A filtering circuit, a filter, and a washing machine

Abstract

The present invention provides a filtering circuit, a filter and a washing machine. The filtering circuit includes a main wire, on which a first magnetic ring and a second magnetic ring are connected in series; a first wire, the current input end of the first wire is connected to the current output end of the main wire, and the current output end of the first wire is connected to a first load; a first capacitor is connected in series between the current input end of the first wire and the first load; a second wire, the current input end of the second wire is connected to the main wire, and the current output end of the second wire is connected to a second load; an inductor is connected in series between the current input end of the second wire and the second load; a second capacitor is connected in series between the inductor and the second load; a third capacitor and a fourth capacitor are connected in parallel between the current input end of the second wire and the inductor, and a fifth capacitor and a sixth capacitor are connected in parallel between the second inductor and the second load. The filtering circuit of the present invention has low cost and high generalization.

Description

Technical Field

[0001] The present invention belongs to the field of filter circuits, and more specifically, relates to a filter circuit, a filter, and a washing machine. Background Art

[0002] With the innovation of technology, washing machine products are increasingly favored by the market. They are convenient to use and have diverse functions, and have spread to every household. While enjoying the convenience brought by the washing machine, the diversification of its functions has also led to increasingly serious electromagnetic interference generated by its load to the outside. The sources of electromagnetic interference in washing machines mainly include the switching power supply and load motor inside the washing machine. Moreover, due to the compact internal structure and small space of the washing machine, the load wiring method is also restricted. In order to suppress the electromagnetic interference generated by the washing machine and at the same time pass the relevant electromagnetic compatibility tests, a large number of filtering measures often need to be added to the product.

[0003] Currently, the filtering measures adopted by washing machines mainly use independent filters, power cords with magnetic rings, and a multi-stage filtering wire combining a main board filter and a drive board filter. However, the above methods are costly, complex in process, and poor in versatility.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a filter circuit, a filter, and a washing machine with low cost and high generalization.

[0006] To solve the above technical problem, the present invention proposes a filter circuit, including

[0007] A main wire, with a first magnetic ring and a second magnetic ring connected in series on the main wire;

[0008] A first wire, the current input end of the first wire is connected to the current output end of the main wire, and the current output end of the first wire is connected to a first load; a first capacitor is connected in series between the current input end of the first wire and the first load;

[0009] A second wire, the current input end of the second wire is connected to the main wire, and the current output end of the second wire is connected to a second load; an inductor is connected in series between the current input end of the second wire and the second load; a second capacitor is connected in series between the inductor and the second load; a third capacitor and a fourth capacitor are connected in parallel between the current input end of the second wire and the inductor, and a fifth capacitor and a sixth capacitor are connected in parallel between the second inductor and the second load.

[0010] Further optionally, the main wire includes a main neutral wire and a main live wire; the first wire includes a first neutral wire and a first live wire, and the first neutral wire is connected to the main neutral wire,

[0011] The first live wire is connected to the main live wire; the first capacitor is connected between the first neutral wire and the first live wire.

[0012] Further optionally, the second wire includes a second neutral wire and a second live wire, the second neutral wire is connected to the main neutral wire, and the second live wire is connected to the main live wire;

[0013] The second capacitor is connected between the second neutral wire and the second live wire between the inductor and the second load;

[0014] The main wire further includes a ground wire. The third capacitor is connected between the second neutral wire and the ground wire between the current input end of the second wire and the inductor; the fourth capacitor is connected between the second live wire and the ground wire between the current input end of the second wire and the inductor; the fifth capacitor is connected between the second neutral wire and the ground wire between the inductor and the second load, and the sixth capacitor is connected between the second live wire and the ground wire between the inductor and the second load.

[0015] Further optionally, a first resistor is further connected in series between the parallel circuit of the third capacitor and the fourth capacitor and the ground wire. The circuit composed of the third capacitor, the fourth capacitor and the first resistor is located between the current input end of the second wire and the inductor.

[0016] Further optionally, a second resistor is further connected in series between the parallel circuit of the fifth capacitor and the sixth capacitor and the ground wire. The circuit composed of the fifth capacitor, the sixth capacitor and the second resistor is located between the second capacitor and the second load.

