CN113252970A

CN113252970A - Load detection circuit and power supply system

Info

Publication number: CN113252970A
Application number: CN202110441991.7A
Authority: CN
Inventors: 兰勇; 孙用刚; 吕万德
Original assignee: Great Wall Power Technology Co ltd
Current assignee: Great Wall Power Technology Co ltd
Priority date: 2021-04-23
Filing date: 2021-04-23
Publication date: 2021-08-13
Anticipated expiration: 2041-04-23
Also published as: CN113252970B

Abstract

The application discloses load detection circuit and electrical power generating system belongs to electron technical field. The load detection circuit comprises a first amplifying circuit, a first conversion circuit, a second amplifying circuit, a second conversion circuit and a controller. The first amplifying circuit is used for acquiring an output signal of the switching power supply and carrying out primary amplification, the second amplifying circuit is used for carrying out secondary amplification on a voltage signal output by the first amplifying circuit, and the first converting circuit and the second converting circuit respectively convert the primary amplified voltage signal and the secondary amplified voltage signal into a current signal. And after detecting a first current value of the first conversion circuit and a second current value of the second conversion circuit, the controller judges the load state of the switching power supply according to the first current value and the second current value. The load detection circuit can enlarge the effective acquisition range of the output signal of the switching power supply, so that the controller can accurately judge the load state of the switching power supply.

Description

Load detection circuit and power supply system

Technical Field

The present application relates to the field of electronic technologies, and in particular, to a load detection circuit and a power supply system.

Background

The switching power supply is a high-frequency electric energy conversion device and can convert a standard voltage into a voltage or a current required by a user. The switch power supply comprises a switch tube, and the output signal of the switch power supply can be adjusted by adjusting the on-off time ratio of the switch tube. The switching power supply has different working modes, and under different working modes, the on-off time ratio of the switching tube is different, and the magnitude of the output signal of the switching power supply is also different.

The load state of the switching power supply comprises a light load state and a heavy load state, and the output signals of the switching power supply required by different load states are different in size. The operating mode of the switching power supply needs to be matched to the load conditions. In the related art, a load detection circuit for detecting a load state of a switching power supply generally includes a two-stage amplification circuit, a sampling resistor, and a controller. The two-stage amplifying circuit collects output signals of the switching power supply, amplifies the output signals twice and outputs the amplified output signals to the sampling resistor, and the controller judges the load state of the switching power supply by detecting the current value of the sampling resistor.

However, when the switching power supply is in a heavy load state, the output signal of the switching power supply is large, and the output signal of the switching power supply amplified by the two-stage amplifying circuit exceeds the working range of the sampling resistor too much, so that the sampling resistor cannot work normally, and the current value of the sampling resistor cannot be used as a basis for judging the load state of the switching power supply, thereby causing the controller to be unable to judge the load state of the switching power supply.

Disclosure of Invention

The embodiment of the application provides a load detection circuit and a power supply system, which can accurately detect the load state of a switching power supply. The technical scheme is as follows:

in a first aspect, a load detection circuit is provided, including: the circuit comprises a first amplifying circuit, a first converting circuit, a second amplifying circuit, a second converting circuit and a controller;

the first input end of the first amplifying circuit is used for being connected with the first output end of the switching power supply, the second input end of the first amplifying circuit is used for being connected with the second output end of the switching power supply, and the first amplifying circuit is used for amplifying the voltage difference between the first input end and the second input end of the first amplifying circuit;

the first end of the first conversion circuit is connected with the output end of the first amplification circuit, the second end of the first conversion circuit is used for being connected with a ground wire GND, the third end of the first conversion circuit is connected with the first input end of the controller, the first conversion circuit is used for converting a voltage signal into a current signal, and the controller is used for detecting the current of the third end of the first conversion circuit to obtain a first current value;

a first input end of the second amplifying circuit is connected with an output end of the first amplifying circuit, a second input end of the second amplifying circuit is used for being connected with the ground wire GND, and the second amplifying circuit is used for amplifying a voltage difference between the first input end and the second input end of the second amplifying circuit;

a first end of the second conversion circuit is connected with an output end of the second amplification circuit, a second end of the second conversion circuit is used for being connected with the ground wire GND, a third end of the second conversion circuit is connected with a second input end of the controller, the second conversion circuit is used for converting a voltage signal into a current signal, and the controller is used for detecting the current of the third end of the second conversion circuit to obtain a second current value;

the controller is used for determining the load state of the switching power supply according to the magnitude relation between the first current value and a preset current value and the magnitude relation between the second current value and the preset current value.

In the present application, the load detection circuit includes a first amplification circuit, a first conversion circuit, a second amplification circuit, a second conversion circuit, and a controller. The first amplifying circuit is used for acquiring an output signal of the switching power supply and performing primary amplification. The first conversion circuit is used for converting the voltage signal output by the first amplification circuit into a current signal, and the controller detects the current value in the first conversion circuit to obtain a first current value. The second amplifying circuit is used for amplifying the voltage signal output by the first amplifying circuit. The second conversion circuit is used for converting the voltage signal output by the second amplification circuit into a current signal, and the controller detects the current value of the second conversion circuit to obtain a second current value. When the load detection circuit works, the controller judges the load state of the switching power supply according to the first current value and the second current value. In the load detection circuit, the second current value is larger than the first current value. If the output signal of the switching power supply is larger, the output signal of the switching power supply does not exceed the working range of the first conversion circuit after being amplified in one stage, and the first current value is accurate and effective. If the output signal of the switching power supply is smaller, the output signal of the switching power supply does not exceed the working range of the second conversion circuit after being amplified for the second stage, and the second current value is accurate and effective. Therefore, the load detection circuit can enlarge the effective acquisition range of the output signal of the switching power supply by the load detection circuit, so that the controller can accurately judge the load state of the switching power supply.

Optionally, the first amplifying circuit comprises: an operational amplifier A1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1 and a capacitor C2;

the operational amplifier A1 has a non-inverting input terminal, an inverting input terminal and an operational amplifier output terminal, and the operational amplifier output terminal of the operational amplifier A1 is connected with the first terminal of the first converting circuit and the first input terminal of the second amplifying circuit;

a first end of the resistor R1 is used for being connected with a first output end of the switching power supply, and a second end of the resistor R1 is connected with a non-inverting input end of the operational amplifier A1;

a first end of the resistor R2 is connected with a second end of the resistor R1, and a second end of the resistor R2 is used for being connected with the ground GND;

the first end of the resistor R3 is used for being connected with the second output end of the switching power supply, and the second end of the resistor R3 is connected with the inverting input end of the operational amplifier A1;

the first plate of the capacitor C1 is connected with the first end of the resistor R1, and the second plate of the capacitor C1 is used for being connected with the ground line GND;

the first plate of the capacitor C2 is used for being connected with the ground line GND, and the second plate of the capacitor C2 is connected with the first end of the resistor R3.

