A method and system for improving dynamic characteristics of switching power supply

Abstract

The present invention provides a method and system for improving the dynamic characteristics of a switching power supply. By discharging the output capacitor when the output voltage reaches a first threshold voltage, the response speed of the dynamic process loop is accelerated, ensuring that the operational amplifier and the optical coupler are both located in the linear region during the dynamic process, so that the switching power supply has normal dynamic adjustment capability, avoiding the output voltage exceeding the safety threshold, and ensuring the safety of the system; by controlling the output capacitor to stop discharging after the dynamic adjustment capability is restored in the loop, the resource consumption caused by long-term discharge or repeated discharge is reduced, the energy efficiency of the system is improved, and at the same time, damage to circuit components is avoided, and the stable operation of the system is maintained.

Description

Technical Field

[0001] The present invention relates to the technical field of switch power supply control, and more specifically to a method and system for improving the dynamic characteristics of a switch power supply. Background Art

[0002] When the switching power supply is switched from full load to no load, the feedback amplifier will be saturated due to output overshoot, causing the optocoupler to enter the saturation zone, which can easily lead to the problem of slow loop response speed. For laptop adapters, its dynamic adjustment characteristics are particularly important, and it is necessary to ensure that the output voltage is within the safety threshold (usually ±7% of the rated voltage) in both steady state and dynamic state.

[0003] When the existing switching power supply adopts the flyback topology, its voltage regulation loop is as follows: Figure 1 As shown, the schematic diagram of its empty and full load dynamic response is as follows Figure 2 As shown in the figure, during the switching process from full load to no-load, the compensation network causes the FB feedback pin voltage Vfb of U1 to respond laggingly, and the primary energy supply is not adjusted in time, causing the output voltage Vo to overshoot; after the optocoupler is saturated, it takes time T1 to restore to the linear region. During this period, if a sudden load is added, the stability of the output voltage Vo is affected and may be lower than the safety threshold, affecting the normal operation of the equipment.

[0004] In order to reduce the optocoupler saturation time T1 and ensure the dynamic regulation rate of the output voltage Vo exceeding the safety threshold due to sudden loading at time T2, the traditional test method is to increase the load with a fixed resistance value so that the switching power supply is not actually absolutely unloaded. For example, if the power supply is fully loaded at 3A, and a large voltage drop occurs during the dynamic test of 0A / 3A, 50ms / 50ms, the test conditions can be changed to 0.01A / 3A, 50ms / 50ms, so that the duration T1 of the optocoupler saturation is less than 50ms, which can avoid the large voltage drop. However, this method is only suitable for testing and does not meet the requirements of computers for low standby power consumption in actual applications. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the prior art and provide a method and system for improving the dynamic characteristics of a switching power supply to solve the technical problem that when a traditional switching power supply switches between no-load and full-load, the operational amplifier saturates and the output voltage easily exceeds the dynamic adjustment safety threshold.

[0006] In a first aspect, an embodiment of the present invention provides a method for improving dynamic characteristics of a switching power supply, wherein the switching power supply comprises a power supply circuit, an output end of the power supply circuit is provided with an output capacitor, and the method comprises the following steps:

[0007] configuring a discharge circuit to ensure that the discharge circuit is connected to the output end of the power supply circuit;

[0008] detecting an output voltage of the power supply circuit;

[0009] When the output voltage of the power supply circuit reaches a first threshold voltage, the discharge circuit and the power supply circuit are turned on to discharge the output capacitor;

[0010] When the output voltage of the power supply circuit drops from the first threshold voltage to the second threshold voltage, or when the discharge of the output capacitor reaches a preset time, the discharge circuit is turned off, so that the output capacitor stops discharging.

[0011] The step of configuring the discharge circuit to ensure that the discharge circuit is connected to the output end of the power supply circuit includes:

[0012] Configure voltage comparator, load resistor and switching unit;

[0013] Ensure that the voltage comparator and the load resistor are connected to two ends of the output capacitor, and the load resistor is connected to the output end of the voltage comparator through the switching unit;

[0014] The voltage comparator is used to determine whether the output voltage reaches a first threshold voltage or a second threshold voltage, and to control the switching unit to be turned on or off so that the load resistor is connected to or disconnected from the power supply circuit.

