Power supply flame-retardant circuit

Abstract

The invention discloses a power supply flame-retardant circuit, which comprises a first voltage-sensitive circuit and a second voltage-sensitive circuit which are respectively connected between a live wire and a zero wire and are fused in an overcurrent state, and a first input circuit and a second input circuit which are respectively connected with two input ends of a rectifier, a connection point L1 is arranged on the first voltage-sensitive branch, a connection point L2 is arranged between the first voltage-sensitive branch and the first resistor, a connection point N1 is arranged on the second voltage-sensitive branch, and a connection point N2 is arranged between the second voltage-sensitive branch and the second resistor; the other end of a first input circuit is connected to N1 or N2, the other end of a second input circuit is connected to L1 or L2, and a third protective tube is arranged according to the connection condition of the other end of the first input circuit and the other end of the second input circuit. Different numbers of protective tubes can be arranged according to actual application requirements to realize a power-off flame-retardant protection function of rapid fusing when overvoltage input of a live line and a zero line occurs or a load at the rear side of the rectifier is short-circuited.

Description

Technical Field

[0001] This invention relates to a flame-retardant power supply circuit. Background Technology

[0002] In existing driver power supplies, especially commercially available potted LED driver power supplies, polyurethane, epoxy resin, and silicone are generally used for potting. These types of adhesives can ignite and emit smoke when some components generate high temperatures after the power supply product is damaged, thus posing a fire risk.

[0003] On the other hand, existing LED driver power supplies have surge protection components on their PCBs, such as varistors, wire-wound resistors, gas discharge tubes, and NTCs. However, varistors can experience thermal runaway when lightning surges exceed their rated values ​​or when the mains voltage exceeds its rated values, potentially igniting the potting compound and causing a fire. Wire-wound resistors can short-circuit after the MOSFET on the back of the LED driver power supply breaks down, thus becoming heat-generating components that can ignite the potting compound and cause a fire. Summary of the Invention

[0004] This invention overcomes the shortcomings of the prior art and provides a flame-retardant power supply circuit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A flame-retardant power supply circuit, characterized in that: it includes a first varistor circuit and a second varistor circuit respectively connected between the live wire and the neutral wire and melted under overcurrent conditions, as well as a first input circuit and a second input circuit respectively connected to the two input terminals of a rectifier; the first varistor circuit includes a first varistor branch and a first resistor connected in series between the live wire and the neutral wire, with a connection point L1 on the first varistor branch and a connection point L2 between the first varistor branch and the first resistor; the second varistor circuit includes a second resistor and a second varistor branch connected in series between the live wire and the neutral wire, with a connection point N1 on the second varistor branch and a connection point N2 between the second varistor branch and the second resistor; When the other end of the second input circuit is connected to connection point L1, the other end of the first input circuit is connected to connection point N1 or connection point N2; when the other end of the second input circuit is connected to connection point L2, the other end of the first input circuit is connected to connection point N1, so that when the live and neutral wires are over-voltage input or the load on the back side of the rectifier is short-circuited, the first varistor circuit and the second varistor circuit are in an overcurrent state. When the other end of the second input circuit is connected to connection point L2 and the other end of the first input circuit is connected to connection point N2, the first input circuit and / or the second input circuit are provided with a third fuse for blowing when the rectifier output is short-circuited, so that the first varistor circuit and the second varistor circuit are in an overcurrent state when the live and neutral wires are over-voltage input, and the first input circuit and / or the second input circuit are in an overcurrent state when the load on the rear side of the rectifier is short-circuited.

[0006] The flame-retardant power supply circuit described above is characterized by: When the other end of the second input circuit is connected to connection point L1 and the other end of the first input circuit is connected to connection point N1, or when the other end of the second input circuit is connected to connection point L1 and the other end of the first input circuit is connected to connection point N2, or when the other end of the second input circuit is connected to connection point L2 and the other end of the first input circuit is connected to connection point N1, The first varistor branch includes a first varistor and a first fuse connected in series between the live wire and the first resistor, with connection point L1 located between the first varistor and the first fuse; the second varistor branch includes a second fuse and a second varistor connected in series between the second resistor and the neutral wire, with connection point N1 located between the second varistor and the second fuse.

