Power conversion and detection circuit and household electrical appliance

Abstract

The utility model discloses a power conversion and detection circuit and a household appliance. The power conversion and detection circuit comprises a signal processing branch, a voltage conversion branch, a feedback branch, a zero-cross detection branch and a controller. And the signal processing branch is used for rectifying and filtering. The voltage conversion branch comprises a power management chip and a transformer, and the voltage conversion branch controls the primary coil to be charged or discharged through the power management chip based on a feedback signal. And the feedback branch outputs a feedback signal. The zero-cross detection branch comprises a first optocoupler, the first optocoupler and a ground pin of the power management chip are connected to a first ground, and the first optocoupler and the secondary coil are connected to a second ground. The zero-crossing detection branch outputs a first level in response to the alternating-current power supply in the positive half cycle and outputs a second level in response to the alternating-current power supply in the negative half axis, so that the controller determines a zero-crossing point. By means of the mode, the non-isolated ground and the isolated ground formed in the power supply conversion process can be used for eliminating power loss when the alternating current power supply is in the negative half cycle.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of electronic circuits, and in particular to a power conversion and detection circuit and a household appliance. Background Art

[0002] At present, household appliances are usually equipped with circuits related to AC power supply, such as power conversion circuit and zero-crossing detection circuit. The power conversion circuit is used to convert AC power supply into DC power supply that can power devices in household appliances, and the zero-crossing detection circuit is used to detect the zero-crossing point of the AC power supply.

[0003] Among them, the existing zero-crossing detection circuit is usually implemented by an optocoupler. Specifically, the live wire of the AC power supply is connected to the optocoupler through a resistor, and the light-emitting device of the optocoupler is connected in parallel with a diode. When the AC power supply is in the positive half cycle, the diode is reverse-cut off and the optocoupler is turned on; when the AC power supply is in the negative half cycle, the diode is forward-conducted and the optocoupler is disconnected. Based on the above two states, it is determined whether the AC power supply has passed the zero point.

[0004] However, when the AC power supply is in the negative half cycle, due to the forward conduction of the diode, the current flows from the neutral line of the AC power supply through the diode and the resistor to the live line of the AC power supply. The AC power supply and the resistor form a loop, and the AC power supply always has power loss on the resistor. Utility Model Content

[0005] The embodiments of the present application provide a power conversion and detection circuit and a household appliance, which can eliminate power loss when the AC power supply is in the negative half cycle by utilizing the non-isolated ground and isolated ground formed during the power conversion process.

[0006] In a first aspect, an embodiment of the present application provides a power conversion and detection circuit, comprising:

[0007] The signal processing branch is connected to the live wire of the AC power supply and is configured to rectify and filter the AC power supply to output a first DC power supply.

[0008] A voltage conversion branch and a feedback branch, wherein the voltage conversion branch includes a power management chip and a transformer, the primary coil of the transformer is connected between the power management chip and the signal processing branch, and the feedback branch is connected between the secondary coil of the transformer and the power management chip;

[0009] The voltage conversion branch is configured to control the primary coil to be charged by the first DC power supply or to discharge the primary coil based on a feedback signal through the power management chip, so as to convert the first DC power supply into a second DC power supply;

[0010] The feedback branch is configured to output the feedback signal to the power management chip based on the voltage of the second DC power supply;

[0011] A zero-crossing detection branch and a controller, the zero-crossing detection branch comprising a first optocoupler, the anode of the light emitter of the first optocoupler being connected to the live wire of the AC power supply, the cathode of the light emitter of the first optocoupler being connected to the ground pin of the power management chip and connected to a first ground, the first end of the light receiver of the first optocoupler being connected to the controller, and the second end of the light receiver of the first optocoupler being connected to the secondary coil and connected to a second ground;

[0012] The zero-crossing detection branch is configured to be turned on in response to the AC power source being in a positive half cycle to output a first level to the controller, and to be turned off in response to the AC power source being in a negative half axis to output a second level to the controller, so that the controller determines the zero-crossing point of the AC power source based on the first level and the second level.

