Power supply circuit for heat preservation bag and heat preservation bag

Abstract

The invention discloses a power supply circuit for a heat preservation bag and the heat preservation bag, the power supply circuit is used for providing electric energy for a heating source of the heat preservation bag when being externally connected with an alternating current power supply or a direct current power supply, and the power supply circuit comprises an alternating current power supply circuit and a direct current power supply circuit, a heating source of the heat preservation bag comprises soft cable type electric heating elements of a first heating electric heating wire, a second heating electric heating wire and a third heating electric heating wire. The alternating current power supply circuit is used for converting an external alternating current power supply into a first direct current and outputting the first direct current to the first heating electric heating wire; and the direct current power supply circuit is used for outputting an external direct current first power supply or a direct current second power supply to the second heating electric heating wire and the third heating electric heating wire which are correspondingly connected. Due to the fact that the heat energy output powers of the first heating electric heating wire, the second heating electric heating wire and the third heating electric heating wire are the same, the heat preservation bag supports power supply of different external power sources, and the same heat preservation effect can also be guaranteed under the condition that the heat preservation bag is externally connected with different power sources.

Description

Technical Field

[0001] The invention relates to the technical field of electric heating, and in particular to a power supply circuit for a heat preservation bag and a heat preservation bag. Background Art

[0002] In real life, people always need to use insulation bags to keep warm food warm. However, no matter how good the insulation bag is, the heat of the food will still disappear over time and eventually become cold. The difference between good and bad insulation bags lies only in the length of time they can keep the food warm. If the food gets cold after being placed for too long, it will seriously affect the taste of the food. Some people cannot eat cold food due to gastrointestinal problems and can only choose to discard it, resulting in food waste. If you choose to reheat the food, you need to find an external heating device (such as a microwave oven). If you cannot find it, you cannot reheat the food, and the heating conditions are greatly limited. In order to solve the above problems, an electric heating insulation bag has appeared on the market. A heating layer is set in the bottom, top and / or surrounding compartments of the insulation bag to convert the electric energy of the external power supply into heat energy through the heating layer to provide a heat source for the insulation bag. However, this type of product only supports one external power supply (mains power or DC power adapter). The original intention of using insulation bags is to be portable, and the single type of external power supply greatly limits the application and popularity of electric heating insulation bags. Therefore, it is necessary to design an electric heating insulation bag that supports multiple types of external power supplies. Summary of the invention

[0003] The main technical problem solved by the present invention is to enable the thermal insulation bag to adapt to a variety of external power sources.

[0004] According to the first aspect, an embodiment provides a power supply circuit for providing electric energy to the heating source of the thermal insulation bag when an AC power supply or a DC power supply is externally connected, the power supply circuit comprising an AC power supply circuit and a DC power supply circuit; the heating source of the thermal insulation bag is a soft cable type electric heating element, and the soft cable type electric heating element comprises a first heating electric heating wire, a second heating electric heating wire and a third heating electric heating wire; The AC power supply circuit is electrically connected to the first heating wire; when the AC power supply circuit is connected to the AC power supply, the AC power supply is converted into a first DC power and then output to the first heating wire, so that the first DC power is used as a heating power supply for the first heating wire; The DC power supply circuit is electrically connected to the second heating wire and the third heating wire respectively; when the DC power supply circuit is externally connected to the DC power supply, the DC power supply is output to the second heating wire or the third heating wire to provide heating power for the second heating wire or the third heating wire; wherein the external DC power supply is a first DC power supply or a second DC power supply, and the supply voltage of the first DC power supply is less than the supply voltage of the second DC power supply; when the DC power supply circuit is externally connected to the first DC power supply, the DC power supply circuit uses the first DC power supply as the heating power supply for the second heating wire; when the DC power supply circuit is externally connected to the second DC power supply, the DC power supply circuit uses the second DC power supply as the heating power supply for the third heating wire; When the first heating wire, the second heating wire and the third heating wire are respectively used as heating sources of the heat preservation bag, their respective heat energy output powers are the same.

[0005] In one embodiment, the external AC power supply is a first AC power supply or a second AC power supply, and the supply voltage of the first AC power supply is greater than the supply voltage of the second AC power supply; When the AC power supply circuit is externally connected to the first AC power supply or the second AC power supply, the first AC power supply or the second AC power supply is converted into the first DC power and then output to the first heating wire, and the first DC power is used as the heating power supply of the first heating wire.

[0006] In one embodiment, the AC power supply circuit includes an AC connection circuit, a first reference voltage acquisition circuit, a first comparison circuit, a first control circuit and a first switching circuit; The AC connection circuit includes an AC positive connection terminal, an AC negative connection terminal and an AC output terminal; the AC positive connection terminal of the AC connection circuit is used to connect to the positive output terminal of the external AC power supply, and the AC negative connection terminal of the AC connection circuit is used to connect to the negative output terminal of the external AC power supply; the AC output terminal of the AC connection circuit is connected to the first reference voltage acquisition circuit, the first switching circuit and the first comparison circuit, and is used to output the electric energy of the external AC power supply to the first reference voltage acquisition circuit, the first switching circuit and the first comparison circuit; The first reference voltage acquisition circuit includes a first AC input terminal and a reference voltage output terminal, the first AC input terminal of the first reference voltage acquisition circuit is connected to the AC output terminal of the AC connection circuit, and the reference voltage output terminal of the first reference voltage acquisition circuit is connected to the first comparison circuit and the first switching circuit; the first reference voltage acquisition circuit is used to convert the electric energy of the AC power supply into a first reference voltage source of a DC voltage value having a preset voltage value, and output the first reference voltage source to the first comparison circuit and the first switching circuit through the reference voltage output terminal of the first reference voltage acquisition circuit; The first comparison circuit includes an AC power input terminal, a reference power input terminal and a comparison result output terminal; the AC power input terminal of the first comparison circuit is connected to the AC output terminal of the AC connection circuit, the reference power input terminal of the first comparison circuit is connected to the reference voltage output terminal of the first reference voltage acquisition circuit, and the comparison result output terminal of the first comparison circuit is connected to the first control circuit; the first comparison circuit is used to convert the power of the AC power supply into a first DC sampling voltage source, and compare the voltages of the first sampling voltage source and the first reference voltage source, and output a first result electrical signal to the first control circuit according to the comparison result; when the AC power supply circuit is externally connected to the AC first power supply, the first result electrical signal is a high level signal, and when the AC power supply circuit is externally connected to the AC second power supply, the first result electrical signal is a low level signal; The first control circuit includes a comparison signal input terminal and a control signal output terminal; the comparison signal input terminal of the first control circuit is connected to the comparison result output terminal of the first comparison circuit, and the control signal output terminal of the first control circuit is connected to the first switching circuit; the first control circuit is used to output a grounded pull-down signal to the first switching circuit according to the first result electrical signal, and when the first result electrical signal is a high-level signal, the control signal output terminal is grounded, and when the first result electrical signal is a low-level signal, the control signal output terminal is empty; The first switching circuit includes a control signal input terminal, a reference voltage connection terminal, an AC power input terminal and a thermal power output terminal; the control signal input terminal of the first switching circuit is connected to the control signal output terminal of the first control circuit, the reference voltage connection terminal of the first switching circuit is connected to the reference voltage output terminal of the first reference voltage acquisition circuit, the AC power input terminal of the first switching circuit is connected to the AC output terminal of the AC connection circuit, and the thermal power output terminal of the first switching circuit is electrically connected to the first heating wire; the first switching circuit is used to convert the AC first power input from the AC power input terminal into the first DC power when the control signal input terminal is grounded, and output the converted first DC power to the first heating wire through the thermal power output terminal; the first switching circuit is also used to convert the AC second power input from the AC power input terminal into the first DC power when the control signal input terminal is empty, and output the converted first DC power to the first heating wire through the thermal power output terminal.