Optionally, the operational amplifier a1 further has a power input VINA1 and a power output VOUTA1, the power output VOUTA1 is configured to be connected to the ground GND;

the first amplification circuit further includes: the circuit comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C5 and a diode D1;

a first end of the resistor R4 is used for being connected with a power supply V1, and a second end of the resistor R4 is connected with a power supply input end VINA1 of the operational amplifier A1;

a first end of the resistor R5 is connected with a second end of the resistor R4, and a second end of the resistor R5 is connected with a non-inverting input end of the operational amplifier A1;

a first end of the resistor R6 is used for being connected with a power supply V2, and a second end of the resistor R6 is connected with a power supply input end VINA1 of the operational amplifier A1;

a first end of the resistor R7 is connected with a second end of the resistor R6, and a second end of the resistor R7 is connected with an inverting input end of the operational amplifier A1;

a first end of the resistor R8 is connected with an inverting input end of the operational amplifier A1, and a second end of the resistor R8 is connected with an operational amplifier output end of the operational amplifier A1;

the first plate of the capacitor C3 is connected with the non-inverting input end of the operational amplifier A1, and the second plate of the capacitor C3 is used for being connected with the ground line GND;

a first plate of the capacitor C4 is connected with a power input end VINA1 of the operational amplifier A1, and a second plate of the capacitor C4 is used for being connected with the ground line GND;

the anode of the diode D1 is used for being connected with the ground line GND, and the cathode of the diode D1 is connected with the inverting input end of the operational amplifier A1;

the first plate of the capacitor C5 is connected with the inverting input end of the operational amplifier A1, and the second plate of the capacitor C5 is connected with the operational amplifier output end of the operational amplifier A1.

Optionally, the first conversion circuit includes: a resistor R9 and a capacitor C6;

a first end of the resistor R9 is connected with the output end of the first amplifying circuit, and a second end of the resistor R9 is connected with a first input end of the controller;

the first plate of the capacitor C6 is connected to the second end of the resistor R9, and the second plate of the capacitor C6 is connected to the ground GND.

Optionally, the load detection circuit further includes: a resistor R10 and a capacitor C7;

a first end of the resistor R10 is connected to an output end of the first amplifying circuit, a second end of the resistor R10 is connected to a third input end of the controller, and the controller is configured to detect a current at the second end of the resistor R10 to obtain a third current value;

the first plate of the capacitor C7 is connected with the second end of the resistor R10, and the second plate of the capacitor C7 is used for being connected with the ground line GND;

the load state comprises a heavy load state and a light load state, the heavy load state means that the load power of the switching power supply is larger than a preset power, the light load state means that the load power of the switching power supply is smaller than or equal to the preset power, and the controller is used for performing loop calculation of the switching power supply according to the third current value under the condition that the switching power supply is in the heavy load state.

Optionally, the second amplifying circuit comprises: an operational amplifier A2, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and a capacitor C8;

the operational amplifier A2 has a non-inverting input terminal, an inverting input terminal and an operational amplifier output terminal, and the operational amplifier output terminal of the operational amplifier A2 is connected with the first terminal of the second conversion circuit;

a first end of the resistor R11 is connected with the output end of the first amplifying circuit, and a second end of the resistor R11 is connected with the non-inverting input end of the operational amplifier A2;

a first end of the resistor R12 is used for being connected with a power supply V2, and a second end of the resistor R12 is connected with a non-inverting input end of the operational amplifier A2;

a first end of the resistor R13 is connected with an inverting input end of the operational amplifier A2, and a second end of the resistor R13 is used for being connected with the ground GND;

a first end of the resistor R14 is connected with an inverting input end of the operational amplifier A2, and a second end of the resistor R14 is connected with an operational amplifier output end of the operational amplifier A2;

the first plate of the capacitor C8 is connected with the inverting input end of the operational amplifier A2, and the second plate of the capacitor C8 is connected with the operational amplifier output end of the operational amplifier A2.

Optionally, the second conversion circuit comprises: a resistor R15 and a capacitor C9;

a first end of the resistor R15 is connected with the output end of the second amplifying circuit, and a second end of the resistor R15 is connected with a second input end of the controller;

the first plate of the capacitor C9 is connected to the second end of the resistor R15, and the second plate of the capacitor C9 is connected to the ground GND.

Optionally, the method further comprises: a resistor R16 and a capacitor C10;

a first end of the resistor R16 is connected to an output end of the second amplifying circuit, a second end of the resistor R16 is connected to a fourth input end of the controller, and the controller is configured to detect a current at the second end of the resistor R16 to obtain a fourth current value;

the first plate of the capacitor C10 is connected with the second end of the resistor R16, and the second plate of the capacitor C10 is connected with the ground line GND;

the load state comprises a heavy load state and a light load state, the heavy load state means that the load power of the switching power supply is larger than a preset power, the light load state means that the load power of the switching power supply is smaller than or equal to the preset power, and the controller is used for performing loop calculation of the switching power supply according to the fourth current value under the condition that the switching power supply is in the light load state.

Optionally, the output end of the controller is configured to be connected to the control end of the switching power supply, and the controller is configured to generate a control signal according to a load state of the switching power supply, and output the control signal from the output end of the controller to the control end of the switching power supply, so as to switch a working mode of the switching power supply.

In a second aspect, a power supply system is provided, comprising the load detection circuit according to the first aspect.

It is understood that the beneficial effects of the second aspect can be referred to the related description of the first aspect, and are not described herein again.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a switching power supply provided in the related art;

fig. 2 is a schematic structural diagram of a first load detection circuit provided in an embodiment of the present application;

fig. 3 is a schematic structural diagram of a second load detection circuit provided in an embodiment of the present application;

fig. 4 is a circuit diagram of a first load detection circuit provided in an embodiment of the present application;

fig. 5 is a schematic structural diagram of a third load detection circuit provided in the embodiment of the present application;

fig. 6 is a circuit diagram of a second load detection circuit provided in an embodiment of the present application.

Wherein, the meanings represented by the reference numerals of the figures are respectively as follows:

10. a load detection circuit;

110. a first amplifying circuit;

120. a first conversion circuit;

130. a second amplifying circuit;

140. a second conversion circuit;

150. a third conversion circuit;

160. a fourth conversion circuit;

170. and a controller.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

It should be understood that reference to "a plurality" in this application means two or more. In the description of the present application, "/" means "or" unless otherwise stated, for example, a/B may mean a or B; "and/or" herein is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, for the convenience of clearly describing the technical solutions of the present application, the terms "first", "second", and the like are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.

Before explaining the embodiments of the present application in detail, an application scenario of the embodiments of the present application will be described.