[0017] Further optionally, the neutral wire, the live wire and the ground wire are jointly wound around the first magnetic ring, the neutral wire and the live wire are jointly wound around the second magnetic ring, and the first magnetic ring is connected between the current output end of the main wire and the second magnetic ring, and the second magnetic ring is connected between the first magnetic ring and the current input end of the main wire.

[0018] Further optionally, the first magnetic ring is a magnetic ring with low impedance at low frequencies and high impedance at high frequencies, and the second magnetic ring is a magnetic ring with high impedance at low frequencies and low impedance at high frequencies.

[0019] The second object of the present invention also proposes a filtering device, which is characterized in that it adopts the above filtering circuit.

[0020] The third object of the present invention also proposes a washing machine, which adopts the above filtering circuit or has the above filtering device.

[0021] Further optionally, the washing machine includes an external power cord, a main board, a drive board, and a motor.

[0022] The current input end of the main wire is connected to the external power cord, the current output end of the first wire is connected to the main board, the current output end of the second wire is connected to the drive board, and the drive board is electrically connected to the motor.

[0023] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0024] The present invention proposes an efficient filtering method that combines a filtering wire and a special winding method of a magnetic ring. By adjusting the device selection, filtering structure, magnetic ring winding method, and load wiring method of the filtering wire, the purpose of efficiently suppressing the broadband electromagnetic interference generated by the washing machine is achieved, and it has the advantages of a wide interference suppression frequency range, high versatility, and low cost.

[0025] The following further describes in detail the specific embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, as part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings in the following description are only some embodiments, and those of ordinary skill in the art can obtain other drawings based on these drawings without creative efforts. In the drawings:

[0027] Figure 1 : Schematic diagram of the existing filtering circuit.

[0028] Figure 2 : Schematic diagram of the filtering circuit of the embodiment of the present invention.

[0029] Figure 3 : Schematic diagram of the existing magnetic ring winding method and wiring.

[0030] Figure 4 : Schematic diagram of the magnetic ring winding method and wiring of the embodiment of the present invention.

[0031] Figure 5 : Schematic diagram of the overall wiring of the washing machine of the embodiment of the present invention.

[0032] Figure 6 : Test result of the terminal interference voltage of the washing machine without adding the filtering circuit of the embodiment of the present invention.

[0033] Figure 7 : Test result of the terminal interference voltage of the washing machine with the filtering circuit of the embodiment of the present invention added.

[0034] Figure 8 : The test result of the conducted emission power of the washing machine without adding the filter circuit of the embodiment of the present invention.

[0035] Figure 9 : The test result of the conducted emission power of the washing machine with the filter circuit of the embodiment of the present invention added.

[0036] Wherein: 1. Filter circuit; 2 - Main board; 3 - Driver board; 4 - Motor; 5 - Motor wire; 6 - Washing machine inlet; 7 - External power cord.

[0037] It should be noted that these drawings and text descriptions are not intended to limit the scope of the concept of the present invention in any way, but to illustrate the concept of the present invention to those skilled in the art by referring to specific embodiments. Detailed implementation manners

[0038] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0039] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, terms such as "installed", "connected", "connected", "contacted", "communicated" 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 directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0040] Figure 1 The existing filter circuit for washing machines mainly uses a multi - stage filter circuit combining an independent filter, a magnetic ring on the power cord, a main board filter and a driver board filter for filtering measures. However, the above - mentioned methods are costly, have complex processes and poor versatility. This embodiment proposes a filter circuit, as Figure 2As shown, the filtering circuit mainly consists of a first capacitor CX1, a second capacitor CX2, an inductor L, a third capacitor CY1, a fourth capacitor CY2, a fifth capacitor CY3, and a sixth capacitor CY4. The filtering circuit of this embodiment includes a main wire and a first wire and a second wire connected to the main wire. A first magnetic ring and a second magnetic ring are connected in series on the main wire; the current input end of the first wire is connected to the current output end of the main wire, and the current output end of the first wire is connected to a first load; a first capacitor CX1 is connected in series between the current input end of the first wire and the first load; the current input end of the second wire is connected to the main wire, and the current output end of the second wire is connected to a second load; an inductor L is connected in series between the current input end of the second wire and the second load; a second capacitor CX2 is connected in series between the inductor L and the second load; a third capacitor CY1 and a fourth capacitor CY2 are connected in parallel between the current input end of the second wire and the inductor L, and a fifth capacitor CY3 and a sixth capacitor CY4 are connected in parallel between the second inductor L and the second load.

