Constant-power adaptive current-limiting protection circuit and constant-power adaptive current-limiting protection method

Abstract

The invention discloses a constant-power adaptive current-limiting protection circuit. The constant-power adaptive current-limiting protection circuit comprises a switching type power supply circuit, a detection circuit and a control circuit, the switching type power supply circuit is provided with at least one power switch assembly and an output end, the at least one power switch assembly is operated by a pulse width modulation signal, and the output end outputs a power signal. The detection circuit is coupled with the output end of the switching type power supply circuit so as to detect the output voltage and the output current of the power supply signal. The control circuit is coupled to the switching power supply circuit and the detection circuit. The control circuit is configured to output a pulse width modulation signal, calculate a current limiting threshold according to the protection power and the output voltage, and compare the output current with the current limiting threshold to selectively execute a protection action. The protection action is to adjust the pulse width modulation signal, so that the output power of the switching type power supply circuit is limited below the protection power.

Description

Technical Field

[0001] The present invention relates to an overcurrent protection technology, and more particularly to a constant power adaptive current limiting protection circuit and a constant power adaptive current limiting protection method. Background Art

[0002] DC power supplies are constantly pursuing high power and wide range output variations, and their power multiples have gradually increased from 1 times to more than 4 times. Therefore, under some test conditions, existing protections (such as overcurrent protection) will fail and cannot effectively protect the circuit. Currently, the overcurrent protection design sets the overcurrent protection setting value to a fixed value to protect power components from being damaged by overcurrent. However, such a design may not operate correctly at high power multiples. For example, if the DC power supply operates at low voltage and high current, the overcurrent protection mechanism can operate correctly. However, if the DC power supply operates under high voltage and low current conditions, since the current cannot reach the overcurrent protection setting value, the protection will not be triggered. But at this time, the overall power of the circuit has exceeded the wattage that the power component can withstand, which will cause damage to the power component. Summary of the Invention

[0003] In view of this, in some embodiments, the present invention provides a constant power adaptive current limiting protection circuit, including a switching power supply circuit, a detection circuit, and a control circuit. The switching power supply circuit has at least one power switch component and an output terminal. The at least one power switch component is operated by a pulse width modulation signal, and the output terminal outputs a power signal. The detection circuit is coupled to the output terminal of the switching power supply circuit to detect the output voltage and output current of the power signal. The control circuit is coupled to the switching power supply circuit and the detection circuit, and is configured to output a pulse width modulation signal, calculate a current limiting threshold according to the protection power and the output voltage, and compare the output current with the current limiting threshold to selectively perform a protection action. The protection action is to adjust the pulse width modulation signal so that the output power of the switching power supply circuit is limited below the protection power.

[0004] In some embodiments, when the output current is greater than or equal to the current limiting threshold, the control circuit adjusts the pulse width modulation signal to limit the output power below the protection power.

[0005] In some embodiments, before comparing the output current with the current limiting threshold, the control circuit first performs digital filtering processing on the current limiting threshold.

[0006] In some embodiments, the protection power is more than twice the maximum power of the switching power supply circuit.

[0007] In some embodiments, when the number of switching power supply circuits is multiple, the control circuit selectively performs protection actions on the corresponding switching power supply circuits according to the output current and current limit threshold of each switching power supply circuit.

[0008] In some embodiments, a constant power adaptive current limit protection method is provided, including: the control circuit receives the detection result of the detection circuit, and the detection result indicates the output voltage and output current of the switching power supply circuit. The control circuit obtains the current limit threshold according to the protection power and the output voltage. And the control circuit compares the output current with the current limit threshold to selectively perform protection actions. The protection action is to adjust the pulse width modulation signal so that the output power of the switching power supply circuit is limited below the protection power.

[0009] In summary, the constant power adaptive current limit protection circuit proposed according to some embodiments of the present invention can adaptively update the current limit threshold according to the actual output state, and determine whether to perform protection actions based on this. And when protection actions need to be performed, the output power of the power signal is limited below the protection power. In this way, the following advantages can be provided: First, during the execution of the protection action, the entire machine is not shut down, but the output current is limited below the current limit threshold, so the output power of the power signal will not exceed the protection power and normal operation is maintained; Second, the current limit threshold is calculated from the output voltage and the protection power, and this overcurrent protection mechanism can be applied to devices with various constant power ratios (including more than 4 times the constant power ratio), so it can be widely applied under different voltage or current conditions; Third, during the execution of the protection action, the output power will not exceed the protection power, so the overall instrument instantaneous power can be reduced, and the stress on the Safe Operating Area (SOA) of the components can also be reduced.