[0007] In one embodiment, the AC connection circuit further includes a fuse F1, a first indicator light Led1 and a first current limiting resistor R1; one end of the fuse F1 is connected to the AC positive connection end of the AC connection circuit, and the other end of the fuse F1 is connected to the AC output end of the AC connection circuit; the first indicator light Led1 and the first current limiting resistor R1 are connected in series, one end of the series connection is connected to the AC negative connection end of the AC connection circuit, and the other end of the series connection is connected to the AC output end of the AC connection circuit; And / or, the first reference voltage acquisition circuit also includes a first capacitor C11, a second capacitor C12, a third capacitor C13, a first diode D11, a second diode D12 and a first resistor R11; one end of the first capacitor C11 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the other end is grounded; one end of the second capacitor C12 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the other end is grounded; the anode of the first diode D11 is connected to the cathode of the second diode D12, the cathode of the first diode D11 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the anode of the second diode D12 is grounded; the third capacitor C13 and the first resistor R11 are connected in series, one end of the series connection is connected to the cathode of the second diode D12, and the other end of the series connection is connected to the first AC input end of the first reference voltage acquisition circuit; And / or, the first comparison circuit further includes a third diode D21, a second resistor R21, a third resistor R22, a fourth resistor R23, a fifth resistor R24, a sixth resistor R25 and a first comparator T1; the third diode D21, the second resistor R21 and the third resistor R22 are connected in series, one end of the series connection is connected to the AC power input end of the first comparison circuit, and the other end of the series connection is connected to the positive input end of the first comparator T1; one end of the fourth resistor R23 is grounded, and the other end is connected to the positive input end of the first comparator T1; one end of the fifth resistor R24 ​​is connected to the reference power input end of the first comparison circuit, and the other end is connected to the negative input end of the first comparator T1; one end of the sixth resistor R25 is grounded, and the other end is connected to the negative input end of the first comparator T1; the output end of the first comparator T1 is connected to the comparison result output end of the first comparison circuit; And / or, the first control circuit further includes a seventh resistor R31, an eighth resistor R32 and a transistor Q1; one end of the seventh resistor R31 is grounded, and the other end is connected to the comparison signal input end of the first control circuit; one end of the eighth resistor R32 is connected to the comparison signal input end of the first control circuit, and the other end is connected to the base of the transistor Q1; the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the control signal output end of the first control circuit; And / or, the first switching circuit also includes a ninth resistor R41, a fourth diode D41, a fifth diode D42 and a first electronic switch U1; one end of the ninth resistor R41 is connected to the reference voltage connection end of the first switching circuit, and the other end is connected to the first electronic switch U1; both ends of the fifth diode D42 are connected to the first electronic switch U1; the positive connection end of the fourth diode D41 is connected to the first electronic switch U1 and the AC power input end of the first switching circuit, and the negative connection end of the fourth diode D41 is connected to the thermal power output end of the first switching circuit and the first electronic switch U1; the first electronic switch U1 is used to output the AC first power input from the AC power input end to the first heating wire through the fourth diode D41 when the control signal input end is grounded; the first switching circuit is also used to output the AC second power input from the AC power input end to the first heating wire through the first electronic switch U1 when the control signal input end is empty.

[0008] In one embodiment, the DC power supply circuit includes a DC connection circuit, a second reference voltage acquisition circuit, a sampling circuit, a second comparison circuit and a third comparison circuit; The DC connection circuit includes a DC positive connection terminal, a DC negative connection terminal and a DC output terminal; the DC positive connection terminal of the DC connection circuit is used to connect to the positive output terminal of the external DC power supply, the DC negative connection terminal of the DC connection circuit is used to connect to the negative output terminal of the external DC power supply, and the DC output terminal of the DC connection circuit is connected to the second reference voltage acquisition circuit, the sampling circuit, the second comparison circuit and the third comparison circuit, and is used to output the DC power supply; The second reference voltage acquisition circuit includes a power input terminal and a reference power output terminal, the power input terminal of the second reference voltage acquisition circuit is connected to the DC output terminal of the DC connection circuit, and the reference power output terminal of the second reference voltage acquisition circuit is connected to the sampling circuit, the second comparison circuit and the third comparison circuit; the second reference voltage acquisition circuit is used to convert the DC power supply into a second reference voltage source with a preset voltage value, and output the second reference voltage source through the reference power output terminal; The sampling circuit comprises a first input connection terminal, a second input connection terminal, a first output connection terminal, a second output connection terminal, a third output connection terminal and a fourth output connection terminal; the first input connection terminal of the sampling circuit is connected to the DC output terminal of the DC connection circuit, the second input connection terminal of the sampling circuit is connected to the reference power supply output terminal of the second reference voltage acquisition circuit, the first output connection terminal and the second output connection terminal of the sampling circuit are connected to the second comparison circuit, and the third output connection terminal and the fourth output connection terminal of the sampling circuit are connected to the third comparison circuit; the sampling circuit is used to perform voltage division sampling on the second reference voltage source and the DC power supply respectively, and output the resultant electrical signals of the two voltage division samplings to the second comparison circuit through the first output connection terminal and the second output connection terminal, and then output them to the third comparison circuit through the third output connection terminal and the fourth output connection terminal; The circuit structures of the second comparison circuit and the third comparison circuit are the same, and they respectively include a first comparison input terminal, a second comparison input terminal and a DC power supply output terminal; the first comparison input terminal and the second comparison input terminal of the second comparison circuit are respectively connected to the output first connection terminal and the output second connection terminal of the sampling circuit, the first comparison input terminal and the second comparison input terminal of the third comparison circuit are respectively connected to the output third connection terminal and the output fourth connection terminal of the sampling circuit, the DC power supply output terminal of the second comparison circuit is connected to the second heating wire, and the DC power supply output terminal of the third comparison circuit is connected to the third heating wire; the second comparison circuit is used for, when the DC power supply is the DC first power supply, outputting the DC first power supply to the second heating wire, so as to use the DC first power supply as the heating power supply for the second heating wire; the third comparison circuit is used for, when the DC power supply is the DC second power supply, outputting the DC second power supply to the third heating wire, so as to use the DC second power supply as the heating power supply for the third heating wire.

