Switching power supply with plc common mode noise rejection

Abstract

The application discloses a switching power supply with PLC common mode noise suppression, and relates to the technical field of switching power supplies. PLC signals first flow into differential mode inductors L1 and L2 through L and N lines of the power supply. A pressure-sensitive resistor is arranged behind the LISN, and an X capacitor is arranged behind the pressure-sensitive resistor and before a common mode inductor. An E1 winding is used to offset the initial common mode current, so that the common mode of the transformer is suppressed, and the lowest-cost PLC function noise suppression technology is realized. The application reduces the common mode interference of the whole power supply by applying a peripheral circuit and introducing a low common mode noise transformer winding structure, so that the switching power supply with the PLC function intelligent home equipment has both the advantage of low cost and meets the common mode noise suppression technology with the PLC function. The high-frequency interference signal suppression transformer with the common mode suppression circuit design and the common mode noise suppression technology can meet the IEC-62684 standard, and finally solves the common mode noise conflict of the traditional switching power supply with the PLC technology, so that the problem of coexistence of the two is solved.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, specifically to a switching power supply with PLC common-mode noise suppression. Background Technology

[0002] With the widespread adoption of 5G technology, numerous well-known domestic and international companies have entered the smart home market. While early smart home technologies utilized wired connections, offering high data transmission reliability and speed, their bulkiness, lack of flexibility, complex wiring, and high cost have rendered them inadequate, leading to the adoption of wireless communication / network technologies. Currently, most mainstream smart home technologies utilize low-cost power line communication (PLC) technology, which uses power lines in the power distribution network as the transmission medium to achieve data transmission and information exchange (as follows). Figure 1 ).

[0003] Advantages of PLC technology in smart homes: Intelligent interconnection; power line carrier communication replaces traditional point-to-point communication, conforming to a smart network structure. Health and environmental friendliness; while widespread electronic technology has led to significant radio frequency pollution, power line carrier technology transmits signals through power lines, eliminating any harmful radio frequency interference. Simple setup; no additional wiring is required, enabling smart home functionality using existing power grids.

[0004] Power supply challenges for smart home technology with PLC functionality: Power supplies for general communication applications (as follows) Figure 2 As long as the system can pass the EN55032 standard test, a 3-6 dB margin in conducted / radiated power is sufficient. However, smart homes, due to the involvement of PLC technology, have their own unique characteristics. In addition to meeting the above standards, they also need to meet the IEC-62684 standard, with common-mode interference within 2V. Therefore, the common-mode interference immunity of power supply equipment presents higher technical requirements and new challenges. Smart home terminal devices with PLC functionality often encounter the following problems when paired with ordinary power supplies: 1. The system PLC is missing, and the terminal system cannot respond.

[0005] 2. The touch panel is malfunctioning, and the terminal system displays garbled characters.

[0006] 3. The control terminal automatically or incorrectly sends control signals, and the terminal system does not respond according to the operator's wishes.

[0007] 4. In more serious cases, the terminal equipment may be damaged, resulting in accidents or reliability issues.

[0008] In summary, when a general power supply is paired with a smart home system with PLC functionality, the high common-mode noise of the power supply will pollute the system through the power lines, making it difficult to achieve the goal of controlling terminal devices using PLC technology. Summary of the Invention