[0010] The following details the detailed features and advantages of the present invention in the embodiments, the content of which is sufficient for any person skilled in the relevant art to understand the technical content of the present invention and implement it accordingly. And according to the content disclosed in this specification, the scope of the patent application and the drawings, any person skilled in the relevant art can easily understand the relevant purposes and advantages of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Shown is a block diagram (one) of the constant power adaptive current limit protection circuit according to some embodiments of the present invention, showing the switching power supply circuit connected to an external power supply and a load.

[0012] Figure 2 Shown is a block diagram (two) of the constant power adaptive current limit protection circuit according to some embodiments of the present invention.

[0013] Figure 3In some embodiments of the present invention, it is the waveform diagram of the power supply signal before digital filtering of the current limiting threshold.

[0014] Figure 4 In some embodiments of the present invention, it is the waveform diagram of the power supply signal after digital filtering of the current limiting threshold.

[0015] Figure 5 In some embodiments of the present invention, when the external power supply is a three-phase power supply and the processing module performs a protection action, it is the waveform diagram of the three-phase synchronous output current.

[0016] Figure 6 In some embodiments of the present invention, when the external power supply is a three-phase power supply and the processing module performs a protection action, it is the waveform diagram of the three-phase asynchronous output current.

[0017] Figure 7 It is the power waveform of each phase of the three-phase power supply in a comparative example.

[0018] Figure 8 In some embodiments of the present invention, it is the flowchart (one) of the constant power adaptive current limiting protection method.

[0019] Figure 9 In some embodiments of the present invention, it is the flowchart (two) of the constant power adaptive current limiting protection method.

[0020] Among them, reference numerals:

[0021] 10: Constant power adaptive current limiting protection circuit

[0022] 102: Switching power supply circuit

[0023] 104: Detection circuit

[0024] 106: Control circuit

[0025] 108: Power switch component

[0026] 110: Output terminal

[0027] 112: Current sensing circuit

[0028] 114: Voltage sensing circuit

[0029] 116: Power element drive circuit

[0030] 118: Processor

[0031] 20: External power supply

[0032] 30: Load

[0033] CT: Current limiting threshold

[0034] IL1, IL2, IL3, IO: Output current

[0035] P1, P2, P3: Power supply

[0036] S1: Pulse width modulation signal

[0037] S2: Power supply signal

[0038] S80, S802, S804, S806, S808, S810, S90, S902, S904, S906, S908, S910: Steps

[0039] VO: Output voltage Detailed implementation manners

[0040] Please refer to Figure 1 and Figure 2 . Figure 1 Shown is a block diagram (I) of a constant - power adaptive current - limiting protection circuit, showing a switching power supply circuit connected to an external power supply and a load. Figure 2 Shown is a block diagram (II) of the constant - power adaptive current - limiting protection circuit in some embodiments of the present invention. As Figure 1 and Figure 2 shown, the constant - power adaptive current - limiting protection circuit 10 includes a switching power supply circuit 102, a detection circuit 104, and a control circuit 106. The switching power supply circuit 102 has at least one power switch component 108 and an output terminal 110. At least one power switch component 108 is operated by a pulse width modulation signal S1, and the output terminal 110 outputs a power supply signal S2. The detection circuit 104 is coupled to the output terminal 110 of the switching power supply circuit 102 to detect an output voltage (output voltage VO as shown in Figure 3 ) and an output current (output current IO as shown in Figure 3 ) of the power supply signal S2. The control circuit 106 is coupled to the switching power supply circuit 102 and the detection circuit 104. The control circuit 106 is configured to output the pulse width modulation signal S1. The control circuit 106 executes a constant - power adaptive current - limiting protection method to calculate a current - limiting threshold CT (current - limiting threshold CT as shown in Figure 3 ) based on a protection power and the output voltage VO, and compares the output current (output current IO as shown in Figure 3 ) with the current - limiting threshold CT to selectively execute a protection action.