[0009] In one embodiment, the second reference voltage acquisition circuit further includes a DC conversion circuit Y1, a fourth capacitor C61, a fifth capacitor C62, a sixth capacitor C63 and a sixth diode D61; the anode of the sixth diode D61 is connected to the power input terminal of the second reference voltage acquisition circuit, and the cathode of the sixth diode D61 is connected to the input terminal of the DC conversion circuit Y1; the output terminal of the DC conversion circuit Y1 is connected to the reference power output terminal of the second reference voltage acquisition circuit; One end of the fourth capacitor C61 is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded; One end of the fifth capacitor C62 is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded; One end of the sixth capacitor C63 is connected to the input end of the DC conversion circuit Y1, and the other end is grounded; And / or, the sampling circuit further includes a tenth resistor R71, an eleventh resistor R72, a twelfth resistor R73, a thirteenth resistor R74 and a seventh diode D71; the seventh diode D71 and the tenth resistor R71 are connected in series, one end of the series connection is connected to the input first connection end of the sampling circuit, and the other end of the series connection is connected to the output second connection end and the output third connection end of the sampling circuit; one end of the eleventh resistor R72 is connected to the input second connection end of the sampling circuit, and the other end is grounded; one end of the twelfth resistor R73 is connected to the input second connection end of the sampling circuit, and the other end is connected to the output first connection end and the output fourth connection end of the sampling circuit; one end of the thirteenth resistor R74 is connected to the output first connection end of the sampling circuit, and the other end is grounded.

[0010] In one embodiment, the second reference voltage acquisition circuit also includes a second indicator light Led2 and a second current limiting resistor R2, the second indicator light Led2 and the second current limiting resistor R2 are connected in series, one end of the series connection is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded.

[0011] In one embodiment, the second comparison circuit further includes a second comparator T2, a fourteenth resistor R81, a fifteenth resistor R82, a sixteenth resistor R83, an eighth diode D81, a second electronic switch U2, and a second triode Q2; One end of the fourteenth resistor R81 is connected to the output end of the second comparator T2, and the other end is connected to the base of the second transistor Q2; one end of the fifteenth resistor R82 is connected to the base of the second transistor Q2, and the other end is grounded; the emitter of the second transistor Q2 is grounded, and the collector of the second transistor Q2 is connected to the second electronic switch U2; both ends of the eighth diode D81 are connected to the second electronic switch U2; one end of the sixteenth resistor R83 is connected to the second electronic switch U2, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit; the second electronic switch U2 is also connected to the DC output end of the DC connection circuit; And / or, the third comparison circuit further includes a third comparator T3, a seventeenth resistor 91, an eighteenth resistor R92, a nineteenth resistor R93, a ninth diode D91, a third electronic switch U3 and a third triode Q3; One end of the seventeenth resistor R91 is connected to the output end of the third comparator T3, and the other end is connected to the base of the third triode Q3; one end of the eighteenth resistor R92 is connected to the base of the third triode Q3, and the other end is grounded; the emitter of the third triode Q3 is grounded, and the collector of the third triode Q3 is connected to the third electronic switch U3; both ends of the ninth diode D91 are connected to the third electronic switch U3; one end of the nineteenth resistor R93 is connected to the third electronic switch U3, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit; the third electronic switch U3 is also connected to the DC output end of the DC connection circuit.

[0012] According to the second aspect, an embodiment provides a thermal insulation bag, comprising the power supply circuit as described in the first aspect.

[0013] In one embodiment, the insulation bag also includes a soft rope type electric heating element, which is a three-core heating wire. The three-core heating wire includes an insulating protective wire sheath and a first heating wire, a second heating wire, and a third heating wire that are each insulated and intertwined in the insulating protective wire sheath.

[0014] According to the thermal insulation bag of the above embodiment, since the thermal energy output power of the first, second and third heating wires used as the heating source is the same, the thermal insulation bag can support different external power supplies and can ensure the same thermal insulation effect even when different external power supplies are connected. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the structure of a soft-cable electric heating element in an embodiment; Figure 2 A schematic diagram of the structural connection of a power supply circuit in an embodiment; Figure 3 A circuit connection diagram of a power supply circuit in an embodiment; Figure 4 FIG. 4 is a circuit connection diagram of a power supply circuit in another embodiment. DETAILED DESCRIPTION

[0016] The present invention is further described in detail below by specific embodiments in conjunction with the accompanying drawings. Wherein similar elements in different embodiments adopt associated similar element numbers. In the following embodiments, many detailed descriptions are for making the present application better understood. However, those skilled in the art can easily recognize that some features can be omitted in different situations, or can be replaced by other elements, materials, methods. In some cases, some operations related to the present application are not shown or described in the specification, this is to avoid the core part of the present application being overwhelmed by too much description, and for those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations according to the description in the specification and the general technical knowledge in the art.

[0017] In addition, the features, operations or characteristics described in the specification can be combined in any appropriate manner to form various implementations. At the same time, the steps or actions in the method description can also be interchanged or adjusted in a manner that is obvious to those skilled in the art. Therefore, the various sequences in the specification and the drawings are only for the purpose of clearly describing a certain embodiment and are not meant to be a required sequence, unless otherwise specified that a certain sequence must be followed.

[0018] The serial numbers assigned to the components herein, such as "first", "second", etc., are only used to distinguish the objects described and do not have any order or technical meaning. The "connection" and "coupling" mentioned in this application, unless otherwise specified, include direct and indirect connections (couplings).

[0019] In the prior art, the electric heat source of the insulation bag uses a heating wire. Even if it supports AC power and DC power as power supplies, it cannot guarantee that the heating power is the same when the two power supplies are supplied, which means that the insulation bag has different insulation effects when the power supplies are different. In the embodiment of the present application, the heating source of the insulation bag is a soft cable type electric heating element including a first heating wire, a second heating wire and a third heating wire. Different external voltages are heated by corresponding adaptive heating wires, so that even if different external power supplies are connected, the insulation bag can still have the same insulation effect.

[0020] Embodiment 1: The heat preservation bag disclosed in the embodiment of the present application comprises a bottom surface, a top surface and four side surfaces, which together form a closed space for heat preservation. The bottom surface, the top surface and the four side surfaces are respectively provided with heat preservation layers. In one embodiment, the bottom surface, the top surface and / or the four side surfaces are also respectively provided with heating layers, and a soft cable-type electric heating element is coiled on the heating layer.

[0021] Please refer to Figure 1, is a schematic diagram of the structure of a soft-cable electric heating element in an embodiment. In one embodiment, the soft-cable electric heating element 100 is a three-core heating wire, which includes an insulating protective wire sheath 104 and a first heating wire 101, a second heating wire 102 and a third heating wire 103 which are insulated and intertwined in the insulating protective wire sheath 104.

[0022] Please refer to Figure 2 , is a schematic diagram of the structural connection of a power supply circuit in an embodiment, the thermal insulation bag further includes a power supply circuit 200, which is used to provide electric energy for the heating source of the thermal insulation bag when an AC power supply or a DC power supply is connected. The power supply circuit 200 includes an AC power supply circuit 201 and a DC power supply circuit 202, and the heating source of the thermal insulation bag is a soft cable type electric heating element 100, and the soft cable type electric heating element 100 includes a first heating electric heating wire L10, a second heating electric heating wire L20 and a third heating electric heating wire L30.

