Circuit and method for reducing startup voltage overshoot of optocoupler isolated feedback switching power supply

Abstract

This invention relates to a circuit and method for reducing startup voltage overshoot in an optocoupler-type isolated feedback switching power supply, and relates to the field of optocoupler-type isolated feedback switching power supplies. The invention manages the startup process of the optocoupler-type isolated feedback switching power supply through a startup controller, Startup-Control, enabling smooth loop establishment when the switching power supply's output voltage VOUT reaches a preset value. By coordinating a constant current source IS, a comparator CMP, and a filter Filter, the loop's DC operating point establishment process after the output voltage VOUT reaches the preset value is eliminated, thereby shortening the loop stabilization time and reducing the overshoot amplitude of the output voltage VOUT.

Description

Technical Field

[0001] The present invention relates to the technical field of optocoupler isolated feedback switching power supplies, and in particular to a circuit and method for reducing startup voltage overshoot of an optocoupler isolated feedback switching power supply. Background Art

[0002] As a core component of modern power electronics technology, switching power supplies (SPSs) hold an irreplaceable position across various industries due to their significant technological advantages. Their conversion efficiency typically exceeds 80%, far exceeding that of traditional linear power supplies. This significantly reduces heat dissipation during the energy conversion process, reducing the design complexity of cooling systems and eliminating the need for bulky heat sinks or fans. This effectively improves the overall energy efficiency of equipment, making them particularly effective in energy-sensitive sectors such as new energy and data centers. Switching power supplies also cover an extremely wide power range, stably adapting to powering microelectronic devices in the milliwatt range to high-power industrial systems in the megawatt range. Compared to linear power supplies of the same power rating, switching power supplies, through optimized topology and integrated design, offer significant cost advantages in mass production, particularly in consumer electronics and smart home applications. Furthermore, their output voltage and current respond to input grid fluctuations and load changes in microseconds, enabling rapid disturbance suppression and ensuring power supply stability. This makes them highly favored in applications with stringent power quality requirements, such as precision instruments and communications equipment. It is precisely these comprehensive advantages that make switching power supplies widely used in many fields such as consumer electronics, industrial control, medical equipment, and new energy vehicles.

[0003] From a technical architecture perspective, switching power supplies can be divided into two categories: isolated and non-isolated, depending on whether there is electrical isolation between the input (power supply) and output (power consumption) ends. Non-isolated switching power supplies, which do not require isolation components, have a simpler structure. Common topologies include boost switching power supplies (suitable for scenarios where the output voltage is higher than the input voltage, such as lithium battery charging), buck switching power supplies (often used in situations where the output voltage is lower than the input voltage, such as mobile phone chargers), and buck-boost switching power supplies (flexibly adapting to situations where the input voltage is higher or lower than the output voltage, such as portable device power supplies). These power supplies are often used in short-range power supply scenarios where electrical isolation is not mandatory. Isolated switching power supplies achieve electrical isolation between the input and output ends through isolation components, significantly improving power safety. Depending on the isolation method, they can be divided into optocoupler switching power supplies, magnetic isolation switching power supplies (which use magnetic field coupling between transformer windings to achieve isolation), and capacitive isolation switching power supplies (which transmit signals through electric field coupling of capacitors). Further divided by topology, isolated switching power supplies include flyback switching power supplies (simple structure, suitable for small and medium power scenarios), forward switching power supplies (larger output power and higher stability), half-bridge switching power supplies (suitable for medium and high power fields, with lower switching losses), and other types. Different topologies are adapted to different power levels and performance requirements.

[0004] Among various types of isolated switching power supplies, optocouplers are one of the most widely used solutions due to their unique technical characteristics. Their isolation voltage (the breakdown voltage between the input and output terminals) can easily reach several thousand volts, meeting the stringent safety isolation requirements of medical equipment, industrial control, and other fields. Furthermore, optocouplers are inherently low-cost, helping to control overall production costs. Furthermore, the optocoupler's photoelectric conversion characteristics virtually eliminate electrical coupling between the input and output signals, effectively preventing electromagnetic interference between the two. This significantly improves the system's electromagnetic compatibility (EMC) and reduces the probability of equipment failure in complex electromagnetic environments.