[0009] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a switching power supply with PLC common-mode noise suppression, comprising an input EMC filter unit, an input rectifier filter unit, an input filter unit, an input detection control unit, an output filter unit, an output voltage detection unit, and a high-frequency interference signal suppression transformer; the input rectifier filter unit is located after the input EMC filter unit, the positive output V+ of the rectifier bridge BD1 of the input rectifier filter unit is connected to the input terminal of the input filter unit, and is connected to the opposite-name terminal of the T1B winding of the high-frequency interference signal suppression transformer; the input detection control unit is used to detect the input voltage waveform for use... To determine the output voltage and serve as a reference for frequency detection, the output filter unit is connected to the T1C winding of the high-frequency interference signal suppression transformer. The output voltage detection unit is used to detect the output voltage and provide feedback. The input EMC filter unit includes differential mode inductors L1 and L2, resistive loads R10 and R11, a varistor MOV1, a cold-start current-limiting resistor NTC1, a common-mode inductor LF1, and an X capacitor CX1. The differential mode inductor L1 and the resistive load R11 are connected in parallel to form a first circuit. The first terminal of the first circuit is finally connected to the power supply line L, and the second terminal of the first circuit is connected to the power supply line L through the cold-start current-limiting resistor NTC1. One end of the first winding of the common-mode inductor LF1 is connected; the differential-mode inductor L2 and the resistive load R10 are connected in parallel to form a second circuit. The first end of the second circuit is connected to the power supply line N, and the second end of the second circuit is connected to one end of the second winding of the common-mode inductor LF1; one end of the X capacitor CX1 is connected between the second end of the first circuit and the cold-start current-limiting resistor NTC1, and the other end of the X capacitor CX1 is connected between the second end of the second circuit and one end of the second winding of the common-mode inductor LF1; one end of the varistor MOV1 is connected between the second end of the first circuit and one end of the X capacitor CX1, and the other end of the varistor MOV1... The first output winding N1 is connected between the second terminal of the second circuit and the other end of the X capacitor CX1; the first output winding N1 is wound on the innermost side of the high-frequency interference signal suppression transformer; the T1B winding is wound outside the first output winding N1; the T1A winding is wound outside the T1B winding, and the T1A winding consists of four parallel windings; the second output winding N4 is wound outside the T1A winding; a layer of winding E1 is inserted between the first output winding N1 and the T1B winding, and the winding E1 consists of four parallel windings, each wound 6 turns, with the starting end of winding E1 connected to the tail end of the T1A winding; the first output winding N1 and the second output winding N4 constitute the T1C winding.

[0011] The present invention provides the following technical solution: The input detection and control unit includes a main control single-chip microcomputer U1, a power supply rectifier diode D1, a current-limiting resistor R15, a current-limiting resistor R13, a filter capacitor C7, and a filter capacitor C10; the anode of the power supply rectifier diode D1 is connected to the same-name terminal of the T1A winding of the high-frequency interference signal suppression transformer through the current-limiting resistor R15, and the cathode of the power supply rectifier diode D1 is connected to the power supply terminal VCC of the main control single-chip microcomputer U1 through the current-limiting resistor R13; the filter capacitors C7 and C10 are both connected between the cathode of the power supply rectifier diode D1 and the ground terminal; the positive output V+ of the rectifier bridge BD1 of the input rectification and filtering unit is also connected to the cathode of the power supply rectifier diode D1 through a resistor string composed of resistors R8, R9, and J1.

[0012] The present invention provides the following technical solution: the output voltage detection unit includes resistors R17, R18, R25 and capacitor C8; resistors R17 and R18 are connected in series and then connected to the two ends of the T1A winding of the high-frequency interference signal suppression transformer respectively; the detection terminal FB of the main control single-chip microcomputer U1 is connected to the voltage divider point of resistors R17 and R18; resistor R25 and capacitor C8 are both connected between the detection terminal FB of the main control single-chip microcomputer U1 and the ground terminal.

[0013] The present invention provides the following technical solution: The input filtering unit includes a filter capacitor C1, a filter capacitor C2, a resistor R5, a resistor R6, a resistor R7, a resistor R14, an absorption capacitor C3, an absorption capacitor C4, and a damping diode D2. The filter capacitor C1 and the filter capacitor C2 are connected in series to form a capacitor string, the resistor R5 and the resistor R14 are connected in series to form a resistor string, and the resistor R6 and the resistor R7 are connected in parallel to form a third circuit. After the capacitor string and the resistor are connected in parallel, one end of the capacitor string is connected to the positive output V+ of the rectifier bridge BD1, and the other end is connected to one end of the third circuit. The other end of the third circuit is connected to the cathode of the damping diode D2. The anode of the damping diode D2 is connected to the same-name terminal of the T1B winding of the high-frequency interference signal suppression transformer.

