Ballast leakage protection circuit compatible with commercial power
By designing a ballast leakage protection circuit compatible with mains power, and using the electrical signal between the output pins before rectification and the reference voltage for precise detection, the problem of leakage protection circuit failure during lamp installation was solved, achieving highly accurate and safe leakage protection.
Patent Information
- Application Number
- CN202520291068.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Priority Date
- 2024-11-01
- Filing Date
- 2025-02-21
- Publication Date
- 2026-01-09
- Estimated Expiration
- 2035-02-21
AI Technical Summary
In the prior art, during the installation of lamps, there is a problem that the leakage protection circuit fails when there is poor contact at the input end, which leads to the risk of electric shock to the operator. This is especially true during the installation of lamps with double-ended inputs, where the existing leakage protection circuit cannot effectively prevent leakage.
A ballast leakage protection circuit compatible with mains power was designed, including a power supply circuit, a step-down circuit, a drive circuit, an LED circuit, and a detection circuit. Through the band-pass filter module, comparator module, and switch module in the detection circuit, the electrical signal between the output pins before rectification and the reference voltage are used for accurate detection, and the on/off state of the drive circuit and LED circuit is controlled to achieve leakage protection.
It improves the accuracy and safety of leakage current detection, ensuring that leakage current can be effectively prevented under any circumstances, thus protecting the operator's safety.
Smart Images
Figure CN223786222U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of LED technology, and in particular to a ballast leakage protection circuit compatible with mains power. Background Technology
[0002] Currently, lamps can be powered either directly by AC mains power or by connecting to a ballast. When AC mains power is selected, it is typically 220V / 50Hz or other voltages; while when a ballast is connected, high voltage is present at the connectors at both ends of the lamp.
[0003] In the lighting field, lamps are divided into two types: single-ended input and double-ended input. Single-ended input means that all the AC input terminals are located at the same end, while double-ended input means that they are located at both ends of the lamp. Since many lamp holders still retain double-ended input interfaces, double-ended input lamps are generally used when replacing or installing existing lamps.
[0004] During the installation of lamp tubes, operators typically insert one end of the lamp tube into the lamp holder first, and then insert the other end. This may result in partial connection. Since the operator's hand needs to hold the end of the lamp tube, if the human body accidentally touches the conductive metal end, electric shock may easily occur, affecting operational safety. Therefore, it is particularly important to implement leakage protection for lamp tubes.
[0005] Current technology primarily uses a switching transistor connected to the power input terminal to detect the current flowing through it, thereby determining whether leakage occurs and achieving leakage protection. However, this technology is not effective in all situations. When there is poor contact at the input terminal, the ballast leakage protection circuit will fail, and the operator will still be at risk of electric shock. Utility Model Content
[0006] The technical problem to be solved by this utility model is to provide a ballast leakage protection circuit that is compatible with mains power, which is compatible with mains power and ballast, and realizes leakage protection of ballast.
[0007] To address the aforementioned technical problems, this utility model provides a ballast leakage protection circuit compatible with mains power, comprising: a power supply circuit, a step-down circuit, a drive circuit, an LED circuit, and a detection circuit; the input terminal of the power supply circuit is connected to the output pin of the power supply terminal, and the output terminal of the power supply circuit is connected to the input terminal of the step-down circuit and the input terminal of the LED circuit, respectively, for rectifying the output power of the power supply terminal to output power to the step-down circuit and the LED circuit; the input terminal of the drive circuit is connected to the output terminal of the LED circuit to drive the LED circuit; the output terminal of the step-down circuit is connected to the detection circuit to step down the power supply output by the power supply circuit to output a reference voltage to the detection circuit; the detection circuit is connected to the output pin of the power supply terminal, the drive circuit, and the LED circuit, respectively, for controlling the operating state of the drive circuit and the LED circuit according to the real-time voltage between the output pins of the power supply terminal and the reference voltage output by the step-down circuit.
[0008] As an improvement to the above solution, the detection circuit includes two bandpass filter modules, a comparison module, and a switching module. The comparison module has two real-time sampling terminals and two reference sampling terminals. The two sets of output pins of the bandpass filter module, the real-time sampling terminals, the reference sampling terminals, and the power supply terminal correspond one-to-one. The bandpass filter module is connected to the corresponding set of output pins to filter the output power supply between the corresponding set of output pins. The real-time sampling terminals are connected to the corresponding bandpass filter modules to detect the real-time voltage between the corresponding set of output pins. The reference sampling terminals are connected to the output terminal of the step-down circuit to obtain the reference voltage. The output terminal of the comparison module is connected to the switching module to control the on / off state of the switching module according to the real-time voltage and the reference voltage.