[0023] The AC power supply circuit 201 is electrically connected to the first heating wire L10. When the AC power supply circuit 201 is used for an external AC power supply, the AC power supply is converted into a first DC power and then output to the first heating wire, so that the first DC power is used as the heating power supply for the first heating wire. The DC power supply circuit 202 is electrically connected to the second heating wire L20 and the third heating wire L30 respectively. When the DC power supply circuit 202 is used for an external DC power supply, the DC power supply is output to the second heating wire L20 or the third heating wire L30, so as to provide heating power for the second heating wire L20 or the third heating wire L30. Among them, the external DC power supply is a DC first power supply or a DC second power supply, and the power supply voltage of the DC first power supply is less than the power supply voltage of the DC second power supply. In one embodiment, the power supply voltage of the DC first power supply is 12 volts. In one embodiment, the power supply voltage of the DC second power supply is 24 volts. When the DC power supply circuit 202 is connected to a first DC power supply, the DC power supply circuit 202 uses the first DC power supply as a heating power supply for the second heating wire L20. When the DC power supply circuit 202 is connected to a second DC power supply, the DC power supply circuit 202 uses the second DC power supply as a heating power supply for the third heating wire L30. When the first heating wire L10, the second heating wire L20, and the third heating wire L30 are respectively used as heating sources for the heat preservation bag, their respective heat energy output powers are the same.

[0024] In one embodiment, the external AC power source is an AC first power source or an AC second power source, and the supply voltage of the AC first power source is greater than the supply voltage of the AC second power source. In one embodiment, the supply voltage of the AC first power source is 230 volts. In one embodiment, the supply voltage of the AC second power source is 120 volts. When the AC power supply circuit 201 is externally connected to the AC first power source or the AC second power source, the AC first power source or the AC second power source is converted into a first direct current and then output to the first heating wire L10, and the first direct current is used as the heating power source of the first heating wire.

[0025] Please refer to Figure 3 , is a circuit connection diagram of a power supply circuit in an embodiment. In an embodiment, the AC power supply circuit 201 includes an AC connection circuit 10, a first reference voltage acquisition circuit 11, a first comparison circuit 12, a first control circuit 13 and a first switching circuit 14. The AC connection circuit 10 includes an AC positive connection terminal, an AC negative connection terminal and an AC output terminal. The AC positive connection terminal of the AC connection circuit 10 is used to connect to the positive output terminal of an external AC power source. The AC negative connection terminal of the AC connection circuit 10 is used to connect to the negative output terminal of an external AC power source. The AC output terminal of the AC connection circuit 10 is connected to the first reference voltage acquisition circuit 11, the first switching circuit 14 and the first comparison circuit 12, and is used to output the electric energy of the external AC power source to the first reference voltage acquisition circuit 11, the first switching circuit 14 and the first comparison circuit 12.

[0026] The first reference voltage acquisition circuit 11 includes a first AC input terminal and a reference voltage output terminal. The first AC input terminal of the first reference voltage acquisition circuit 11 is connected to the AC output terminal of the AC connection circuit 10, and the reference voltage output terminal of the first reference voltage acquisition circuit 11 is connected to the first comparison circuit 12 and the first switching circuit 14. The first reference voltage acquisition circuit 11 is used to convert the electric energy of the AC power supply into a DC first reference voltage source VC1 with a preset voltage value, and output the first reference voltage source VC1 to the first comparison circuit 12 and the first switching circuit 14 through the reference voltage output terminal of the first reference voltage acquisition circuit 11.

[0027] The first comparison circuit 12 includes an AC power input terminal, a reference power input terminal and a comparison result output terminal. The AC power input terminal of the first comparison circuit 12 is connected to the AC output terminal of the AC connection circuit 10, the reference power input terminal of the first comparison circuit 12 is connected to the reference voltage output terminal of the first reference voltage acquisition circuit 11, and the comparison result output terminal of the first comparison circuit 12 is connected to the first control circuit 13. The first comparison circuit 12 is used to convert the power of the AC power supply into a first DC sampling voltage source, and compare the voltages of the first sampling voltage source and the first reference voltage source VC1, and output a first result electrical signal to the first control circuit 13 according to the comparison result. When the AC power supply circuit 201 is externally connected to the AC first power supply, the first result electrical signal is a high level signal, and when the AC power supply circuit 201 is externally connected to the AC second power supply, the first result electrical signal is a low level signal.

[0028] The first control circuit 13 includes a comparison signal input terminal and a control signal output terminal. The comparison signal input terminal of the first control circuit 13 is connected to the comparison result output terminal of the first comparison circuit 12. The control signal output terminal of the first control circuit 13 is connected to the first switching circuit 14. The first control circuit 13 is used to output a grounded pull-down signal to the first switching circuit 14 according to the first result electrical signal, and when the first result electrical signal is a high-level signal, the control signal output terminal is grounded, and when the first result electrical signal is a low-level signal, the control signal output terminal is empty.

[0029] The first switching circuit 14 includes a control signal input terminal, a reference voltage connection terminal, an AC power input terminal and a thermal power output terminal. The control signal input terminal of the first switching circuit 14 is connected to the control signal output terminal of the first control circuit 13, the reference voltage connection terminal of the first switching circuit 14 is connected to the reference voltage output terminal of the first reference voltage acquisition circuit 11, the AC power input terminal of the first switching circuit 14 is connected to the AC output terminal of the AC connection circuit 10, and the thermal power output terminal of the first switching circuit 14 is electrically connected to the first heating wire L10. The first switching circuit 14 is used to convert the AC first power input from the AC power input terminal into a first DC power when the control signal input terminal is grounded, and output the converted first DC power to the first heating wire L10 through the thermal power output terminal. The first switching circuit 14 is also used to convert the AC second power input from the AC power input terminal into a first DC power when the control signal input terminal is empty, and output the converted first DC power to the first heating wire L10 through the thermal power output terminal.

[0030] In one embodiment, the AC connection circuit 10 further includes a fuse F1, a first indicator light Led1, and a first current limiting resistor R1. One end of the fuse F1 is connected to the AC positive connection end of the AC connection circuit 10, and the other end of the fuse F1 is connected to the AC output end of the AC connection circuit 10. The first indicator light Led1 and the first current limiting resistor R1 are connected in series, and one end of the series connection is connected to the AC negative connection end of the AC connection circuit 10, and the other end of the series connection is connected to the AC output end of the AC connection circuit 10.

[0031] In one embodiment, the first reference voltage acquisition circuit 11 further includes a first capacitor C11, a second capacitor C12, a third capacitor C13, a first diode D11, a second diode D12 and a first resistor R11. One end of the first capacitor C11 is connected to the reference voltage output end of the first reference voltage acquisition circuit 11, and the other end is grounded. One end of the second capacitor C12 is connected to the reference voltage output end of the first reference voltage acquisition circuit 11, and the other end is grounded. The anode of the first diode D11 is connected to the cathode of the second diode D12, the cathode of the first diode D11 is connected to the reference voltage output end of the first reference voltage acquisition circuit 11, and the anode of the second diode D12 is grounded. The third capacitor C13 and the first resistor R11 are connected in series, one end of the series connection is connected to the cathode of the second diode D12, and the other end of the series connection is connected to the first AC input end of the first reference voltage acquisition circuit 11.

[0032] In one embodiment, the first comparison circuit 12 further includes a third diode D21, a second resistor R21, a third resistor R22, a fourth resistor R23, a fifth resistor R24, a sixth resistor R25 and a first comparator T1. The third diode D21, the second resistor R21 and the third resistor R22 are connected in series in sequence, one end of the series connection is connected to the AC power input terminal of the first comparison circuit 12, and the other end of the series connection is connected to the positive input terminal of the first comparator T1. One end of the fourth resistor R23 is grounded, and the other end is connected to the positive input terminal of the first comparator T1. One end of the fifth resistor R24 ​​is connected to the reference power input terminal of the first comparison circuit 12, and the other end is connected to the negative input terminal of the first comparator T1. One end of the sixth resistor R25 is grounded, and the other end is connected to the negative input terminal of the first comparator T1. The output terminal of the first comparator T1 is connected to the comparison result output terminal of the first comparison circuit 12.