The switching power supply is a high-frequency electric energy conversion device, comprises a constant voltage power supply and a constant current power supply, and can convert a standard voltage into voltage or current required by a user. The switch power supply comprises a switch tube, and the output signal of the switch power supply can be adjusted by adjusting the on-off time ratio of the switch tube. The output signal of the switch power supply refers to a current signal of a constant voltage switch or a voltage signal of a constant current power supply. The switching power supply has different working modes, and under different working modes, the on-off time ratio of the switching tube is different, and the magnitude of the output signal of the switching power supply is also different. Common switching power supplies are a Boost Chopper circuit (Boost Chopper) and a Buck Chopper circuit (Buck Chopper). Fig. 1 is a schematic circuit diagram of a switching power supply, and a boost chopper circuit is shown in the diagram. Taking the boost chopper circuit as an example, referring to fig. 1, a standard voltage is input from the first input terminal VIN1 of the boost chopper circuit and the second input terminal VIN2 of the switching power supply. The boost chopper circuit comprises a switching tube Q, and the output voltage of the boost chopper circuit can be adjusted by adjusting the on-off time ratio of the switching tube Q. The output voltage of the boost chopper circuit refers to a voltage difference between the first output terminal OUT1 and the second output terminal OUT2 of the boost chopper circuit. Under different working modes, the on-off time ratio of the switching tube Q is different, and the output voltage of the boost chopper circuit is also different.

The load state of the switching power supply comprises a light load state and a heavy load state, and the output signals of the switching power supply required by different load states are different in size. The operating mode of the switching power supply needs to be matched to the load conditions.

Therefore, the embodiment of the application provides a load detection circuit and a power supply system, which can accurately detect the load state of a switching power supply.

The load detection circuit and the power supply system provided by the embodiments of the present application are explained in detail below. In various embodiments of the present application, the connection between two electrical devices is referred to as an electrical connection. Here, the electrical connection means that two electrical devices are connected by wire or wireless to transmit an electrical signal.

Fig. 2 is a schematic structural diagram of a load detection circuit 10 according to an embodiment of the present application, and fig. 3 is a schematic structural diagram of another load detection circuit 10 according to an embodiment of the present application. The load detection circuit 10 is used to detect the load state of the switching power supply. As shown in fig. 2 and 3, the load detection circuit 10 includes a first amplification circuit 110, a first conversion circuit 120, a second amplification circuit 130, a second conversion circuit 140, and a controller 170.

The switching power supply has a first output terminal OUT1 and a second output terminal OUT 2. The output voltage of the switching power supply refers to the voltage difference between the first output terminal OUT1 of the switching power supply and the second output terminal OUT2 of the switching power supply; the output current of the switching power supply refers to the current difference between the first output terminal OUT1 of the switching power supply and the second output terminal OUT2 of the switching power supply. Generally, the load state of the switching power supply includes a heavy load state and a light load state, where the heavy load state indicates that the load power of the switching power supply is greater than a preset power, and the light load state indicates that the load power of the switching power supply is less than or equal to the preset power. Specifically, when the switching power supply is a constant voltage power supply, the magnitude of the output current signal changes with the change of the load resistance. If the resistance value of the load is too small, the output power of the switching power supply is larger than the preset power, and the switching power supply is in a heavy load state; otherwise, the switching power supply is in a light load state. When the switching power supply is a constant current power supply, the magnitude of the output voltage signal changes along with the change of the load resistance. If the resistance value of the load is too large, the output power of the switching power supply is larger than the preset power, and the switching power supply is in a heavy load state; otherwise, the switching power supply is in a light load state.

The first amplification circuit 110 has a first input terminal, a second input terminal, and an output terminal. A first input of the first amplifying circuit 110 is adapted to be connected to a first output of the switching power supply, and a second input of the first amplifying circuit 110 is adapted to be linked to a second output of the switching power supply. The first amplifying circuit 110 is configured to amplify a voltage difference between a first input terminal and a second input terminal of the first amplifying circuit 110 to obtain a voltage signal, and output the voltage signal from an output terminal of the first amplifying circuit 110. Specifically, when the output signal of the switching power supply is a voltage signal, as shown in fig. 2, the first amplifying circuit 110 may directly collect and amplify the voltage signal. When the output signal of the switching power supply is a current signal, as shown in fig. 3, the current signal may be converted into a voltage signal through the sampling resistor R0, and then the voltage signal is collected and amplified by the first amplifying circuit 110. The current signal may be a current signal output by an inductor of the switching power supply. The first amplifying circuit 110 is used for amplifying the output signal of the switching power supply once.

The first conversion circuit 120 has a first terminal, a second terminal, and a third terminal. The controller 170 has a first input and a second input. The first conversion circuit 120 is connected between the output terminal of the first amplification circuit 110 and the ground GND, the first input terminal of the controller 170. In other words, the first terminal of the first converting circuit 120 is connected to the output terminal of the first amplifying circuit 110. The second terminal of the first conversion circuit 120 is connected to the ground GND. The third terminal of the first converting circuit 120 is connected to the first input terminal of the controller 170. After the output end of the first amplifying circuit 110 outputs the voltage signal, the first converting circuit 120 is configured to convert the voltage signal into a current signal. The controller 170 detects a current magnitude of the third terminal of the first converting circuit 120 through the first input terminal of the controller 170 to obtain a first current value.

The second amplification circuit 130 also has a first input terminal, a second input terminal, and an output terminal. A first input terminal of the second amplification circuit 130 is connected to the output terminal of the first amplification circuit 110, and a second input terminal of the second amplification circuit 130 is connected to the ground GND. The second amplifying circuit 130 is configured to amplify a voltage difference between a first input terminal and a second input terminal of the second amplifying circuit 130 to obtain a voltage signal, and output the voltage signal from an output terminal of the second amplifying circuit 130. Specifically, after the first amplifying circuit 110 outputs the voltage signal, the second amplifying circuit 130 may amplify the voltage signal, that is, amplify the output signal of the switching power supply for the second time.

The second conversion circuit 140 has a first terminal, a second terminal, and a third terminal. The second conversion circuit 140 is connected between the output terminal of the second amplification circuit 130 and the ground GND, and the second input terminal of the controller 170. In other words, the first terminal of the second conversion circuit 140 is connected to the output terminal of the second amplification circuit 130. A second terminal of the second conversion circuit 140 is connected to the ground GND. The third terminal of the second switching circuit 140 is connected to the second input terminal of the controller 170. After the output end of the second amplifying circuit 130 outputs the voltage signal, the second converting circuit 140 is configured to convert the voltage signal into a current signal. The controller 170 detects a current magnitude of the third terminal of the second converting circuit 140 through the second input terminal of the controller 170 to obtain a second current value.