[0014] The present invention provides the following technical solution: the output filtering unit includes a rectifier chip U2 and peripheral circuits.

[0015] The present invention provides the following technical solution: the T1B winding has a total of 62 turns, with 21 turns in the first layer, 21 turns in the second layer, and 20 turns in the third layer. The conductors of the third layer are wound into the concave gap between the two conductors of the second layer.

[0016] The present invention provides the following technical solution: the inductance value of differential mode inductor L1 is 50-300μH, and the inductance value of differential mode inductor L2 is 50-300μH.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: The PLC signal first arrives at the L and N lines of the power supply and flows into the differential mode inductors L1 and L2, which can effectively reduce the attenuation of the PLC signal. The varistor MOV1 has a static capacitance and is placed after LISN, which can effectively avoid absorbing the PLC signal. The X capacitor CX1 is located after the varistor MOV1 and before the common mode inductor LF1, which can effectively reduce the attenuation of the PLC signal. The E1 shielding winding is used to cancel the initial common mode current, so as to suppress the common mode of the high-frequency transformer and realize the lowest cost PLC function noise suppression technology. This invention reduces the common-mode interference of the power supply by applying peripheral circuits and introducing a low common-mode noise transformer winding structure. This enables the switching power supply for smart home devices with PLC functionality to have both the advantage of low cost and compliance with common-mode noise suppression technology for PLC functionality. By using circuit design for common-mode suppression of PLC functions and high-frequency interference signal suppression transformers for common-mode noise suppression technology, compliance with IEC-62684 standards can be achieved. This ultimately resolves the conflict between common-mode noise and PLC technology in traditional switching power supplies, thus solving the problem of compatibility and coexistence between the two.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of power line carrier communication technology. Figure 2 This is a schematic diagram of the EMI circuit at the input terminal of a switching power supply in the existing technology; Figure 3 This is the circuit schematic diagram of the present invention; Figure 4 This is another circuit schematic diagram of the present invention, and... Figure 3 The difference lies in the fact that it indicates the specific location of the high-frequency interference signal suppression transformer; Figure 5 This is a common-mode noise path diagram of a power supply high-frequency transformer; Figure 6 This is a schematic diagram of the planar structure of a high-frequency transformer in the prior art; Figure 7 This is a schematic diagram of the planar structure of the high-frequency interference signal suppression transformer of the present invention; Figure 8 This is a schematic diagram of the common-mode noise test principle for high-frequency transformers. Figure 9 This is a schematic diagram of the common-mode noise test results of the present invention. CH1: Test signal 20V, CH2: High-frequency interference signal suppression transformer common-mode noise 7.1mV.

[0021] Figure 10 This is a schematic diagram of the common-mode noise test results of existing high-frequency transformers. CH1: Test signal 20V, CH2: Common-mode noise of high-frequency transformer 153mV.

[0022] Figure 11 This is a schematic diagram of the IEC-62684 standard power supply common-mode noise test. Figure 12 This is a schematic diagram of the common-mode noise test results of the present invention, where the common-mode noise is 0.48V; Figure 13 The common-mode noise test results are from existing EMI suppression technologies, with a common-mode noise level of 7.72V. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the embodiments of the present invention, please refer to Figure 3-13 A switching power supply with PLC common-mode noise suppression includes an input EMC filter unit 10, an input rectifier filter unit 20, an input filter unit 30, an input detection and control unit 40, an output filter unit 50, an output voltage detection unit 60, and a high-frequency interference signal suppression transformer 70.

