Power switching circuit, household appliance and refrigerator

Abstract

The utility model relates to a power conversion circuit, a household electrical appliance and a refrigerator, and the circuit comprises a DC-DC switching power supply chip which is used for converting a first DC voltage into a second DC voltage; the power supply input end of the DC-DC switching power supply chip is used for receiving a first voltage; the power supply output end of the DC-DC switching power supply chip is used for outputting a second voltage; an isolation transformer; the primary side of the isolation transformer is connected with the power supply output end of the DC-DC switching power supply chip and is used for receiving the second voltage; the secondary side of the isolation transformer is connected to the first load for providing a third voltage electrically isolated from the second voltage to the first load. The primary side of the isolation transformer is connected to the power output end of the DC-DC switching power supply chip, and the secondary side of the isolation transformer supplies power to the first load, so that electrical isolation between the first load and the voltage of the primary side of the isolation transformer can be realized, and the safety of using the first load is enhanced.

Description

Technical Field

[0001] The utility model relates to the technical field of circuits, and in particular to a power conversion circuit, and a household appliance and a refrigerator equipped with the power conversion circuit. Background Art

[0002] Some loads in household appliances have higher safety requirements, which may include parts exposed outside the housing of household appliances, such as the display touch panel on the refrigerator door. In order to ensure the safety of users' electricity use, the related technology usually wraps the exposed loads by adding insulation, for example, wrapping the exposed circuit harness between the refrigerator door and the refrigerator body with a reinforced insulation layer. However, this method still has certain safety risks. Utility Model Content

[0003] The technical problem to be solved by the utility model is that the method of adding an insulating layer to the exposed part of the load in the related art has potential safety hazards.

[0004] The utility model provides a technical solution to the above technical problems as follows: a power conversion circuit, comprising: a DC-DC switching power supply chip, used to convert a first DC voltage into a second DC voltage; a power input end of the DC-DC switching power supply chip is used to receive the first voltage; a power output end of the DC-DC switching power supply chip is used to output the second voltage; an isolation transformer; the primary side of the isolation transformer is connected to the power output end of the DC-DC switching power supply chip, used to receive the second voltage; the secondary side of the isolation transformer is connected to a first load, used to provide the first load with a third voltage electrically isolated from the second voltage, wherein the first load is a load in a household appliance.

[0005] The beneficial effect of the utility model is that by connecting the primary side of the isolation transformer to the power output end of the DC-DC switching power supply chip and supplying power to the first load through the secondary side of the isolation transformer, electrical isolation between the first load and the voltage on the primary side of the isolation transformer can be achieved, thereby enhancing the safety of using the first load.

[0006] On the basis of the above technical solution, the present invention can also be improved as follows.

[0007] Furthermore, the main line of the primary side of the isolation transformer is connected to the power output end of the DC-DC switching power supply chip; the neutral line of the primary side of the isolation transformer is connected to the second load for providing the second voltage to the second load.

[0008] The beneficial effect of adopting the above further solution is that the second voltage can be provided to the second load that does not need to be isolated, thereby improving the utilization efficiency of the output voltage of the DC-DC switching power supply chip.

[0009] Furthermore, a voltage stabilizing circuit module is connected between the secondary side of the isolation transformer and the first load; the voltage stabilizing circuit module is used to stabilize the third voltage to provide the stabilized third voltage to the first load.

[0010] The beneficial effect of adopting the above further solution is that the third voltage is stabilized by the voltage stabilizing circuit module, thereby improving the stability and reliability of power supply to the first load.

[0011] Furthermore, the voltage stabilizing circuit module includes at least one of the following electrical components: a first diode, wherein the positive electrode of the first diode is connected to the main line on the secondary side of the isolation transformer, and the negative electrode of the first diode is connected to the first load; a first capacitor, wherein the first end of the first capacitor is connected to the first load, and the second end of the first capacitor is grounded; a first resistor, wherein the first end of the first resistor is connected to the first load, and the second end of the first resistor is grounded; and a second diode, wherein the positive electrode of the second diode is connected to the first load, and the negative electrode of the second diode is grounded.