[0015] Wherein, before the step of detecting the output voltage of the power supply circuit, the step further includes:

[0016] Setting the first threshold voltage and the second threshold voltage;

[0017] The first threshold voltage and the second threshold voltage are higher than the rated output voltage of the switching power supply; and the first threshold voltage and the second threshold voltage are within the safety threshold of the switching power supply.

[0018] Wherein, the first threshold voltage is Where V e is the rated output voltage of the switching power supply, V ref is the reference voltage of the voltage comparator, V od is the saturation voltage of the voltage comparator.

[0019] Among them, the saturation voltage V of the voltage comparator od is 0.075V, the reference voltage V of the voltage comparator ref 1.25V or 2.5V.

[0020] The second threshold voltage is 0.1V-0.3V lower than the first threshold voltage; or the second threshold voltage is 0.5%-2% lower than the first threshold voltage.

[0021] The method for improving the dynamic characteristics of a switching power supply according to claim 6, wherein the first threshold voltage is 3%-5% higher than the rated output voltage of the switching power supply; and the second threshold voltage is 2%-4% higher than the rated output voltage of the switching power supply.

[0022] In a second aspect, an embodiment of the present invention provides a system for improving the dynamic characteristics of a switching power supply, which is used to perform the above method, and the system includes:

[0023] A power supply circuit, the power supply circuit comprising: a rectifier module, a PWM modulation module, an optical coupler, a compensation module, a transformer and an output capacitor; the two ends of the output capacitor are connected to the two ends of the secondary side of the transformer; the compensation module, the optical coupler and the PWM modulation module are connected in sequence to form a negative feedback circuit, the input end of the compensation module is connected to the output capacitor, the output end of the PWM modulation module is connected to one end of the primary side of the transformer, and the rectifier module is connected to the other end of the primary side of the transformer;

[0024] A discharge circuit, the discharge circuit comprising: a voltage detection module, a voltage comparator, a load resistor and a switching unit; the voltage detection module and the load resistor are connected to the output capacitor, the two input ends of the voltage comparator are respectively connected to the voltage detection module and the reference voltage, the load resistor is connected to the voltage comparator through the switching unit; the voltage comparator is used to control the on or off of the switching unit so that the load resistor is connected to or disconnected from the power supply circuit.

[0025] Wherein, the voltage detection module includes a resistor R5 and a resistor R6, the resistor R5 and the resistor R6 are connected in series, the resistor R5 is connected to the output end of the power supply circuit, and the resistor R6 is grounded;

[0026] One input terminal of the voltage comparator is connected to the middle node of the resistor R5 and the resistor R6, and is connected to the output terminal of the voltage comparator through the resistor R4, and the other input terminal of the voltage comparator is connected to the reference voltage;

[0027] The switching unit is a switch tube Q2, a first end of the switch tube Q2 is connected to the output end of the voltage comparator, a second end of the switch tube Q2 is connected to the load resistor, and a third end of the switch tube Q2 is grounded.

[0028] Wherein, the discharge circuit further includes a power management chip, and the voltage comparator and the voltage detection module are integrated in the power management chip;

[0029] The power management chip is provided with a port DIS, a port Vo, and a port GND; the port DIS is connected to the output end of the power circuit through a load resistor, the port Vo is connected to the output end of the power circuit, and the port GND is grounded;

[0030] The voltage detection module includes: a resistor R401 and a resistor R402; the resistor R401 and the resistor R402 are connected in series, the resistor R401 is connected to the port Vo, and the resistor R402 is connected to the port GND;

[0031] Two input terminals of the voltage comparator are respectively connected to the middle node of the resistor R401 and the resistor R402 and a reference voltage.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention accelerates the response speed of the dynamic process loop by discharging the output capacitor when the output voltage reaches the first threshold voltage, ensures that the operational amplifier and the optocoupler are both in the linear region during the dynamic process, so that the switching power supply has normal dynamic adjustment capability, avoids the output voltage exceeding the safety threshold, and ensures system safety; after the loop restores the dynamic adjustment capability, the output capacitor stops discharging, reduces the resource consumption caused by long-term discharge or repeated discharge, and improves the energy efficiency of the system.