[0025] The input rectifier filter unit 20 is located after the input EMC filter unit 10. The positive output V+ of the rectifier bridge BD1 of the input rectifier filter unit 20 is connected to the input terminal of the input filter unit 30 and is connected to the opposite terminal of the T1B winding of the high-frequency interference signal suppression transformer 70. The input detection control unit 40 is used to detect the input voltage waveform to determine the output voltage and as a reference for frequency detection. The output filter unit 50 is connected to the T1C winding of the high-frequency interference signal suppression transformer 70. The output voltage detection unit 60 is used to detect the output voltage and provide feedback.

[0026] The input rectifier and filter unit is used to rectify the input AC power into DC power; the input filter unit is used for smoothing and filtering after rectification; the output filter unit is used for rectification to provide a stable DC level for the subsequent circuits.

[0027] The input EMC filter unit includes differential-mode inductors L1 and L2, resistive loads R10 and R11, a varistor MOV1, a cold-start current-limiting resistor NTC1, a common-mode inductor LF1, and an X capacitor CX1. Differential-mode inductor L1 and resistive load R11 are connected in parallel to form a first circuit. The first terminal of the first circuit is ultimately connected to the power supply line L. The second terminal of the first circuit is connected to one end of the first winding of the common-mode inductor LF1 through the cold-start current-limiting resistor NTC1. Differential-mode inductor L2 and resistive load R10 are connected in parallel to form a second circuit. The first terminal is connected to the power supply line N; the second terminal of the second circuit is connected to one end of the second winding of the common-mode inductor LF1; one end of the X capacitor CX1 is connected between the second terminal of the first circuit and the cold-start current-limiting resistor NTC1; the other end of the X capacitor CX1 is connected between the second terminal of the second circuit and one end of the second winding of the common-mode inductor LF1; one end of the varistor MOV1 is connected between the second terminal of the first circuit and one end of the X capacitor CX1; the other end of the varistor MOV1 is connected between the second terminal of the second circuit and the other end of the X capacitor CX1.

[0028] A first output winding N1 is wound on the innermost side of the high-frequency interference signal suppression transformer; a T1B winding is wound outside the first output winding N1; a T1A winding is wound outside the T1B winding, consisting of four parallel windings; a second output winding N4 is wound outside the T1A winding; a winding E1 is inserted between the first output winding N1 and the T1B winding, consisting of four parallel windings, each wound with 6 turns, and the starting end of winding E1 is connected to the tail end of winding T1A; the first output winding N1 and the second output winding N4 constitute the T1C winding.

[0029] The input detection and control unit includes a main control microcomputer U1, a power supply rectifier diode D1, current-limiting resistors R15 and R13, filter capacitors C7 and C10. The anode of the power supply rectifier diode D1 is connected to the same-name terminal of the T1A winding of the high-frequency interference signal suppression transformer through the current-limiting resistor R15. The cathode of the power supply rectifier diode D1 is connected to the power supply terminal VCC of the main control microcomputer U1 through the current-limiting resistor R13. Filter capacitors C7 and C10 are both connected between the cathode of the power supply rectifier diode D1 and the ground terminal. The positive output V+ of the rectifier bridge BD1 of the input rectification and filtering unit is also connected to the cathode of the power supply rectifier diode D1 through a resistor string composed of resistors R8, R9, and J1.

[0030] The output voltage detection unit includes resistors R17, R18, R25, and capacitor C8. Resistors R17 and R18 are connected in series and then connected to the two ends of the T1A winding of the high-frequency interference signal suppression transformer. The detection terminal FB of the main control microcomputer U1 is connected to the voltage divider point of resistors R17 and R18. Resistor R25 and capacitor C8 are both connected between the detection terminal FB of the main control microcomputer U1 and the ground terminal.

