Washing machine

Abstract

The utility model discloses a washing machine which comprises a variable frequency driver, the power input end of the variable frequency driver is provided with a rectification filter circuit, and the rectification filter circuit comprises a first X capacitor connected between a zero line and a live line; a first primary end and a second primary end of the first common mode inductor are respectively connected with the zero line and the live line; the first Y capacitor is connected between the zero line and the ground; the second Y capacitor is connected between the live wire and the ground; the second X capacitor is connected between the zero line and the live line and located at the rear ends of the first Y capacitor and the second Y capacitor; the rectifying circuit is connected to the rear end of the second X capacitor and used for rectifying the alternating current into direct current and outputting the direct current; and the third Y capacitor is connected between the positive electrode output end of the rectifying circuit and the ground or between the negative electrode output end of the rectifying circuit and the ground. According to the washing machine, a common-mode signal generated by a load can be inhibited by arranging one Y capacitor, and compared with the mode that Y capacitors need to be arranged for a live wire and a zero wire respectively before rectification, the washing machine achieves the purpose of saving electronic devices.

Description

Technical Field

[0001] The utility model belongs to the technical field of washing machines, and in particular relates to an electromagnetic interference filter circuit of a washing machine variable frequency drive. Background Art

[0002] Currently, EMI (Electromagnetic Interference) testing is performed during the production of household appliances. During these tests, EMI levels often exceed standards in the low-frequency range (150 kHz to 1 MHz). Therefore, to filter out interference from the power grid during washing machine operation, a filter circuit must be added to the frequency conversion design to ensure that the interference generated during circuit operation is suppressed and absorbed to a level that meets national standards.

[0003] EMI interference is primarily divided into two components: common-mode interference and differential-mode interference. Differential-mode interference accounts for a relatively small proportion in variable-frequency equipment, while common-mode interference accounts for a relatively large proportion. During debugging, differential-mode interference can be suppressed and absorbed by increasing differential-mode inductance or increasing X-capacitance. Common-mode interference can be suppressed and absorbed by increasing common-mode inductance or adjusting Y-capacitance. Existing EMI mitigation solutions for variable-frequency solutions have poor suppression effectiveness in the common-mode frequency bands of 150kHz-500kHz, 8MHz-20MHz, and 30MHz-50MHz (these frequency bands also experience significant interference in variable-frequency circuits). These solutions often struggle to pass EMI testing, requiring additional external filters to meet EMI testing requirements.

[0004] The above information disclosed in this background technology is only used to increase the understanding of the background technology of this application. Therefore, it may contain information that does not constitute the prior art known to ordinary technicians in this field. Summary of the Invention

[0005] The utility model aims to solve the technical problems that the existing common-mode interference of household appliances is mainly suppressed and absorbed by increasing common-mode inductance or adjusting Y capacitors, which uses many devices and has complex circuit redundancy. A washing machine is proposed to solve the above problems.

[0006] In order to achieve the above-mentioned utility model / design purpose, this utility model adopts the following technical solutions:

[0007] A washing machine includes a variable frequency drive, wherein a rectifier and filter circuit is provided at a power input end of the variable frequency drive, and the rectifier and filter circuit includes:

[0008] A first X capacitor connected between the neutral line and the live line;

[0009] A first common-mode inductor, wherein a first primary end and a second primary end of the inductor are connected to the neutral wire and the live wire respectively;

[0010] A first Y capacitor is connected between the neutral line and the ground;

[0011] The second Y capacitor is connected between the live wire and the ground;

[0012] a second X capacitor connected between the neutral line and the live line and located at the rear end of the first Y capacitor and the second Y capacitor;

[0013] a rectifier circuit connected to the rear end of the second X capacitor, configured to rectify the alternating current into a direct current and output the direct current;

[0014] A third Y capacitor is connected between the positive output terminal of the rectifier circuit and the ground, or between the negative output terminal of the rectifier circuit and the ground.

[0015] In some embodiments, the rectification and filtering circuit further includes:

[0016] The second common-mode inductor has a first primary end and a second primary end connected to the neutral line and the live line respectively, and is located between the second X capacitor and the rectifier circuit.

[0017] In some embodiments, the rectification and filtering circuit further includes:

[0018] An electrolytic capacitor is connected between the positive output terminal of the rectifier circuit and the system ground, and the third Y capacitor is located at the rear end of the electrolytic capacitor.