[0012] The beneficial effect of adopting the above further solution is that multiple implementation methods of the voltage stabilizing circuit module are provided, and different designs can be flexibly selected according to different usage scenarios.

[0013] Furthermore, a filter circuit module is connected between the power output terminal of the DC-DC switching power supply chip and the ground terminal of the DC-DC switching power supply chip, and the filter circuit module is used for filtering the second voltage.

[0014] The beneficial effect of adopting the above further solution is that the output second voltage is made smoother, and power can be supplied to a load that requires a smooth voltage, thereby improving the output quality of the second voltage.

[0015] Furthermore, the power conversion circuit also includes at least one of the following electrical components: a first jumper pin, a first end of the first jumper pin is connected to the first voltage, a second end of the first jumper pin is connected to the power input end of the DC-DC switching power supply chip, and the first jumper pin is used to connect or disconnect the electrical connection between the first voltage and the power input end of the DC-DC switching power supply chip; a second jumper pin is connected between the neutral line on the primary side of the isolation transformer and the second load, and is used to connect or disconnect the electrical connection between the neutral line on the primary side of the isolation transformer and the second load.

[0016] The beneficial effect of adopting the above further solution is that the electrical connection at both ends of the jumper can be connected or disconnected through the first jumper and the second jumper, which can facilitate testing by R&D personnel during design and development.

[0017] Furthermore, the DC-DC switching power supply chip includes a first buck converter chip, and the second voltage is lower than the first voltage.

[0018] The beneficial effect of adopting the above further solution is that a higher voltage can be reduced by the first buck converter chip to supply it to a load with a lower driving voltage.

[0019] Furthermore, the power conversion circuit also includes: a second buck converter chip, used to step down a fourth voltage higher than the first voltage to the first voltage; the power input end of the second buck converter chip is used to receive the fourth voltage, the power output end of the second buck converter chip is connected to the primary side of the first buck converter chip, and the primary side of the first buck converter chip is connected to a third load.

[0020] The beneficial effect of adopting the above further scheme is that by setting a second buck converter chip between the fourth voltage and the first buck converter chip, multi-stage bucking of the fourth voltage can be achieved, providing a step-down first voltage and a second voltage, which can meet the needs of loads with different driving voltage requirements.

[0021] Furthermore, the primary side and the secondary side of the isolation transformer are both single windings.

[0022] The beneficial effect of adopting the above further solution is that the circuit cost can be reduced by using an isolation transformer with a simple structure.

[0023] The technical problem to be solved by the utility model is that there is a safety risk in the solution of using a DC-DC switching power supply chip to power a load in household appliances in the related technology.

[0024] The technical solution of the utility model to solve the above technical problems is as follows: a household appliance, comprising: a shell; the power conversion circuit provided by any embodiment of the utility model, arranged inside the shell; a first load, partially exposed to the outside of the shell, the first load is powered by the secondary side of the isolation transformer in the power conversion circuit.

[0025] The beneficial effects of the present invention are the same as those of the above-mentioned power conversion circuit, and will not be described in detail here.

[0026] The technical problem to be solved by the utility model is that the solution of using a DC-DC switching power supply chip to supply power to a load in a refrigerator in the related art has a safety risk.

[0027] The technical solution of the utility model for solving the above technical problems is as follows: a refrigerator, comprising: a box shell and a refrigerator door shell; the power conversion circuit provided by any embodiment of the utility model is arranged inside the box shell; the lead of the secondary side of the isolation transformer in the power conversion circuit extends from the box shell and probes into the interior of the refrigerator door shell; a display component is partially exposed to the outside of the refrigerator door shell, and the display component is powered by the secondary side of the isolation transformer in the power conversion circuit.

