Switching power supply with active dummy load and dummy load control method thereof

Abstract

The invention relates to the technical field of switching power supplies, in particular to a switching power supply with an active dummy load and a dummy load control method thereof.The input end of a boosting module is electrically connected with the output end of a dimming output module, and the output end of the boosting module is electrically connected with the positive electrode of an output capacitor of a PFC module through a linear voltage stabilization module; the controller is electrically connected with the input end of the boosting module through the input detection module to obtain input voltage; the controller is electrically connected with the output end of the boosting module through the output detection module to obtain output voltage; the boosting module is provided with an active switch and is electrically connected and controlled by the controller and the active switch; consumption current is preset in the controller, and the controller calculates turn-on time and turn-off time of the active switch to form a PWM (Pulse Width Modulation) signal to control the active switch to work; the problem that a resistance-type dummy load cannot constantly consume a preset current value under the condition that the output voltage changes, and finally lower dimming cannot be achieved is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies, in particular to a switching power supply with an active dummy load and a dummy load control method thereof. Background Art

[0002] Traditional switching power supplies typically cannot be dimmed down to, for example, 10mA. Therefore, a dummy load is required at the output to consume additional output current to achieve a lower dimming range. Traditional switching power supplies typically use a resistor as a dummy load to passively consume output power. However, since the output voltage is limited to a certain range, the energy consumed by the resistor varies at the maximum output voltage (Vmax) and the minimum output voltage (Vmin). If the difference between Vmax and Vmin is significant (i.e., in applications with a wide output voltage range), the current consumption also varies significantly, making it impossible to maintain a constant current consumption value despite changes in the output voltage, ultimately preventing the achievement of lower dimming. Summary of the Invention

[0003] In response to the above-mentioned drawbacks, the present invention aims to provide a switching power supply with an active dummy load and a dummy load control method thereof, so as to solve the problem that a resistive dummy load cannot consume a constant preset current value when the output voltage changes, and ultimately cannot achieve a lower dimming.

[0004] To achieve this object, the present invention adopts the following technical solutions: A switching power supply with an active dummy load, comprising a PFC module, a dimming output module, and a controller; further comprising a boost module, a linear voltage regulator module, an input detection module, and an output detection module; the input end of the boost module is electrically connected to the output end of the dimming output module, and the output end of the boost module is electrically connected to the positive electrode of the output capacitor of the PFC module via the linear voltage regulator module; The controller is electrically connected to the input end of the boost module via the input detection module to obtain the input voltage The controller is electrically connected to the output terminal of the boost module via the output detection module to obtain the output voltage ; The boost module is provided with an active switch, which is electrically connected to the active switch by the controller; the controller is preset with a consumption current , the controller consumes current by , the input voltage and the output voltage Calculate the on-time of the active switch and off time , by the on-time and the off time The PWM signal is composed to control the operation of the active switch.

[0005] Furthermore, the boost module includes a capacitor CE10, a diode D22, an inductor L12, and a capacitor C50; the capacitor C50 serves as the input end of the boost module, the cathode of the diode D22 serves as the output end of the boost module, and one end and the other end of the capacitor C50 are electrically connected to the positive output terminal and the negative output terminal of the dimming output module, respectively; The positive electrode of the capacitor CE10 is electrically connected to the cathode of the diode D22, the anode of the diode D22 is electrically connected to one end of the inductor L12, the other end of the inductor L12 is electrically connected to one end of the capacitor C50, and the other end of the capacitor C50 is electrically connected to the negative electrode of the capacitor CE10; The active switch is coupled between one end of the inductor L12 and the other end of the capacitor C50 .

[0006] Furthermore, the linear voltage regulator module includes a passive switch and a self-driving module; the output end of the boost module is electrically connected to the PFC module via the passive switch, and the self-driving module is coupled between the output end of the boost module and the passive switch; When the active switch is turned off by the controller, the boost module operates to increase the voltage output to the self-driving module, and the self-driving module drives the passive switch to turn on.