[0007] The flame-retardant power supply circuit described above is characterized in that a third varistor is connected between the two input terminals of the rectifier.

[0008] The flame-retardant power supply circuit described above is characterized by: When the other end of the second input circuit is connected to connection point L2, the other end of the first input circuit is connected to connection point N2, and a third fuse is provided in the first input circuit and / or the second input circuit, The first varistor branch includes a first varistor and a first fuse connected in series between the live wire and the first resistor; the second varistor branch includes a second fuse and a second varistor connected in series between the second resistor and the neutral wire.

[0009] The flame-retardant power supply circuit described above is characterized in that a third varistor is connected between the two input terminals of the rectifier.

[0010] The flame-retardant power supply circuit described above is characterized in that: one output terminal of the rectifier is grounded, the other output terminal of the rectifier is connected to one input terminal of the transformer, the other input terminal of the transformer is connected to the drain terminal of the MOS transistor, the source terminal of the MOS transistor is connected to one end of a third resistor, and the other end of the third resistor is grounded.

[0011] The flame-retardant power supply circuit described above is characterized in that: the input terminal of the transformer connected to the rectifier is connected to one end of a capacitor, and the other end of the capacitor is grounded.

[0012] The beneficial effects of this invention are: This invention features a first varistor circuit and a second varistor circuit connected in parallel between the live wire and the neutral wire, which fuse under overcurrent conditions. The first varistor circuit includes a first varistor branch and a first resistor connected in series between the live wire and the neutral wire, and a fuse is installed in the first varistor branch. The second varistor circuit includes a second resistor and a second varistor branch connected in series between the live wire and the neutral wire, and a fuse is installed in the second varistor branch. One end of the first input circuit and one end of the second input circuit are respectively connected to the first varistor circuit and the second varistor circuit. This invention enables the fuses in the first varistor branch and the second varistor branch to quickly fuse when there is a short circuit in the load after the rectifier or an overvoltage input to the live and neutral wires, thereby avoiding the risk of thermal runaway and fire, and achieving the flame-retardant function of the power supply. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of Embodiment 4 of the present invention; Figure 5 This is a schematic diagram of Embodiment 5 of the present invention; Figure 6 This is a schematic diagram of Embodiment Six of the present invention; Figure 7 This is a schematic diagram of Embodiment Seven of the present invention; Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0015] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly. Furthermore, descriptions involving "preferred," "second-best," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "preferred" or "second-best" may explicitly or implicitly include at least one of those features.

[0016] A flame-retardant power supply circuit includes a first varistor circuit and a second varistor circuit connected between a live wire and a neutral wire, respectively, which melt under overcurrent conditions; and a first input circuit 4 and a second input circuit 5 connected to the two input terminals of a rectifier 3, respectively. The first varistor circuit includes a first varistor branch 11 and a first resistor 12 connected in series between the live wire and the neutral wire. A connection point L1 is provided on the first varistor branch 11, and a connection point L2 is provided between the first varistor branch 11 and the first resistor 12. The second varistor circuit includes a second resistor 21 and a second varistor branch 22 connected in series between the live wire and the neutral wire. A connection point N1 is provided on the second varistor branch 22, and a connection point N2 is provided between the second varistor branch 22 and the second resistor 21. Example 1: A first example in a double-fuse flame-retardant circuit. Figure 1 As shown, when the other end of the first input circuit 4 is connected to connection point N1, and the other end of the second input circuit 5 is connected to connection point L1, the first varistor branch 11 includes a first varistor 111 and a first fuse 112 connected in series between the live wire and the first resistor 12, and connection point L1 is located between the first varistor 111 and the first fuse 112; the second varistor branch 22 includes a second fuse 221 and a second varistor 222 connected in series between the second resistor 21 and the neutral wire, and connection point N1 is located between the second varistor 222 and the second fuse 221.