[0013] In one or more embodiments, the signal processing branch includes a rectifier bridge, a first capacitor, a second capacitor, a first resistor, and a first inductor;

[0014] The first end of the rectifier bridge is connected to the live wire of the AC power supply, the second end of the rectifier bridge is connected to the neutral wire of the AC power supply, the third end of the rectifier bridge is respectively connected to the first end of the first capacitor, the first end of the first inductor and the first end of the first resistor, the fourth end of the rectifier bridge, the second end of the first capacitor and the second end of the second capacitor are all connected to the first ground, and the second end of the first inductor is respectively connected to the second end of the first resistor, the first end of the second capacitor and the opposite end of the primary coil.

[0015] In one or more embodiments, the voltage conversion branch further includes a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode, and a second diode;

[0016] The first end of the third capacitor is respectively connected to the signal processing branch, the first end of the second resistor and the opposite-name end of the primary coil, the second end of the third capacitor is respectively connected to the second end of the second resistor and the first end of the third resistor, the second end of the third resistor is respectively connected to the cathode of the first diode, the anode of the first diode is respectively connected to the same-name end of the primary coil and the switch pin of the power management chip, the same-name end of the secondary coil is respectively connected to the first end of the fourth capacitor and the anode of the second diode, the opposite-name end of the secondary coil, the second end of the fifth capacitor and the second end of the fifth resistor are all connected to the first ground, the second end of the fourth capacitor is connected to the first end of the fourth resistor, the second end of the fourth resistor is respectively connected to the cathode of the second diode, the first end of the fifth capacitor, the first end of the fifth resistor and the feedback branch, and outputs the second DC power supply.

[0017] In one or more embodiments, the voltage conversion branch further includes a seventh capacitor;

[0018] The seventh capacitor is connected between the first ground and the second ground.

[0019] In one or more embodiments, the feedback branch includes a sixth resistor, a seventh resistor, a voltage stabilizing diode, and a second optocoupler;

[0020] The first end of the sixth resistor is connected to the voltage conversion branch, the second end of the sixth resistor is connected to the cathode of the voltage-stabilizing diode, the anode of the voltage-stabilizing diode is respectively connected to the first end of the seventh resistor and the anode of the light-emitting device of the second optocoupler, the second end of the seventh resistor and the cathode of the light-emitting device of the second optocoupler are both connected to the second ground, the first end of the light receiver of the second optocoupler is connected to the feedback pin of the power management chip, and the second end of the light receiver of the second optocoupler is connected to the power pin of the power management chip.

[0021] In one or more embodiments, the zero-crossing detection branch further includes an eighth resistor, a ninth resistor, a tenth resistor, and an eighth capacitor;

[0022] The eighth resistor is connected between the live wire of the AC power supply and the anode of the light emitter of the first optocoupler, the cathode of the light emitter of the first optocoupler is connected to the first ground, the first end of the light receiver of the first optocoupler is respectively connected to the first end of the ninth resistor and the first end of the tenth resistor, the second end of the ninth resistor is connected to the second DC power supply, the second end of the tenth resistor is respectively connected to the controller and the first end of the eighth resistor, the second end of the light receiver of the first optocoupler and the second end of the eighth capacitor are both connected to the second ground.

[0023] In one or more embodiments, the power conversion and detection circuit further includes a fuse and a bidirectional transient voltage suppression diode;

[0024] The fuse is connected between the neutral line of the AC power supply and the signal processing branch, and the bidirectional transient voltage suppression diode is connected between the live line and the neutral line of the AC power supply.

[0025] In a second aspect, an embodiment of the present application provides a household appliance comprising the power conversion and detection circuit as described above.