[0007] Furthermore, the self-driving module includes a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128 and a comparator U12; one end of the resistor R124 is electrically connected to the output end of the boost module; the other end of the resistor R124 is connected in series with the resistor R125 and the resistor R126, and then connected to the GND ground end; the common point of the resistor R125 and the resistor R126 is electrically connected to the positive input end of the comparator U12; The power supply voltage passes through the resistor R127 and the resistor R128 and is connected to the GND ground terminal; the common point of the resistor R127 and the resistor R128 is electrically connected to the negative input terminal of the comparator U12, and the output terminal of the comparator U12 is electrically connected to the passive switch.

[0008] Furthermore, the passive switch includes a resistor R120, a resistor R121, a resistor R123, a diode D23, a transistor Q18, and a transistor Q17; the anode of the diode D23 is electrically connected to the output end of the boost module, and the cathode of the diode D23 is electrically connected to the emitter of the transistor Q18; The base of the transistor Q18 is connected in series with the resistor R120 and the resistor R121, and then electrically connected to the collector of the transistor Q17; the emitter of the transistor Q17 is connected to the GND ground terminal; the base of the transistor Q17 is connected in series with the resistor R123, and then electrically connected to the self-driving module; The collector of the transistor Q18 is electrically connected to the positive electrode of the output capacitor of the PFC module.

[0009] Furthermore, the active switch includes a MOS transistor Q16, a resistor R129, and a resistor R130; the drain of the MOS transistor Q16 is electrically connected to one end of the inductor L12, and the source of the MOS transistor Q16 is electrically connected to the other end of the capacitor C50; The gate of the MOS transistor Q16 is connected in series with the resistor R129 and then electrically connected to the controller; the resistor R130 is connected in parallel between the gate and source of the MOS transistor Q16.

[0010] Furthermore, the circuit structures of the input detection module and the output detection module are the same; The input detection module includes a resistor R132, a resistor R133 and a resistor R134; one end of the resistor R132 is electrically connected to the input end of the boost module; the other end of the resistor R132 is connected in series with the resistor R133 and the resistor R134 in sequence, and then connected to the GND ground end; the common point of the resistor R133 and the resistor R134 is electrically connected to the controller.

[0011] A control method for an active dummy load is applied to the above-mentioned switching power supply with an active dummy load and is loaded on the controller; the method comprises the following steps: A1: Calculate the preset inductance for charging the inductor L12: ; in, is the preset minimum frequency; A2: Calculate the real-time operating frequency of the boost module: ; A3: If , then execute step A4; if , then execute step A5; in other cases, the controller controls the active switch to remain off; wherein, is the preset maximum frequency; A4: The on-time ; The off time ; A5: The on-time ; The off time .

[0012] The technical solution provided by the present invention can include the following beneficial effects: a dummy load feedback path is constructed between the output end of the dimming output module and the positive electrode of the output capacitor of the PFC module by utilizing a boost module and a linear voltage regulator module, so that the voltage obtained from the output end of the dimming output module is boosted to a voltage matching the PFC module, thereby compensating for the output voltage of the PFC module (generally, there will be some loss when the PFC module outputs to the dimming output module, which is just compensated by this), thereby consuming the output current of the dimming output module and achieving a lower dimming range.

[0013] On this basis, in order to adapt to the change of the output voltage of the dimming output module (such as Vmin to Vmax), the input detection module and the output detection module are set to detect the input voltage of the boost module 3 and the output voltage , it can be seen that the boost module wants to consume (For example, when the output current is originally set to the lowest setting, it is 10mA. Now the output current is set to 5mA. The preset current consumption is =5mA, so the boost module is actively turned on to compensate for the PFC module consuming 5mA). The boost module needs to work at what PWM signal, that is, calculate the on-time. and off time It should be noted that due to the input voltage and the output voltage It changes with the output voltage of the dimming output module, so the preset consumption current can be guaranteed by detection. . BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The diagram is a circuit diagram of a switching power supply with an active dummy load according to one embodiment of the present invention.

[0015] Figure 2 This is a flow chart of a method for controlling an active dummy load according to one embodiment of the present invention.

[0016] Among them: PFC module 1, dimming output module 2, boost module 3, linear voltage regulator module 4, input detection module 5, output detection module 6, active switch 31, capacitor CE10, diode D22, inductor L12, capacitor C50, passive switch 41, self-driving module 42, resistor R124, resistor R125, resistor R126, resistor R127, resistor R128, comparator U12, resistor R120, resistor R121, resistor R123, diode D23, transistor Q18, transistor Q17, MOS transistor Q16, resistor R129, resistor R130, resistor R132, resistor R133, resistor R134. DETAILED DESCRIPTION

[0017] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0018] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise specifically specified.