[0017] Specifically, such as Figure 1 As shown, the first varistor circuit consists of a first varistor TVR1, a first fuse FS1, and a first resistor R1 connected sequentially between the live wire and the neutral wire. The first varistor TVR1 and the first fuse FS1 form the first varistor branch 11, and the connection point L1 is located between the first varistor TVR1 and the first fuse FS1. Meanwhile, the second varistor circuit consists of a second resistor R2, a second fuse FS2, and a second varistor TVR2 connected sequentially between the live wire and the neutral wire. The second fuse FS2 and the second varistor TVR2 form the second varistor branch 22, and the connection point N1 is located between the second fuse FS2 and the second varistor TVR2.

[0018] In practical application, when the MOSFET Q1 breaks down, the short-circuit current rapidly melts the first fuse FS1 in the first varistor circuit and the second fuse FS2 in the second varistor circuit. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current then rapidly melts the first fuse FS1 and the second fuse FS2 in the first varistor circuit. Because the short-circuit current is very large, and the fuses are designed to melt with a small current, the rapid melting of the first fuse FS1 and the second fuse FS2 achieves power-off protection, thereby preventing thermal runaway and fire. Example 2: A second example in a double-fuse flame-retardant circuit. Figure 2 As shown, the difference from Embodiment 1 is that the other end of the first input circuit 4 is connected to the pole N2.

[0019] In practical application, when the MOSFET Q1 is broken down, the short-circuit current rapidly melts the first fuse FS1 in the first varistor circuit. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current then rapidly melts the first fuse FS1 and the second fuse FS2 in the first varistor circuit. Because the short-circuit current is very large, and the fuses are designed to melt with a small current, the rapid melting of the first fuse FS1 and the second fuse FS2 achieves power-off protection, thereby preventing thermal runaway and fire. Example 3: A third example in a double-fuse flame-retardant circuit. Figure 3 As shown, the difference from Embodiment 1 is that the other end of the second input circuit 5 is connected to the pole L2.

[0020] In practical application, when the MOSFET Q1 is broken down, the short-circuit current rapidly melts the second fuse FS2 in the second varistor circuit. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current then rapidly melts the first fuse FS1 and the second fuse FS2 in both circuits. Because the short-circuit current is very large, and the fuses are designed to melt with a small current, the rapid melting of the first fuse FS1 and the second fuse FS2 provides power-off protection, thereby preventing thermal runaway and fire.

[0021] In this case, the flame-retardant circuit with dual fuses is used in practical applications. The parameters of both the first fuse FS1 and the second fuse FS2 are 2A / 250V; the first resistor R1 and the second resistor R2 are both used for surge voltage division, with parameters of 2.2R 1W; the first varistor TVR1, the second varistor TVR2, and the third varistor TVR3 are all used for surge absorption, with parameters of 7D621 (national standard); the rectifier consists of four rectifier diodes D1-D4, with parameters of S2M 2A / 1000V; capacitor C1 is a CBB filter capacitor used for filtering after rectification, with parameters of 334 / 630V; transformer T1 is a high-frequency transformer used for high-frequency isolation transformation, with parameters of PQ2014 24-40V 1500MA; MOSFET Q1 is used as a high-frequency switching transistor, with parameters of 7N65; and the third resistor R3 is used for current sampling, with parameters of 0.25R. The dual-fuse flame-retardant circuit in this case has an input voltage range of AC100-440V 50-60Hz and an output voltage range of 20-40V 1500MA. It is suitable for use in products with lightning surges of 2KV-5KV and power consumption below 50W, and can achieve fuse blowing at the millisecond level. Example 4: First embodiment of a four-fuse flame-retardant circuit Figure 4 As shown, when the other end of the first input circuit 4 is connected to connection point N2, and the other end of the second input circuit 5 is connected to connection point L2, and a third fuse 6 is provided on the first input circuit 4 and the second input circuit 5, the first varistor branch 11 includes a first fuse 112 and a first varistor 111 connected in series between the live wire and the first resistor 12, and connection point L2 is located between the first varistor 111 and the first resistor 12; the second varistor branch 22 includes a second varistor 222 and a second fuse 221 connected in series between the second resistor 21 and the neutral wire, and connection point N2 is located between the second resistor 21 and the second varistor 222.