[0031] The input filtering unit includes filter capacitor C1, filter capacitor C2, resistors R5, R6, R7, R14, absorption capacitor C3, absorption capacitor C4, and damping diode D2. Filter capacitors C1 and C2 are connected in series to form a capacitor string, resistors R5 and R14 are connected in series to form a resistor string, and resistors R6 and R7 are connected in parallel to form a third circuit. One end of the capacitor string and the parallel resistors are connected to the positive output V+ of rectifier bridge BD1, and the other end is connected to one end of the third circuit. The other end of the third circuit is connected to the cathode of damping diode D2, and the anode of damping diode D2 is connected to the same-name terminal of the T1B winding of the high-frequency interference signal suppression transformer.

[0032] The output filtering unit includes a rectifier chip U2 and peripheral circuitry.

[0033] The T1B winding has a total of 62 turns, with 21 turns in the first layer, 21 turns in the second layer, and 20 turns in the third layer. The conductors in the third layer are wound into the concave gap between the two conductors in the second layer.

[0034] The PLC signal first arrives at the L and N lines of the power supply and flows into the differential mode inductors L1 and L2. The differential mode inductance value of the power input LISN port is in the range of 50~300uH, and its characteristic requires that the distributed capacitance be as low as possible, which can effectively reduce the attenuation of the PLC signal. The varistor MOV1 has a static capacitance and is placed after LISN, which can effectively avoid absorbing the PLC signal.

[0035] The X capacitor CX1 is located after the varistor MOV1 and before the common mode inductor LF1. The X capacitor CX1 is preferably a low-capacity resistor to effectively reduce the attenuation of the PLC signal. The cold start current limiting resistor NTC1 is preferably a non-cement resistor to reduce the attenuation of the PLC signal.

[0036] The E1 shielding winding is used to cancel the initial common-mode current, thereby suppressing the common-mode current of the high-frequency transformer and achieving the lowest-cost PLC function noise suppression technology.

[0037] This invention reduces the common-mode interference of the power supply by applying peripheral circuits and introducing a low common-mode noise transformer winding structure. This enables the switching power supply of smart home devices with PLC functionality to have both the advantage of low cost and compliance with common-mode noise suppression technology for PLC-enabled devices.

[0038] By using circuit design for common-mode suppression of PLC functions and high-frequency interference signal suppression transformers for common-mode noise suppression technology, compliance with IEC-62684 standards can be achieved. This ultimately resolves the conflict between common-mode noise and PLC technology in traditional switching power supplies, thus solving the problem of compatibility and coexistence between the two.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. Switching power supply with PLC common mode noise rejection, characterized in that, It includes an input EMC filter unit, an input rectifier filter unit, an input filter unit, an input detection and control unit, an output filter unit, an output voltage detection unit, and a high-frequency interference signal suppression transformer; The input rectifier filter unit is located after the input EMC filter unit. The positive output V+ of the rectifier bridge BD1 of the input rectifier filter unit is connected to the input terminal of the input filter unit and connected to the opposite terminal of the T1B winding of the high-frequency interference signal suppression transformer. The input detection control unit is used to detect the input voltage waveform to determine the output voltage and as a reference for frequency detection. The output filter unit is connected to the T1C winding of the high-frequency interference signal suppression transformer. The output voltage detection unit is used to detect the output voltage and provide feedback. The input EMC filter unit includes differential mode inductor L1, differential mode inductor L2, resistive load R10, resistive load R11, varistor MOV1, cold start current limiting resistor NTC1, common mode inductor LF1, and X capacitor CX1. Differential-mode inductor L1 and resistive load R11 are connected in parallel to form a first circuit. The first terminal of the first circuit is ultimately connected to the power supply line L. The second terminal of the first circuit is connected to one end of the first winding of common-mode inductor LF1 through cold-start current-limiting resistor NTC1. Differential-mode inductor L2 and resistive load R10 are connected in parallel to form a second circuit. The first terminal of the second circuit is connected to the power supply line N. The second terminal of the second circuit is connected to one end of the second winding of common-mode inductor LF1. One end of capacitor X CX1 is connected between the second terminal of the first circuit and cold-start current-limiting resistor NTC1. The other end of capacitor X CX1 is connected between the second terminal of the second circuit and one end of the second winding of common-mode inductor LF1. One end of varistor MOV1 is connected between the second terminal of the first circuit and one end of capacitor X CX1. The other end of varistor MOV1 is connected between the second terminal of the second circuit and the other end of capacitor X CX1. The first output winding N1 is wound on the innermost side of the high-frequency interference signal suppression transformer; In addition to the first output winding N1, wind T1B is wound. In addition to the T1B winding, the T1A winding is wound in parallel with four strands. In addition to the T1A winding, a second output winding N4 is wound; Between the first output winding N1 and the T1B winding, a layer of winding E1 is inserted. Winding E1 consists of four parallel windings, each wound 6 times. The starting end of winding E1 is connected to the tail end of winding T1A. The first output winding N1 and the second output winding N4 constitute the T1C winding.