[0033] In one embodiment, the first control circuit 13 further includes a seventh resistor R31, an eighth resistor R32 and a transistor Q1. One end of the seventh resistor R31 is grounded, and the other end is connected to the comparison signal input end of the first control circuit 13. One end of the eighth resistor R32 is connected to the comparison signal input end of the first control circuit 13, and the other end is connected to the base of the transistor Q1. The emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the control signal output end of the first control circuit 13.

[0034] In one embodiment, the first switching circuit 14 further includes a ninth resistor R41, a fourth diode D41, a fifth diode D42 and a first electronic switch U1. One end of the ninth resistor R41 is connected to the reference voltage connection end of the first switching circuit 14, and the other end is connected to the first electronic switch U1. Both ends of the fifth diode D42 are connected to the first electronic switch U1. The positive connection end of the fourth diode D41 is connected to the first electronic switch U1 and the AC power input end of the first switching circuit 14, and the negative connection end of the fourth diode D41 is connected to the thermal power output end of the first switching circuit 14 and the first electronic switch U1. The first electronic switch U1 is used to output the AC first power input from the AC power input end to the first heating wire L10 through the fourth diode D41 when the control signal input end is grounded. The first switching circuit 14 is also used to output the AC second power input from the AC power input end to the first heating wire L10 through the first electronic switch U1 when the control signal input end is empty.

[0035] In one embodiment, the DC power supply circuit 202 includes a DC connection circuit 15, a second reference voltage acquisition circuit 16, a sampling circuit 17, a second comparison circuit 18, and a third comparison circuit 19. The DC connection circuit 15 includes a DC positive connection terminal, a DC negative connection terminal, and a DC output terminal. The DC positive connection terminal of the DC connection circuit 15 is used to connect to the positive output terminal of an external DC power supply, the DC negative connection terminal of the DC connection circuit 15 is used to connect to the negative output terminal of an external DC power supply, and the DC output terminal of the DC connection circuit 15 is connected to the second reference voltage acquisition circuit 16, the sampling circuit 17, the second comparison circuit 18, and the third comparison circuit 19 for outputting DC power. The second reference voltage acquisition circuit 16 includes a power input terminal and a reference power output terminal, the power input terminal of the second reference voltage acquisition circuit 16 is connected to the DC output terminal of the DC connection circuit 15, and the reference power output terminal of the second reference voltage acquisition circuit 16 is connected to the sampling circuit 17, the second comparison circuit 18, and the third comparison circuit 19. The second reference voltage acquisition circuit 16 is used to convert the DC power supply into a second reference voltage source VC2 of a preset voltage value, and output the second reference voltage source VC2 through the reference power output terminal. The sampling circuit 17 includes a first input connection terminal, a second input connection terminal, a first output connection terminal, a second output connection terminal, a third output connection terminal and a fourth output connection terminal. The first input connection terminal of the sampling circuit 17 is connected to the DC output terminal of the DC connection circuit 15, the second input connection terminal of the sampling circuit 17 is connected to the reference power output terminal of the second reference voltage acquisition circuit 16, the first output connection terminal and the second output connection terminal of the sampling circuit 17 are connected to the second comparison circuit 18, and the third output connection terminal and the fourth output connection terminal of the sampling circuit 17 are connected to the third comparison circuit 19. The sampling circuit 17 is used to perform voltage division sampling on the second reference voltage source and the DC power supply respectively, and output the resultant electrical signals of the two voltage division samplings to the second comparison circuit 18 through the first output connection terminal and the second output connection terminal, and then output to the third comparison circuit 19 through the third output connection terminal and the fourth output connection terminal.

[0036] In one embodiment, the circuit structures of the second comparison circuit 18 and the third comparison circuit 19 are the same, and they respectively include a first comparison input terminal, a second comparison input terminal, and a DC power supply output terminal. The first comparison input terminal and the second comparison input terminal of the second comparison circuit 18 are respectively connected to the output first connection terminal and the output second connection terminal of the sampling circuit 17, and the first comparison input terminal and the second comparison input terminal of the third comparison circuit 19 are respectively connected to the output third connection terminal and the output fourth connection terminal of the sampling circuit 17. The DC power supply output terminal of the second comparison circuit 18 is connected to the second heating wire L20, and the DC power supply output terminal of the third comparison circuit 19 is connected to the third heating wire L30. The second comparison circuit 18 is used to output the DC first power supply DC1 to the second heating wire L20 when the DC power supply is the DC first power supply DC1, so as to use the DC first power supply DC1 as the heating power supply of the second heating wire L20. The third comparison circuit 19 is used for outputting the second DC power supply DC2 to the third heating wire L30 when the DC power supply is the second DC power supply DC2, so as to use the second DC power supply DC2 as the heating power supply for the third heating wire L30.

[0037] like Figure 3 As shown, the second reference voltage acquisition circuit 16 also includes a DC conversion circuit Y1, a fourth capacitor C61, a fifth capacitor C62, a sixth capacitor C63 and a sixth diode D61. The anode of the sixth diode D61 is connected to the power input terminal of the second reference voltage acquisition circuit 16, the cathode of the sixth diode D61 is connected to the input terminal of the DC conversion circuit Y1, and the output terminal of the DC conversion circuit Y1 is connected to the reference power output terminal of the second reference voltage acquisition circuit 16. One end of the fourth capacitor C61 is connected to the reference power output terminal of the second reference voltage acquisition circuit 16, and the other end is grounded. One end of the fifth capacitor C62 is connected to the reference power output terminal of the second reference voltage acquisition circuit 16, and the other end is grounded. One end of the sixth capacitor C63 is connected to the input terminal of the DC conversion circuit Y1, and the other end is grounded.

[0038] In one embodiment, the sampling circuit 17 further includes a tenth resistor R71, an eleventh resistor R72, a twelfth resistor R73, a thirteenth resistor R74 and a seventh diode D71. The seventh diode D71 and the tenth resistor R71 are connected in series, one end of the series connection is connected to the first input connection terminal of the sampling circuit 17, and the other end of the series connection is connected to the second output connection terminal and the third output connection terminal of the sampling circuit 17. One end of the eleventh resistor R72 is connected to the second input connection terminal of the sampling circuit 17, and the other end is grounded. One end of the twelfth resistor R73 is connected to the second input connection terminal of the sampling circuit 17, and the other end is connected to the first output connection terminal and the fourth output connection terminal of the sampling circuit 17. One end of the thirteenth resistor R74 is connected to the first output connection terminal of the sampling circuit 17, and the other end is grounded.

[0039] In one embodiment, the second reference voltage acquisition circuit 16 also includes a second indicator light Led2 and a second current limiting resistor R2. The second indicator light Led2 and the second current limiting resistor R2 are connected in series, one end of the series connection is connected to the reference power supply output end of the second reference voltage acquisition circuit 16, and the other end is grounded.