[0019] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediate medium; they may refer to internal communication between two components or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0020] The following combination Figures 1 to 2 , describing a switching power supply with an active dummy load and a dummy load control method thereof according to an embodiment of the present invention.

[0021] Example 1 A switching power supply with an active dummy load includes a PFC module 1, a dimming output module 2, and a controller; a boost module 3, a linear voltage regulator module 4, an input detection module 5, and an output detection module 6; the input end of the boost module 3 is electrically connected to the output end of the dimming output module 2, and the output end of the boost module 3 is electrically connected to the positive electrode of the output capacitor of the PFC module 1 via the linear voltage regulator module 4; The controller is electrically connected to the input end of the boost module 3 via the input detection module 5 to obtain the input voltage The controller is electrically connected to the output terminal of the boost module 3 via the output detection module 6 to obtain the output voltage ; The boost module 3 is provided with an active switch 31, which is electrically connected to the active switch 31 by a controller; the controller is preset with a consumption current , the controller consumes current , input voltage and output voltage Calculate the on-time of the active switch 31 and off time , by the on-time and off time Composed of PWM signal (ie Figure 1 PWM_DUMMY in the control circuit 31 controls the operation of the active switch 31.

[0022] The present invention proposes a preferred embodiment of a switching power supply with an active dummy load, such as Figure 1 As shown, a dummy load feedback path is constructed between the output end of the dimming output module 2 (e.g., BUCK dimming) and the positive electrode of the output capacitor of the PFC module 1 by using the boost module 3 and the linear voltage regulator module 4. The voltage obtained from the output end of the dimming output module 2 is boosted to match the voltage of the PFC module 1, thereby compensating for the output voltage of the PFC module 1 (generally, there will be some loss when the PFC module 1 outputs to the dimming output module 2, which is just compensated by this), thereby consuming the output current of the dimming output module 2 and achieving a smaller dimming range.

[0023] On this basis, in order to adapt to the change of the output voltage of the dimming output module 2 (such as Vmin to Vmax), the input detection module 5 and the output detection module 6 are set to detect the input voltage of the boost module 3 and the output voltage , it can be seen that the boost module 3 wants to consume (For example, when the output current is originally set to the lowest setting, it is 10mA. Now the output current is set to 5mA. The preset current consumption is The current consumed by the boost module 3 is 5mA, so the boost module 3 is turned on to compensate the PFC module 1 for consuming 5mA. , set according to actual conditions), what PWM signal does the boost module 3 need to work on, that is, calculate the on-time and off time It should be noted that due to the input voltage and the output voltage It changes with the output voltage of the dimming output module 2, so the preset consumption current can be guaranteed by detection. .

[0024] It should be noted that if Figure 1 The circuit structure of the dimming output module 2 shown is for illustration only, where the HV terminal represents the output voltage of the PFC module 1, FB1 represents the feedback terminal of the PWM2 dimming output module 2, and thus the external load dimming is achieved through the LED+ and LED- terminals; the PWM2 terminal represents the controller for preventing ghost lights.

[0025] Furthermore, the boost module 3 includes a capacitor CE10, a diode D22, an inductor L12, and a capacitor C50; the capacitor C50 serves as the input end of the boost module 3, the cathode of the diode D22 serves as the output end of the boost module 3, and one end and the other end of the capacitor C50 are electrically connected to the positive output terminal and the negative output terminal of the dimming output module 2, respectively; The positive electrode of capacitor CE10 is electrically connected to the cathode of diode D22, the anode of diode D22 is electrically connected to one end of inductor L12, the other end of inductor L12 is electrically connected to one end of capacitor C50, and the other end of capacitor C50 is electrically connected to the negative electrode of capacitor CE10; The active switch 31 is coupled between one end of the inductor L12 and the other end of the capacitor C50 .