After the controller 170 detects the first current value and the second current value, the load state of the switching power supply may be determined according to a magnitude relationship between the first current value and the preset current value and a magnitude relationship between the second current value and the preset current value. When both the first current value and the second current value are greater than the preset current value, the controller 170 determines that the switching power supply is in the heavy load state. On the contrary, when at least one of the first current value and the second current value is less than the preset current value, the controller 170 determines that the switching power supply is in the light load state. When the load detection circuit 10 operates, the second current value is larger than the first current value. If the load of the switching power supply is in a heavy load state, the output signal of the switching power supply is large at this time, the output signal of the switching power supply does not exceed the working range of the first conversion circuit 120 after being amplified in a first stage, the first conversion circuit 120 normally works at this time, and the first current value is accurate and effective. The controller 170 may determine that the switching power supply is in the heavy load state according to the first current value and the second current value. If the load of the switching power supply is in a light load state, the output signal of the switching power supply is small at this time, the output signal of the switching power supply does not exceed the working range of the second conversion circuit 140 after being amplified by the two-stage amplification circuit, the second conversion circuit 140 works normally, and the second current value is accurate and effective. The controller 170 may determine that the switching power supply is in the light load state according to the first current value and the second current value. When the load detection circuit 10 works, the controller 170 judges the load state of the switching power supply according to the first current value and the second current value, so that the problem that the output signal of the switching power supply exceeds the working range of the second conversion circuit 140 after two-stage amplification when the output signal of the switching power supply is large, and the second conversion circuit 140 cannot work normally can be avoided; the problem that the output signal of the switching power supply is lower than the working range of the first conversion circuit 120 after being amplified by one stage when the output signal is small, so that the first conversion circuit 120 cannot work can be solved. Therefore, the load detection circuit can enlarge the effective collection range of the output signal of the switching power supply by the load detection circuit 10, thereby accurately judging the load state of the switching power supply.

Fig. 3 is a circuit diagram of a load detection circuit 10 according to an embodiment of the present application. As shown in fig. 3, in some embodiments, the first amplification circuit 110 includes: operational amplifier A1, resistor R1, resistor R2, resistor R3, capacitor C1 and capacitor C2.

Specifically, the operational amplifier a1 has a non-inverting input, an inverting input, and an operational amplifier output. The operational amplifier output terminal of the operational amplifier a1 is connected to the first terminal of the first converting circuit 120 and the first input terminal of the second amplifying circuit 130. In other words, the operational amplifier output terminal of the operational amplifier a1 is the output terminal of the first amplifying circuit 110.

The resistor R1 is connected between the first output terminal OUT1 of the switching power supply and the non-inverting input terminal of the operational amplifier a 1. In other words, a first terminal of the resistor R1 is used for being connected to a first output terminal of the switching power supply, and a second terminal of the resistor R1 is connected to a non-inverting input terminal of the operational amplifier a 1. I.e., the first terminal of the resistor R1, is the first input terminal of the first amplifying circuit 110.

The resistor R2 is connected between the second end of the resistor R1 and the ground GND. In other words, the first terminal of the resistor R2 is connected to the second terminal of the resistor R1, and the second terminal of the resistor R2 is used for connecting to the ground GND.

The resistor R3 is connected between the second output terminal OUT2 of the switching power supply and the inverting input terminal of the operational amplifier a 1. In other words, the first terminal of the resistor R3 is used for being connected to the second output terminal of the switching power supply, and the second terminal of the resistor R3 is connected to the inverting input terminal of the operational amplifier a 1. I.e., the first terminal of the resistor R3, is the second input terminal of the first amplifying circuit 110.

The capacitor C1 is connected between the first end of the resistor R1 and the ground GND. In other words, the first plate of the capacitor C1 is connected to the first terminal of the resistor R1, and the second plate of the capacitor C1 is connected to the ground GND.

The capacitor C2 is connected between the first end of the resistor R3 and the ground GND. In other words, the first plate of the capacitor C2 is used to connect to the ground GND, and the second plate of the capacitor C2 is connected to the first terminal of the resistor R3.

Further, as also shown in fig. 3, the operational amplifier a1 further has a power input VINA1 and a power output VOUTA1, the power output VOUTA1 being for connection to ground GND. The first amplification circuit 110 further includes: the circuit comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C5 and a diode D1.

Specifically, the resistor R4 is connected between the power supply V1 and the power supply input VINA1 of the operational amplifier a 1. In other words, a first terminal of the resistor R4 is used for connecting to the power supply V1, and a second terminal of the resistor R4 is connected to the power supply input terminal VINA1 of the operational amplifier a 1.

The resistor R5 is connected between the second terminal of the resistor R4 and the non-inverting input terminal of the operational amplifier a 1. In other words, the first terminal of the resistor R5 is connected to the second terminal of the resistor R4, and the second terminal of the resistor R5 is connected to the non-inverting input terminal of the operational amplifier a 1.

The resistor R6 is connected between the power supply V2 and the power supply input terminal VINA1 of the operational amplifier a 1. In other words, a first terminal of the resistor R6 is used for connecting to the power supply V2, and a second terminal of the resistor R6 is connected to the power supply input terminal VINA1 of the operational amplifier a 1.

The resistor R7 is connected between the second end of the resistor R6 and the inverting input terminal of the operational amplifier a 1. In other words, the first terminal of the resistor R7 is connected to the second terminal of the resistor R6, and the second terminal of the resistor R7 is connected to the inverting input terminal of the operational amplifier a 1.

The resistor R8 is connected between the inverting input terminal of the operational amplifier a1 and the operational amplifier output terminal of the operational amplifier a 1. In other words, the first terminal of the resistor R8 is connected to the inverting input terminal of the operational amplifier a1, and the second terminal of the resistor R8 is connected to the operational amplifier output terminal of the operational amplifier a 1.

The capacitor C3 is connected between the non-inverting input terminal of the operational amplifier a1 and the ground GND. In other words, the first plate of the capacitor C3 is connected to the non-inverting input of the operational amplifier a1, and the second plate of the capacitor C3 is connected to the ground GND.

The capacitor C4 is connected between the power input terminal VINA1 of the operational amplifier a1 and the ground GND. In other words, the first plate of the capacitor C4 is connected to the power input VINA1 of the operational amplifier a1, and the second plate of the capacitor C4 is connected to the ground GND.

The diode D1 is connected between the ground GND and the inverting input terminal of the operational amplifier a 1. In other words, the anode of the diode D1 is used to be connected to the ground GND, and the cathode of the diode D1 is connected to the inverting input terminal of the operational amplifier a 1.

The capacitor C5 is connected between the inverting input terminal of the operational amplifier a1 and the operational amplifier output terminal of the operational amplifier a 1. In other words, the first plate of the capacitor C5 is connected to the inverting input of the operational amplifier a1, and the second plate of the capacitor C5 is connected to the operational amplifier output of the operational amplifier a 1.

Further, the voltage of the power supply V1 may be greater than the voltage of the power supply V2. For example, the voltage of the power supply V1 may be 12V, and the voltage of the power supply V2 may be 3.3V.

Still as shown in fig. 3, in some embodiments, the first conversion circuit 120 may include a resistor R9 and a capacitor C6.

Specifically, the resistor R9 is a sampling resistor for converting a voltage signal into a current signal. The resistor R9 is connected between the output terminal of the first amplifying circuit 110 and the first input terminal of the controller 170. In other words, a first terminal of the resistor R9 is connected to the output terminal of the first amplifying circuit 110, and a second terminal of the resistor R9 is connected to the first input terminal of the controller 170. The controller 170 is configured to detect a current level at the second end of the resistor R9 to obtain a first current value. I.e., the first terminal of the resistor R9, is the first terminal of the first converting circuit 120. The second terminal of the resistor R9 is the third terminal of the first converting circuit 120.