[0026] The beneficial effects of the present application are as follows: The power conversion and detection circuit of the embodiment of the present application includes a signal processing branch, a voltage conversion branch, a feedback branch, a zero-crossing detection branch, and a controller. The signal processing branch rectifies and filters the AC power supply to output a first DC power supply. The voltage conversion branch includes a power management chip and a transformer. The voltage conversion branch is configured to control the primary coil to be charged by the first DC power supply or to control the primary coil to discharge based on a feedback signal from the power management chip, thereby converting the first DC power supply into a second DC power supply. The feedback branch outputs a feedback signal to the power management chip based on the voltage of the second DC power supply. Thus, the power conversion process of converting the AC power supply into the second DC power supply is implemented. At the same time, due to the presence of the transformer in this process, a first ground serving as a non-isolated ground and a second ground serving as an isolated ground are formed. Next, the zero-crossing detection branch includes a first optocoupler. The anode of the light emitter of the first optocoupler is connected to the live wire of the AC power supply, the cathode of the light emitter of the first optocoupler is connected to the ground pin of the power management chip and connected to the first ground. The first end of the light receiver of the first optocoupler is connected to the controller, and the second end of the light receiver of the first optocoupler is connected to the secondary coil and connected to the second ground. The zero-crossing detection branch is turned on in response to the AC power supply being in the positive half-cycle to output a first electrical level to the controller, and is turned off in response to the AC power supply being in the negative half-axis to output a second electrical level to the controller, so that the controller determines the zero-crossing point of the AC power supply based on the first and second electrical levels. At this point, the zero-crossing detection process is implemented. In this process, since the first and second grounds are non-isolated and isolated, respectively, the light emitter and light receiver of the first optocoupler are connected to the first and second grounds respectively to maintain normal operation. Therefore, the zero-crossing detection function remains normal, and since the light emitting device of the first optocoupler is connected to the first ground, when the AC power supply is in the negative half cycle, the light emitting device of the first optocoupler cannot be turned on, that is, at this time there is no power supply circuit of the AC power supply, and there is no power loss in the AC power supply. It can be seen that the power loss when the AC power supply is in the negative half cycle can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] One or more embodiments are exemplarily described by the figures in the accompanying drawings, which are not intended to limit the embodiments. Elements with the same reference numerals in the drawings represent similar elements.

[0028] Figure 1 is a schematic diagram of a block diagram of a power conversion and detection circuit provided in an embodiment of the present application;

[0029] Figure 2 is with Figure 1 The schematic diagram of the circuit structure corresponding to the composition block diagram shown. DETAILED DESCRIPTION

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application.

[0031] It should be noted that, when an element is referred to as being “connected to” another element, it may be directly connected to the other element, or one or more intervening elements may exist therebetween.

[0032] In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as there is no structural conflict between them.

[0033] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a block diagram of a power conversion and detection circuit according to an embodiment of the present application. Figure 1 As shown, the power conversion and detection circuit 100 includes a signal processing branch 10, a voltage conversion branch 20, a feedback branch 30, a zero-crossing detection branch 40, and a controller 50. The voltage conversion branch 20 includes a power management chip U1 and a transformer T1, and the zero-crossing detection branch 40 includes a first optocoupler U2.

[0034] In the power conversion process, the first end of the signal processing branch 10 is connected to the live wire L of the AC power supply 200. The primary coil of the transformer T1 is connected between the power management chip U1 and the signal processing branch 10, that is, the same-name end of the primary coil of the transformer T1 is connected to the switch pin of the power management chip U1, and the opposite-name end of the primary coil of the transformer T1 is connected to the second end of the signal processing branch 10, and the power source at the connection point is the first DC power source VC1. The feedback branch 30 is connected between the secondary coil of the transformer T1 and the power management chip U1, that is, the first end of the feedback branch 30 is connected to the same-name end of the secondary coil of the transformer T1, and the power source at the connection point is the second DC power source VC2, and the second end of the feedback branch 30 is connected to the feedback pin of the power management chip U1.

[0035] In some embodiments, the AC power source 200 is commercial power.

[0036] In some embodiments, the power management chip U1 can be a KP36572 or LN9T12A chip. It is understood that, since power management chips come in different models, the specific pin definitions may differ when using different models of power management chips, but the functions and signal definitions are the same. If a different model of power management chip is used, the configuration can be similar to that described in the embodiments of this application. This is within the scope of easy understanding for those skilled in the art and will not be further elaborated here.

[0037] Specifically, the signal processing branch 10 is configured to rectify and filter the AC power supply 200 to output a first DC power supply VC1. The voltage conversion branch 20 is configured to control the primary coil to be charged by the first DC power supply VC1 or to discharge the primary coil based on a feedback signal through the power management chip U1, thereby converting the first DC power supply VC1 into a second DC power supply VC2. Specifically, the switch pin of the power management chip U1 is connected to a switching transistor within the power management chip U1. When the switching transistor is turned on, the first DC power supply VC1 and the primary coil form a loop, charging the primary coil. When the switching transistor is turned off, the loop between the first DC power supply VC1 and the primary coil is disconnected, discharging the primary coil. At this time, the energy previously charged in the primary coil is output through the secondary coil. Therefore, within a cycle, the longer the switching transistor is on, the more energy is charged in the primary coil, and the higher the voltage output by the secondary coil, i.e., the higher the second DC power supply. The duration of the switch's conduction is determined by the feedback signal. In summary, the power management chip U1 controls the primary coil to be charged by the first DC power supply VC1 or to discharge the primary coil based on the feedback signal, thereby controlling the voltage of the second DC power supply VC2. The feedback branch 30 is configured to output a feedback signal to the power management chip U1 based on the voltage of the second DC power supply VC2. Specifically, the feedback signal changes with the voltage of the second DC power supply VC2, and the feedback signal corresponds to the voltage of the second DC power supply VC2. Subsequently, the power management chip U1 adjusts the conduction duration of the switch based on the feedback signal, thereby adjusting the voltage of the second DC power supply VC2 until the voltage of the second DC power supply VC2 reaches the required voltage.