[0005] However, in the practical application of low-cost optocoupler-based isolated feedback switching power supplies, designers often reduce the number of discrete components used for loop compensation to reduce hardware costs. The primary function of loop compensation components is to stabilize the control loop, ensuring rapid system response and output stability to input voltage fluctuations or load changes. Reducing the number of these components directly reduces loop bandwidth, impairing the system's dynamic response. This drawback is particularly evident during the power supply's startup phase: the output voltage will experience a significant overshoot (i.e., exceeding the designed value) and significantly prolong the time required for voltage stabilization. This overshoot may exceed the rated withstand voltage of downstream electrical equipment. At the very least, this can disrupt the normal startup process and shorten the overall startup time. In severe cases, it can cause irreversible damage to components such as capacitors and chips in downstream circuits, shortening the equipment's lifespan or even causing direct damage, resulting in financial losses.

[0006] In summary, how to effectively reduce the startup voltage overshoot of the optocoupler-type isolated feedback switching power supply has become a key technical issue to improve the reliability of this type of power supply and expand its application scenarios, and has important research value and practical significance. Summary of the Invention

[0007] The object of the present invention is to provide a circuit and method for reducing the startup voltage overshoot of an optocoupler type isolated feedback switching power supply, so as to solve the problems existing in the above-mentioned prior art.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] In a first aspect, the present invention provides a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply, comprising:

[0010] An output voltage divider module is used to sample the output voltage VOUT of the switching power supply in real time, and its output end is connected to the sampling voltage node VS;

[0011] a comparator CMP, whose non-inverting input terminal is connected to the sampling voltage node VS, and whose inverting input terminal is connected to a reference voltage source VREF, and is used to determine whether the output voltage VOUT reaches a preset value;

[0012] a transconductance amplifier GM, having a non-inverting input terminal connected to the sampling voltage node VS and an inverting input terminal connected to a reference voltage source VREF, for amplifying the error between the sampling voltage node VS and the reference voltage source VREF, and converting the voltage difference between the sampling voltage node VS and the reference voltage source VREF into a current output;

[0013] a filter Filter, a first input end of which is connected to the output end of the transconductance amplifier GM, and configured to filter the current output by the transconductance amplifier GM to ensure that the power loop has an appropriate phase margin and unity gain bandwidth, so that the output voltage VOUT does not oscillate and can quickly and smoothly stabilize to a preset value when the input and output change;

[0014] a constant current source IS, configured to drive an optocoupler OPTO when the output voltage VOUT does not reach a preset value;

[0015] an optocoupler driver Driver, configured to, when the output voltage VOUT does not reach a preset value, cause the output voltage of the filter Filter to be consistent with the voltage of the optocoupler OPTO through negative feedback, and, when the output voltage VOUT reaches a preset value, cause the voltage of the optocoupler OPTO to be consistent with the output voltage of the filter Filter through negative feedback;

[0016] The startup controller Startup-Control has an input end connected to the output end of the comparator CMP, and a control end thereof controls the filter Filter, the optocoupler driver Driver and the constant current source IS to work in coordination.

[0017] In a possible implementation, the second input terminal of the filter Filter is connected to the output terminal of the optocoupler driver Driver via a switch ST1 , and the switch ST1 is connected to the control terminal of the startup controller Startup-Control.

[0018] In a possible implementation, the non-inverting input terminal of the optocoupler driver Driver is connected to the optocoupler OPTO via a switch ST2 , and the switch ST2 is connected to the control terminal of the startup controller Startup-Control.

[0019] In a possible implementation, the constant current source IS is connected to the optocoupler OPTO via a switch ST3 , and the switch ST3 is connected to a control terminal of the startup controller Startup-Control.

[0020] In a possible implementation, the output end of the filter Filter is connected to the non-inverting input end of the optocoupler driver Driver via a switch SW1 , and the switch SW1 is connected to the control end of the startup controller Startup-Control.

[0021] In a possible implementation, the output end of the optocoupler driver Driver is connected to the optocoupler OPTO via a switch SW2 , and the switch SW2 is connected to the control end of the startup controller Startup-Control.

[0022] In a possible implementation, the inverting input terminal of the optocoupler driver Driver is connected to the output terminal of the optocoupler driver Driver.

[0023] In a possible implementation, the output voltage dividing module includes:

[0024] A voltage dividing resistor R1, one end of which is connected to the output voltage VOUT; and

[0025] The voltage-dividing resistor R2 has one end connected to the ground, and the other end thereof and the other end of the voltage-dividing resistor R1 are connected together to the sampling voltage node VS.