[0022] Specifically, such as Figure 4 As shown, the first varistor circuit consists of a first fuse FS1, a first varistor TVR1, and a first resistor R1 connected sequentially between the live wire and the neutral wire. The first varistor TVR1 and the first fuse FS1 form the first varistor branch 11, and the connection point L2 is located between the first varistor TVR1 and the first resistor R1. The second varistor circuit consists of a second resistor R2, a second varistor TVR2, and a second fuse FS2 connected sequentially between the live wire and the neutral wire. The second fuse FS2 and the second varistor TVR2 form the second varistor branch 22, and the connection point N2 is located between the second resistor R2 and the second varistor TVR2. At the same time, a fuse FS3 is connected to the first input circuit 4, and a fuse FS4 is connected to the second input circuit 5.

[0023] In practical application, when the MOSFET Q1 is broken down, the short-circuit current rapidly melts the fuse FS3 in the first input circuit 4 and the fuse FS4 in the second input circuit 5. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current rapidly melts the first fuse FS1 and the second fuse FS2 in the first varistor circuit. Due to the large short-circuit current and the design of the fuses to melt with a small current, the short-circuit current rapidly melts the first fuse FS1, the second fuse FS2, the fuse FS3, and the fuse FS4 to achieve power-off protection, thereby preventing thermal runaway and fire. Example 5: First embodiment of a three-fuse flame-retardant circuit Figure 5 As shown, the difference from Embodiment 4 is that the fuse FS4 is not connected to the second input circuit 5.

[0024] In practical application, when the MOSFET Q1 is broken down, the short-circuit current rapidly melts the fuse FS3 in the first input circuit 4. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current then rapidly melts the first fuse FS1 and the second fuse FS2 in the first varistor circuit. Because the short-circuit current is very large, and the fuses are designed to melt with a small current, the short-circuit current rapidly melts the first fuse FS1, the second fuse FS2, and the fuse FS3, achieving power-off protection and thus preventing thermal runaway and fire. Example 6: A second embodiment of a three-fuse flame-retardant circuit. Figure 6 As shown, the difference from Embodiment 4 is that the fuse FS3 is not connected to the first input circuit 4.

[0025] In practical application, when the MOSFET Q1 is broken down, the short-circuit current rapidly melts the fuse FS4 in the second input circuit 5. When an overvoltage is applied to the live and neutral lines, the first varistor TVR1 in the first varistor circuit and the second varistor TVR2 in the second varistor circuit short-circuit due to leakage. The short-circuit current then rapidly melts the first fuse FS1 and the second fuse FS2 in the first varistor circuit. Because the short-circuit current is very large, and the fuses are designed to melt with a small current, the short-circuit current rapidly melts the first fuse FS1, the second fuse FS2, and the fuse FS4, achieving power-off protection and thus preventing thermal runaway and fire. Example 7: A second embodiment of a four-fuse flame-retardant circuit. Figure 7As shown, the difference from Embodiment 4 is that in the first varistor branch 11, the first varistor TVR1 and the first fuse FS1 are connected in series between the live wire and the first resistor R1; in the second varistor branch 22, the second fuse FS2 and the second varistor TVR2 are connected in series between the second resistor R2 and the neutral wire. The working principle is the same as in Embodiment 4. Similarly, based on Embodiment 7, the fuse FS3 can be omitted from the first input circuit 4 as a third embodiment of the three-fuse flame-retardant circuit, or the fuse FS4 can be omitted from the second input circuit 5 as a fourth embodiment of the three-fuse flame-retardant circuit.

[0026] In this case, the flame-retardant circuit with three or four fuses, in practical applications, uses fuses FS1, FS2, FS3, and FS4, all with a parameter of 2A / 250V. Resistors R1 and R2 are used for surge voltage division, both with a parameter of 2.2R 2W. Varistors TVR1, TVR2, and TVR3 are used for surge absorption; TVR1 and TVR2 both meet the 10D621 national standard, and TVR3 meets the 7D621 national standard. The rectifier consists of four rectifier diodes D1-D4, with a parameter of S2M 2A / 1000V. Capacitor C1 is a CBB filter capacitor used for filtering after rectification, with a parameter of 334 / 630V. Transformer T1 is a high-frequency transformer used for high-frequency isolation transformation, with a parameter of PQ2014 24-40V. 1500mA; MOSFET Q1 is used as a high-frequency switch, with parameters 7N65; the third resistor R3 is used for current sampling, with parameters 0.25R. The three or four fuse flame-retardant circuit in this case has an input voltage range of AC100-440V 50-60Hz and an output voltage range of 20-40V 1500mA, suitable for 4KV-8KV lightning surges and products below 200W, and can achieve fuse blowing in milliseconds.