[0041] As Figure 2As shown, the switching power supply circuit 102 can receive an external power supply 20 and output it to a load 30 after conversion processing. The switching power supply circuit 102 can include multiple stages of circuits, and each stage of circuit can be, but is not limited to, an AC-to-DC converter, a DC-to-AC converter, or a DC-to-DC converter. In this article, the DC-to-DC converter commonly used in the subsequent stage circuit will be used for illustration. The DC-to-DC converter can be, for example, a buck converter, a boost converter, or a buck-boost converter according to the application requirements of the system for voltage. Taking the buck converter as an example, it includes a power switch component 108, an inductor, and a capacitor. Here, the aforementioned output current IO is the inductor current, and the output voltage VO is the capacitor voltage. The power switch component 108 can be implemented by a power semiconductor switch, such as a metal oxide semiconductor field effect transistor or an insulated gate bipolar transistor (IGBT), etc. The aforementioned "the power switch component 108 is operated by the pulse width modulation signal S1, and the power signal S2 is output from the output terminal 110" means that the power switch component 108 is controlled by the pulse width modulation signal S1 to adjust its duty ratio, so that the power signal S2 corresponding to this duty ratio is output from the output terminal 110. In some embodiments, the external power supply 20 can be a single-phase power supply or a three-phase power supply (to be described later).

[0042] For another example Figure 2 As shown, in some embodiments, the detection circuit 104 includes a current sensing circuit 112 and a voltage sensing circuit 114. The current sensing circuit 112 and the voltage sensing circuit 114 respectively sense the voltage value and current value of the power signal S2 and immediately feedback them to the control circuit 106.

[0043] After receiving the voltage value and current value of the power signal S2, the control circuit 106 calculates the current limit threshold CT based on the protection power and the output voltage VO. Among them, the current value can be calculated by dividing the protection power by the output voltage VO, and the control circuit 106 can use this current value as the current limit threshold CT. In addition, the control circuit 106 can immediately calculate a new current limit threshold CT as the output voltage VO in the power signal S2 changes, and determine whether to perform a protection action on the switching power supply circuit 102. It should be noted that the protection power can be determined according to a maximum power of the switching power supply circuit 102. Among them, the maximum power refers to the rated power of the switching power supply circuit 102. In some embodiments, the protection power can be more than twice the maximum power of the switching power supply circuit 102 (to be described later). For example, when the maximum power is 6KW, the protection power can be set to 14KW.

[0044] After the control circuit 106 obtains the current limit threshold CT, the control circuit 106 compares the output current IO with the current limit threshold CT. Among them, the aforementioned protection action is to adjust the pulse width modulation signal S1. For example, when the output current IO is greater than or equal to the current limit threshold CT, the control circuit 106 adjusts the pulse width modulation signal S1. On the contrary, when the output current IO is less than the current limit threshold CT, the control circuit 106 does not adjust the pulse width modulation signal S1. According to the adjusted pulse width modulation signal S1, the duty cycle of the power switch component 108 changes accordingly, so that an output power of the switching power supply circuit 102 (that is, the product of the output voltage VO and the output current IO) is reduced and limited below the protection power. Thereby, under the action of the control circuit 106 performing the protection action, the external power supply 20 or the load 30 connected to the switching power supply circuit 102 can maintain normal operation, rather than forcing the entire machine to shut down, resulting in an interruption of operation.

[0045] As Figure 2 shown, in some embodiments, the control circuit 106 includes a power element drive circuit 116 and a processor 118. The power element drive circuit 116 can be a gate drive circuit that receives a low-power signal generated by the processor 118 and drives the gate of the power semiconductor switch accordingly to turn on or off the power semiconductor switch. The processor 118 is configured to receive the power supply signal S2 and the protection power to calculate the current limit threshold CT, and compare the currently detected output current IO with the current limit threshold CT to determine whether the condition for triggering the protection action is reached. The control circuit 106 can be, for example, a microprocessor, a microcontroller, a digital signal processor (DSP), a central processing unit (CPU), a programmable logic controller (PLC), an application specific integrated circuit (ASIC), or a field programmable gate array (FPGA), etc.

[0046] Please refer to Figure 3 。 Figure 3 This is a waveform diagram of the power supply signal before digital filtering of the current limit threshold in some embodiments of the present invention. As Figure 3As shown, the processor 118 of the control circuit 106 repetitively executes the constant-power adaptive current-limiting protection method at a refresh interval (e.g., 1 microsecond). Therefore, the shortest update time of the current-limiting threshold CT is one refresh interval, and this refresh interval depends on the operating clock of the processor 118. Figure 3 The waveform relationships of the output voltage VO, output current IO, and current-limiting threshold CT of the switched-mode power supply circuit 102 are presented therein. Herein, the horizontal axis is the data point ordinal number and is not normalized to a time unit. At each refresh time point, the processor 118 calculates the current-limiting threshold CT based on the currently obtained output voltage VO. Before approximately the 150th data point, the output voltage VO is 433V, and the current-limiting threshold CT calculated by the processor 118 is 10.85A. At the 170th data point, the output voltage VO changes to 375.6V, and the current-limiting threshold CT calculated by the processor 118 is 12.47A. Compared with the previous refresh time point, the change amount difference of the current-limiting threshold CT is 1.62A. After another 1 microsecond, at the 237th data point, the output voltage VO drops to 158.8V, and the current-limiting threshold CT calculated by the processor 118 is 24A. Compared with the previous refresh time point, the change amount difference of the current-limiting threshold CT is 11.53A. At this time, the output current IO surges due to the instantaneous increase in the current-limiting threshold CT, resulting in the generation of a large amount of energy, and the pre-stage circuit of the switched-mode power supply circuit 102 may thus quickly execute protection.