[0033] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following preferred embodiments are specifically cited and described in detail as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a power supply circuit in the prior art;

[0035] Figure 2 A schematic diagram of the dynamic response of a power supply circuit in the prior art;

[0036] Figure 3 A schematic diagram of an application scenario of a method for improving the dynamic characteristics of a switching power supply provided by the present invention;

[0037] Figure 4 A flow chart of a method for improving the dynamic characteristics of a switching power supply provided by the present invention;

[0038] Figure 5 A schematic diagram of the structure of a system for improving the dynamic characteristics of a switching power supply provided by the present invention;

[0039] Figure 6 A schematic diagram of the structure of another system for improving the dynamic characteristics of a switching power supply provided by the present invention;

[0040] Figure 7 A dynamic response schematic diagram of a system power supply circuit for improving the dynamic characteristics of a switching power supply provided by the present invention.

[0041] Reference numerals:

[0042] 1. Output capacitor; 2. PWM modulation module; 3. Optocoupler; 4. Compensation module; 5. Transformer; 6. Rectification module. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail in conjunction with the accompanying drawings and specific implementation methods. The technical solution in the embodiment of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment 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 creative work are within the scope of protection of the present invention.

[0044] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0045] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0046] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0047] Embodiment 1

[0048] See also Figure 3-4 As shown, this embodiment discloses a method for improving the dynamic characteristics of a switching power supply. Figure 3 is a schematic diagram of an application scenario of the method of this embodiment, wherein the switching power supply includes a power supply circuit, and an output capacitor is provided at the output end of the power supply circuit. The method includes the following steps:

[0049] Step S100, configuring a discharge circuit to ensure that the discharge circuit is connected to the output end of the power circuit;

[0050] Step S110, detecting the output voltage of the power supply circuit;

[0051] Step S120, when the output voltage of the power circuit reaches a first threshold voltage, the discharge circuit and the power circuit are turned on to discharge the output capacitor;

[0052] In step S130, when the output voltage of the power circuit drops from the first threshold voltage to the second threshold voltage, or when the discharge of the output capacitor reaches a preset time, the discharge circuit is turned off to stop the discharge of the output capacitor.

[0053] The output voltage of this embodiment refers to the instantaneous output value of the power supply circuit at any time.

[0054] The method for improving the dynamic characteristics of the switching power supply of this embodiment accelerates the response speed of the dynamic process loop by discharging the output capacitor when the output voltage reaches the first threshold voltage, ensures that the operational amplifier and the optocoupler are both in the linear region during the dynamic process, so that the switching power supply has normal dynamic adjustment capability, avoids the output voltage exceeding the safety threshold, and ensures system safety; after the loop restores the dynamic adjustment capability, the output capacitor stops discharging, reduces resource consumption caused by long-term discharge or repeated discharge, improves the energy efficiency of the system, and avoids damage to circuit components, maintaining the stable operation of the system.

[0055] Specifically, step S100 includes:

[0056] Configure a voltage comparator, a load resistor and a switching unit, ensure that the voltage comparator and the load resistor are connected to both ends of the output capacitor, and the load resistor is connected to the output end of the voltage comparator through the switching unit;

[0057] The voltage comparator is used to determine whether the output voltage reaches the first threshold voltage or the second threshold voltage, and to control the switching unit to be turned on or off so that the load resistor is connected to or disconnected from the power circuit.

[0058] In practical applications, the voltage comparator, the load resistor and the switching unit are pre-connected so that in the dynamic process, the voltage comparator compares the output voltage with the first threshold voltage and the second threshold voltage to drive the switching unit to turn on or off, so that the load resistor is connected to the power circuit or open. When the load resistor is connected to the power circuit, due to its own resistance pressure, the output capacitor is discharged, the optocoupler and the operational amplifier are prevented from entering the saturation zone, and the dynamic adjustment capability of the switching power supply is guaranteed.

[0059] Specifically, the switching unit includes but is not limited to a switch, a relay, a transistor, a triode, and an analog switch. The switching unit is used to switch the circuit on and off to accurately control the state of the output capacitor.

[0060] Specifically, before step S110, the following steps are also included:

[0061] Setting a first threshold voltage and a second threshold voltage;

[0062] The first threshold voltage and the second threshold voltage are higher than the rated output voltage of the switching power supply; and the first threshold voltage and the second threshold voltage are within the safety threshold of the switching power supply.