[0026] In a second aspect, the present invention provides a method for reducing the startup voltage overshoot of an optocoupler-type isolated feedback switching power supply. The method is applied to the circuit for reducing the startup voltage overshoot of an optocoupler-type isolated feedback switching power supply as described above, and the method comprises:

[0027] In response to the output voltage VOUT of the switching power supply not reaching the preset value, the comparator CMP outputs a low level signal;

[0028] The startup controller Startup-Control receives and responds to the low-level signal, controls switches ST1, ST2, and ST3 to be in a closed state, and controls switches SW1 and SW2 to be in an open state;

[0029] Providing a driving current to the optocoupler OPTO through a constant current source IS, so that the non-inverting input terminal of the optocoupler driver Driver is connected to the voltage of the optocoupler OPTO;

[0030] By utilizing the stronger driving capability of the optocoupler driver Driver compared to the transconductance amplifier GM, the output voltage of the filter Filter is clamped to the driving voltage of the optocoupler OPTO, so as to suppress the overshoot of the output voltage VOUT during the startup phase.

[0031] In a possible implementation, the method further includes:

[0032] In response to the output voltage VOUT of the switching power supply reaching a preset value, the comparator CMP outputs a high level signal;

[0033] The startup controller Startup-Control receives and responds to the high-level signal, controls the switches ST1, ST2, and ST3 to switch to an open state, and controls the switches SW1 and SW2 to switch to a closed state;

[0034] Based on the non-mutational characteristics of the filter output voltage, the voltage synchronization of the optocoupler OPTO is maintained without mutation;

[0035] By utilizing the characteristic that the transconductance amplifier GM and the filter Filter are continuously in the working state before the output voltage VOUT reaches the preset value, the voltage settling time is eliminated, so that the voltages at the non-inverting input terminal and the inverting input terminal of the transconductance amplifier GM, the driving voltage of the optocoupler driver Driver, and the output voltage of the filter Filter tend to be consistent with each other;

[0036] By slightly increasing the output voltage of the filter Filter, the current of the optocoupler OPTO meets the loop stability requirement, and the circuit enters a stable state by relying on the negative feedback mechanism, and the output voltage VOUT is stably controlled at a preset value.

[0037] In a third aspect, the present invention provides a computer device, comprising a processor and a memory, wherein the memory stores at least one instruction, at least one program, code set or instruction set, and the processor can load and execute at least one instruction, at least one program, code set or instruction set to implement the method provided above for reducing the startup voltage overshoot of an optocoupler-type isolated feedback switching power supply.

[0038] In a fourth aspect, the present invention provides a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set. The processor can load and execute at least one instruction, at least one program, code set or instruction set to implement the method provided above for reducing the startup voltage overshoot of the optocoupler-type isolated feedback switching power supply.

[0039] In a fifth aspect, the present invention provides a computer program product or computer program, comprising computer program instructions stored in a computer-readable storage medium. A processor reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the method for reducing startup voltage overshoot in an optocoupler-type isolated feedback switching power supply as provided above.

[0040] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0041] The present invention manages the startup process of an optocoupler-type isolated feedback switching power supply through a startup controller Startup-Control, and can achieve smooth loop establishment when the output voltage VOUT of the switching power supply reaches a preset value. Through the coordinated cooperation of a constant current source IS, a comparator CMP, and a filter Filter, the process of establishing the DC operating point of the loop after the output voltage VOUT reaches the preset value is omitted, thereby shortening the loop stabilization time and reducing the overshoot amplitude of the output voltage VOUT. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0043] Figure 1 A schematic diagram of a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown.

[0044] Figure 2 A flow chart of a method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown.

[0045] Figure 3 A schematic diagram of the output voltage at startup of a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown.

[0046] Figure 4 The figure shows a circuit diagram of a traditional optocoupler type isolated feedback switching power supply provided by the prior art.

[0047] Figure 5 The figure shows the output voltage of a conventional optocoupler type isolated feedback switching power supply provided by the prior art when it is started.

[0048] Figure 6 A schematic diagram of a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by another exemplary embodiment of the present invention is shown.

[0049] Figure 7 A circuit diagram showing a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by another exemplary embodiment of the present invention, which is applied to a flyback optocoupler-type isolated feedback switching power supply.