[0038] At this point, the power conversion process of converting the AC power supply 200 into the second DC power supply VC2 is completed. At the same time, in this process, due to the presence of the transformer T1, a first ground SGND as a non-isolated ground and a second ground GND as an isolated ground are formed.

[0039] Regarding the zero-crossing detection process: the anode of the light emitter of the first optocoupler U2 is connected to the live wire of the AC power supply 200, the cathode of the light emitter of the first optocoupler U2 is connected to the ground pin of the power management chip U1, and is connected to the first ground SGND, the first end of the light receiver of the first optocoupler U2 is connected to the controller 50, and the second end of the light receiver of the first optocoupler U2 is connected to the secondary coil and is connected to the second ground GND. It can be understood that since the live wire L of the AC power supply 200 is connected to the light emitter of the first optocoupler U2, and the live wire L of the AC power supply 200 is located at the non-isolated end, the light emitter of the first optocoupler U2 should also be connected to the non-isolated ground, that is, the first ground SGND; and the controller 50 is at the isolated end, so the light receiver of the first optocoupler U2 should also be connected to the isolated ground, that is, the second ground GND.

[0040] The zero-crossing detection branch 40 is configured to be turned on in response to the AC power source 200 being in the positive half cycle to output a first level to the controller 50, and to be turned off in response to the AC power source 200 being in the negative half cycle to output a second level to the controller 50, so that the controller 50 determines the zero-crossing point of the AC power source 200 based on the first level and the second level. The first level and the second level are different levels, and the embodiment of the present application takes the first level as a low level and the second level as a high level as an example.

[0041] Specifically, when the AC power source 200 is in the positive half cycle, the light emitter of the first optocoupler U2 is forward-conducting, and the light receiver of the first optocoupler U2 is also turned on, corresponding to the first optocoupler U2 being turned on. At this time, the controller 50 is connected to the second ground GND via the light receiver of the first optocoupler U2, corresponding to the zero-crossing detection branch 40 outputting a first level (i.e., a low level).

[0042] When the AC power source 200 is in the negative half cycle, the light emitter of the first optocoupler U2 is reversely cut off, and the light receiver of the first optocoupler U2 is also turned off, correspondingly disconnecting the first optocoupler U2. At this time, it can be considered that the zero-crossing detection branch 40 outputs the second level (i.e., high level) to the controller 50.

[0043] The controller 50 may determine the zero-crossing point of the AC power source 200 based on the time when the first level is switched to the second level, or the time when the second level is switched to the first level.

[0044] At this point, the zero-crossing detection process is realized, and in this process, since the first ground SGND and the second ground GND are non-isolated ground and isolated ground respectively, the light emitter and the light receiver of the first optocoupler U2 can maintain normal operation after being connected to the first ground SGND and the second ground GND respectively. Thus, the zero-crossing detection function remains normal. Moreover, since the light emitter of the first optocoupler U2 is connected to the first ground SGND, when the AC power supply 200 is in the negative half cycle, the light emitter of the first optocoupler U2 remains reverse cutoff, that is, at this time, there is no power supply circuit in the AC power supply 200, that is, there is no power loss in the AC power supply 200. It can be seen that the power loss when the AC power supply 200 is in the negative half cycle can be eliminated.

[0045] Please refer to Figure 2 , Figure 2 An example is shown with Figure 1 A circuit structure corresponding to the block diagram shown in FIG. Figure 2 As shown, the signal processing branch 10 includes a rectifier bridge U3 , a first capacitor C1 , a second capacitor C2 , a first resistor R1 , and a first inductor L1 .