[0047] Please refer to Figure 4 。 Figure 4 In some embodiments of the present invention, it is a waveform diagram of the power supply signal after digital filtering of the current-limiting threshold. To avoid drastic changes in the current-limiting threshold CT, in some embodiments, the control circuit 106 first performs digital filtering on the current-limiting threshold CT before comparing the output current IO and the current-limiting threshold CT. It should be noted that the processor 118 of the control circuit 106 executes digital filtering. The program for digital filtering can be pre-stored in the processor 118. As Figure 4 shown, the current-limiting threshold CT after digital filtering processing changes slowly and does not have a huge change as Figure 3 shown. When the processor 118 performs the comparison, the comparison is made based on the current-limiting threshold CT after digital filtering processing, so that the output current IO does not exceed 20A, and thus the pre-stage circuit does not trigger fast protection.

[0048] In some embodiments, when there are multiple switching power supply circuits 102, the control circuit 106 selectively performs protection actions on the corresponding switching power supply circuits 102 according to the output current IO of each switching power supply circuit 102 and the current limit threshold CT. Specifically, when the switching power supply circuit 102 adopts an interleaved design, the advantage is that the output ripple can be reduced by canceling the output current IO (inductor current). In this embodiment, the detection circuit 104 senses a corresponding phase voltage and a phase current (the phase voltage is the output voltage VO of each phase power supply, and the phase current is the output current IO of each phase power supply) for each phase of the switching power supply circuit 102 and transmits them to the processor 118 of the control circuit 106, so that the processor 118 can calculate the current limit threshold CT of each phase power supply based on the phase voltage and the protection power. The processor 118 then compares the current limit threshold CT of the same phase power supply with the phase current, and starts protection actions for each phase power supply respectively according to the comparison result.

[0049] Please also refer to Figure 2 , Figure 5 and Figure 6 . Figure 5 This is the output current waveform diagram of three-phase synchronization in some embodiments of the present invention when the external power supply is a three-phase power supply and the control circuit 106 performs protection actions. Figure 6 This is the output current waveform diagram of three-phase non-synchronization in some embodiments of the present invention when the external power supply is a three-phase power supply and the processing module performs protection actions. As Figure 5 shown, the three-phase power supply adopts synchronous current limit protection, and the three-phase power supplies are all compared with a single current limit threshold CT. When the output current of any one phase (IL1, IL2 or IL3) is greater than or equal to the current limit threshold CT, the control circuit 106 will perform protection actions on the three-phase power supplies at the same time. In this way, it may cause the output currents (IL1, IL2, IL3) of the three-phase power supplies to be out of synchronization (as shown in Figure 5 ), resulting in protection failure. In contrast, as shown in Figure 6 , the three-phase power supply adopts non-synchronous current limit protection, and the three-phase power supplies are all compared with the current limit threshold CT corresponding to the phase power supply respectively. When the output current of any one phase (IL1, IL2, IL3) is greater than or equal to the current limit threshold CT, the control circuit 106 will only perform protection actions on the phase power supply that meets the trigger condition (without starting protection for the other phase power supplies), thereby avoiding interference between the phase power supplies and ensuring the consistency of the three-phase output currents (IL1, IL2, IL3).