[0028] The beneficial effects of the present invention are the same as those of the above-mentioned power conversion circuit, and will not be described in detail here.

[0029] On the basis of the above technical solution, the present invention can also be improved as follows.

[0030] Furthermore, the refrigerator also includes: a variable frequency compressor; a driving circuit for the variable frequency compressor; a variable frequency control chip, which is arranged inside the cabinet shell and is used to control the driving circuit of the variable frequency compressor of the refrigerator, and the variable frequency control chip is connected to the power input terminal or the power output terminal of the DC-DC switching power supply chip in the power conversion circuit.

[0031] The beneficial effect of adopting the above further solution is that different loads in the refrigerator can be centrally powered by the DC-DC switching power supply chip, which can simplify the circuit wiring design of the power supply and reduce the complexity of the power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the circuit structure of a power conversion circuit provided by the utility model;

[0033] Figure 2 A schematic diagram of the circuit structure of a power conversion circuit provided by the utility model;

[0034] Figure 3 A schematic diagram of the circuit structure of a power conversion circuit provided by the utility model. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0036] Embodiment 1

[0037] like Figure 1 to Figure 3 As shown, a power conversion circuit 100 is provided, which specifically includes: a DC-DC switching power supply chip 10 and an isolation transformer 20.

[0038] The DC-DC switching power supply chip 10 is used to convert a first DC voltage V1 into a second DC voltage V2; the power input terminal 11 of the DC-DC switching power supply chip 10 is used to receive the first voltage V1; the power output terminal 12 of the DC-DC switching power supply chip 10 is used to output the second voltage V2. Optionally, the DC-DC switching power supply chip 10 can be a first buck converter chip 10, that is, a BUCK switching power supply chip, which is used to reduce the first voltage V1 to a second voltage V2, and the second voltage V2 is lower than the first voltage V1. Optionally, the input voltage received by the power input terminal 11 of the DC-DC switching power supply chip 10 and the output voltage of the power output terminal 12 can both be low voltages. In some application scenarios, the voltage range of the low voltage can be between 0V and 42V. For example, the first voltage V1 can be 15V, and the second voltage V2 can be 12V, that is, the DC-DC switching power supply chip 10 is a buck converter chip.

[0039] The primary side 21 of the isolation transformer 20 is connected to the power output terminal 12 of the DC-DC switching power supply chip 10 for receiving the second voltage V2; the secondary side 22 of the isolation transformer 20 is connected to the first load 101 for providing the first load 101 with a third voltage V3 electrically isolated from the second voltage V2. The first load is a load in a household appliance. For example, the power conversion circuit 100 can be applied to a refrigerator, and accordingly, the first load 101 can be a display component on a refrigerator door, or a lighting lamp of a refrigerator, etc. Optionally, the transformation ratio of the isolation transformer can be 1:1, which is only used to realize the function of electrical isolation.

[0040] The power conversion circuit 100 provided in this embodiment connects the primary side 21 of the isolation transformer 20 to the power output terminal 12 of the DC-DC switching power supply chip 10, and can supply power to the first load 101 through the secondary side 22 of the isolation transformer 20, thereby achieving electrical isolation between the first load 101 and the receiving voltage of the primary side 21 of the isolation transformer 20, thereby enhancing the safety of using the first load 101.

[0041] Optionally, the power input terminal 11 of the DC-DC switching power supply chip 10 can be connected to a third load to provide the first voltage V1 to the third load. For example, the power conversion circuit 100 can be applied to a variable frequency refrigerator, and the third load can be a control chip of a variable frequency compressor drive circuit in the variable frequency refrigerator, that is, a variable frequency control chip. Optionally, the primary side or the secondary side of the isolation transformer can be a single winding.

[0042] In addition, the isolation transformer 20 used in the power conversion circuit 100 provided in this embodiment can be a simple isolation transformer type including two windings, which has low cost and simple circuit connection method, and is suitable for use environments with high requirements for cost control.