[0026] In this embodiment, the boosting principle of the boost module 3 is: when the active switch 31 is turned on, the output end of the dimming output module 2 charges the inductor L12 (that is, consumes the consumption current ),at this time , after the conduction time After that, the consumption current is consumed , the active switch 31 is turned off; when the active switch 31 is turned off, the voltage of the capacitor C50 (ie ) and inductor L12 are connected in series to charge capacitor CE10, then (in The voltage of capacitor CE10 at this time is, This is the voltage of the inductor L12 at this time), thereby achieving voltage boost.

[0027] Furthermore, the linear voltage regulator module 4 includes a passive switch 41 and a self-driving module 42; the output end of the boost module 3 is electrically connected to the PFC module 1 via the passive switch 41, and the self-driving module 42 is coupled between the output end of the boost module 3 and the passive switch 41; When the active switch 31 is turned off by the controller, the boost module 3 works to increase the voltage output to the self-driving module 42 , and the self-driving module 42 drives the passive switch 41 to turn on.

[0028] In this embodiment, the principle of the linear voltage regulator module 4 is mainly to use the self-driving module 42 to sense that the charging of the capacitor C10 is completed (that is, the voltage increases), and then passively turn on the passive switch 41 to establish a compensation channel between the PFC module 1 and the dimming output module 2, thereby realizing linear voltage regulation compensation to the PFC module 1.

[0029] Furthermore, the self-driving module 42 includes a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128, and a comparator U12; one end of the resistor R124 is electrically connected to the output end of the boost module 3; the other end of the resistor R124 is connected in series with the resistor R125 and the resistor R126, and then connected to the GND ground end; the common point of the resistor R125 and the resistor R126 is electrically connected to the positive input end of the comparator U12; Supply voltage (e.g. Figure 1 The 3.3V in the voltage is connected to the GND ground terminal after passing through the resistor R127 and the resistor R128; the common point of the resistor R127 and the resistor R128 is electrically connected to the negative input terminal of the comparator U12, and the output terminal of the comparator U12 is electrically connected to the passive switch 41.

[0030] In this embodiment, the sensing function of the self-driving module 42 is mainly realized by the comparator U12. When the voltage of the voltage-dividing capacitor CE10 exceeds the reference voltage preset by the comparator U12 (such as Figure 1 When the voltage at the middle point Vref is greater than the voltage at the middle point Vref, the passive switch 41 is driven to be turned on.

[0031] Furthermore, the passive switch 41 includes a resistor R120, a resistor R121, a resistor R123, a diode D23, a transistor Q18, and a transistor Q17; the anode of the diode D23 is electrically connected to the output end of the boost module 3, and the cathode of the diode D23 is electrically connected to the emitter of the transistor Q18; The base of the transistor Q18 is connected in series with the resistors R120 and R121, and then electrically connected to the collector of the transistor Q17; the emitter of the transistor Q17 is connected to the GND ground terminal; the base of the transistor Q17 is connected in series with the resistor R123, and then electrically connected to the self-driving module 42; The collector of the transistor Q18 is electrically connected to the positive electrode of the output capacitor of the PFC module 1 .

[0032] In this embodiment, the passive switch 41 is preferably composed of a dual triode, which can accelerate switching.

[0033] Furthermore, the active switch 31 includes a MOS transistor Q16, a resistor R129, and a resistor R130; the drain of the MOS transistor Q16 is electrically connected to one end of the inductor L12, and the source of the MOS transistor Q16 is electrically connected to the other end of the capacitor C50; The gate of the MOS transistor Q16 is connected in series with a resistor R129 and then electrically connected to the controller; the resistor R130 is connected in parallel between the gate and source of the MOS transistor Q16.

[0034] In this embodiment, since the inductor L12 is charged when the active switch 31 is turned on, the active switch 31 needs to carry a larger power and is preferably formed of a MOS transistor.

[0035] Furthermore, the circuit structures of the input detection module 5 and the output detection module 6 are the same; The input detection module 5 includes a resistor R132, a resistor R133 and a resistor R134; one end of the resistor R132 is electrically connected to the input end of the boost module 3; the other end of the resistor R132 is connected in series with the resistor R133 and the resistor R134, and then connected to the GND ground terminal; the common point of the resistor R133 and the resistor R134 (i.e. Figure 1 Vin or Vout in the circuit is electrically connected to the controller.