[0063] The first threshold voltage and the second threshold voltage are pre-set to ensure that the first threshold voltage and the second threshold voltage are within the safety threshold to prevent the dynamic process output voltage from exceeding the safety threshold and causing damage to the system. The safety threshold is the dynamic voltage range, which usually does not exceed ±7% of the rated voltage, such as a switching power supply with a rated voltage of 9V, 15V, 20V, etc. The safety threshold of some switching power supplies does not exceed ±10% of the rated voltage, such as a switching power supply with a rated voltage of 5V.

[0064] Specifically, the first threshold voltage is Where V e is the rated output voltage of the switching power supply, V ref is the reference voltage of the voltage comparator, V od is the saturation voltage of the voltage comparator.

[0065] The definition standard of the first threshold voltage of this embodiment is:

[0066] (1) Consider the dynamic specification requirements of the power supply: For example, the 5V safety threshold is required to be within ±10% of the rated voltage, and other gears cannot exceed ±7%. The first threshold voltage and the second threshold voltage are within the safety threshold;

[0067] (2) Consider the OVP point (Over Voltage Protection): When the voltage on the output terminal of the switching power supply exceeds the preset OVP point, the switching power supply will automatically shut down or take other protective measures to protect the system from damage. Usually the OVP point design value is 1.3 times the rated voltage of the switching power supply;

[0068] (3) Consider the saturation of the op amp: Usually, when the voltage comparator of the switching power supply reaches the saturation voltage, the op amp output reaches saturation, causing the optocoupler to also enter the saturation region, causing the loop to lose control and enter an open-loop state, making it impossible to achieve dynamic rapid adjustment.

[0069] Taking into account the above points (1), (2) and (3), the first threshold voltage requirement is: Ensure that the first threshold voltage does not exceed the safety threshold, thereby ensuring the dynamic characteristics of the switching power supply.

[0070] Specifically, the saturation voltage of the voltage comparator is 0.075 V, and the reference voltage of the voltage comparator is 1.25 V or 2.5 V. In practical applications, the voltage comparator can use TL431 for voltage judgment. The voltage comparator usually reaches operational amplifier saturation when the inverting terminal voltage is 0.075 V higher than the non-inverting terminal voltage, and the reference voltage of the voltage comparator is usually 1.25 V or 2.5 V.

[0071] Specifically, the second threshold voltage is 0.1V-0.3V lower than the first threshold voltage; or the second threshold voltage is 0.5%-2% lower than the first threshold voltage. There is a hysteresis between the second threshold voltage and the first threshold voltage, so that the output capacitor can release the voltage. The setting of the second threshold voltage avoids the load resistor from bearing pressure for too long and increasing power consumption, and prevents the load resistor from burning out.

[0072] Specifically, the first threshold voltage is 3%-5% higher than the rated output voltage of the switching power supply; the second threshold voltage is 2%-4% higher than the rated output voltage of the switching power supply. The first threshold voltage and the second threshold voltage are within the safety threshold, and can timely control the discharge of the output capacitor when switching from no-load to full-load or from full-load to no-load, so that the output voltage responds to dynamic changes, avoids saturation of the operational amplifier and the optical coupler, ensures that the output voltage does not exceed the safety threshold, and ensures the stability and safety of the system.

[0073] Embodiment 2

[0074] See also Figure 5-7 This embodiment discloses a system for improving the dynamic characteristics of a switching power supply, which is used to execute the method for improving the dynamic characteristics of a switching power supply of the first embodiment. Figure 7 The dynamic response diagram of the power supply circuit of this embodiment is shown in FIG. The system includes: a power supply circuit and a discharge circuit;

[0075] The power supply circuit includes: a rectifier module 6, a PWM modulation module 2, an optical coupler 3, a compensation module 4, a transformer 5 and an output capacitor 1; two ends of the output capacitor 1 are connected to two ends of the secondary side of the transformer 5; the compensation module 4, the optical coupler 3 and the PWM modulation module 2 are connected in sequence to form a negative feedback circuit, the input end of the compensation module 4 is connected to the output capacitor 1, the output end of the PWM modulation module 2 is connected to one end of the primary side of the transformer 5, and the rectifier module 6 is connected to the other end of the primary side of the transformer 5;

[0076] The discharge circuit includes: a voltage detection module, a voltage comparator, a load resistor and a switching unit; the voltage detection module and the load resistor are connected to the output capacitor 1, the two input ends of the voltage comparator are respectively connected to the voltage detection module and the reference voltage, and the load resistor is connected to the voltage comparator through the switching unit; the voltage comparator is used to control the on or off of the switching unit so that the load resistor is connected to or disconnected from the power supply circuit.