[0043] refer to Figure 2 or Figure 3 The main line 201 of the primary side 21 of the isolation transformer 20 is connected to the power output terminal 12 of the DC-DC switching power supply chip 10; the neutral line 202 of the primary side 21 of the isolation transformer 20 is connected to the second load, for providing the second voltage V2 to the second load.

[0044] The voltage output by the DC-DC switching power supply chip can provide a second voltage to a second load that does not need to be isolated, thereby improving the efficiency of using the output voltage of the DC-DC switching power supply chip. The power conversion circuit provided in this embodiment is simple to connect, and can provide isolated low voltage and non-isolated low voltage at the same time through a single DC-DC switching power supply chip 10, which can be applied to different loads. In addition, the winding of the primary side 21 of the isolation transformer 20 can be regarded as an inductor, and the second voltage output by the voltage output terminal 12 is stored and stepped down. The second load is connected to the neutral line 202 of the primary side 21 of the isolation transformer 20, and a more stable power supply can be obtained.

[0045] refer to Figure 2 or Figure 3 , the secondary side 21 of the isolation transformer 20 is connected to the first load (or Figure 2 or Figure 3 A voltage stabilizing circuit module is connected between the third voltage V3 terminal in the first load and the third voltage V3 terminal in the second load. The voltage stabilizing circuit module is used to stabilize the third voltage V3 to provide the stabilized third voltage V3 to the first load. By stabilizing the third voltage with the voltage stabilizing circuit module, the stability and reliability of power supply to the first load are improved.

[0046] refer to Figure 2 or Figure 3 The voltage stabilizing circuit module may include at least one of the following electrical components: a first diode D1, a first capacitor C7, a first resistor R4, and a second diode DZ1.

[0047] The first diode D1 has an anode connected to the main line 204 of the secondary side 22 of the isolation transformer 20 , and a cathode connected to the first load.

[0048] A first capacitor C7, a first end of the first capacitor C7 is connected to the first load, and a second end of the first capacitor C7 is grounded GND. Optionally, the grounding may be a power ground (P-GND).

[0049] A first resistor R4, a first end of the first resistor is connected to the first load, and a second end of the first resistor is grounded.

[0050] The second diode DZ1 has an anode connected to the first load and a cathode connected to the ground.

[0051] Through the above-mentioned various specific implementations, the flexibility of the voltage stabilizing circuit module is improved, and different designs can be flexibly selected according to different usage scenarios.

[0052] refer to Figure 2 or Figure 3 A filter circuit module 202 is connected between the power output terminal 12 of the DC-DC switching power supply chip 10 and the ground terminal 14 of the DC-DC switching power supply chip 10, and the filter circuit module 202 is used to filter the second voltage V2. Optionally, the filter circuit module 202 may include a capacitor C6 and a resistor R3. The filter circuit module 202 may make the output second voltage V2 smoother, and may supply power to a load that needs to use a smooth voltage, thereby improving the output quality of the second voltage V2.

[0053] refer to Figure 2 or Figure 3 The power conversion circuit also includes a first jumper pin J1 and / or a second jumper pin J2.

[0054] The first jumper J1 is connected between the first voltage V1 and the power input terminal 11 of the DC-DC switching power supply chip 10, and is used to connect or disconnect the electrical connection between the first voltage V1 and the power input terminal 11 of the DC-DC switching power supply chip 10.

[0055] The second jumper pin J2 is connected between the neutral line 202 of the primary side 21 of the isolation transformer 20 and the second load (or Figure 2 or Figure 3 The second voltage V2 terminal in the isolation transformer 20 is used to connect or disconnect the electrical connection between the neutral line 202 of the primary side 21 of the isolation transformer 20 and the second load.

[0056] The electrical connection at both ends of the jumper pin can be connected or disconnected through the first jumper pin and the second jumper pin, which can facilitate testing by R&D personnel during design and development.