[0050] Figure 8 A schematic structural diagram of a computer device for executing a method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0053] Figure 1 A schematic diagram of a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown. The circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply includes: an output voltage divider module, which is used to sample the output voltage VOUT of the switching power supply in real time, and its output end is connected to the sampling voltage node VS; a comparator CMP, whose non-inverting input end is connected to the sampling voltage node VS, and whose reverse input end is connected to the reference voltage source VREF, and is used to determine whether the output voltage VOUT reaches a preset value; a transconductance amplifier GM, whose non-inverting input end is connected to the sampling voltage node VS, and whose reverse input end is connected to the reference voltage source VREF, and is used to amplify the error between the sampling voltage node VS and the reference voltage source VREF, and convert the voltage difference between the sampling voltage node VS and the reference voltage source VREF into a current output; a filter Filter, whose first input end is connected to the transconductance amplifier GM is connected to the output end of the comparator CMP, which is used to filter the current output by the transconductance amplifier GM to ensure that the power supply loop has a suitable phase margin and unity gain bandwidth, so that the output voltage VOUT will not oscillate and can stabilize to the preset value quickly and smoothly when the input and output change; the constant current source IS is used to drive the optocoupler OPTO when the output voltage VOUT does not reach the preset value; the optocoupler driver Driver is used to make the output voltage of the filter Filter consistent with the voltage of the optocoupler OPTO through negative feedback when the output voltage VOUT does not reach the preset value, and make the voltage of the optocoupler OPTO consistent with the output voltage of the filter Filter through negative feedback when the output voltage VOUT reaches the preset value; the startup controller Startup-Control has an input end connected to the output end of the comparator CMP, and a control end thereof controls the coordinated operation of the filter Filter, the optocoupler driver Driver and the constant current source IS.

[0054] In this embodiment, the output voltage divider module samples the output voltage VOUT in real time, providing a reference for the comparator CMP and transconductance amplifier GM. Comparator CMP compares the sampled voltage with the reference voltage VREF to determine whether the output meets the required standards and provides feedback to the startup controller Startup-Control. The transconductance amplifier GM converts the voltage difference into a current, which is then processed by a filter to ensure loop stability. Based on the comparator CMP signal, the startup controller Startup-Control coordinates the operating states of the constant current source IS and the optocoupler driver Driver. Switching between the start-up and stabilization phases ensures a smooth transition, ultimately suppressing voltage overshoot and accelerating stabilization.

[0055] Furthermore, the second input terminal of the filter Filter is connected to the output terminal of the optocoupler driver Driver via switch ST1, which is connected to the control terminal of the startup controller Startup-Control. The non-inverting input terminal of the optocoupler driver Driver is connected to the optocoupler OPTO via switch ST2, which is connected to the control terminal of the startup controller Startup-Control. The constant current source IS is connected to the optocoupler OPTO via switch ST3, which is connected to the control terminal of the startup controller Startup-Control.

[0056] Furthermore, the output of the filter is connected to the non-inverting input of the optocoupler driver via switch SW1, which is connected to the control terminal of the startup controller Startup-Control. The output of the optocoupler driver is connected to the optocoupler OPTO via switch SW2, which is connected to the control terminal of the startup controller Startup-Control. The inverting input of the optocoupler driver is connected to the output of the optocoupler driver.

[0057] In the embodiment of the present application, during the startup phase, switches ST1, ST2, and ST3 are closed, switches SW1 and SW2 are disconnected, switch ST2 connects the optocoupler OPTO voltage to the optocoupler driver Driver's non-inverting input terminal, and switch ST1 feeds the optocoupler driver Driver's output back to the filter Filter's second input terminal, combining the optocoupler driver Driver's strong driving capability to clamp the filter Filter voltage; switch ST3 turns on the constant current source IS to directly drive the optocoupler OPTO to ensure basic operation. During the stable phase, the switch state is reversed, switch SW1 connects the filter Filter with the optocoupler driver Driver's non-inverting input terminal, and switch SW2 allows the optocoupler driver Driver's output to directly drive the optocoupler OPTO. Switches ST1, ST2, and ST3 are disconnected to cut off the temporary loop. The optocoupler driver Driver's inverting input terminal is connected to its own output to form negative feedback, ensuring that the optocoupler OPTO voltage is consistent with the filter Filter output. Through switch timing control, a two-stage smooth transition is achieved, which not only suppresses startup overshoot, but also ensures loop performance after stabilization and accelerates voltage stabilization.