[0046] Among them, the first end of the rectifier bridge U3 is connected to the live wire L of the AC power supply 200, the second end of the rectifier bridge U3 is connected to the neutral wire N of the AC power supply 200, the third end of the rectifier bridge U3 is respectively connected to the first end of the first capacitor C1, the first end of the first inductor L1 and the first end of the first resistor R1, the fourth end of the rectifier bridge U3, the second end of the first capacitor C1 and the second end of the second capacitor C2 are all connected to the first ground SGND, and the second end of the first inductor L1 is respectively connected to the second end of the first resistor R1, the first end of the second capacitor C2 and the opposite end of the primary coil.

[0047] Specifically, the rectifier bridge U3 is used to implement full-wave rectification, and the first capacitor C1, the second capacitor C2, the first resistor R1 and the first inductor L1 are used to implement filtering.

[0048] In this embodiment, the voltage conversion branch 20 further includes a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a first diode D1 and a second diode D2.

[0049] Among them, the first end of the third capacitor C3 is respectively connected to the signal processing branch 10, the first end of the second resistor R2 and the opposite-name end of the primary coil, the second end of the third capacitor C3 is respectively connected to the second end of the second resistor R2 and the first end of the third resistor R3, the second end of the third resistor R3 is respectively connected to the cathode of the first diode D1, the anode of the first diode D1 is respectively connected to the same-name end of the primary coil and the switch pin D of the power management chip U1, the same-name end of the secondary coil is respectively connected to the first end of the fourth capacitor C4 and the anode of the second diode D2, the opposite-name end of the secondary coil, the second end of the fifth capacitor C5 and the second end of the fifth resistor R5 are all connected to the first ground SGND, the second end of the fourth capacitor C4 is connected to the first end of the fourth resistor R4, the second end of the fourth resistor R4 is respectively connected to the cathode of the second diode D2, the first end of the fifth capacitor C5, the first end of the fifth resistor R5 and the feedback branch 30, and outputs the second DC power supply VC2.

[0050] Specifically, the first diode D1, third resistor R3, second resistor R2, and third capacitor C3 provide a discharge circuit for the primary coil. The second diode D2 is used for rectification. The fourth resistor R4 and fourth capacitor C4 are used to discharge any spikes that may occur on the second diode D2. The fifth capacitor C5 is used for filtering. The fifth resistor R5 acts as a load.

[0051] In this embodiment, the voltage conversion branch 20 further includes a seventh capacitor C7.

[0052] The seventh capacitor C7 is connected between the first ground SGND and the second ground GND to meet safety regulations.

[0053] In this embodiment, the feedback branch 30 includes a sixth resistor R6 , a seventh resistor R7 , a Zener diode DW, and a second optocoupler U4 .

[0054] Among them, the first end of the sixth resistor R6 is connected to the voltage conversion branch 20, the second end of the sixth resistor R6 is connected to the cathode of the Zener diode DW, the anode of the Zener diode DW is respectively connected to the first end of the seventh resistor R7 and the anode of the light-emitting device of the second optocoupler U4, the second end of the seventh resistor R7 and the cathode of the light-emitting device of the second optocoupler U4 are both connected to the second ground GND, the first end of the light receiver of the second optocoupler U4 is connected to the feedback pin FB of the power management chip U1, and the second end of the light receiver of the second optocoupler U4 is connected to the power pin VCC of the power management chip U1.

[0055] Specifically, the voltage of the second DC power supply VC2 determines the degree of conduction of the light receiver of the second optocoupler U4, that is, the magnitude of the on-resistance of the light receiver of the second optocoupler U4. The feedback signal is determined by the ratio between the voltage output from the power pin VCC of the power management chip U1 and the on-resistance of the light receiver of the second optocoupler U4.

[0056] The zero-crossing detection branch 40 further includes an eighth resistor R8 , a ninth resistor R9 , a tenth resistor R10 , and an eighth capacitor C8 .

[0057] The eighth resistor R8 is connected between the live wire L of the AC power supply 200 and the anode of the light emitter of the first optocoupler U2. The cathode of the light emitter of the first optocoupler U2 is connected to the first ground SGND. The first end of the light receiver of the first optocoupler U2 is connected to the first end of the ninth resistor R9 and the first end of the tenth resistor R10, respectively. The second end of the ninth resistor R9 is connected to the second DC power supply VC2. The second end of the tenth resistor R10 is connected to the controller 50 and the first end of the eighth resistor R8, respectively. The second end of the light receiver of the first optocoupler U2 and the second end of the eighth capacitor C8 are both connected to the second ground GND. The eighth capacitor C8 and the tenth resistor R10 form an RC filter.