[0050] Please refer to Figure 7 , Figure 7It is the power waveform of each phase power supply of a three-phase power supply in a comparative example. Here, a comparative example is used to illustrate why the aforementioned protection power is set to more than twice the maximum power of the switching power supply circuit 102. In this comparative example, the protection power is set to less than twice the maximum power of the switching power supply circuit 102. The total power of the three-phase power supply is 18 kW (kilowatts), and the maximum power of each phase power supply is 6 kW. If the protection power is set to 10 kW (less than twice the maximum power), and the three-phase power supply operates in the fixed voltage mode, when the load is pulled from 0 A to 10 A, the fixed voltage will drop to 1558 V and cannot be stabilized at 1600 V. From Figure 7 From the power information of each phase power supply during the protection action, it can be known that the peak power measured by the first-phase power supply P1 and the third-phase power supply P3 reaches the protection power of 10 kW instantaneously, because the control circuit 106 compares the individual limited current thresholds CT of the three-phase power supplies (P1, P2, P3) respectively to perform the protection action. Therefore, the protection time of each phase power supply (P1, P2, P3) is different, and at this time, the energy of the three-phase power supplies (P1, P2, P3) will interact and transfer. In contrast, if the protection power of each phase power supply is set to 12 kW (twice the maximum power of 6 W), then each phase power supply (P1, P2, P3) will be stabilized at 1600 V. Specifically, the limited current threshold CT must consider the influence of instantaneous load pulling and measurement noise. It can be understood that although a three-phase power supply is used for illustration here, a single-phase power supply is still applicable due to similar considerations.

[0051] Please also refer to Figure 1 、 Figure 2 and Figure 8 。 Figure 8 This is the flowchart (one) of the constant power adaptive limited current protection method in some embodiments of the present invention. In some embodiments, the constant power adaptive limited current protection method S80 includes: the control circuit 106 receives the detection result of the detection circuit 104, and the detection result indicates the output voltage VO and output current IO of the switching power supply circuit 102 (step S802); the control circuit 106 obtains the limited current threshold CT according to the protection power and the output voltage VO (step S804); and the control circuit 106 compares the output current IO with the limited current threshold CT to selectively perform the protection action (step S806). It should be noted that the constant power adaptive limited current protection method S80 can be applied to existing devices with a switching power supply circuit 102. After the detection circuit 104 and the control circuit 106 are coupled to the switching power supply circuit 102, the control circuit 106 can execute the constant power adaptive limited current protection method S80.

[0052] In some embodiments, before step S806 is executed, it further includes: the control circuit 106 performs digital filtering on the current limit threshold CT (step S808). Thereby, after the current limit threshold CT undergoes program digital filtering, the change amount of the current limit threshold CT can change slowly, and it is avoided that the switched-mode power supply circuit 102 will not trigger pre-stage protection due to the excessive change between the previous current limit threshold and the current current limit threshold CT, resulting in a sudden rapid increase in the output current IO.

[0053] In some embodiments, step S806 may include: the control circuit 106 determines that the output current IO is greater than or equal to the current limit threshold CT to adjust the pulse width modulation signal S1 (step S810). Wherein, when the output current IO is greater than or equal to the current limit threshold CT, the control circuit 106 can adjust the pulse width modulation signal S1 to limit the output power of the switched-mode power supply circuit 102 below the protection power.

[0054] Please refer to Figure 1 、 Figure 2 and Figure 9 . Figure 9 This is the flowchart (two) of the constant power adaptive current limit protection method in some embodiments of the present invention. As Figure 1 、 Figure 2 and Figure 9 shown, in some embodiments, the constant power adaptive current limit protection method S90 includes: the control circuit 106 receives the detection results of each phase detection circuit 104, and each phase detection result indicates the output voltage VO and output current IO of the corresponding phase switched-mode power supply circuit 102 (step S902); the control circuit 106 respectively obtains the current limit threshold of each phase according to the protection power and the output voltage VO of each phase switched-mode power supply circuit 102 (step S904); and the control circuit 106 selectively performs protection actions on the corresponding phase switched-mode power supply circuits 102 according to the output current IO and the current limit threshold CT of each phase switched-mode power supply circuit 102 (step S906). In this embodiment, if the switched-mode power supply circuit 102 adopts an interleaved design, the control circuit 106 can calculate the current limit threshold of each phase power supply according to each phase voltage and the protection power respectively. The control circuit 106 can then compare the current limit threshold CT and the phase current of the same phase power supply, and start protection actions for each phase power supply according to the comparison results.

[0055] In some embodiments, before step S906 is executed, it further includes: the control circuit 106 performs digital filtering on each phase current threshold CT (step S908). Thereby, after the digital filtering of the program for each phase current threshold CT, the change amount of each phase current threshold CT can change slowly, and it is avoided that the switching power supply circuit 102 will not cause the output current IO of each phase to suddenly increase rapidly due to the excessive change between the previous current threshold CT and the current current threshold CT, resulting in the triggering of the front-stage protection.