[0077] The system for improving the dynamic characteristics of the switching power supply of this embodiment detects the output voltage of the power supply circuit through the voltage detection module, and the voltage comparator determines the output voltage. When the output voltage reaches the first threshold voltage, the switching unit is turned on, so that the load resistor is connected to the output end of the power supply circuit to discharge the output capacitor 1. When the output voltage is about to reach the second threshold voltage or the output capacitor 1 is discharged to a preset time, the switching unit is turned off, and the output capacitor 1 ends discharging. The discharge circuit ensures that the operational amplifier and the optical coupler 3 are both in the linear region during the dynamic process, so that the switching power supply has normal dynamic adjustment capabilities, avoids the output voltage exceeding the safety threshold, and ensures the safety of the system; at the same time, it reduces the resource consumption caused by long-term discharge or repeated discharge, improves the energy efficiency of the system, and avoids damage to circuit components, maintaining the stable operation of the system.

[0078] Specifically, in the power supply circuit, the PWM modulation module 2 includes: a switch Q1, a PWM IC chip U1 and a capacitor C3; the PWMIC chip includes a terminal pin Vg, a terminal pin Vcc, a terminal pin GND and a terminal pin FB; the terminal pin Vg is connected to one end of the primary side of the transformer 5 through the switch Q1; one end of the capacitor C3 is connected to the terminal pin Vcc, and the other end is grounded; the terminal pin GND is grounded; and the terminal pin FB is connected to the optical coupler 3. The PWM IC chip controls the transmission of energy through the switch Q1 to achieve power and voltage regulation. When a loop abnormality is detected, the output signal can be automatically adjusted or the output can be turned off to protect the load and circuit from damage.

[0079] Specifically, the diode input end of the optocoupler 3 is connected to the output end of the power supply circuit, the diode output end of the optocoupler 3 is connected to the error voltage Verror, the collector of the optocoupler 3 of the optocoupler is connected to the terminal pin FB, and the emitter is grounded. The primary side of the optocoupler 3 is the diode side, and the secondary side is the transistor side.

[0080] Specifically, Figure 7 The figure is a schematic diagram of the dynamic response of the power supply circuit of this embodiment. Among them, Vo is the output voltage of the power supply circuit, Vfb is the voltage of the terminal pin FB of the PWM IC chip U1, that is, the secondary voltage of the optocoupler 3, and I out is the output current of the power supply circuit. When the output current Iout quickly switches from full load to no load, the corresponding Figure 7At the time point t1, due to the existence of the compensation module, the Verror signal cannot change suddenly, resulting in Vfb not responding quickly with the change of the output current I out. The energy provided by the primary side is still based on full load, but at this time Iout has been switched to zero, that is, no-load, so the output voltage Vo has an overshoot trend. When the output voltage Vo reaches the first threshold voltage, the discharge circuit drives the load resistor to connect to the output end of the power supply circuit to discharge the output capacitor 1, causing the output voltage Vo to drop. The change in the output voltage Vo affects the primary voltage of the optocoupler 3, and then drives the secondary voltage of the optocoupler 3 to change rapidly, that is, Vfb immediately responds to the change of the output current Iout, avoiding the optocoupler 3 from entering the saturation region, so that the optocoupler 3 is maintained in the linear region to ensure the normal dynamic adjustment function. When the output voltage Vo is about to reach the second threshold voltage, the output capacitor 1 stops discharging, and the power supply circuit can release the output voltage Vo normally through the compensation module. The setting of the first threshold voltage and the second threshold voltage also makes the fluctuation of the output voltage Vo more stable, ensuring the stability and safety of the system. Even in the dynamic change period of full load switching, if full load or heavy load is suddenly added, such as Figure 7 At time point t2, optocoupler 3 is still in the linear region and can timely sense the change of the primary voltage of optocoupler 3. It also has the ability to dynamically adjust and transfer enough energy to the secondary side in time to ensure the stability of the output voltage and avoid problems such as system downtime due to low voltage.