[0058] It's worth noting that the output voltage divider module includes a voltage divider resistor R1, one end of which is connected to the output voltage VOUT; and a voltage divider resistor R2, one end of which is grounded, and the other end of which, along with the other end of resistor R1, is connected to the sampling voltage node VS. Resistors R1 and R2 divide the voltage to obtain a sampling voltage, which provides input to the comparator CMP and transconductance amplifier GM, enabling real-time monitoring of the output voltage VOUT.

[0059] Figure 2 A flow chart of a method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown. The method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply is applied to the above-mentioned circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply. The method includes:

[0060] In step 201 , in response to the output voltage VOUT of the switching power supply not reaching a preset value, the comparator CMP outputs a low level signal.

[0061] In step 202 , the startup controller Startup-Control receives and responds to the low-level signal, controls the switches ST1 , ST2 , and ST3 to be in a closed state, and controls the switches SW1 and SW2 to be in an open state.

[0062] Step 203 : providing a driving current to the optocoupler OPTO via the constant current source IS, so that the non-inverting input terminal of the optocoupler driver Driver is connected to the voltage of the optocoupler OPTO.

[0063] In step 204 , the output voltage of the filter Filter is clamped to the driving voltage of the optocoupler OPTO by utilizing the stronger driving capability of the optocoupler driver Driver compared to the transconductance amplifier GM, so as to suppress the overshoot of the output voltage VOUT during the startup phase.

[0064] In steps 201 to 204, when the output voltage VOUT fails to reach the preset value, the conventional feedback path of the transconductance amplifier GM is disconnected (SW1 is disconnected), and a constant current source IS is used to provide a stable bias current to the optocoupler OPTO. Simultaneously, leveraging the optocoupler driver's enhanced drive capability (e.g., high input impedance and low output impedance), the output voltage of the filter Filter is forcibly clamped to the optocoupler voltage. This design eliminates the startup delay effect of a traditional feedback loop. The pre-drive of the constant current source IS avoids the startup dead zone, and the voltage-following characteristics (high bandwidth) of the optocoupler driver suppress the risk of ringing caused by insufficient phase margin. Furthermore, the filter voltage is pre-adjusted to a near-steady-state value, paving the way for the subsequent switch to closed-loop control. This significantly shortens the transition time and is particularly suitable for scenarios requiring high startup speed and voltage accuracy. This mechanism prevents overshoot of the output voltage VOUT during startup.

[0065] Step 205 : In response to the output voltage VOUT of the switching power supply reaching a preset value, the comparator CMP outputs a high level signal.

[0066] In step 206 , the startup controller Startup-Control receives and responds to the high-level signal, controls the switches ST1 , ST2 , and ST3 to be switched to an open state, and controls the switches SW1 and SW2 to be switched to a closed state.

[0067] Step 207 : Based on the non-mutational characteristic of the output voltage of the filter Filter, the voltage of the optocoupler OPTO is maintained synchronously without mutation.

[0068] In step 208, the voltage settling time is eliminated by utilizing the characteristic that the transconductance amplifier GM and the filter Filter are continuously in an operating state before the output voltage VOUT reaches a preset value. This allows the voltages at the non-inverting input and inverting input of the transconductance amplifier GM, the driving voltage of the optocoupler driver Driver, and the output voltage of the filter Filter to converge to the same level.

[0069] In step 209 , the output voltage of the filter Filter is slightly increased so that the current of the optocoupler OPTO meets the loop stability requirement. The circuit enters a stable state by relying on the negative feedback mechanism, and the output voltage VOUT is stably controlled at a preset value.

[0070] In steps 205 to 209, when the output voltage VOUT reaches the preset value, the comparator CMP outputs a high-level signal, which the startup controller Startup-Control receives and triggers a switch state reversal. This process is not a simple path switching, but rather a smooth transition achieved by leveraging the non-abrupt nature of the filter output voltage. Because the transconductance amplifier GM and the filter Filter remain operational during the startup phase, signal preprocessing is already complete, avoiding the voltage settling delay common in traditional circuits. The optocoupler driver Driver then automatically calibrates the voltage through negative feedback. Only fine-tuning the filter output requires fine-tuning the optocoupler OPTO's exponential current-voltage characteristic to quickly meet loop stabilization requirements. This design compresses the transition between the startup and stabilization phases to an instantaneous time, eliminating switching disturbances while ensuring immediate negative feedback through a pre-operation mechanism. Ultimately, this results in precise and stable output voltage VOUT.