[0040] In one embodiment, the second comparison circuit 18 further includes a second comparator T2, a fourteenth resistor R81, a fifteenth resistor R82, a sixteenth resistor R83, an eighth diode D81, a second electronic switch U2 and a second triode Q2. One end of the fourteenth resistor R81 is connected to the output end of the second comparator T2, and the other end is connected to the base of the second triode Q2. One end of the fifteenth resistor R82 is connected to the base of the second triode Q2, and the other end is grounded. The emitter of the second triode Q2 is grounded, and the collector of the second triode Q2 is connected to the second electronic switch U2. Both ends of the eighth diode D81 are connected to the second electronic switch U2. One end of the sixteenth resistor R83 is connected to the second electronic switch U2, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit 16. The second electronic switch U2 is also connected to the DC output end of the DC connection circuit 15.

[0041] In one embodiment, the third comparison circuit further includes a third comparator T3, a seventeenth resistor 91, an eighteenth resistor R92, a nineteenth resistor R93, a ninth diode D91, a third electronic switch U3 and a third triode Q3. One end of the seventeenth resistor R91 is connected to the output end of the third comparator T3, and the other end is connected to the base of the third triode Q3. One end of the eighteenth resistor R92 is connected to the base of the third triode Q3, and the other end is grounded. The emitter of the third triode Q3 is grounded, and the collector of the third triode Q3 is connected to the third electronic switch U3. Both ends of the ninth diode D91 are connected to the third electronic switch U3. One end of the nineteenth resistor R93 is connected to the third electronic switch U3, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit 16. The third electronic switch U3 is also connected to the DC output end of the DC connection circuit 15.

[0042] like Figure 2 As shown, in one embodiment, the thermal insulation bag further includes an interface adapter 300, which is used to electrically connect the AC power supply circuit 201 with an external AC power supply, and is also used to electrically connect the DC power supply circuit 202 with an external DC power supply. The interface adapter 300 can only be connected to one AC power supply or one DC power supply at the same time.

[0043] Please refer to Figure 4, is a circuit connection diagram of the power supply circuit in another embodiment, the AC power supply circuit 201 only supports one external AC power supply, that is, the external AC power supply is the AC first power supply. In one embodiment of the present application, the first heating wire L10, the second heating wire L20 and the third heating wire L30 respectively work at different DC voltages. When the interface adapter is connected to the AC power supply, the first indicator light Led1 lights up after power is turned on, and the first DC power obtained by converting the AC first power supply is heated by the first heating wire L10, and the temperature is controlled by temperature control. When the interface adapter is connected to the DC power supply (the DC first power supply 12V or the DC second power supply 24V), the second reference voltage source of 9V is output after being stabilized by the DC conversion circuit Y1. At this time, the second indicator light Led2 lights up, and the sampling circuit divides the 9V second reference voltage source through a resistor to obtain a 3V comparison reference voltage, and outputs it to the positive input end of the second comparator T2 of the second comparison circuit and the negative input end of the third comparator T3 of the third comparison circuit respectively. The sampling circuit then divides the external DC power supply (12V or 24V). When the external power supply is 12V of the DC first power supply, the voltage is 2.3V after voltage division, and the obtained comparison reference voltage is 2.3V; when the external power supply is 24V of the DC second power supply, the voltage is 4.6V after voltage division, and the obtained comparison reference voltage is 4.6V; the comparison reference voltage is then output to the negative input terminal of the second comparator T2 of the second comparison circuit and the positive input terminal of the third comparator T3 of the third comparison circuit. When the DC power supply is the DC first power supply, the second transistor Q2 of the second comparison circuit is turned on, and the second electronic switch U2 of the second comparison circuit outputs the 12V DC power supply DC1 to the second heating wire L20. The DC first power supply is heated by the second heating wire L20, and the temperature is controlled by temperature control. When the DC power supply is 24V of the DC second power supply, the third transistor Q3 of the third comparison circuit is turned on, and the third electronic switch U3 of the third comparison circuit outputs the 24V DC power supply DC2 to the third heating wire L30, and the DC second power supply is heated by the third heating wire L30, and the temperature is controlled by temperature control. The first heating wire L10, the second heating wire L20 and the third heating wire L30 do not interfere with each other, and three voltage sources (AC, DC first power supply and DC second power supply) are realized through a three-core heating wire to generate heat. In one embodiment, the second electronic switch U2 and the third electronic switch U3 are relay switches.

[0044] like Figure 3As shown, in one embodiment of the present application, when the AC power source connected to the interface adapter is 120V, the first reference voltage source obtained by the first reference voltage acquisition circuit is 11.3V, then the negative input end of the first comparator T1 obtains a comparison voltage of about 3.4V, and the positive input end of the first comparator T1 obtains a comparison voltage of 2.15V (divided by resistors R21, R22 and R23). At this time, the output end of the first comparator T1 outputs a low level, and the first transistor Q1 turns off the first electronic switch U1 (in one embodiment, the first electronic switch U1 is a relay SW DPDT, and the relay is not attracted and is in a normally closed state). The first electronic switch U1 allows the 120V AC power to be directly output to the first heating wire L10 without passing through the fourth diode D41 to achieve heating. When the AC power source connected to the interface adapter is 230V, the positive input terminal of the first comparator T1 obtains a 4.13V comparison voltage. At this time, the output terminal of the first comparator T1 outputs a high level, the first transistor Q1 is turned on, the first electronic switch U1 (relay SW DPDT) is turned off, and the 230V AC power passes through the fourth diode D41 to form a power supply circuit for the first heating wire L10, so as to achieve heating through the first heating wire L10. Figure 3 In the power supply circuit shown, four external power sources (120V or 230V AC, 12V or 24V DC) are heated through a three-core heating wire without interfering with each other, and by setting the resistance values ​​of the first heating wire L10, the second heating wire L20 and the third heating wire L30, the heating power of the four different external power sources is ensured to remain consistent.

[0045] The power supply circuit disclosed in the embodiment of the present application is used to provide electric energy for the heating source of the insulation bag when an external AC power supply or a DC power supply is connected, and includes an AC power supply circuit and a DC power supply circuit, wherein the heating source of the insulation bag includes a soft rope-type heating element of a first heating wire, a second heating wire, and a third heating wire. The AC power supply circuit is used to convert the external AC power supply into a first DC power and output it to the first heating wire, and the DC power supply circuit is used to output the external DC first power supply or the DC second power supply to the correspondingly connected second heating wire and the third heating wire. Since the heat output power of the first, second, and third heating wires is the same, the insulation bag can support power supply from different external power supplies and can also ensure the same insulation effect when different external power supplies are connected.

[0046] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. A power supply circuit for a heat preservation bag, used to provide power for a heating source of the heat preservation bag when connected to an external AC power supply or a DC power supply, characterized in that: Including AC power supply circuit and DC power supply circuit; The heating source of the heat preservation bag is a soft cable type electric heating element, and the soft cable type electric heating element includes a first heating wire, a second heating wire and a third heating wire; The AC power supply circuit is electrically connected to the first heating wire; when the AC power supply circuit is connected to the AC power supply, the AC power supply is converted into a first DC power and then output to the first heating wire, so that the first DC power is used as a heating power supply for the first heating wire; The DC power supply circuit is electrically connected to the second heating wire and the third heating wire respectively; when the DC power supply circuit is externally connected to the DC power supply, the DC power supply is output to the second heating wire or the third heating wire to provide heating power for the second heating wire or the third heating wire; wherein the external DC power supply is a first DC power supply or a second DC power supply, and the supply voltage of the first DC power supply is less than the supply voltage of the second DC power supply; when the DC power supply circuit is externally connected to the first DC power supply, the DC power supply circuit uses the first DC power supply as the heating power supply for the second heating wire; when the DC power supply circuit is externally connected to the second DC power supply, the DC power supply circuit uses the second DC power supply as the heating power supply for the third heating wire; When the first heating wire, the second heating wire and the third heating wire are respectively used as heating sources of the heat preservation bag, their respective heat energy output powers are the same.