[0041] In this embodiment, the electromagnetic interference can be suppressed by a first-stage filtering circuit. Compared with the existing filtering measures, the use of an independent filter and motherboard filtering can be reduced. The filtering circuit has an excellent filtering effect on interference in the full frequency band, and has a simple structure, good versatility, and low cost, which can greatly save the product development time and cost. Further optionally, the main wire includes a main neutral line N and a main live wire L; the first wire includes a first neutral line and a first live wire, the first neutral line is connected to the main neutral line N, and the first live wire is connected to the main live wire L; the first capacitor CX1 is connected between the first neutral line and the first live wire. The second wire includes a second neutral line and a second live wire, the second neutral line is connected to the main neutral line N, and the second live wire is connected to the main live wire L; the second capacitor CX2 is connected between the second neutral line and the second live wire between the inductor L and the second load; the main wire further includes a ground wire PE, the third capacitor CY1 is connected between the second neutral line between the current input end of the second wire and the inductor L and the ground wire; the fourth capacitor CY2 is connected between the second live wire between the current input end of the second wire and the inductor L and the ground wire; the fifth capacitor CY3 is connected between the second neutral line between the inductor L and the second load and the ground wire, and the sixth capacitor CY4 is connected between the second live wire between the inductor L and the second load and the ground wire. The inductor L can be a common-mode inductor. The X capacitor and the Y capacitor are both filtering capacitors. The X capacitor is mainly connected between the neutral line N and the live wire L to eliminate differential-mode interference. The Y capacitor is mainly connected between the live wire L / neutral line N and the ground PE to eliminate common-mode interference.

[0042] Further optionally, to improve the suppression effect on high-frequency interference and optimize the interference signal release path, a first resistor R1 is further connected in series between the parallel circuit of the third capacitor CY1 and the fourth capacitor CY2 and the ground wire. The circuit composed of the third capacitor CY1, the fourth capacitor CY2, and the first resistor R1 is located between the current input end of the second wire and the inductor L.

[0043] Further optionally, to improve the high-frequency interference suppression effect and optimize the interference signal release path, a second resistor R2 is also connected in series between the parallel circuit of the fifth capacitor CY3 and the sixth capacitor CY4 and the ground wire. The circuit composed of the fifth capacitor CY3, the sixth capacitor CY4, and the second resistor R2 is located between the second capacitor CX2 and the second load.

[0044] Further optionally, it is set that the inductance value of the inductor L is L, the capacitance value is C, and the resonance frequency of the filter circuit is f, satisfying In the existing filter circuit, the common-mode inductor L has a value of 450 uH - 25 mH and is composed of an inductor coil and a magnetic core, or a hollow coil. The values of CX1, CX2, CY1, CY2, CY3, CY4 are 0.01 nF - 10 uF, and generally safety capacitors or film capacitors are selected. The values of R1 and R2 are 10 Ω - 300 Ω, and generally color ring resistors or chip resistors are selected. To ensure the optimal filtering effect, the filter circuit of this embodiment can adjust the selection of L, CX1, CX2, CY1, CY2, CY3, CY4, R1, and R2 according to the interference frequency points, so that the resonance frequency of the filter circuit is mainly concentrated on the frequency points with higher interference intensity, and it satisfies the formula The size of the capacitor is selected within a general numerical range according to the resonance frequency by the theoretical formula. Finally, it is necessary to accurately select according to other parasitic parameters (parasitic capacitance, parasitic inductance) of the circuit, and the optimal value selected can be specifically verified by experiments. Taking the interference at a frequency of 500 KHz as an example, when L is selected as 10 mH, CX1 is selected as 10 nF, CX2 is selected as 0.47 uF, CY1, CY2, CY3, CY4 are selected as 4.7 nF, and R1 and R2 are selected as 200 Ω, it has the optimal filtering effect;