[0036] In this embodiment, both the input detection module 5 and the output detection module 6 preferably adopt voltage division detection.

[0037] Example 2 A control method for an active dummy load is applied to the above-mentioned switching power supply with an active dummy load and is loaded on a controller; the method comprises the following steps: A1: Calculate the preset inductance for charging inductor L12: ; in, is a preset minimum frequency (i.e., to limit the operating frequency range of the boost module 3, excluding the continuous mode, as described in detail below); A2: Calculate the real-time operating frequency of boost module 3: ; A3: If , then execute step A4; if , then execute step A5; in other cases, the controller controls the active switch to remain off; wherein, is a preset maximum frequency (i.e., to limit the operating frequency range of the boost module 3, excluding the continuous mode, as described in detail below); A4: On-time ; Off time ; A5: On-time ; Off time .

[0038] Based on the fact that the boost module 3 is composed of a capacitor CE10, a diode D22, an inductor L12 and a capacitor C50 to form a boost circuit, the boost module 3 will work in multiple working modes. For example, when the active switch 31 is turned off, the current of the inductor L12 decreases linearly. When the inductor current does not drop to 0mA, the active switch 31 is turned on again. This is a continuous mode. When the inductor current drops to 0mA, the active switch 31 is turned on again immediately. This working mode is a critical mode. When the inductor current drops to 0mA, after a period of time, the active switch 31 is turned on again. This working mode is an intermittent mode. Since the input of the boost module 3 is a very wide range, the operating frequency range of the module according to the PWM signal is also wide. If it is not restricted, when the operating frequency is too low, the human ear will hear noise. When the operating frequency is too high, electromagnetic compatibility problems will occur, so a preset minimum frequency is required. and maximum frequency , so that the boost module 3 works within a specific operating frequency range, avoiding noise caused by too low a frequency and electromagnetic compatibility problems caused by too high a frequency. Among these three working modes, the operating frequency of the continuous mode is always lower than the preset minimum frequency. , this working mode is not selected (i.e., the active switch 31 remains off; only when the active switch 31 is repeatedly switched on and off can feedback compensation for the current consumption of the PFC module 1 be achieved, otherwise the boost module 3 and the linear voltage regulator module 4 will not work), and only the boost module 3 is set to the critical mode and the discontinuous mode.

[0039] Therefore, the present invention also proposes a preferred embodiment of a control method for an active dummy load, such as Figure 2 As shown, the controller first executes step A1 and substitutes the preset consumption current , preset minimum frequency (this excludes continuous mode), the detected input voltage and output voltage , calculate the inductance that the inductor L12 will charge ; Then substitute into step A2, it can be determined that the working frequency of the boost module 3 falls into the critical mode , or intermittent mode Then, correspondingly executing step A4 or A5 forms a PWM signal to control the on-off of the active switch 31, and determines the current consumption It should be noted that the formula is derived through the analysis of the boost module 3 circuit, wherein step A4 is mainly to put the boost module 3 in the variable frequency mode, at the preset minimum frequency and preset maximum frequency Step A5 is mainly to put the boost module 3 in fixed frequency mode, and substitute the preset maximum frequency , constant at the preset maximum frequency .

[0040] Other structures and operations of a switching power supply with an active dummy load and a dummy load control method thereof according to an embodiment of the present invention are well known to those skilled in the art and will not be described in detail here.

[0041] Throughout this specification, reference to terms such as "embodiment" or "example" indicates that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A switching power supply with an active dummy load, comprising a PFC module, a dimming output module, and a controller; characterized in that: It also includes a boost module, a linear voltage regulator module, an input detection module and an output detection module; the input end of the boost module is electrically connected to the output end of the dimming output module, and the output end of the boost module is electrically connected to the positive electrode of the output capacitor of the PFC module via the linear voltage regulator module; The controller is electrically connected to the input end of the boost module via the input detection module to obtain the input voltage The controller is electrically connected to the output terminal of the boost module via the output detection module to obtain the output voltage ; The boost module is provided with an active switch, which is electrically connected to the active switch by the controller; the controller is preset with a consumption current , the controller consumes current by , the input voltage and the output voltage Calculate the on-time of the active switch and off time , by the on-time and the off time The PWM signal is composed to control the operation of the active switch.