The capacitor C6 is a filter capacitor. The capacitor C6 is connected between the second terminal of the resistor R9 and the ground GND. In other words, the first plate of the capacitor C6 is connected to the second terminal of the resistor R9, and the second plate of the capacitor C6 is connected to the ground GND. The second plate of the capacitor C6 is the second terminal of the first converting circuit 120.

As also shown in fig. 3, in some embodiments, the second amplification circuit 130 includes: operational amplifier A2, resistor R11, resistor R12, resistor R13, resistor R14 and capacitor C8.

Specifically, the operational amplifier a2 has a non-inverting input terminal, an inverting input terminal, and an operational output terminal, and the operational output terminal of the operational amplifier a2 is connected to the first terminal of the second conversion circuit 140. In other words, the operational amplifier output terminal of the operational amplifier a2 is the output terminal of the second amplifying circuit 130.

The resistor R11 is connected between the output terminal of the first amplifier circuit 110 and the non-inverting input terminal of the operational amplifier a 2. In other words, a first terminal of the resistor R11 is connected to the output terminal of the first amplifier circuit 110, and a second terminal of the resistor R11 is connected to the non-inverting input terminal of the operational amplifier a 2. I.e., the first terminal of the resistor R11, is the first input terminal of the second amplifying circuit 130.

The resistor R12 is connected between the power supply V2 and the non-inverting input of the operational amplifier a 2. In other words, a first terminal of the resistor R12 is used for connecting with the power supply V2, and a second terminal of the resistor R12 is connected with the non-inverting input terminal of the operational amplifier a 2.

The resistor R13 is connected between the inverting input terminal of the operational amplifier a2 and the ground GND. In other words, the first terminal of the resistor R13 is connected to the inverting input terminal of the operational amplifier a2, and the second terminal of the resistor R13 is used for connection to the ground GND. I.e., the second terminal of the resistor R13, is the second input terminal of the second amplifying circuit 130.

The resistor R14 is connected between the inverting input terminal of the operational amplifier a2 and the operational amplifier output terminal of the operational amplifier a 2. In other words, the first terminal of the resistor R14 is connected to the inverting input terminal of the operational amplifier a2, and the second terminal of the resistor R14 is connected to the operational amplifier output terminal of the operational amplifier a 2.

The capacitor C8 is connected between the inverting input terminal of the operational amplifier a2 and the operational amplifier output terminal of the operational amplifier a 2. In other words, the first plate of the capacitor C8 is connected to the inverting input of the operational amplifier a2, and the second plate of the capacitor C8 is connected to the operational amplifier output of the operational amplifier a 2.

Still as shown in fig. 3, in some embodiments, the second conversion circuit 140 may include a resistor R15 and a capacitor C9.

Specifically, the resistor R15 is a sampling resistor for converting a voltage signal into a current signal. The resistor R15 is connected between the output terminal of the second amplifying circuit 130 and the second input terminal of the controller 170. In other words, a first terminal of the resistor R15 is connected to the output terminal of the second amplifying circuit 130, and a second terminal of the resistor R15 is connected to the second input terminal of the controller 170. The controller 170 is configured to detect a current magnitude at the second end of the resistor R15 to obtain a second current value. A first terminal of the resistor R15 is a first terminal of the second converting circuit 140. The second terminal of the resistor R15 is the third terminal of the second converting circuit 140.

The capacitor C9 is a filter capacitor. The capacitor C9 is connected between the second terminal of the resistor R15 and the ground GND. In other words, the first plate of the capacitor C9 is connected to the second terminal of the resistor R15, and the second plate of the capacitor C9 is connected to the ground GND. The second plate of the capacitor C9 is the second terminal of the second converting circuit 140.

Fig. 4 is a schematic structural diagram of another load detection circuit 10 according to an embodiment of the present disclosure. Referring to fig. 3, the load detection circuit 10 may further include a third conversion circuit 150 and a fourth conversion circuit 160.

Specifically, the third conversion circuit 150 has a first terminal, a second terminal, and a third terminal. The controller 170 has a third input and a fourth input. The third conversion circuit 150 is connected between the output terminal of the first amplification circuit 110, the ground GND, and the third input terminal of the controller 170. In other words, the first terminal of the third conversion circuit 150 is connected to the output terminal of the first amplification circuit 110. A second terminal of the third conversion circuit 150 is connected to the ground GND. The third terminal of the third switching circuit 150 is connected to the third input terminal of the controller 170. After the output end of the first amplifying circuit 110 outputs the voltage signal, the third converting circuit 150 is configured to convert the voltage signal into a current signal. The controller 170 detects a current magnitude of the third terminal of the third converting circuit 150 through the third input terminal of the controller 170 to obtain a third current value.

The fourth conversion circuit 160 has a first terminal, a second terminal, and a third terminal. The fourth conversion circuit 160 is connected between the output terminal of the second amplification circuit 130 and the ground GND and the fourth input terminal of the controller 170. In other words, the first terminal of the fourth conversion circuit 160 is connected to the output terminal of the second amplification circuit 130. A second terminal of the fourth conversion circuit 160 is connected to the ground GND. The third terminal of the fourth switching circuit 160 is connected to the fourth input terminal of the controller 170. After the output end of the second amplifying circuit 130 outputs the voltage signal, the fourth converting circuit 160 is configured to convert the voltage signal into a current signal. The controller 170 detects a current magnitude of the third terminal of the fourth converting circuit 160 through the fourth input terminal of the controller 170 to obtain a fourth current value.

Further, fig. 5 is a circuit diagram of another load detection circuit 10 provided in the embodiment of the present application. As shown in fig. 5, in some embodiments, the third conversion circuit 150 may include a resistor R10 and a capacitor C7. The fourth switching circuit 160 may include a resistor R16 and a capacitor C10.

Specifically, the resistor R10 is a sampling resistor for converting a voltage signal into a current signal. The resistor R10 is connected between the output terminal of the first amplifying circuit 110 and the third input terminal of the controller 170. In other words, a first terminal of the resistor R10 is connected to the output terminal of the first amplifying circuit 110, and a second terminal of the resistor R10 is connected to the third input terminal of the controller 170. The controller 170 is configured to detect a current magnitude of the second end of the resistor R10 to obtain a third current value. A first terminal of the resistor R10 is a first terminal of the third converting circuit 150. The second terminal of the resistor R10 is the third terminal of the third converting circuit 150.

The capacitor C7 is a filter capacitor. The capacitor C7 is connected between the second terminal of the resistor R10 and the ground GND. In other words, the first plate of the capacitor C7 is connected to the second terminal of the resistor R10, and the second plate of the capacitor C7 is connected to the ground GND. The second plate of the capacitor C7 is the second terminal of the third converting circuit 150.

Specifically, the resistor R16 is a sampling resistor for converting a voltage signal into a current signal. The resistor R16 is connected between the output terminal of the second amplifying circuit 130 and the fourth input terminal of the controller 170. In other words, a first terminal of the resistor R16 is connected to the output terminal of the second amplifying circuit 130, and a second terminal of the resistor R16 is connected to the fourth input terminal of the controller 170. The controller 170 is configured to detect a current magnitude of the second end of the resistor R16 to obtain a fourth current value. A first terminal of the resistor R16 is a first terminal of the fourth converting circuit 160. The second terminal of the resistor R16 is the third terminal of the fourth switching circuit 160.