2. The switching power supply with PLC common mode noise rejection of claim 1, wherein, The input detection and control unit includes a main control single-chip microcomputer U1, a power supply rectifier diode D1, a current limiting resistor R15, a current limiting resistor R13, a filter capacitor C7, and a filter capacitor C10; The anode of the power supply rectifier diode D1 is connected to the same-name terminal of the T1A winding of the high-frequency interference signal suppression transformer through the current limiting resistor R15. The cathode of the power supply rectifier diode D1 is connected to the power supply terminal VCC of the main control single-chip microcomputer U1 through the current limiting resistor R13. The filter capacitors C7 and C10 are both connected between the cathode of the power supply rectifier diode D1 and the ground terminal. The positive output V+ of the rectifier bridge BD1 of the input rectifier filter unit is also connected to the cathode of the power supply rectifier diode D1 through a resistor string consisting of resistors R8, R9, and J1.

3. The switching power supply with PLC common mode noise rejection of claim 2, wherein, The output voltage detection unit includes resistors R17, R18, and R25, and capacitor C8; Resistors R17 and R18 are connected in series and then connected to the two ends of the T1A winding of the high-frequency interference signal suppression transformer. The detection terminal FB of the main control single-chip microcomputer U1 is connected to the voltage divider point of resistors R17 and R18. Resistor R25 and capacitor C8 are both connected between the detection terminal FB of the main control single-chip microcomputer U1 and the ground terminal.

4. The switching power supply with PLC common-mode noise suppression according to claim 1, characterized in that, The input filtering unit includes filter capacitor C1, filter capacitor C2, resistors R5, R6, R7, R14, absorption capacitor C3, absorption capacitor C4, and damping diode D2. The capacitor string formed by connecting filter capacitor C1 and filter capacitor C2 in series, the resistor string formed by connecting resistor R5 and resistor R14 in series, and the third circuit formed by connecting resistor R6 and resistor R7 in parallel; one end of the capacitor string and the resistor in parallel is connected to the positive output V+ of rectifier bridge BD1, and the other end is connected to one end of the third circuit; the other end of the third circuit is connected to the cathode of damping diode D2, and the anode of damping diode D2 is connected to the same-name terminal of the T1B winding of the high-frequency interference signal suppression transformer.

5. The switching power supply with PLC common-mode noise suppression according to claim 1, characterized in that, The output filtering unit includes a rectifier chip U2 and peripheral circuitry.

6. The switching power supply with PLC common-mode noise suppression according to claim 1, characterized in that, The T1B winding has a total of 62 turns, with 21 turns in the first layer, 21 turns in the second layer, and 20 turns in the third layer. The conductors in the third layer are wound into the concave gap between the two conductors in the second layer.

7. The switching power supply with PLC common-mode noise suppression according to claim 1, characterized in that, The inductance value of differential mode inductor L1 is 50-300μH, and the inductance value of differential mode inductor L2 is 50-300μH.

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