2. The switching power supply with an active dummy load according to claim 1, characterized in that: The boost module includes a capacitor CE10, a diode D22, an inductor L12, and a capacitor C50; the capacitor C50 serves as the input end of the boost module, the cathode of the diode D22 serves as the output end of the boost module, and one end and the other end of the capacitor C50 are electrically connected to the positive output terminal and the negative output terminal of the dimming output module, respectively; The positive electrode of the capacitor CE10 is electrically connected to the cathode of the diode D22, the anode of the diode D22 is electrically connected to one end of the inductor L12, the other end of the inductor L12 is electrically connected to one end of the capacitor C50, and the other end of the capacitor C50 is electrically connected to the negative electrode of the capacitor CE10; The active switch is coupled between one end of the inductor L12 and the other end of the capacitor C50 .

3. The switching power supply with an active dummy load according to claim 1, characterized in that: The linear voltage regulator module includes a passive switch and a self-driving module; the output end of the boost module is electrically connected to the PFC module via the passive switch, and the self-driving module is coupled between the output end of the boost module and the passive switch; When the active switch is turned off by the controller, the boost module operates to increase the voltage output to the self-driving module, and the self-driving module drives the passive switch to turn on.

4. The switching power supply with an active dummy load according to claim 3, characterized in that: The self-driving module includes a resistor R124, a resistor R125, a resistor R126, a resistor R127, a resistor R128 and a comparator U12; one end of the resistor R124 is electrically connected to the output end of the boost module; the other end of the resistor R124 is connected in series with the resistor R125 and the resistor R126, and then connected to the GND ground terminal; the common point of the resistor R125 and the resistor R126 is electrically connected to the positive input end of the comparator U12; The power supply voltage passes through the resistor R127 and the resistor R128 and is connected to the GND ground terminal; the common point of the resistor R127 and the resistor R128 is electrically connected to the negative input terminal of the comparator U12, and the output terminal of the comparator U12 is electrically connected to the passive switch.

5. The switching power supply with active dummy load according to claim 3, characterized in that: The passive switch includes a resistor R120, a resistor R121, a resistor R123, a diode D23, a transistor Q18 and a transistor Q17; the anode of the diode D23 is electrically connected to the output end of the boost module, and the cathode of the diode D23 is electrically connected to the emitter of the transistor Q18; The base of the transistor Q18 is connected in series with the resistor R120 and the resistor R121, and then electrically connected to the collector of the transistor Q17; the emitter of the transistor Q17 is connected to the GND ground terminal; the base of the transistor Q17 is connected in series with the resistor R123, and then electrically connected to the self-driving module; The collector of the transistor Q18 is electrically connected to the positive electrode of the output capacitor of the PFC module.

6. The switching power supply with an active dummy load according to claim 2, characterized in that: The active switch includes a MOS transistor Q16, a resistor R129, and a resistor R130; the drain of the MOS transistor Q16 is electrically connected to one end of the inductor L12, and the source of the MOS transistor Q16 is electrically connected to the other end of the capacitor C50; The gate of the MOS transistor Q16 is connected in series with the resistor R129 and then electrically connected to the controller; the resistor R130 is connected in parallel between the gate and source of the MOS transistor Q16.

7. The switching power supply with an active dummy load according to claim 1, characterized in that: The circuit structures of the input detection module and the output detection module are the same; The input detection module includes a resistor R132, a resistor R133 and a resistor R134; one end of the resistor R132 is electrically connected to the input end of the boost module; the other end of the resistor R132 is connected in series with the resistor R133 and the resistor R134 in sequence, and then connected to the GND ground end; the common point of the resistor R133 and the resistor R134 is electrically connected to the controller.

8. A method for controlling an active dummy load, characterized in that: The switching power supply with an active dummy load according to claim 2 or 6 is loaded on the controller; comprising the following steps: A1: Calculate the preset inductance for charging the inductor L12: ； in, is the preset minimum frequency; A2: Calculate the real-time operating frequency of the boost module: ； A3: If , then execute step A4; if , then execute step A5; in other cases, the controller controls the active switch to remain off; wherein, is the preset maximum frequency; A4: The on-time ; The off time ; A5: The on-time ; The off time .

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