[0019] In some embodiments, the rectification and filtering circuit further includes:

[0020] A current limiting resistor is connected to the neutral line and is located between the first Y capacitor and the second X capacitor.

[0021] In some embodiments, the current limiting resistor is a thermistor.

[0022] In some embodiments, a relay switch is connected in parallel to both ends of the current-limiting resistor, and a control end of the relay switch is connected to the control module.

[0023] In some embodiments, the input circuit of the relay switch is further connected to a switching circuit, and the switching circuit includes:

[0024] An NPN transistor has a base connected to the control module, an emitter connected to the system ground, and a collector connected to the input circuit of the relay switch via a current-limiting resistor.

[0025] In some embodiments, the rectification and filtering circuit further includes:

[0026] The discharge circuit includes a resistor or multiple resistors connected in series, two ends of the discharge circuit are connected to the neutral line and the live line respectively, and the discharge circuit is located between the first X capacitor and the second X capacitor.

[0027] In some embodiments, the rectification and filtering circuit further includes:

[0028] The varistor has two ends connected to the neutral wire and the live wire respectively and is located at the front end of the first common-mode inductor.

[0029] In some embodiments, the rectification and filtering circuit further includes:

[0030] The reactance is connected to the neutral line or the live line and is located between the first X capacitor and the first common-mode inductor.

[0031] Compared with the prior art, the advantages and positive effects of the present invention are:

[0032] The washing machine of the present invention provides a third Y capacitor after the rectifier circuit. The third Y capacitor can be connected between the positive output terminal of the rectifier circuit and the ground or between the negative output terminal of the rectifier circuit and the ground. Since the common-mode interference signal generated by the load invades the line located between the output terminal of the rectifier circuit and the ground, the common-mode signal generated by the load can be suppressed by providing one Y capacitor. Compared with the need to provide two Y capacitors for the live wire and the neutral wire before rectification, the invention achieves the purpose of saving the use of electronic components.

[0033] By setting a Y capacitor for the live wire and the neutral wire at the front end of the rectifier circuit, it is used to suppress the common-mode interference generated by the load circuit and transmit it to the power grid through the live wire and the neutral wire respectively. This solution can effectively suppress the common-mode interference signals generated by multiple links that may generate common-mode interference.

[0034] After reading the specific embodiments of the present invention in conjunction with the accompanying drawings, other features and advantages of the present invention will become more clear. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 This is a principle block diagram of an embodiment of the washing machine proposed by the present utility model;

[0037] Figure 2This is a circuit diagram of an embodiment of the washing machine proposed by the present utility model;

[0038] Figure 3 This is a circuit diagram of another embodiment of the washing machine proposed by the present utility model;

[0039] Figure 4 This is a circuit diagram of another embodiment of the washing machine proposed by the present utility model;

[0040] Figure 5 This is a circuit diagram of another embodiment of the washing machine proposed by the present invention. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship 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 device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0043] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections. A person of ordinary skill in the art will understand the specific meanings of the above terms in the present invention in specific circumstances. In the description of the embodiments, specific features, structures, materials, or characteristics may be combined in any appropriate manner in any one or more embodiments or examples.

[0044] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the quantity of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features.

[0045] In the description of the present invention, unless otherwise specified, “a plurality of” means two or more.

[0046] This embodiment provides a washing machine, such as Figure 1 As shown, the VFD includes a rectifier and filter circuit at its power input. The input of the rectifier and filter circuit is connected to the power grid, rectifying AC power into DC and outputting it to the VFD. The VFD and its load generate EMI during operation, which is transmitted to the power grid through the connection point, causing impact and interference to the grid.

[0047] like Figure 2 As shown, the rectification and filtering circuit in this embodiment includes a rectification circuit DB1, whose input end is connected to the power grid through the socket CN, and is used to rectify AC power into DC power and output it to the variable frequency drive located at the rear end.

[0048] In order to solve the above problems, Figure 2 、 Figure 3 As shown, the rectifier and filter circuit in this embodiment further includes a third Y capacitor CY3, which is connected between the positive output terminal of the rectifier circuit and the ground, or connected between the negative output terminal of the rectifier circuit and the ground.