The capacitor C10 is a filter capacitor. The capacitor C10 is connected between the second terminal of the resistor R16 and the ground GND. In other words, the first plate of the capacitor C10 is connected to the second terminal of the resistor R16, and the second plate of the capacitor C10 is connected to the ground GND. The second plate of the capacitor C10 is the second terminal of the fourth converting circuit 160.

Further, the capacitance value of the capacitor C6 is larger than that of the capacitor C7. The capacitance value of the capacitor C9 is larger than that of the capacitor C10. The load state of the switching power supply comprises a heavy load state and a light load state, wherein the heavy load state means that the load power of the switching power supply is greater than the preset power, and the light load state means that the load power of the switching power supply is less than or equal to the preset power. The controller 170 is configured to perform loop calculation of the switching power supply according to the third current value when the switching power supply is in the heavy load state; and under the condition that the switching power supply is in a light load state, performing loop calculation of the switching power supply according to the fourth current value. In the embodiment of the application, the precision of the third current value is higher when the switching power supply is in a heavy load state; and the fourth current value has higher precision when the switching power supply is in a light load state. Therefore, the controller 170 performs loop calculation of the switching power supply according to the third current value when the switching power supply is in the heavy load state, and performs loop calculation of the switching power supply according to the fourth current value when the switching power supply is in the light load state, so that the loop calculation can be more accurate.

In some embodiments, the controller 170 may further calculate a load power of the switching power supply according to the third current value and the fourth current value, and determine the load state of the switching power supply according to the load power of the switching power supply. When the load power of the switching power supply is greater than the preset power, the controller 170 determines that the switching power supply is in the heavy load state. When the load power of the switching power supply is less than or equal to the preset power, the controller 170 determines that the switching power supply is in the light load state.

Further, the controller 170 may determine the load state of the switching power supply according to the first current value, the second current value, and the load power of the switching power supply at the same time. That is, when both the first current value and the second current value are greater than the preset current value, the controller 170 determines that the switching power supply is in the heavy load state. At this time, the controller 170 calculates the load power of the switching power supply according to the third current value. If the load power of the switching power supply is greater than the preset power, the controller 170 determines that the switching power supply is maintained in the heavy load state. If the load power of the switching power supply is less than or equal to the preset power, the controller 170 determines that the switching power supply is in the light load state. And when the switching power supply is in a light load state, determining whether the switching power supply is in a heavy load state according to whether the first current value and the second current value are both larger than a preset current value, so as to form a loop. In the embodiment of the present application, the light load and the heavy load of the switching power supply have different reference conditions, and different reference conditions can be used in combination, so that the judgment of the controller 170 on the load state of the switching power supply can be more accurate, and the influence of the instability of the output signal of the switching power supply on the judgment result of the controller 170 is avoided.

As also shown in fig. 5, in some embodiments, the controller 170 also has an output. The output end of the controller 170 is configured to be connected to the control end of the switching power supply, and the controller 170 is configured to generate a control signal according to a load state of the switching power supply, and output the control signal from the output end of the controller 170 to the control end of the switching power supply, so as to switch a working mode of the switching power supply.

Further, the controller 170 may also be provided with a hysteresis function. The hysteresis function is used for carrying out the time delay with controller 170 to switching Power supply's mode and switches to avoid when switching Power supply output signal is undulant, controller 170 control switching Power supply's mode makes a round trip to switch between light load and heavy load, thereby improve the stability of loop, and then can reduce switching Power supply's Total Harmonic Distortion (Total Harmonic Distortion, THD), improve switching Power supply's Power Factor (Power Factor, PF). Therefore, the adverse effect of the switching power supply on the quality of the power grid can be reduced, and the compatibility of the switching power supply is improved.

In some embodiments, the load detection circuit 10 of the present application may perform load detection on a high power switching power supply, and the preset power may be 2700W (watt) to 3500W. Specifically, the preset power may be 2700W, 3500W, 3000W, 3200W, or 3475W.

The load detection circuit 10 of the present application includes a first amplification circuit 110, a first conversion circuit 120, a second amplification circuit 130, a second conversion circuit 140, and a controller 170. The first amplifying circuit 110 is configured to collect an output signal of the switching power supply and perform first-stage amplification. The first converting circuit 120 is configured to convert the voltage signal output by the first amplifying circuit 110 into a current signal, and the controller 170 detects a current value in the first converting circuit 120 to obtain a first current value. The second amplifying circuit 130 is configured to amplify the voltage signal output by the first amplifying circuit 110. The second converting circuit 140 is configured to convert the voltage signal output by the second amplifying circuit 130 into a current signal, and the controller 170 detects a current value of the second converting circuit 140 to obtain a second current value. When the load detection circuit 10 works, the controller 170 judges the load state of the switching power supply according to the first current value and the second current value, so that the problem that the output signal of the switching power supply exceeds the working range of the second conversion circuit 140 after two-stage amplification when the output signal of the switching power supply is large, and the second conversion circuit 140 cannot work normally can be avoided; the problem that the output signal of the switching power supply is lower than the working range of the first conversion circuit 120 after being amplified by one stage when the output signal is small, so that the first conversion circuit 120 cannot work can be solved. The load detection circuit can enlarge the effective acquisition range of the output signal of the switch power supply by the load detection circuit 10, thereby accurately judging the load state of the switch power supply. The load detection circuit 10 may further include a third conversion circuit 150 and a fourth conversion circuit 160. The third converting circuit 150 is also configured to convert the voltage signal output by the first amplifying circuit 110 into a current signal, and the filter capacitance of the first converting circuit 120 is greater than the filter capacitance of the third converting circuit 150. The controller 170 detects the current value in the third converting circuit 150 to obtain a third current value. The fourth converting circuit 160 is also used for converting the voltage signal output by the second amplifying circuit 130 into a current signal, and the filter capacitance value of the second converting circuit 140 is greater than that of the fourth converting circuit 160. The controller 170 detects the current value in the fourth converting circuit 160 to obtain a fourth current value. The precision of the third current value is higher when the switching power supply is in a heavy load state; and the fourth current value has higher precision when the switching power supply is in a light load state. Therefore, the controller 170 performs loop calculation of the switching power supply according to the third current value when the switching power supply is in the heavy load state, and performs loop calculation of the switching power supply according to the fourth current value when the switching power supply is in the light load state, so that the loop calculation can be more accurate. According to the load detection circuit 10, the controller 170 can also judge the load state of the switching power supply according to the first current value, the second current value and the load power of the switching power supply, so that the judgment of the controller 170 on the load state of the switching power supply is more accurate, and the influence of the instability of the output signal of the switching power supply on the judgment result of the controller 170 is avoided. This controller 170 can also be equipped with the hysteresis loop function, and the hysteresis loop function is used for carrying out the time delay with controller 170 to switching power supply's operating mode and switches over to avoid when switching power supply output signal is undulant, controller 170 control switching power supply's operating mode makes a round trip to switch between underload and heavy load, thereby improves the stability of loop, and then can reduce switching power supply's total harmonic distortion, improves switching power supply's power factor. Therefore, the adverse effect of the switching power supply on the quality of the power grid can be reduced, and the compatibility of the switching power supply is improved.