[0081] Embodiment 3

[0082] See also Figure 5 This embodiment discloses a system for improving the dynamic characteristics of a switching power supply. Based on the second embodiment, when the switching power supply is a single-input power supply or a PD power supply, the system of the third embodiment is used to execute the method of improving the dynamic characteristics of the switching power supply of the first embodiment.

[0083] Specifically, in the power supply circuit, the compensation module 4 includes: a resistor R11, a resistor R12, a resistor R13, a capacitor C14, a capacitor C15, and an operational amplifier U13; the resistor R11 and the resistor R12 are connected in series, the resistor R11 is connected to the output end of the power supply circuit, and the resistor R12 is grounded; the two input ends of the operational amplifier U13 are respectively connected to the middle node of the resistor R11 and the resistor R12 and the reference voltage Vref0, and the output end of the operational amplifier U13 is connected to the diode output end of the optocoupler 3; the resistor R13 is connected in series with the capacitor C15, and is connected in parallel with the capacitor C14, and the two ends of the capacitor C14 are respectively connected to the middle node of the resistor R11 and the resistor R12 and the diode output end of the optocoupler 3; the diode input end of the optocoupler 3 is connected to the output end of the power supply circuit through the resistor R14, and the diode output end of the optocoupler 3 is connected to the error voltage Verror; the collector of the transistor of the optocoupler 3 is connected to the terminal pin FB, and the emitter is grounded. The compensation module 4 detects the output voltage of the power supply circuit through the resistors R1 and R2, and realizes precise control and rapid response of the output voltage through the feedback mechanism of the operational amplifier U13 and the optocoupler 3, thereby ensuring the continuity and stability of the output voltage.

[0084] Specifically, in the discharge circuit, the voltage detection module includes a resistor R15 and a resistor R16, which are connected in series, the resistor R15 is connected to the output end of the power supply circuit, and the resistor R16 is grounded; the in-phase end of the voltage comparator U14 is connected to the intermediate node of the resistor R15 and the resistor R16, and is connected to the output end of the voltage comparator U14 through the resistor R14 to form a hysteresis comparator, which is used to set the hysteresis between the first threshold voltage and the second threshold voltage, wherein the hysteresis between the first threshold voltage and the second threshold voltage can be set to 0.1V-0.3V, and the inverting end of the voltage comparator U14 is connected to the reference voltage Vref1; the switching unit is a switch tube Q12, the first end of the switch tube Q12 is connected to the output end of the voltage comparator U14, the second end of the switch tube Q12 is connected to the load resistor R17, and the third end of the switch tube Q12 is grounded. In this embodiment, the discharge circuit is independent of the power supply circuit and is an external circuit of the power supply circuit. It has a separate voltage detection module, a voltage comparator and a load resistor R17, which improves the flexibility and modularity of the system, realizes accurate monitoring and protection of the discharge process, and ensures the safety and stability of the system operation.

[0085] Specifically, the switch tube Q12 is a MOSFET or an IGBT. When the switch tube Q12 is a MOSFET, the first terminal is the gate, the second terminal is the drain, and the third terminal is the source; if the switch tube Q12 is an IGBT, the first terminal is the base, the second terminal is the collector, and the third terminal is the emitter. In this embodiment, the switch tube Q12 is a MOSFET, which has high switching speed, low on-resistance and good current driving capability, which helps to improve the response speed of the loop, thereby improving the dynamic characteristics of the switching power supply.

[0086] Embodiment 4

[0087] See also Figure 6 This embodiment discloses a system for improving the dynamic characteristics of a switching power supply. Based on the second embodiment, when the switching power supply is a PD power supply, the system of the fourth embodiment can be used to execute the method for improving the dynamic characteristics of the switching power supply of the first embodiment.

[0088] Specifically, the discharge circuit also includes a power management chip, and the voltage comparator and the voltage detection module are integrated in the power management chip. The power management chip is a PD IC chip, and the PD IC chip has a discharge function inside. The system for improving the dynamic characteristics of the switching power supply of this embodiment controls the discharge of the output capacitor 1 through the PD IC chip.