[0058] Specifically, when the AC power source 200 is in the positive half cycle, the light emitter of the first optocoupler U2 is forward-conducting, and the light receiver of the first optocoupler U2 is also turned on, corresponding to the first optocoupler U2 being turned on. At this time, the controller 50 is connected to the second ground GND via the tenth resistor R10 and the light receiver of the first optocoupler U2, corresponding to the zero-crossing detection branch 40 outputting a first level (i.e., a low level).

[0059] When the AC power source 200 is in the negative half cycle, the light emitter of the first optocoupler U2 is reversely cut off, and the light receiver of the first optocoupler U2 is also turned off, correspondingly disconnecting the first optocoupler U2. At this time, the second DC power source VC2 is input to the controller 50 through the ninth resistor R9 and the tenth resistor R10. It can be considered that the zero-crossing detection branch 40 outputs the second level (i.e., a high level) to the controller 50.

[0060] The controller 50 may determine the zero-crossing point of the AC power source 200 based on the time when the first level is switched to the second level, or the time when the second level is switched to the first level.

[0061] At this point, the zero-crossing detection process is realized, and in this process, since the first ground SGND and the second ground GND are non-isolated ground and isolated ground respectively, the light emitter and the light receiver of the first optocoupler U2 can maintain normal operation after being connected to the first ground SGND and the second ground GND respectively. Thus, the zero-crossing detection function remains normal. Moreover, since the light emitter of the first optocoupler U2 is connected to the first ground SGND, when the AC power supply 200 is in the negative half cycle, the light emitter of the first optocoupler U2 remains reverse cutoff, that is, at this time, there is no power supply circuit in the AC power supply 200, that is, there is no power loss in the AC power supply 200. It can be seen that the power loss when the AC power supply 200 is in the negative half cycle can be eliminated.

[0062] In this embodiment, the power conversion and detection circuit 100 further includes a fuse FU and a bidirectional transient voltage suppressor diode DV.

[0063] The fuse FU is connected between the neutral line N of the AC power source 200 and the signal processing branch 10 , and the bidirectional transient voltage suppression diode DV is connected between the live line L and the neutral line N of the AC power source 200 .

[0064] Specifically, a fuse FU is a device used for circuit protection that melts when the current exceeds a predetermined value, thereby cutting off the circuit to prevent damage caused by overload or short circuit. A fuse FU is usually composed of a low-melting-point metal wire or metal sheet placed in an insulating housing.

[0065] Bidirectional transient voltage suppression (TVS) diodes (DV) are semiconductor devices used to protect electronic equipment from transient voltage spikes. These spikes can originate from lightning, switching operations, or other sources of electromagnetic interference. Bidirectional transient voltage suppression diodes (DV) absorb excessive voltage within a very short time and limit it to a safe level, thereby protecting connected circuits from damage.

[0066] An embodiment of the present application further provides a household appliance, which includes the power conversion and detection circuit 100 in any embodiment of the present application.

[0067] In some embodiments, the household appliance is one of an air conditioner, a refrigerator, a washing machine, an oven, or a juicer.

[0068] The above description is merely an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

[0069] The above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit them. Based on the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, and the steps may be implemented in any order. A person skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some of the technical features may be replaced by equivalents. However, such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A power conversion and detection circuit, characterized in that: include: The signal processing branch is connected to the live wire of the AC power supply and is configured to rectify and filter the AC power supply to output a first DC power supply. A voltage conversion branch and a feedback branch, wherein the voltage conversion branch includes a power management chip and a transformer, the primary coil of the transformer is connected between the power management chip and the signal processing branch, and the feedback branch is connected between the secondary coil of the transformer and the power management chip; The voltage conversion branch is configured to control the primary coil to be charged by the first DC power supply or to discharge the primary coil based on a feedback signal through the power management chip, so as to convert the first DC power supply into a second DC power supply; The feedback branch is configured to output the feedback signal to the power management chip based on the voltage of the second DC power supply; A zero-crossing detection branch and a controller, the zero-crossing detection branch comprising a first optocoupler, the anode of the light emitter of the first optocoupler being connected to the live wire of the AC power supply, the cathode of the light emitter of the first optocoupler being connected to the ground pin of the power management chip and connected to a first ground, the first end of the light receiver of the first optocoupler being connected to the controller, and the second end of the light receiver of the first optocoupler being connected to the secondary coil and connected to a second ground; The zero-crossing detection branch is configured to be turned on in response to the AC power source being in a positive half cycle to output a first level to the controller, and to be turned off in response to the AC power source being in a negative half axis to output a second level to the controller, so that the controller determines the zero-crossing point of the AC power source based on the first level and the second level.