[0049] By providing a third Y capacitor CY3 after the rectifier circuit, connected either between the positive output terminal of the rectifier circuit and ground or between the negative output terminal of the rectifier circuit and ground, the common-mode interference signal generated by the load can be suppressed by providing a single Y capacitor. This reduces the need to provide separate Y capacitors for both the live and neutral lines before rectification, thus achieving the goal of saving electronic components.

[0050] Furthermore, compared to the solution of placing two Y capacitors at the front end of the rectifier circuit, according to the leakage current calculation formula I = 2π*f*V*Cy, where Cy is the total capacitance of the Y capacitors in the circuit, it can be seen that two Y capacitors increase the leakage current, which affects human safety. The solution of this embodiment uses only one Y capacitor, which has lower leakage current and higher safety performance.

[0051] In some embodiments, the rectifier and filter circuit further includes a first Y capacitor CY1 and a second Y capacitor CY2 , wherein the first Y capacitor CY1 is connected between the neutral line N and the ground, and the second Y capacitor CY2 is connected between the live line L and the ground.

[0052] The first Y capacitor CY1 and the second Y capacitor CY2 are located at the front end of the rectifier circuit. By setting a Y capacitor for the live wire and the neutral wire at the front end of the rectifier circuit respectively, they are used to suppress the common-mode interference generated by the load circuit and transmit it to the power grid through the live wire and the neutral wire respectively. This solution can effectively suppress the common-mode interference signals generated by multiple links that may generate common-mode interference.

[0053] In some embodiments, the capacitance of the first Y capacitor CY1 and the second Y capacitor CY2 is adjusted according to the strength of the common-mode interference, and is generally between 1000PF and 6800PF.

[0054] In some embodiments, the rectifier and filter circuit further includes a first X capacitor CX1 and a first common-mode inductor L1 , wherein the first X capacitor CX1 is connected between the neutral line N and the live line L to absorb differential-mode interference between the neutral line N and the live line L.

[0055] The capacitance of the first X capacitor CX1 is adjusted according to the intensity of the differential mode interference, and is generally between 100nF and 680nF.

[0056] The first primary end and the second primary end of the first common-mode inductor L1 are connected to the neutral line N and the live line L respectively, so as to suppress common-mode interference between the neutral line N and the live line L.

[0057] In some embodiments, the impedance of the first common-mode inductor L1 needs to be greater than 1000 ohms in the frequency range of 150K to 50M.

[0058] In some embodiments, the rectifier and filter circuit further includes a second X capacitor CX2 , which is connected between the neutral line N and the live line L and is located at the rear end of the first Y capacitor CY1 and the second Y capacitor CY2 .

[0059] The second X capacitor CX2 is used to absorb differential mode interference. The capacitance value is adjusted according to the intensity of the differential mode interference and is generally between 100nF and 680nF.

[0060] In some embodiments, the rectifier and filter circuit further includes a second common-mode inductor L2 , whose first and second primary ends are connected to the neutral line N and the live line L, respectively, and located between the second X capacitor CX2 and the rectifier circuit.

[0061] In some embodiments, the second common-mode inductor L2 is used to suppress common-mode interference, and is required to have an impedance greater than 1000 ohms in the frequency range of 150K to 50M.

[0062] In some embodiments, Figure 2 As shown, the rectifier and filter circuit also includes an electrolytic capacitor E1, which is connected between the positive output terminal of the rectifier circuit DB1 and the system ground GND. The third Y capacitor CY3 is located at the rear end of the electrolytic capacitor E1, which is used to convert the current output by the rectifier circuit DB1 into direct current and output it to the rear end variable frequency drive.

[0063] When the electrolytic capacitor E1 is initially charged, the current on the line is relatively large. In order to limit the input current, in some embodiments, such as Figure 4As shown, the rectifier and filter circuit further includes a current limiting resistor NTC1 , which is connected to the neutral line N and is located between the first Y capacitor CY1 and the second X capacitor CX2 .

[0064] In some embodiments, the current limiting resistor NTC1 may be implemented by a thermistor.

[0065] When the electrolytic capacitor E1 is charged to a certain voltage, the charging current decreases, and current limiting is not required, thus reducing energy consumption. Figure 5 As shown, a relay switch K1 is connected in parallel across the current-limiting resistor NTC1, with the control terminal of the relay switch K1 connected to the control module. When the electrolytic capacitor E1 is charged to a certain voltage, the relay switch K1 is controlled to close, short-circuiting the current-limiting resistor NTC1 and preventing the current from flowing through the current-limiting resistor NTC1.