[0089] Specifically, in the power supply circuit, the compensation module 4 includes: a resistor R23, a capacitor C24 and a capacitor C25; the resistor R23 and the capacitor C25 are connected in series, and in parallel with the capacitor C24, and the two ends of the capacitor C24 are respectively connected to the power management chip and the diode output end of the optocoupler 3; the diode input end of the optocoupler 3 is connected to the output end of the power supply circuit through the resistor R24, and the diode output end of the optocoupler 3 is connected to the error voltage; the collector of the transistor of the optocoupler 3 is connected to the terminal pin FB, and the emitter is grounded.

[0090] Specifically, the power management chip is provided with an operational amplifier U23, a port Vcomp and a port Verror; the output end of the operational amplifier U23 is connected to the port Verror, and the inverting input end of the operational amplifier U23 is connected to the port Vcomp; the two ends of the capacitor C4 are connected to the port Vcomp and the port Verror respectively. When the operational amplifier U23 reaches the saturation voltage, the port Verror is 0V, which will cause the current of the optical coupler 3 to be too large and enter the saturation region, causing the loop to lose control, so the first threshold voltage is set before the voltage comparator U24 reaches the saturation voltage to avoid the saturation of the optical coupler 3.

[0091] Specifically, the power management chip is also provided with a port DIS, a port Vo, and a port GND; the port DIS is connected to the output end of the power supply circuit through a load resistor R27, the port Vo is connected to the output end of the power supply circuit, and the port GND is grounded; the voltage detection module includes: a resistor R21 and a resistor R22; the resistor R21 and the resistor R22 are connected in series, the resistor R21 is connected to the port Vo, and the resistor R22 is connected to the port GND; the inverting end of the voltage comparator U24 is connected to the middle node of the resistor R21 and the resistor R22, and the inverting end of the voltage comparator U24 is connected to the reference voltage Vref2, and the reference voltage Vref2 can be set to the first threshold voltage or the second threshold voltage through the power management chip. The voltage comparator U24 is used to compare the output voltage of the power supply circuit and the reference voltage Vref2, and output the result to the port DIS. When the output voltage of the power supply circuit reaches the first threshold voltage, the port DIS is set to a low level, so that the load resistor R27 is connected to the output end of the power supply circuit; when the output voltage of the power supply circuit drops to the second threshold voltage or the output capacitor 1 is discharged to a preset time, the port DIS is set to a high level, so that the load resistor R27 is open.

[0092] A method and system for improving the dynamic characteristics of a switching power supply of the present invention accelerates the response speed of a dynamic process loop by discharging an output capacitor when the output voltage reaches a first threshold voltage, ensures that an operational amplifier and an optical coupler operate in a linear region during the dynamic process, and enables the switching power supply to have normal dynamic adjustment capability, thereby preventing the output voltage from exceeding a safety threshold and ensuring system safety; after the loop recovers its dynamic adjustment capability, the output capacitor stops discharging, thereby reducing resource consumption caused by long-term discharge or repeated discharge and improving the energy efficiency of the system.

[0093] The above examples are only used to further illustrate the technical content of the present invention, so that readers can understand it more easily, but they do not mean that the implementation of the present invention is limited to this. Any technical extension or re-creation made according to the present invention is protected by the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for improving the dynamic characteristics of a switching power supply, the switching power supply comprising a power supply circuit, the output end of the power supply circuit being provided with an output capacitor, characterized in that: The method comprises the following steps: configuring a discharge circuit to ensure that the discharge circuit is connected to the output end of the power supply circuit; detecting an output voltage of the power supply circuit; When the output voltage of the power supply circuit reaches a first threshold voltage, the discharge circuit and the power supply circuit are turned on to discharge the output capacitor; When the output voltage of the power supply circuit drops from the first threshold voltage to the second threshold voltage, or when the discharge of the output capacitor reaches a preset time, the discharge circuit is turned off, so that the output capacitor stops discharging.

2. The method for improving the dynamic characteristics of a switching power supply according to claim 1, characterized in that: The step of configuring the discharge circuit to ensure that the discharge circuit is connected to the output end of the power circuit includes: Configure voltage comparator, load resistor and switching unit; Ensure that the voltage comparator and the load resistor are connected to two ends of the output capacitor, and the load resistor is connected to the output end of the voltage comparator through the switching unit; The voltage comparator is used to determine whether the output voltage reaches a first threshold voltage or a second threshold voltage, and to control the switching unit to be turned on or off so that the load resistor is connected to or disconnected from the power supply circuit.