[0071] Compared with existing technologies: Figure 4 The circuit diagram of a conventional optocoupler-type isolated feedback switching power supply provided by the prior art is shown, including a voltage divider resistor R1, one end of which is connected to the output voltage VOUT; a voltage divider resistor R2, one end of which is grounded, and the other end thereof and the other end of the voltage divider resistor R1 are connected to the sampling voltage node VS; a transconductance amplifier GM, whose non-inverting input is connected to the sampling voltage node VS, and whose reverse input is connected to the reference voltage source VREF; a filter Filter, whose input is connected to the output of the transconductance amplifier GM; and an optocoupler driver Driver, whose non-inverting input is connected to the output of the filter Filter, whose reverse input is connected to its output, and whose output is connected to the optocoupler OPTO. In this case, Figure 3 A schematic diagram of the output voltage at startup of a circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown. Figure 5 The output voltage diagram of the conventional optocoupler type isolated feedback switching power supply provided by the prior art is shown. Figure 3 and Figure 5 It can be seen that the circuit for reducing the startup voltage overshoot of the optocoupler type isolated feedback switching power supply provided by the present invention can save the process of establishing the loop DC operating point after the output voltage VOUT reaches the preset value, thereby shortening the loop stabilization time and significantly reducing the overshoot amplitude of the output voltage.

[0072] Figure 6 FIG2 is a schematic diagram showing a circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply provided by another exemplary embodiment of the present invention. Figure 7A circuit diagram of a circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply, provided by another exemplary embodiment of the present invention, is applied to a flyback optocoupler-type isolated feedback switching power supply. In this embodiment, the output voltage VOUT of the switching power supply is 5V, and the voltage divider resistors R1 and R2 of the output voltage divider module are both 5K; the transconductance amplifier GM is 20uS; the filter parameters are affected by factors such as the main power switch controller PWM, the output power supply load capacity, and the transformer inductance. Sufficient phase margin should be ensured in the loop to avoid oscillation, and the loop unity gain bandwidth should be one order of magnitude lower than the switching frequency or lower; the startup constant current source IS is 100uA.

[0073] The PWM switching frequency of the main power switch controller is 65 kHz, and the loop bandwidth is 2 kHz (time constant is 500 μs). After adding the startup controller Startup-Control, since there is no need to establish a DC operating point, the loop requires 3 time constants of about 1.5 ms to reduce the overshoot voltage to 5%. Since the comparator CMP can monitor the output voltage VOUT to reach the preset value during startup, the actual overshoot voltage is less than 10% of the preset value. After 1.5 ms, the difference between the output voltage VOUT and the preset value will be less than 5‰, which is equivalent to the ripple voltage of the switching power supply. The negative feedback regulation of the output voltage VOUT is completed.

[0074] After the optocoupler isolated feedback switching power supply without the startup controller Startup-Control is started, the DC operating point needs to be established first. In order to ensure loop stability, the DC operating point establishment time is designed to be 2 time constants, about 1ms. During the DC operating point establishment process, the optocoupler OPTO has no current, and the main power switch controller PWM controls the power supply to transfer energy to the output end at maximum power. The output voltage VOUT will rise rapidly and deviate from the design value. The overshoot voltage calculated based on the 2ms startup time (that is, the time for the output voltage VOUT to rise from 0V to the preset value) will eventually exceed the design value by 50%. Only when the DC operating point is established can the negative feedback work. The loop requires 4.6 time constants, about 2.3ms, to adjust the output voltage VOUT to a deviation from the preset value of less than 5‰, which is equivalent to the ripple voltage of the switching power supply. The negative feedback regulation of the output voltage VOUT is completed.

[0075] After adding the startup controller Startup-Control, the output voltage VOUT takes 2ms to increase from 0V to the preset value, and 1.5ms to complete negative feedback regulation, with a cumulative startup time of 3.5ms; the overshoot voltage is less than 10%.