[0045] Further optionally, both the first magnetic ring and the second magnetic ring in the existing filter circuit are ferrite magnetic rings. The first magnetic ring and the second magnetic ring are both selected as magnetic rings suitable for the high-frequency band, and the existing magnetic ring winding method is as Figure 3 shown, the zero wire and the live wire are co-wound around the first magnetic ring, and the ground wire is single-wound around the second magnetic ring; the magnetic ring winding method of the filter circuit of this embodiment is as Figure 4 shown, the zero wire, the live wire, and the ground wire are commonly wound around the first magnetic ring, the zero wire and the live wire are commonly wound around the second magnetic ring, and the first magnetic ring is connected between the current output end of the main wire and the second magnetic ring, and the second magnetic ring is connected between the first magnetic ring and the current input end of the main wire.

[0046] Further optionally, both the first magnetic ring and the second magnetic ring of the existing filter circuit are ferrite magnetic rings. To avoid excessive ground wire impedance affecting the filtering effect at low frequencies (150 kHz - 30 MHz), the first magnetic ring of this embodiment is selected as a magnetic ring with low impedance at low frequencies and high impedance at high frequencies, and the second magnetic ring is selected as a magnetic ring with high impedance at low frequencies and low impedance at high frequencies.

[0047] The filtering circuit of this embodiment forms an efficient filtering method by combining with the special winding methods of the first magnetic ring and the second magnetic ring. By adjusting the device selection, filtering structure, magnetic ring winding method, and load wiring method of the filtering circuit, the purpose of efficiently suppressing electromagnetic interference is achieved, and it has the advantages of a wide interference suppression frequency range, high versatility, and low cost.

[0048] This embodiment optimizes the device selection of the filtering circuit, the magnetic ring winding method, and the wire outlet method of the internal load, making this solution highly versatile.

[0049] This embodiment also proposes a filtering device, which is characterized in that it uses the above-mentioned filtering circuit.

[0050] This embodiment also proposes a washing machine, as Figure 5 shown, which uses the above-mentioned filtering circuit 1 or has the above-mentioned filtering device. The washing machine includes an external power cord 7, a main board 2, a drive board 3, and a motor 4. The current input end of the main wire is connected to the external power cord 7 through the washing machine inlet 6. The current output end of the first wire is connected to the main board 2, the current output end of the second wire is connected to the drive board 3, and the drive board 3 is electrically connected to the motor 4 through the motor wire 5. To avoid interference on the motor wire of the drive board from being coupled to the power supply zero and live wires of the drive board through the wire-to-wire coupling and reduce the crosstalk between wires, the motor wire needs to be routed separately from the zero and live wires of the drive board, as shown in the appendix Figure 5 shown.

[0051] The inventor also separately tested the terminal interference voltage and interference power of a washing machine that did not use the filtering circuit of this embodiment, and the test results are as shown in Figure 6 and Figure 8 shown; in addition, the inventor also separately tested the interference voltage and interference power of the terminals of a washing machine that used the filtering circuit of this embodiment, and the test results are as shown in Figure 7 and Figure 9 shown.

[0052] From the above test results, it can be seen that when the filtering circuit of this embodiment was not added to the washing machine, the terminal interference voltage test exceeded the standard by 29.39 dB, and the result is as shown in the appendix Figure 6 shown; the interference power test exceeded the standard by 9.84 dB, and the result is as shown in the appendix Figure 8 shown. Neither meets the national standard requirements;

[0053] When the washing machine uses the filtering circuit of this embodiment, the magnetic ring winding method in the appendix Figure 4 and the wiring method shown in the appendix Figure 5 shown, the terminal interference voltage test has a margin of 7.39 dB, and the result is as shown in the appendix Figure 7 shown; the interference power test has a margin of 6.2 dB, and the result is as shown in the appendix Figure 9As shown, all meet the national standard requirements and have a relatively high margin, and the interference suppression effect is obvious.