3. The method for improving the dynamic characteristics of a switching power supply according to claim 2, characterized in that: Before the step of detecting the output voltage of the power supply circuit, the step further includes: Setting the first threshold voltage and the second threshold voltage; The first threshold voltage and the second threshold voltage are higher than the rated output voltage of the switching power supply; and the first threshold voltage and the second threshold voltage are within the safety threshold of the switching power supply.

4. The method for improving the dynamic characteristics of a switching power supply according to claim 3, characterized in that: The first threshold voltage is Where V e is the rated output voltage of the switching power supply, V ref is the reference voltage of the voltage comparator, V od is the saturation voltage of the voltage comparator.

5. The method for improving the dynamic characteristics of a switching power supply according to claim 4, characterized in that: The saturation voltage V of the voltage comparator od is 0.075V, the reference voltage V of the voltage comparator ref 1.25V or 2.5V.

6. The method for improving the dynamic characteristics of a switching power supply according to claim 5, characterized in that: The second threshold voltage is 0.1V-0.3V lower than the first threshold voltage; or the second threshold voltage is 0.5%-2% lower than the first threshold voltage.

7. The method for improving the dynamic characteristics of a switching power supply according to claim 6, characterized in that: The first threshold voltage is 3%-5% higher than the rated output voltage of the switching power supply; the second threshold voltage is 2%-4% higher than the rated output voltage of the switching power supply.

8. A system for improving the dynamic characteristics of a switching power supply, used to execute the method according to any one of claims 1 to 7, characterized in that: The system comprises: A power supply circuit, the power supply circuit comprising: a rectifier module, a PWM modulation module, an optical coupler, a compensation module, a transformer and an output capacitor; the two ends of the output capacitor are connected to the two ends of the secondary side of the transformer; the compensation module, the optical coupler and the PWM modulation module are connected in sequence to form a negative feedback circuit, the input end of the compensation module is connected to the output capacitor, the output end of the PWM modulation module is connected to one end of the primary side of the transformer, and the rectifier module is connected to the other end of the primary side of the transformer; A discharge circuit, the discharge circuit comprising: a voltage detection module, a voltage comparator, a load resistor and a switching unit; the voltage detection module and the load resistor are connected to the output capacitor, the two input ends of the voltage comparator are respectively connected to the voltage detection module and the reference voltage, the load resistor is connected to the voltage comparator through the switching unit; the voltage comparator is used to control the on or off of the switching unit so that the load resistor is connected to or disconnected from the power supply circuit.

9. The system for improving the dynamic characteristics of a switching power supply according to claim 8, characterized in that: The voltage detection module includes a resistor R5 and a resistor R6, the resistor R5 and the resistor R6 are connected in series, the resistor R5 is connected to the output end of the power supply circuit, and the resistor R6 is grounded; One input terminal of the voltage comparator is connected to the middle node of the resistor R5 and the resistor R6, and is connected to the output terminal of the voltage comparator through the resistor R4, and the other input terminal of the voltage comparator is connected to the reference voltage; The switching unit is a switch tube Q2, a first end of the switch tube Q2 is connected to the output end of the voltage comparator, a second end of the switch tube Q2 is connected to the load resistor, and a third end of the switch tube Q2 is grounded.

10. The system for improving the dynamic characteristics of a switching power supply according to claim 8, characterized in that: The discharge circuit further includes a power management chip, and the voltage comparator and the voltage detection module are integrated in the power management chip; The power management chip is provided with a port DIS, a port Vo, and a port GND; the port DIS is connected to the output end of the power circuit through a load resistor, the port Vo is connected to the output end of the power circuit, and the port GND is grounded; The voltage detection module includes: a resistor R401 and a resistor R402; the resistor R401 and the resistor R402 are connected in series, the resistor R401 is connected to the port Vo, and the resistor R402 is connected to the port GND; Two input terminals of the voltage comparator are respectively connected to the middle node of the resistor R401 and the resistor R402 and a reference voltage.

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