2. The power conversion and detection circuit according to claim 1, wherein: The signal processing branch includes a rectifier bridge, a first capacitor, a second capacitor, a first resistor and a first inductor; The first end of the rectifier bridge is connected to the live wire of the AC power supply, the second end of the rectifier bridge is connected to the neutral wire of the AC power supply, the third end of the rectifier bridge is respectively connected to the first end of the first capacitor, the first end of the first inductor and the first end of the first resistor, the fourth end of the rectifier bridge, the second end of the first capacitor and the second end of the second capacitor are all connected to the first ground, and the second end of the first inductor is respectively connected to the second end of the first resistor, the first end of the second capacitor and the opposite end of the primary coil.

3. The power conversion and detection circuit according to claim 1, wherein: The voltage conversion branch further includes a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first diode and a second diode; The first end of the third capacitor is respectively connected to the signal processing branch, the first end of the second resistor and the opposite-name end of the primary coil, the second end of the third capacitor is respectively connected to the second end of the second resistor and the first end of the third resistor, the second end of the third resistor is respectively connected to the cathode of the first diode, the anode of the first diode is respectively connected to the same-name end of the primary coil and the switch pin of the power management chip, the same-name end of the secondary coil is respectively connected to the first end of the fourth capacitor and the anode of the second diode, the opposite-name end of the secondary coil, the second end of the fifth capacitor and the second end of the fifth resistor are all connected to the first ground, the second end of the fourth capacitor is connected to the first end of the fourth resistor, the second end of the fourth resistor is respectively connected to the cathode of the second diode, the first end of the fifth capacitor, the first end of the fifth resistor and the feedback branch, and outputs the second DC power supply.

4. The power conversion and detection circuit according to claim 3, characterized in that: The voltage conversion branch further includes a seventh capacitor; The seventh capacitor is connected between the first ground and the second ground.

5. The power conversion and detection circuit according to claim 1, wherein: The feedback branch includes a sixth resistor, a seventh resistor, a voltage stabilizing diode and a second optical coupler; The first end of the sixth resistor is connected to the voltage conversion branch, the second end of the sixth resistor is connected to the cathode of the voltage-stabilizing diode, the anode of the voltage-stabilizing diode is respectively connected to the first end of the seventh resistor and the anode of the light-emitting device of the second optocoupler, the second end of the seventh resistor and the cathode of the light-emitting device of the second optocoupler are both connected to the second ground, the first end of the light receiver of the second optocoupler is connected to the feedback pin of the power management chip, and the second end of the light receiver of the second optocoupler is connected to the power pin of the power management chip.

6. The power conversion and detection circuit according to claim 1, wherein: The zero-crossing detection branch further includes an eighth resistor, a ninth resistor, a tenth resistor and an eighth capacitor; The eighth resistor is connected between the live wire of the AC power supply and the anode of the light emitter of the first optocoupler, the cathode of the light emitter of the first optocoupler is connected to the first ground, the first end of the light receiver of the first optocoupler is respectively connected to the first end of the ninth resistor and the first end of the tenth resistor, the second end of the ninth resistor is connected to the second DC power supply, the second end of the tenth resistor is respectively connected to the controller and the first end of the eighth resistor, the second end of the light receiver of the first optocoupler and the second end of the eighth capacitor are both connected to the second ground.

7. The power conversion and detection circuit according to any one of claims 1 to 6, characterized in that: The power conversion and detection circuit further includes a fuse and a bidirectional transient voltage suppression diode; The fuse is connected between the neutral line of the AC power supply and the signal processing branch, and the bidirectional transient voltage suppression diode is connected between the live line and the neutral line of the AC power supply.

8. A household appliance, characterized in that: The method comprises the power conversion and detection circuit according to any one of claims 1 to 7.

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