[0057] refer to Figure 3 The power conversion circuit may further include a second buck converter chip 30, which is used to step down the fourth voltage V4 to the first voltage V1; the power input terminal 31 of the second buck converter chip 30 is used to receive the fourth voltage V4, and the power output terminal 32 of the second buck converter chip 30 is used to output the first voltage V1, and the power output terminal 32 of the second buck converter chip 30 is connected to the third load.

[0058] The second buck converter chip is arranged between the fourth voltage and the first buck converter chip, which can improve the conversion efficiency of the first buck converter chip and reduce heat generation. This embodiment can implement multi-stage voltage reduction for the fourth voltage, provide a step-down first voltage and a step-down second voltage, and can meet loads with different driving voltage requirements.

[0059] In some application scenarios, the fourth voltage V4 may be a high voltage. In some application scenarios, the fourth voltage V4 may be a higher DC voltage obtained by converting the AC voltage of the mains into a DC voltage, and the voltage range may be 220V to 310V. The first voltage V1 is a lower DC voltage output after the fourth voltage V4 has been stepped down by the second buck converter chip 30, for example, a DC power of 0V to 42V. In this embodiment, the voltages output by the first buck converter chip 10 and the second buck converter chip 30 are not isolated from the higher fourth voltage V4, and the third voltage V3 output by the secondary side 21 of the isolation transformer 20 can be electrically isolated from the fourth voltage V4, thereby improving the safety of the first load.

[0060] refer to Figure 2 or Figure 3 The power conversion circuit may further include a capacitor C2 connected between the power output terminal 12 of the DC-DC switching power supply chip 10 and the start-up terminal 16 of the DC-DC switching power supply chip 10, for raising the second voltage V2 to provide a start-up voltage to the start-up terminal 16.

[0061] refer to Figure 2 or Figure 3 The power conversion circuit may further include a capacitor C1, a first end of the capacitor C1 is connected to the power input terminal 11 of the DC-DC switching power supply chip 10, a second end of the capacitor C1 is grounded GND, and the capacitor C1 is used for energy storage and voltage stabilization.

[0062] refer to Figure 3 The power conversion circuit may further include a resistor R5, which is connected between the power input terminal 11 and the enable terminal 13 of the DC-DC switching power supply chip 10. The enable terminal 13 is used to enable the DC-DC switching power supply chip 10 through the acquired voltage. The resistor R5 is used to protect the DC-DC switching power supply chip 10 to prevent the first voltage V1 from being directly connected to the enable terminal 13.

[0063] refer to Figure 2 or Figure 3 A voltage divider circuit module 203 is connected between the neutral line 202 of the primary side 21 of the isolation transformer 20 and the feedback terminal 15 of the DC-DC switching power supply chip 10. The voltage divider circuit module 203 is used to reduce the second voltage V2 to a fifth voltage and feed it back to the feedback terminal 15. The DC-DC switching power supply chip 10 can adjust the second voltage V2 output by the power output terminal 12 of the DC-DC switching power supply chip 10 according to the difference between the fifth voltage and the reference voltage.

[0064] refer to Figure 2 or Figure 3The voltage divider circuit module 203 may include capacitors C3, C4 and C5, as well as resistors R1 and R2. Capacitors C4 and C5 are connected in parallel between the neutral line 202 of the primary side 21 of the isolation transformer 20 and the ground. Resistors R1 and R2 are connected in series and then connected in parallel with capacitor C4. Resistors R1 and R2 are used to divide the second voltage V2. Capacitor C3 is connected in parallel with resistor R1.

[0065] Embodiment 2

[0066] The present embodiment provides a household appliance, for example, a refrigerator, a rice cooker, a washing machine, etc. The household appliance comprises: a housing, a power conversion circuit and a first load. The power conversion circuit may be the power conversion circuit provided in the first embodiment, which is arranged inside the housing. The first load is partially exposed to the outside of the housing, and the first load is powered by the secondary side of the isolation transformer in the power conversion circuit. For example, the first load may be a lighting indicator light, a touch display panel, etc. on household appliances such as refrigerators, rice cookers, and washing machines.