The embodiment of the present application also provides a power supply system, which includes the load detection circuit 10 in any one of the above embodiments.

Specifically, the load detection circuit 10 includes a first amplification circuit 110, a first conversion circuit 120, a second amplification circuit 130, a second conversion circuit 140, and a controller 170. A first input terminal of the first amplifying circuit 110 is configured to be connected to a first output terminal of the switching power supply, a second input terminal of the first amplifying circuit 110 is configured to be connected to a second output terminal of the switching power supply, and the first amplifying circuit 110 is configured to amplify a voltage difference between the first input terminal and the second input terminal of the first amplifying circuit 110. A first end of the first conversion circuit 120 is connected to an output end of the first amplification circuit 110, a second end of the first conversion circuit 120 is used for being connected to a ground GND, a third end of the first conversion circuit 120 is connected to a first input end of the controller 170, the first conversion circuit 120 is used for converting a voltage signal into a current signal, and the controller 170 is used for detecting a current at the third end of the first conversion circuit 120 to obtain a first current value. A first input terminal of the second amplifying circuit 130 is connected to the output terminal of the first amplifying circuit 110, a second input terminal of the second amplifying circuit 130 is connected to the ground GND, and the second amplifying circuit 130 is configured to amplify a voltage difference between the first input terminal and the second input terminal of the second amplifying circuit 130. A first end of the second conversion circuit 140 is connected to the output end of the second amplification circuit 130, a second end of the second conversion circuit 140 is used for being connected to the ground GND, a third end of the second conversion circuit 140 is connected to a second input end of the controller 170, the second conversion circuit 140 is used for converting the voltage signal into the current signal, and the controller 170 is used for detecting the current at the third end of the second conversion circuit 140 to obtain a second current value. The controller 170 is configured to determine a load state of the switching power supply according to a magnitude relationship between the first current value and the preset current value and a magnitude relationship between the second current value and the preset current value.

In some embodiments, the first amplification circuit 110 includes: operational amplifier A1, resistor R1, resistor R2, resistor R3, capacitor C1 and capacitor C2. The operational amplifier a1 has a non-inverting input terminal, an inverting input terminal, and an operational output terminal, and the operational output terminal of the operational amplifier a1 is connected to the first terminal of the first converting circuit 120 and the first input terminal of the second amplifying circuit 130. A first terminal of the resistor R1 is used for being connected with a first output terminal of the switching power supply, and a second terminal of the resistor R1 is connected with a non-inverting input terminal of the operational amplifier a 1. The first end of the resistor R2 is connected to the second end of the resistor R1, and the second end of the resistor R2 is connected to the ground GND. The first end of the resistor R3 is used for being connected with the second output end of the switching power supply, and the second end of the resistor R3 is connected with the inverting input end of the operational amplifier a 1. The first plate of the capacitor C1 is connected to the first terminal of the resistor R1, and the second plate of the capacitor C1 is connected to the ground GND. The first plate of the capacitor C2 is used for connecting with the ground GND, and the second plate of the capacitor C2 is connected with the first end of the resistor R3.

In some embodiments, the operational amplifier a1 further has a power input VINA1 and a power output VOUTA1, the power output VOUTA1 being for connection to ground GND. The first amplification circuit 110 further includes: the circuit comprises a resistor R4, a resistor R5, a resistor R6, a resistor R7, a resistor R8, a capacitor C3, a capacitor C4, a capacitor C5 and a diode D1. A first terminal of the resistor R4 is used for connection with the power supply V1, and a second terminal of the resistor R4 is connected with the power supply input terminal VINA1 of the operational amplifier a 1. A first terminal of the resistor R5 is connected to a second terminal of the resistor R4, and a second terminal of the resistor R5 is connected to the non-inverting input terminal of the operational amplifier a 1. A first terminal of the resistor R6 is used for connection with the power supply V2, and a second terminal of the resistor R6 is connected with the power supply input terminal VINA1 of the operational amplifier a 1. A first terminal of the resistor R7 is connected to a second terminal of the resistor R6, and a second terminal of the resistor R7 is connected to the inverting input terminal of the operational amplifier a 1. A first terminal of the resistor R8 is connected to the inverting input terminal of the operational amplifier a1, and a second terminal of the resistor R8 is connected to the operational amplifier output terminal of the operational amplifier a 1. The first plate of the capacitor C3 is connected to the non-inverting input of the operational amplifier a1, and the second plate of the capacitor C3 is connected to the ground GND. The first plate of the capacitor C4 is connected to the power input VINA1 of the operational amplifier a1, and the second plate of the capacitor C4 is connected to the ground GND. The anode of the diode D1 is connected to the ground GND, and the cathode of the diode D1 is connected to the inverting input terminal of the operational amplifier a 1. The first plate of the capacitor C5 is connected with the inverting input terminal of the operational amplifier A1, and the second plate of the capacitor C5 is connected with the operational amplifier output terminal of the operational amplifier A1.

In some embodiments, the first conversion circuit 120 includes: resistor R9 and capacitor C6. A first terminal of the resistor R9 is connected to the output terminal of the first amplifying circuit 110, and a second terminal of the resistor R9 is connected to a first input terminal of the controller 170. The first plate of the capacitor C6 is connected to the second terminal of the resistor R9, and the second plate of the capacitor C6 is connected to the ground GND.

In some embodiments, the load detection circuit 10 further includes: resistor R10 and capacitor C7. The first end of the resistor R10 is connected to the output end of the first amplifying circuit 110, the second end of the resistor R10 is connected to the third input end of the controller 170, and the controller 170 is configured to detect the current at the second end of the resistor R10 to obtain a third current value. The first plate of the capacitor C7 is connected to the second terminal of the resistor R10, and the second plate of the capacitor C7 is connected to the ground GND. The load state includes a heavy load state and a light load state, the heavy load state indicates that the load power of the switching power supply is greater than the preset power, the light load state indicates that the load power of the switching power supply is less than or equal to the preset power, and the controller 170 is configured to perform loop calculation of the switching power supply according to the third current value when the switching power supply is in the heavy load state.