2. The power supply circuit according to claim 1, characterized in that The external AC power supply is a first AC power supply or a second AC power supply, and the supply voltage of the first AC power supply is greater than the supply voltage of the second AC power supply; When the AC power supply circuit is externally connected to the first AC power supply or the second AC power supply, the first AC power supply or the second AC power supply is converted into the first DC power and then output to the first heating wire, and the first DC power is used as the heating power supply of the first heating wire.

3. The power supply circuit according to claim 2, characterized in that: The AC power supply circuit includes an AC connection circuit, a first reference voltage acquisition circuit, a first comparison circuit, a first control circuit and a first switching circuit; The AC connection circuit includes an AC positive connection terminal, an AC negative connection terminal and an AC output terminal; the AC positive connection terminal of the AC connection circuit is used to connect to the positive output terminal of the external AC power supply, and the AC negative connection terminal of the AC connection circuit is used to connect to the negative output terminal of the external AC power supply; the AC output terminal of the AC connection circuit is connected to the first reference voltage acquisition circuit, the first switching circuit and the first comparison circuit, and is used to output the electric energy of the external AC power supply to the first reference voltage acquisition circuit, the first switching circuit and the first comparison circuit; The first reference voltage acquisition circuit includes a first AC input terminal and a reference voltage output terminal, the first AC input terminal of the first reference voltage acquisition circuit is connected to the AC output terminal of the AC connection circuit, and the reference voltage output terminal of the first reference voltage acquisition circuit is connected to the first comparison circuit and the first switching circuit; the first reference voltage acquisition circuit is used to convert the electric energy of the AC power supply into a first reference voltage source of a DC voltage value having a preset voltage value, and output the first reference voltage source to the first comparison circuit and the first switching circuit through the reference voltage output terminal of the first reference voltage acquisition circuit; The first comparison circuit includes an AC power input terminal, a reference power input terminal and a comparison result output terminal; the AC power input terminal of the first comparison circuit is connected to the AC output terminal of the AC connection circuit, the reference power input terminal of the first comparison circuit is connected to the reference voltage output terminal of the first reference voltage acquisition circuit, and the comparison result output terminal of the first comparison circuit is connected to the first control circuit; the first comparison circuit is used to convert the power of the AC power supply into a first DC sampling voltage source, and compare the voltages of the first sampling voltage source and the first reference voltage source, and output a first result electrical signal to the first control circuit according to the comparison result; when the AC power supply circuit is externally connected to the AC first power supply, the first result electrical signal is a high level signal, and when the AC power supply circuit is externally connected to the AC second power supply, the first result electrical signal is a low level signal; The first control circuit includes a comparison signal input terminal and a control signal output terminal; the comparison signal input terminal of the first control circuit is connected to the comparison result output terminal of the first comparison circuit, and the control signal output terminal of the first control circuit is connected to the first switching circuit; the first control circuit is used to output a grounded pull-down signal to the first switching circuit according to the first result electrical signal, and when the first result electrical signal is a high-level signal, the control signal output terminal is grounded, and when the first result electrical signal is a low-level signal, the control signal output terminal is empty; The first switching circuit includes a control signal input terminal, a reference voltage connection terminal, an AC power input terminal and a thermal power output terminal; the control signal input terminal of the first switching circuit is connected to the control signal output terminal of the first control circuit, the reference voltage connection terminal of the first switching circuit is connected to the reference voltage output terminal of the first reference voltage acquisition circuit, the AC power input terminal of the first switching circuit is connected to the AC output terminal of the AC connection circuit, and the thermal power output terminal of the first switching circuit is electrically connected to the first heating wire; the first switching circuit is used to convert the AC first power input from the AC power input terminal into the first DC power when the control signal input terminal is grounded, and output the converted first DC power to the first heating wire through the thermal power output terminal; the first switching circuit is also used to convert the AC second power input from the AC power input terminal into the first DC power when the control signal input terminal is empty, and output the converted first DC power to the first heating wire through the thermal power output terminal.

4. The power supply circuit according to claim 3, characterized in that: The AC connection circuit also includes a fuse F1, a first indicator light Led1 and a first current limiting resistor R1; one end of the fuse F1 is connected to the AC positive connection end of the AC connection circuit, and the other end of the fuse F1 is connected to the AC output end of the AC connection circuit; the first indicator light Led1 and the first current limiting resistor R1 are connected in series, one end of the series connection is connected to the AC negative connection end of the AC connection circuit, and the other end of the series connection is connected to the AC output end of the AC connection circuit; And / or, the first reference voltage acquisition circuit also includes a first capacitor C11, a second capacitor C12, a third capacitor C13, a first diode D11, a second diode D12 and a first resistor R11; one end of the first capacitor C11 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the other end is grounded; one end of the second capacitor C12 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the other end is grounded; the anode of the first diode D11 is connected to the cathode of the second diode D12, the cathode of the first diode D11 is connected to the reference voltage output end of the first reference voltage acquisition circuit, and the anode of the second diode D12 is grounded; the third capacitor C13 and the first resistor R11 are connected in series, one end of the series connection is connected to the cathode of the second diode D12, and the other end of the series connection is connected to the first AC input end of the first reference voltage acquisition circuit; And / or, the first comparison circuit further includes a third diode D21, a second resistor R21, a third resistor R22, a fourth resistor R23, a fifth resistor R24, a sixth resistor R25 and a first comparator T1; the third diode D21, the second resistor R21 and the third resistor R22 are connected in series, one end of the series connection is connected to the AC power input end of the first comparison circuit, and the other end of the series connection is connected to the positive input end of the first comparator T1; one end of the fourth resistor R23 is grounded, and the other end is connected to the positive input end of the first comparator T1; one end of the fifth resistor R24 ​​is connected to the reference power input end of the first comparison circuit, and the other end is connected to the negative input end of the first comparator T1; one end of the sixth resistor R25 is grounded, and the other end is connected to the negative input end of the first comparator T1; the output end of the first comparator T1 is connected to the comparison result output end of the first comparison circuit; And / or, the first control circuit further includes a seventh resistor R31, an eighth resistor R32 and a transistor Q1; one end of the seventh resistor R31 is grounded, and the other end is connected to the comparison signal input end of the first control circuit; one end of the eighth resistor R32 is connected to the comparison signal input end of the first control circuit, and the other end is connected to the base of the transistor Q1; the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the control signal output end of the first control circuit; And / or, the first switching circuit also includes a ninth resistor R41, a fourth diode D41, a fifth diode D42 and a first electronic switch U1; one end of the ninth resistor R41 is connected to the reference voltage connection end of the first switching circuit, and the other end is connected to the first electronic switch U1; both ends of the fifth diode D42 are connected to the first electronic switch U1; the positive connection end of the fourth diode D41 is connected to the first electronic switch U1 and the AC power input end of the first switching circuit, and the negative connection end of the fourth diode D41 is connected to the thermal power output end of the first switching circuit and the first electronic switch U1; the first electronic switch U1 is used to output the AC first power input from the AC power input end to the first heating wire through the fourth diode D41 when the control signal input end is grounded; the first switching circuit is also used to output the AC second power input from the AC power input end to the first heating wire through the first electronic switch U1 when the control signal input end is empty.