[0056] In some embodiments, step S906 may include: the control circuit 106 determines that any one of the output currents IO is greater than or equal to the current threshold CT to adjust the pulse width modulation signal S1 corresponding to the phase power supply (step S910). Among them, when any one of the output currents IO is greater than or equal to the current threshold CT, the control circuit 106 can adjust the pulse width modulation signal S1 corresponding to the phase power supply to limit the output power of the switching power supply circuit 102 corresponding to the phase power supply below the protection power.

[0057] In summary, according to the constant-power adaptive current-limiting protection circuit 10 proposed in some embodiments of the present invention, the current threshold CT can be adaptively updated according to the actual output state, and based on this, it is determined whether to execute the protection action. And when the protection action needs to be executed, the output power of the power signal S2 is limited below the protection power. In this way, the following advantages can be provided: First, during the execution of the protection action, the entire machine is not shut down, but the output current IO is limited below the current threshold CT, so the output power of the power signal S2 will not exceed the protection power and normal operation is maintained; Second, the current threshold CT is calculated from the output voltage VO and the protection power, and this overcurrent protection mechanism can be applied to devices with various power multiples (including more than 4 times the power multiple), so it can be widely applied under different voltage or current conditions; Third, during the execution of the protection action, the output power will not exceed the protection power, so the overall instantaneous power of the instrument can be reduced, and the stress on the safe operating area of the components can also be reduced.

[0058] Although the technical content of the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in this art, without departing from the spirit of the present invention, makes some modifications and refinements, and all should be covered within the scope of the present invention. Therefore, the protection scope of the present invention should be determined by the scope of the appended patent application.

Claims

1. A constant-power adaptive current-limiting protection circuit, characterized in that Comprising: A switching power supply circuit having at least one power switch component and an output terminal, the at least one power switch component being operated by a pulse width modulation signal, and the output terminal outputting a power signal; A detection circuit coupled to the output terminal of the switching power supply circuit to detect an output voltage and an output current of the power signal; And A control circuit coupled to the switching power supply circuit and the detection circuit, configured to output the pulse width modulation signal, calculate a current limit threshold based on a protection power and the output voltage, and compare the output current with the current limit threshold to selectively perform a protection action, wherein the protection action is to adjust the pulse width modulation signal such that an output power of the switching power supply circuit is limited below the protection power.

2. The constant-power adaptability current-limiting protection circuit according to claim 1, wherein Wherein, When the output current is greater than or equal to the current limit threshold, the control circuit adjusts the pulse width modulation signal to limit the output power below the protection power.

3. The constant-power adaptability current-limiting protection circuit according to claim 1, characterized in that, Wherein, Before comparing the output current with the current limit threshold, the control circuit performs digital filtering on the current limit threshold.

4. The constant-power adaptability current-limiting protection circuit according to claim 1, characterized in that, Wherein, The protection power is more than twice the maximum power of the switching power supply circuit.

5. The constant-power adaptability current-limiting protection circuit according to claim 1, wherein Wherein, When the number of the switching power supply circuits is multiple, the control circuit selectively performs the protection action on each corresponding switching power supply circuit according to the output current and the current limit threshold of each switching power supply circuit.

6. A constant power adaptability limited current protection method, characterized in that, Comprising: A control circuit receives a detection result of a detection circuit, and the detection result indicates an output voltage and an output current of a switching power supply circuit; The control circuit obtains a current limit threshold based on a protection power and the output voltage; And The control circuit compares the output current with the current limit threshold to selectively perform a protection action; Wherein the protection action is to adjust a pulse width modulation signal such that an output power of the switching power supply circuit is limited below the protection power.

7. The constant-power adaptability current-limiting protection method according to claim 6, characterized in that Wherein, When the output current is greater than or equal to the current limit threshold, the control circuit adjusts the pulse width modulation signal to limit the output power below the protection power.

8. The constant power adaptability current limiting protection method according to claim 6, characterized in that Wherein, Before the step of comparing the output current with the current limit threshold by the control circuit to selectively perform the protection action, it further includes: the control circuit performs digital filtering on the current limit threshold.

9. The constant-power adaptability current-limiting protection method according to claim 6, characterized in that, Wherein, The protection power is more than twice the maximum power of the switching power supply circuit.

10. The constant-power adaptability current-limiting protection method according to claim 6, characterized in that Wherein, When the number of the switching power supply circuits is multiple, the control circuit selectively performs the protection action on each corresponding switching power supply circuit according to the output current and the current limit threshold of each switching power supply circuit.

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