[0066] In some embodiments, the input circuit of the relay switch K1 is also connected to a switching circuit, which includes an NPN transistor N3, whose base is connected to the control module, the emitter is connected to the system ground GND, and the collector is connected to the input circuit of the relay switch K1 through current limiting resistors R11 and R15.

[0067] The X-capacitor stores a certain amount of electrical energy. To prevent a safety hazard caused by discharge of the X-capacitor when the power plug is unplugged, in some embodiments, the rectifier and filter circuit further includes a discharge circuit, whose two ends are connected to the neutral line N and the live line L, respectively. The discharge circuit is located between the first X-capacitor CX1 and the second X-capacitor CX2. The electrical energy in the first X-capacitor CX1 and the second X-capacitor CX2 can be released through the discharge circuit.

[0068] The discharge circuit includes a resistor or multiple resistors connected in series. Figure 5 As shown, in some embodiments, the discharge circuit includes a plurality of resistors R41, R42 and R43 connected in series.

[0069] In some embodiments, the rectifier and filter circuit further includes a varistor RV1 , whose two ends are respectively connected to the neutral line N and the live line L and is located at the front end of the first common-mode inductor CX1 for absorbing surge current in the power grid.

[0070] In some embodiments, the rectifier and filter circuit further includes a reactor L3 connected to the neutral line N or the live line L and located between the first X capacitor CX1 and the first common-mode inductor L1. The reactor L3 plays a role in suppressing harmonics.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the above embodiments, or to replace some of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions claimed to be protected by the present invention.

Claims

1. A washing machine, characterized in that: The invention comprises a variable frequency drive, wherein the power input end of the variable frequency drive is provided with a rectifier and filter circuit, and the rectifier and filter circuit comprises: A first X capacitor connected between the neutral line and the live line; A first common-mode inductor, wherein a first primary end and a second primary end of the inductor are connected to the neutral wire and the live wire respectively; A first Y capacitor is connected between the neutral line and the ground; The second Y capacitor is connected between the live wire and the ground; a second X capacitor connected between the neutral line and the live line and located at the rear end of the first Y capacitor and the second Y capacitor; a rectifier circuit connected to the rear end of the second X capacitor, configured to rectify the alternating current into a direct current and output the direct current; A third Y capacitor is connected between the positive output terminal of the rectifier circuit and the ground, or between the negative output terminal of the rectifier circuit and the ground.

2. The washing machine according to claim 1, wherein The rectifier and filter circuit further includes: The second common-mode inductor has a first primary end and a second primary end connected to the neutral line and the live line respectively, and is located between the second X capacitor and the rectifier circuit.

3. The washing machine according to claim 1, wherein The rectifier and filter circuit further includes: An electrolytic capacitor is connected between the positive output terminal of the rectifier circuit and the system ground, and the third Y capacitor is located at the rear end of the electrolytic capacitor.

4. The washing machine according to claim 3, characterized in that The rectifier and filter circuit further includes: A current limiting resistor is connected to the neutral line and is located between the first Y capacitor and the second X capacitor.

5. The washing machine according to claim 4, characterized in that The current limiting resistor is a thermistor.

6. The washing machine according to claim 4, characterized in that A relay switch is connected in parallel to both ends of the current limiting resistor, and a control end of the relay switch is connected to the control module.

7. The washing machine according to claim 6, characterized in that The input circuit of the relay switch is further connected to a switch circuit, and the switch circuit includes: An NPN transistor has a base connected to the control module, an emitter connected to the system ground, and a collector connected to the input circuit of the relay switch via a current-limiting resistor.

8. The washing machine according to any one of claims 1 to 7, characterized in that: The rectifier and filter circuit further includes: The discharge circuit includes a resistor or multiple resistors connected in series, two ends of the discharge circuit are connected to the neutral line and the live line respectively, and the discharge circuit is located between the first X capacitor and the second X capacitor.

9. The washing machine according to any one of claims 1 to 7, characterized in that: The rectifier and filter circuit further includes: The varistor has two ends connected to the neutral wire and the live wire respectively and is located at the front end of the first common-mode inductor.

10. The washing machine according to any one of claims 1 to 7, characterized in that: The rectifier and filter circuit further includes: The reactance is connected to the neutral line or the live line and is located between the first X capacitor and the first common-mode inductor.

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