In some embodiments, the second amplification circuit 130 includes: operational amplifier A2, resistor R11, resistor R12, resistor R13, resistor R14 and capacitor C8. The operational amplifier a2 has a non-inverting input terminal, an inverting input terminal, and an operational output terminal, and the operational output terminal of the operational amplifier a2 is connected to the first terminal of the second switching circuit 140. A first terminal of the resistor R11 is connected to the output terminal of the first amplifier circuit 110, and a second terminal of the resistor R11 is connected to the non-inverting input terminal of the operational amplifier a 2. A first terminal of the resistor R12 is for connection to a power supply V2, and a second terminal of the resistor R12 is connected to the non-inverting input of the operational amplifier a 2. A first terminal of the resistor R13 is connected to the inverting input terminal of the operational amplifier a2, and a second terminal of the resistor R13 is connected to the ground GND. A first terminal of the resistor R14 is connected to the inverting input terminal of the operational amplifier a2, and a second terminal of the resistor R14 is connected to the operational amplifier output terminal of the operational amplifier a 2. The first plate of the capacitor C8 is connected with the inverting input terminal of the operational amplifier A2, and the second plate of the capacitor C8 is connected with the operational amplifier output terminal of the operational amplifier A2.

In some embodiments, the second conversion circuit 140 includes: resistor R15 and capacitor C9. A first terminal of the resistor R15 is connected to the output terminal of the second amplifying circuit 130, and a second terminal of the resistor R15 is connected to a second input terminal of the controller 170. The first plate of the capacitor C9 is connected to the second terminal of the resistor R15, and the second plate of the capacitor C9 is connected to the ground GND.

In some embodiments, the load detection circuit 10 further comprises: resistor R16 and capacitor C10. The first end of the resistor R16 is connected to the output end of the second amplifying circuit 130, the second end of the resistor R16 is connected to the fourth input end of the controller 170, and the controller 170 is configured to detect the current at the second end of the resistor R16 to obtain a fourth current value. The first plate of the capacitor C10 is connected with the second end of the resistor R16, and the second plate of the capacitor C10 is connected with the ground GND. The load state includes a heavy load state and a light load state, the heavy load state indicates that the load power of the switching power supply is greater than the preset power, the light load state indicates that the load power of the switching power supply is less than or equal to the preset power, and the controller 170 is configured to perform loop calculation of the switching power supply according to the fourth current value when the switching power supply is in the light load state.

In some embodiments, the output terminal of the controller 170 is configured to be connected to a control terminal of the switching power supply, and the controller 170 is configured to generate a control signal according to a load state of the switching power supply, and output the control signal from the output terminal of the controller 170 to the control terminal of the switching power supply to switch an operation mode of the switching power supply.

In the power supply system of the present application, the load detection circuit 10 includes a first amplification circuit 110, a first conversion circuit 120, a second amplification circuit 130, a second conversion circuit 140, and a controller 170. The first amplifying circuit 110 is configured to collect an output signal of the switching power supply and perform first-stage amplification. The first converting circuit 120 is configured to convert the voltage signal output by the first amplifying circuit 110 into a current signal, and the controller 170 detects a current value in the first converting circuit 120 to obtain a first current value. The second amplifying circuit 130 is configured to amplify the voltage signal output by the first amplifying circuit 110. The second converting circuit 140 is configured to convert the voltage signal output by the second amplifying circuit 130 into a current signal, and the controller 170 detects a current value of the second converting circuit 140 to obtain a second current value. When the load detection circuit 10 works, the controller 170 judges the load state of the switching power supply according to the first current value and the second current value, so that the problem that the output signal of the switching power supply exceeds the working range of the second conversion circuit 140 after two-stage amplification when the output signal of the switching power supply is large, and the second conversion circuit 140 cannot work normally can be avoided; the problem that the output signal of the switching power supply is lower than the working range of the first conversion circuit 120 after being amplified by one stage when the output signal is small, so that the first conversion circuit 120 cannot work can be solved. Therefore, the load detection circuit can enlarge the effective collection range of the output signal of the switching power supply by the load detection circuit 10, thereby accurately judging the load state of the switching power supply. The load detection circuit 10 may further include a third conversion circuit 150 and a fourth conversion circuit 160. The third converting circuit 150 is also configured to convert the voltage signal output by the first amplifying circuit 110 into a current signal, and the filter capacitance of the first converting circuit 120 is greater than the filter capacitance of the third converting circuit 150. The controller 170 detects the current value in the third converting circuit 150 to obtain a third current value. The fourth converting circuit 160 is also used for converting the voltage signal output by the second amplifying circuit 130 into a current signal, and the filter capacitance value of the second converting circuit 140 is greater than that of the fourth converting circuit 160. The controller 170 detects the current value in the fourth converting circuit 160 to obtain a fourth current value. The precision of the third current value is higher when the switching power supply is in a heavy load state; and the fourth current value has higher precision when the switching power supply is in a light load state. Therefore, the controller 170 performs loop calculation of the switching power supply according to the third current value when the switching power supply is in the heavy load state, and performs loop calculation of the switching power supply according to the fourth current value when the switching power supply is in the light load state, so that the loop calculation can be more accurate. According to the load detection circuit 10, the controller 170 can also judge the load state of the switching power supply according to the first current value, the second current value and the load power of the switching power supply, so that the judgment of the controller 170 on the load state of the switching power supply is more accurate, and the influence of the instability of the output signal of the switching power supply on the judgment result of the controller 170 is avoided. This controller 170 can also be equipped with the hysteresis loop function, and the hysteresis loop function is used for carrying out the time delay with controller 170 to switching power supply's operating mode and switches over to avoid when switching power supply output signal is undulant, controller 170 control switching power supply's operating mode makes a round trip to switch between underload and heavy load, thereby improves the stability of loop, and then can reduce switching power supply's total harmonic distortion, improves switching power supply's power factor. Therefore, the adverse effect of the switching power supply on the quality of the power grid can be reduced, and the compatibility of the switching power supply is improved.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A load detection circuit, comprising: the circuit comprises a first amplifying circuit, a first converting circuit, a second amplifying circuit, a second converting circuit and a controller;

2. The load detection circuit of claim 1, wherein the first amplification circuit comprises: an operational amplifier A1, a resistor R1, a resistor R2, a resistor R3, a capacitor C1 and a capacitor C2;

3. The load detection circuit of claim 2, wherein the operational amplifier a1 further has a power input VINA1 and a power output VOUTA1, the power output VOUTA1 being for connection to the ground GND;

4. The load detection circuit of claim 1, wherein the first conversion circuit comprises: a resistor R9 and a capacitor C6;

5. The load detection circuit of any of claims 1-4, further comprising: a resistor R10 and a capacitor C7;

6. The load detection circuit of claim 1, wherein the second amplification circuit comprises: an operational amplifier A2, a resistor R11, a resistor R12, a resistor R13, a resistor R14 and a capacitor C8;

7. The load detection circuit of claim 1, wherein the second conversion circuit comprises: a resistor R15 and a capacitor C9;

8. The load detection circuit according to any one of claims 1 to 4 and 6 to 7, further comprising: a resistor R16 and a capacitor C10;

9. The load detection circuit according to any one of claims 1 to 4 and 6 to 7, wherein the output terminal of the controller is configured to be connected to the control terminal of the switching power supply, and the controller is configured to generate a control signal according to a load state of the switching power supply, and output the control signal from the output terminal of the controller to the control terminal of the switching power supply to switch an operation mode of the switching power supply.

10. A power supply system comprising a switching power supply and a load detection circuit as claimed in any one of claims 1 to 9.