[0067] Embodiment 3

[0068] The present embodiment provides a refrigerator. For example, the type of the refrigerator may be a refrigerator with a bottom mounted freezer (Bottom Mounted Freezer, BMF for short). Alternatively, in another classification method, the refrigerator may be a household refrigerator or a motorhome refrigerator.

[0069] The refrigerator provided in this embodiment includes: a box shell and a refrigerator door shell, a power conversion circuit, and a display component. The power conversion circuit is arranged inside the box shell. The lead of the secondary side of the isolation transformer in the power conversion circuit extends from the box shell and penetrates into the interior of the refrigerator door shell to power the display component. The display component can be a functional load, such as a touch display panel, a refrigerator lighting, etc. The display component is partially exposed to the outside of the refrigerator door shell, and the display component is powered by the secondary side of the isolation transformer in the power conversion circuit.

[0070] In the refrigerator provided in this embodiment, the power conversion circuit uses the power conversion circuit provided in Example 1, and a display component can be set on the refrigerator door. Since the refrigerator door is usually a metal door, if it is necessary to set a load such as a display component on the refrigerator door, it is necessary to lead a low-voltage line from the refrigerator body and supply power to the load on the refrigerator door through the hinge. If a non-isolated power conversion circuit is used, the safety risk is relatively high, and the user will be at risk of electric shock when touching the refrigerator door, which does not meet the requirements of reinforced insulation in safety regulations. If a reinforced insulation layer is added to the exposed intermediate transfer wiring harness between the refrigerator body and the refrigerator door, the cost will increase significantly compared to the solution of adding an isolation transformer in Example 1, and since the refrigerator door is frequently opened and closed for a long time, the distortion and cracking of the reinforced insulation layer is also a major safety hazard.

[0071] Optionally, the refrigerator may be a variable frequency refrigerator, including a variable frequency compressor and a driving circuit of the variable frequency compressor, and accordingly, the refrigerator may also include a variable frequency control chip for controlling the driving circuit of the variable frequency compressor of the refrigerator. The variable frequency control chip is arranged inside the housing, and the variable frequency control chip is connected to the power input terminal or the power output terminal of the DC-DC switching power supply chip in the power conversion circuit.

[0072] In some application scenarios, variable frequency refrigerators use a dual-chip control solution. Specifically, one of them is a variable frequency control chip, which is used to control the drive circuit of the variable frequency compressor. The variable frequency control chip does not require an isolated power supply. Optionally, the drive voltage of the variable frequency control chip is 15V. The other is a load control chip, which is used to control other functional loads and application devices of the refrigerator, such as the display component on the refrigerator door, the refrigerator lighting, etc. The load control chip requires an isolated power supply. Optionally, the drive voltage of the load control chip is 12V.

[0073] In a specific example, refer to Figure 3 , the non-isolated power supply of the frequency conversion control chip can be Figure 3 The 15V non-isolated voltage obtained by the second buck converter chip 30 after bucking, and the isolated power supply of the load control chip can be Figure 3 The secondary side 22 of the isolation transformer 20 provides a 12V isolation voltage. Here, the first buck converter chip 20 can reduce the 15V voltage to 12V, that is, the isolation transformer 20 does not need to perform voltage up / down conversion. Compared with other technical solutions in the related art, the circuit layout of this embodiment is simpler and the cost is lower.

[0074] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0075] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0076] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0077] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0078] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0079] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations of the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A power conversion circuit, characterized in that: include: A DC-DC switching power supply chip, used for converting a first DC voltage into a second DC voltage; a power input terminal of the DC-DC switching power supply chip is used for receiving the first voltage; and a power output terminal of the DC-DC switching power supply chip is used for outputting the second voltage; Isolation transformer; The primary side of the isolation transformer is connected to the power output end of the DC-DC switching power supply chip for receiving the second voltage; the secondary side of the isolation transformer is connected to a first load for providing a third voltage electrically isolated from the second voltage to the first load, and the first load is a load in a household appliance.