[0027] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct or indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A power supply flameproof circuit, characterized by: The first and second pressure-sensitive circuits are connected between the live wire and the zero wire and are fused under overcurrent state, and the first and second input circuits (4) and (5) are connected with the two input terminals of the rectifier (3) respectively; the first pressure-sensitive circuit comprises a first pressure-sensitive branch (11) and a first resistor (12) connected in series between the live wire and the zero wire, a connection point L1 is arranged on the first pressure-sensitive branch (11), and a connection point L2 is arranged between the first pressure-sensitive branch (11) and the first resistor (12); the second pressure-sensitive circuit comprises a second resistor (21) and a second pressure-sensitive branch (22) connected in series between the live wire and the zero wire, a connection point N1 is arranged on the second pressure-sensitive branch (22), and a connection point N2 is arranged between the second pressure-sensitive branch (22) and the second resistor (21); When the other end of the second input circuit (5) is connected with the connection point L1, the other end of the first input circuit (4) is connected with the connection point N1 or the connection point N2; when the other end of the second input circuit (5) is connected with the connection point L2, the other end of the first input circuit (4) is connected with the connection point N1; When the other end of the second input circuit (5) is connected with the connection point L2 and the other end of the first input circuit (4) is connected with the connection point N2, a third fuse (6) is arranged on the first input circuit (4) and / or the second input circuit (5) for fusing when the output terminal of the rectifier (3) is short-circuited.

2. The power supply fireproof circuit according to claim 1, characterized in that: when the other end of the second input circuit (5) is connected with the connection point L1 and the other end of the first input circuit (4) is connected with the connection point N1, or when the other end of the second input circuit (5) is connected with the connection point L1 and the other end of the first input circuit (4) is connected with the connection point N2, or when the other end of the second input circuit (5) is connected with the connection point L2 and the other end of the first input circuit (4) is connected with the connection point N1, the first pressure-sensitive branch (11) comprises a first pressure-sensitive resistor (111) and a first fuse (112) connected in series between the live wire and the first resistor (12), and the connection point L1 is arranged between the first pressure-sensitive resistor (111) and the first fuse (112); the second pressure-sensitive branch (22) comprises a second fuse (221) and a second pressure-sensitive resistor (222) connected in series between the second resistor (21) and the zero wire, and the connection point N1 is arranged between the second pressure-sensitive resistor (222) and the second fuse (221).

3. A power supply flameproof circuit according to claim 2, characterised in that: A third pressure-sensitive resistor (7) is connected between the two input terminals of the rectifier (3).

4. The power supply fireproof circuit according to claim 1, characterized in that: when the other end of the second input circuit (5) is connected with the connection point L2, the other end of the first input circuit (4) is connected with the connection point N2, and the third fuse (6) is arranged on the first input circuit (4) and / or the second input circuit (5), The first pressure sensitive branch (11) comprises a first pressure sensitive resistor (111) and a first safety tube (112) connected in series between the live wire and a first resistor (12); the second pressure sensitive branch (22) comprises a second safety tube (221) and a second pressure sensitive resistor (222) connected in series between the second resistor (21) and the zero line.

5. A power supply flameproof circuit according to claim 4, characterised in that: The rectifier (3) is connected with a third pressure sensitive resistor (7) between two input ends.

6. A power supply flameproof circuit according to claim 1, characterized in that: One output end of the rectifier (3) is grounded, the other output end of the rectifier (3) is connected with one input end of a transformer (41), the other input end of the transformer (41) is connected with a drain end of a MOS tube (42), a source end of the MOS tube (42) is connected with one end of a third resistor (43), the other end of the third resistor (43) is grounded.

7. A power supply flameproof circuit according to claim 6, characterised in that: The input end of the transformer (41) connected with the rectifier (3) is connected with one end of a capacitor (44), the other end of the capacitor (44) is grounded.

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