[0076] Without adding the startup controller Startup-Control, the output voltage VOUT takes 2ms to rise from 0V to the preset value, the overshoot time is 1ms, and then it takes 2.3ms to complete the negative feedback regulation. The cumulative startup time is 5.3ms; the overshoot voltage is 50%.

[0077] Therefore, adding the startup controller reduces the overshoot voltage by 80%, and the time it takes for the output voltage VOUT to stabilize from 0V is reduced by approximately 34%. Therefore, adding the startup controller can shorten the loop stabilization time and significantly reduce the overshoot amplitude of the output voltage VOUT.

[0078] Figure 8 A schematic diagram of the structure of a computer device for executing a method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply provided by an exemplary embodiment of the present invention is shown. The computer device includes:

[0079] The processor 801 includes one or more processing cores. The processor 801 executes various functional applications and data processing by running software programs and modules.

[0080] Receiver 802 and transmitter 803 can be implemented as a communication component, which can be a communication chip. Optionally, the communication component can include signal transmission functionality. That is, transmitter 803 can be used to transmit control signals to the image acquisition device and scanning device, and receiver 802 can be used to receive corresponding feedback instructions.

[0081] The memory 804 is connected to the processor 801 via a bus 805 .

[0082] The memory 804 may be used to store at least one instruction, and the processor 801 may be used to execute the at least one instruction to implement each step in the above method embodiment.

[0083] An embodiment of the present invention also provides a computer-readable storage medium, which stores at least one instruction, at least one program, code set or instruction set, which is loaded and executed by a processor to implement the above-mentioned method of reducing the startup voltage overshoot of the optocoupler-type isolated feedback switching power supply.

[0084] The present invention also provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform the method for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply as described in any of the above embodiments.

[0085] Optionally, the computer-readable storage medium may include: read-only memory (ROM), random access memory (RAM), solid-state drives (SSDs), or optical disks. Random access memory may include resistance random access memory (ReRAM) and dynamic random access memory (DRAM). The serial numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0086] It should be understood that the specific examples herein are only intended to help those skilled in the art to better understand the present disclosure, rather than to limit the scope of the present invention.

[0087] It can be understood that in the various implementations of this specification, the size of the sequence number of each process does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of this disclosure.

[0088] It can be understood that the various embodiments described in this specification can be implemented individually or in combination, and the present disclosure is not limited thereto.

[0089] Unless otherwise indicated, all technical and scientific terms used in this disclosure have the same meaning as commonly understood by those skilled in the art in the technical field of this specification. The terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the scope of this specification. The term "and / or" used in this specification includes any and all combinations of one or more related listed items. The singular forms "a", "above", and "the" used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0090] It is understood that the processor of the present disclosure can be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above-mentioned method embodiment can be completed by hardware integrated logic circuits in the processor or software instructions. The above-mentioned processor can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The various methods, steps, and logic block diagrams disclosed in this disclosure can be implemented or executed. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this disclosure can be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module can be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory, and the processor reads the information in the memory and, in conjunction with its hardware, completes the steps of the above-mentioned method.

[0091] It will be understood that the memory in the present disclosure may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. Among them, the non-volatile memory may be read-only memory (ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), electrically erasable programmable read-only memory (EEPROM) or flash memory. The volatile memory may be random access memory (RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0092] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this specification.

[0093] The above description is merely a specific embodiment of this specification, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this specification should be included in the scope of protection of this specification. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply, characterized in that: include: An output voltage divider module is used to sample the output voltage VOUT of the switching power supply in real time, and its output end is connected to the sampling voltage node VS; a comparator CMP, whose non-inverting input terminal is connected to the sampling voltage node VS, and whose inverting input terminal is connected to a reference voltage source VREF, and is used to determine whether the output voltage VOUT reaches a preset value; a transconductance amplifier GM, having a non-inverting input terminal connected to the sampling voltage node VS and an inverting input terminal connected to a reference voltage source VREF, for amplifying the error between the sampling voltage node VS and the reference voltage source VREF, and converting the voltage difference between the sampling voltage node VS and the reference voltage source VREF into a current output; a filter Filter, a first input end of which is connected to the output end of the transconductance amplifier GM, and configured to filter the current output by the transconductance amplifier GM to ensure that the power loop has an appropriate phase margin and unity gain bandwidth, so that the output voltage VOUT does not oscillate and can quickly and smoothly stabilize to a preset value when the input and output change; a constant current source IS, configured to drive an optocoupler OPTO when the output voltage VOUT does not reach a preset value; an optocoupler driver Driver, configured to, when the output voltage VOUT does not reach a preset value, cause the output voltage of the filter Filter to be consistent with the voltage of the optocoupler OPTO through negative feedback, and, when the output voltage VOUT reaches a preset value, cause the voltage of the optocoupler OPTO to be consistent with the output voltage of the filter Filter through negative feedback; The startup controller Startup-Control has an input end connected to the output end of the comparator CMP, and a control end thereof controls the filter Filter, the optocoupler driver Driver and the constant current source IS to work in coordination.

2. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 1, characterized in that: The second input terminal of the filter Filter is connected to the output terminal of the optocoupler driver Driver via a switch ST1 , and the switch ST1 is connected to the control terminal of the startup controller Startup-Control.

3. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 2, characterized in that: The non-inverting input terminal of the optocoupler driver Driver is connected to the optocoupler OPTO via a switch ST2 , and the switch ST2 is connected to the control terminal of the startup controller Startup-Control.

4. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 3, characterized in that: The constant current source IS is connected to the optical coupler OPTO via a switch ST3 , and the switch ST3 is connected to a control terminal of the startup controller Startup-Control.

5. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 1, characterized in that: The output end of the filter Filter is connected to the non-inverting input end of the optocoupler driver Driver via a switch SW1 , and the switch SW1 is connected to the control end of the startup controller Startup-Control.

6. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 5, characterized in that: The output end of the optocoupler driver Driver is connected to the optocoupler OPTO via a switch SW2 , and the switch SW2 is connected to the control end of the startup controller Startup-Control.

7. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 1, characterized in that: The inverting input terminal of the optocoupler driver Driver is connected to the output terminal of the optocoupler driver Driver.

8. The circuit for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 1, characterized in that: The output voltage divider module includes: A voltage dividing resistor R1, one end of which is connected to the output voltage VOUT; and The voltage-dividing resistor R2 has one end connected to the ground, and the other end thereof and the other end of the voltage-dividing resistor R1 are connected together to the sampling voltage node VS.

9. A method for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply, characterized in that: The method is applied to the circuit for reducing startup voltage overshoot of an optocoupler-type isolated feedback switching power supply according to any one of claims 1 to 8, and the method comprises: In response to the output voltage VOUT of the switching power supply not reaching the preset value, the comparator CMP outputs a low level signal; The startup controller Startup-Control receives and responds to the low-level signal, controls switches ST1, ST2, and ST3 to be in a closed state, and controls switches SW1 and SW2 to be in an open state; Providing a driving current to the optocoupler OPTO through a constant current source IS, so that the non-inverting input terminal of the optocoupler driver Driver is connected to the voltage of the optocoupler OPTO; By utilizing the stronger driving capability of the optocoupler driver Driver compared to the transconductance amplifier GM, the output voltage of the filter Filter is clamped to the driving voltage of the optocoupler OPTO, so as to suppress the overshoot of the output voltage VOUT during the startup phase.

10. The method for reducing startup voltage overshoot of an optocoupler type isolated feedback switching power supply according to claim 9, characterized in that: The method further comprises: In response to the output voltage VOUT of the switching power supply reaching a preset value, the comparator CMP outputs a high level signal; The startup controller Startup-Control receives and responds to the high-level signal, controls the switches ST1, ST2, and ST3 to switch to an open state, and controls the switches SW1 and SW2 to switch to a closed state; Based on the non-mutational characteristics of the filter output voltage, the voltage synchronization of the optocoupler OPTO is maintained without mutation; By utilizing the characteristic that the transconductance amplifier GM and the filter Filter are continuously in the working state before the output voltage VOUT reaches the preset value, the voltage settling time is eliminated, so that the voltages at the non-inverting input terminal and the inverting input terminal of the transconductance amplifier GM, the driving voltage of the optocoupler driver Driver, and the output voltage of the filter Filter tend to be consistent with each other; By slightly increasing the output voltage of the filter Filter, the current of the optocoupler OPTO meets the loop stability requirement, and the circuit enters a stable state by relying on the negative feedback mechanism, and the output voltage VOUT is stably controlled at a preset value.

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