[0054] In this embodiment, a broadband and efficient electromagnetic interference suppression circuit is designed for a washing machine, which has the advantages of a wide interference suppression frequency range, high versatility and low cost; by optimizing the selection of magnetic cores and their winding methods, a winding method combining two-wire co-winding and three-wire co-winding is designed to broaden the interference suppression frequency band and ability of the magnetic core, and at the same time solve the problem of high-frequency crosstalk formed between the wiring of the washing machine.

[0055] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art of this patent, without departing from the scope of the technical solution of the present invention, can make some changes or modifications to the above-mentioned technical content by using the technical content prompted above as equivalent embodiments with equivalent changes, but any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the present invention.

Claims

1. A filtering circuit, characterized in that, it includes a main wire, with a first magnetic ring and a second magnetic ring connected in series on the main wire; a first wire, the current input end of the first wire is connected to the current output end of the main wire, and the current output end of the first wire is connected to a first load; a first capacitor is connected in series between the current input end of the first wire and the first load; a second wire, the current input end of the second wire is connected to the main wire, and the current output end of the second wire is connected to a second load; an inductor is connected in series between the current input end of the second wire and the second load; a second capacitor is connected in series between the inductor and the second load; a third capacitor and a fourth capacitor are connected in parallel between the current input end of the second wire and the inductor, and a fifth capacitor and a sixth capacitor are connected in parallel between the second capacitor and the second load; the main wire includes a main neutral wire and a main live wire; the first wire includes a first neutral wire and a first live wire, the first neutral wire is connected to the main neutral wire, and the first live wire is connected to the main live wire; the first capacitor is connected between the first neutral wire and the first live wire; the second wire includes a second neutral wire and a second live wire, the second neutral wire is connected to the main neutral wire, and the second live wire is connected to the main live wire; the second capacitor is connected between the second neutral wire and the second live wire between the inductor and the second load; the main wire further includes a ground wire, the third capacitor is connected between the second neutral wire and the ground wire between the current input end of the second wire and the inductor; the fourth capacitor is connected between the second live wire and the ground wire between the current input end of the second wire and the inductor; the fifth capacitor is connected between the second neutral wire and the ground wire between the inductor and the second load, and the sixth capacitor is connected between the second live wire and the ground wire between the inductor and the second load.

2. A filtering circuit according to claim 1, characterized in that, a first resistor is further connected in series between the parallel circuit of the third capacitor and the fourth capacitor and the ground wire, and the circuit composed of the third capacitor, the fourth capacitor and the first resistor is located between the current input end of the second wire and the inductor.

3. A filtering circuit according to claim 1, characterized in that, a second resistor is further connected in series between the parallel circuit of the fifth capacitor and the sixth capacitor and the ground wire, and the circuit composed of the fifth capacitor, the sixth capacitor and the second resistor is located between the second capacitor and the second load.

4. A filtering circuit according to any one of claims 1-3, characterized in that, the neutral wire, the live wire and the ground wire are jointly wound around the first magnetic ring, the neutral wire and the live wire are jointly wound around the second magnetic ring, and the first magnetic ring is connected between the current output end of the main wire and the second magnetic ring, and the second magnetic ring is connected between the first magnetic ring and the current input end of the main wire.

5. A filtering circuit according to claim 4, characterized in that, The first magnetic ring is a magnetic ring with low impedance at low frequencies and high impedance at high frequencies, and the second magnetic ring is a magnetic ring with high impedance at low frequencies and low impedance at high frequencies.

6. A filtering device, characterized in that it adopts the filtering circuit described in any one of claims 1-5.

7. A washing machine, characterized in that it adopts the filtering circuit described in any one of claims 1-5, or has the filtering device described in claim 6.

8. A washing machine according to claim 7, characterized in that the washing machine includes an external power cord, a main board, a drive board and a motor, the current input end of the main wire is connected to the external power cord, the current output end of the first wire is connected to the main board, the current output end of the second wire is connected to the drive board, and the drive board is electrically connected to the motor.

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