loop circuit, the second signal input terminal of the first optocoupler circuit is connected to the output terminal of the voltage loop circuit, and the signal output terminal of the first optocoupler circuit is connected to the control terminal of the drive circuit. The power supply terminal on the input side of the second optocoupler circuit is connected to the output terminal of the secondary auxiliary winding circuit, the signal input terminal of the second optocoupler circuit is connected to the output terminal of the output circuit, and the signal output terminal of the second optocoupler circuit is connected to the control terminal of the drive circuit.

10. The switching power supply circuit according to claim 1, characterized in that, The driving circuit includes a driving chip, wherein... The power supply terminal of the driver chip is connected to the output terminal of the primary-side auxiliary winding circuit, the input terminal of the driver chip is connected to the signal output terminal of the first optocoupler circuit and the signal output terminal of the second optocoupler circuit, and the output terminal of the driver chip is connected to the gate of the switching device in the input circuit.

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