5. The power supply circuit according to claim 1, characterized in that: The DC power supply circuit includes a DC connection circuit, a second reference voltage acquisition circuit, a sampling circuit, a second comparison circuit and a third comparison circuit; The DC connection circuit includes a DC positive connection terminal, a DC negative connection terminal and a DC output terminal; the DC positive connection terminal of the DC connection circuit is used to connect to the positive output terminal of the external DC power supply, the DC negative connection terminal of the DC connection circuit is used to connect to the negative output terminal of the external DC power supply, and the DC output terminal of the DC connection circuit is connected to the second reference voltage acquisition circuit, the sampling circuit, the second comparison circuit and the third comparison circuit, and is used to output the DC power supply; The second reference voltage acquisition circuit includes a power input terminal and a reference power output terminal, the power input terminal of the second reference voltage acquisition circuit is connected to the DC output terminal of the DC connection circuit, and the reference power output terminal of the second reference voltage acquisition circuit is connected to the sampling circuit, the second comparison circuit and the third comparison circuit; the second reference voltage acquisition circuit is used to convert the DC power supply into a second reference voltage source with a preset voltage value, and output the second reference voltage source through the reference power output terminal; The sampling circuit comprises a first input connection terminal, a second input connection terminal, a first output connection terminal, a second output connection terminal, a third output connection terminal and a fourth output connection terminal; the first input connection terminal of the sampling circuit is connected to the DC output terminal of the DC connection circuit, the second input connection terminal of the sampling circuit is connected to the reference power supply output terminal of the second reference voltage acquisition circuit, the first output connection terminal and the second output connection terminal of the sampling circuit are connected to the second comparison circuit, and the third output connection terminal and the fourth output connection terminal of the sampling circuit are connected to the third comparison circuit; the sampling circuit is used to perform voltage division sampling on the second reference voltage source and the DC power supply respectively, and output the resultant electrical signals of the two voltage division samplings to the second comparison circuit through the first output connection terminal and the second output connection terminal, and then output them to the third comparison circuit through the third output connection terminal and the fourth output connection terminal; The circuit structures of the second comparison circuit and the third comparison circuit are the same, and they respectively include a first comparison input terminal, a second comparison input terminal and a DC power supply output terminal; the first comparison input terminal and the second comparison input terminal of the second comparison circuit are respectively connected to the output first connection terminal and the output second connection terminal of the sampling circuit, the first comparison input terminal and the second comparison input terminal of the third comparison circuit are respectively connected to the output third connection terminal and the output fourth connection terminal of the sampling circuit, the DC power supply output terminal of the second comparison circuit is connected to the second heating wire, and the DC power supply output terminal of the third comparison circuit is connected to the third heating wire; the second comparison circuit is used for, when the DC power supply is the DC first power supply, outputting the DC first power supply to the second heating wire, so as to use the DC first power supply as the heating power supply for the second heating wire; the third comparison circuit is used for, when the DC power supply is the DC second power supply, outputting the DC second power supply to the third heating wire, so as to use the DC second power supply as the heating power supply for the third heating wire.

6. The power supply circuit according to claim 5, characterized in that: The second reference voltage acquisition circuit further includes a DC conversion circuit Y1, a fourth capacitor C61, a fifth capacitor C62, a sixth capacitor C63 and a sixth diode D61; the anode of the sixth diode D61 is connected to the power input terminal of the second reference voltage acquisition circuit, and the cathode of the sixth diode D61 is connected to the input terminal of the DC conversion circuit Y1; the output terminal of the DC conversion circuit Y1 is connected to the reference power output terminal of the second reference voltage acquisition circuit; One end of the fourth capacitor C61 is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded; One end of the fifth capacitor C62 is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded; One end of the sixth capacitor C63 is connected to the input end of the DC conversion circuit Y1, and the other end is grounded; And / or, the sampling circuit further includes a tenth resistor R71, an eleventh resistor R72, a twelfth resistor R73, a thirteenth resistor R74 and a seventh diode D71; the seventh diode D71 and the tenth resistor R71 are connected in series, one end of the series connection is connected to the input first connection end of the sampling circuit, and the other end of the series connection is connected to the output second connection end and the output third connection end of the sampling circuit; one end of the eleventh resistor R72 is connected to the input second connection end of the sampling circuit, and the other end is grounded; one end of the twelfth resistor R73 is connected to the input second connection end of the sampling circuit, and the other end is connected to the output first connection end and the output fourth connection end of the sampling circuit; one end of the thirteenth resistor R74 is connected to the output first connection end of the sampling circuit, and the other end is grounded.

7. The power supply circuit according to claim 6, characterized in that: The second reference voltage acquisition circuit also includes a second indicator light Led2 and a second current limiting resistor R2. The second indicator light Led2 and the second current limiting resistor R2 are connected in series, one end of the series connection is connected to the reference power supply output end of the second reference voltage acquisition circuit, and the other end is grounded.

8. The power supply circuit according to claim 6, characterized in that: The second comparison circuit further includes a second comparator T2, a fourteenth resistor R81, a fifteenth resistor R82, a sixteenth resistor R83, an eighth diode D81, a second electronic switch U2, and a second triode Q2; One end of the fourteenth resistor R81 is connected to the output end of the second comparator T2, and the other end is connected to the base of the second transistor Q2; one end of the fifteenth resistor R82 is connected to the base of the second transistor Q2, and the other end is grounded; the emitter of the second transistor Q2 is grounded, and the collector of the second transistor Q2 is connected to the second electronic switch U2; both ends of the eighth diode D81 are connected to the second electronic switch U2; one end of the sixteenth resistor R83 is connected to the second electronic switch U2, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit; the second electronic switch U2 is also connected to the DC output end of the DC connection circuit; And / or, the third comparison circuit further includes a third comparator T3, a seventeenth resistor 91, an eighteenth resistor R92, a nineteenth resistor R93, a ninth diode D91, a third electronic switch U3 and a third triode Q3; One end of the seventeenth resistor R91 is connected to the output end of the third comparator T3, and the other end is connected to the base of the third triode Q3; one end of the eighteenth resistor R92 is connected to the base of the third triode Q3, and the other end is grounded; the emitter of the third triode Q3 is grounded, and the collector of the third triode Q3 is connected to the third electronic switch U3; both ends of the ninth diode D91 are connected to the third electronic switch U3; one end of the nineteenth resistor R93 is connected to the third electronic switch U3, and the other end is connected to the reference power supply output end of the second reference voltage acquisition circuit; the third electronic switch U3 is also connected to the DC output end of the DC connection circuit.

9. A heat preservation bag, characterized in that: Comprising the power supply circuit according to any one of claims 1 to 8.

10. The heat preservation bag according to claim 9, characterized in that: It also includes a soft-cable electric heating element, which is a three-core heating wire. The three-core heating wire includes an insulating protective wire sheath and a first heating wire, a second heating wire, and a third heating wire that are each insulated and intertwined in the insulating protective wire sheath.

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