2. A power conversion circuit according to claim 1, characterized in that: The main line of the primary side of the isolation transformer is connected to the power output end of the DC-DC switching power supply chip; the neutral line of the primary side of the isolation transformer is connected to the second load for providing the second voltage to the second load.

3. A power conversion circuit according to claim 1, characterized in that: A voltage stabilizing circuit module is connected between the secondary side of the isolation transformer and the first load; the voltage stabilizing circuit module is used to stabilize the third voltage to provide the stabilized third voltage to the first load.

4. A power conversion circuit according to claim 3, characterized in that: The voltage stabilizing circuit module includes at least one of the following electrical components: a first diode, wherein an anode of the first diode is connected to a main line on a secondary side of the isolation transformer, and a cathode of the first diode is connected to the first load; A first capacitor, wherein a first end of the first capacitor is connected to the first load, and a second end of the first capacitor is grounded; a first resistor, wherein a first end of the first resistor is connected to the first load, and a second end of the first resistor is grounded; A second diode, wherein an anode of the second diode is connected to the first load, and a cathode of the second diode is grounded.

5. A power conversion circuit according to claim 1, characterized in that: A filter circuit module is connected between the power output terminal of the DC-DC switching power supply chip and the ground terminal of the DC-DC switching power supply chip, and the filter circuit module is used for filtering the second voltage.

6. A power conversion circuit according to claim 2, characterized in that: Also includes at least one of the following electrical components: a first jumper pin, wherein a first end of the first jumper pin is connected to the first voltage, a second end of the first jumper pin is connected to a power input terminal of the DC-DC switching power supply chip, and the first jumper pin is used to connect or disconnect an electrical connection between the first voltage and the power input terminal of the DC-DC switching power supply chip; The second jumper pin is connected between the neutral line on the primary side of the isolation transformer and the second load, and is used to connect or disconnect the electrical connection between the neutral line on the primary side of the isolation transformer and the second load.

7. A power conversion circuit according to any one of claims 1 to 6, characterized in that: The DC-DC switching power supply chip includes a first buck converter chip, and the second voltage is lower than the first voltage.

8. A power conversion circuit according to claim 7, characterized in that: Also includes: A second buck converter chip is used to step down a fourth voltage higher than the first voltage to the first voltage; a power input end of the second buck converter chip is used to receive the fourth voltage, a power output end of the second buck converter chip is connected to the primary side of the first buck converter chip, and the primary side of the first buck converter chip is connected to a third load.

9. A power conversion circuit according to any one of claims 1 to 6, characterized in that: The primary side and the secondary side of the isolation transformer are both single windings.

10. A household appliance, characterized in that: include: case; The power conversion circuit according to any one of claims 1 to 9 is arranged inside the housing; A first load is partially exposed outside the shell, and the first load is powered by the secondary side of the isolation transformer in the power conversion circuit.

11. A refrigerator, characterized in that: include: Cabinet shell and refrigerator door shell; The power conversion circuit of any one of claims 1 to 9 is arranged inside the box housing; The lead wire of the secondary side of the isolation transformer in the power conversion circuit extends from the box shell and penetrates into the interior of the refrigerator door shell; A display component is partially exposed outside the refrigerator door housing, and the display component is powered by the secondary side of the isolation transformer in the power conversion circuit.

12. A refrigerator according to claim 11, characterized in that: Also includes: A variable frequency compressor; a driving circuit of the variable frequency compressor; A frequency conversion control chip is arranged inside the box shell and is used to control the drive circuit of the frequency conversion compressor. The frequency conversion control chip is connected to the power input terminal or the power output terminal of the DC-DC switching power supply chip in the power conversion circuit.

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