[0009] As an improvement to the above scheme, the bandpass filter module includes two diodes connected in series in opposite phases, and the real-time sampling terminal of the comparison module is connected between the two diodes.
[0010] As an improvement to the above solution, the switch module includes a first switch, the control terminal of the first switch is connected to the output terminal of the comparison module, one terminal of the first switch is connected to the driving circuit and the LED circuit, and the other terminal of the first switch is connected to the power supply circuit.
[0011] As an improvement to the above solution, the comparison module includes a first comparator, a second comparator, a second switch, and a third switch; one input terminal of the first comparator is connected to a real-time sampling terminal of the comparison module, and the other input terminal of the first comparator is connected to a reference sampling terminal of the comparison module. The first comparator is used to control the on / off state of the second switch based on the real-time voltage detected by the real-time sampling terminal and the reference voltage obtained by the reference sampling terminal; one input terminal of the second comparator is connected to another real-time sampling terminal of the comparison module, and the other input terminal of the second comparator is connected to another reference sampling terminal of the comparison module. The second comparator is used to control the on / off state of the third switch based on the real-time voltage detected by the other real-time sampling terminal and the reference voltage obtained by the other reference sampling terminal; the second switch, the third switch, and the switch module are connected in sequence, and the on / off state of the second switch and the third switch controls the on / off state of the switch module, which in turn controls the operating state of the driving circuit and the LED circuit.
[0012] As an improvement to the above solution, when the second switch and the third switch are turned on, the switch module is turned on, so that the driving circuit is not working and the power supply circuit, LED circuit and detection circuit form an LED loop, and the LED circuit is working; when the second switch and / or the third switch are turned off, the switch module is turned off, so that the LED circuit is disconnected from the detection circuit.
[0013] As an improvement to the above scheme, the control electrode of the second switch is connected to the output terminal of the first comparator, the first electrode of the second switch is connected to the output terminal of the step-down circuit, and the second electrode of the second switch is connected to the first electrode of the third switch; the control electrode of the third switch is connected to the output terminal of the second comparator, and the second electrode of the third switch is connected to the switch module.
[0014] As an improvement to the above scheme, the comparison module further includes a first voltage divider resistor group, a second voltage divider resistor group, a third voltage divider resistor group, and a fourth voltage divider resistor group; one input terminal of the first comparator is connected to a real-time sampling terminal of the comparison module through the first voltage divider resistor group, and the other input terminal of the first comparator is connected to a reference sampling terminal of the comparison module through the second voltage divider resistor group; one input terminal of the second comparator is connected to another real-time sampling terminal of the comparison module through the third voltage divider resistor group, and the other input terminal of the second comparator is connected to another reference sampling terminal of the comparison module through the fourth voltage divider resistor group.
[0015] As an improvement to the above solution, the detection circuit further includes an anti-interference module, and the comparison module and the switch module are connected through the anti-interference module.
[0016] As an improvement to the above solution, when the power supply circuit is connected to the ballast, the driving circuit does not work; when the power supply circuit is connected to the mains power, the driving circuit works to drive the LED circuit.
[0017] The beneficial effects of implementing this utility model are as follows:
[0018] This utility model's ballast leakage protection circuit, compatible with mains power, uses the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage between the output pins of the power supply end with the reference voltage. Using voltage factors as the judgment basis, it achieves accurate leakage detection from the voltage perspective, greatly improving the accuracy of detection. This effectively controls the on / off state of the LED circuit, plays a role in preventing leakage, and ensures human safety.
[0019] Furthermore, the leakage protection circuit of this invention incorporates control components such as comparators and switching transistors, enabling layer-by-layer comparison of electrical signals and flexible switching of the circuit, thereby more precisely controlling the on / off state of the LED circuit with high accuracy. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the leakage protection circuit of the ballast compatible with mains power according to this utility model;
[0021] Figure 2 This is a circuit diagram of an embodiment of the leakage protection circuit for a ballast compatible with mains power according to this utility model;
[0022] Figure 3 This is a circuit diagram of an embodiment of the step-down circuit in the leakage protection circuit of the ballast compatible with mains power of this utility model;
[0023] Figure 4 This is a circuit diagram of another embodiment of the step-down circuit in the leakage protection circuit of the ballast compatible with mains power of this utility model;
[0024] Figure 5 This is another schematic diagram of the leakage protection circuit of the ballast compatible with mains power according to this utility model. Detailed Implementation
[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the following will describe this utility model in further detail with reference to the accompanying drawings. It is hereby declared that the terms "up," "down," "left," "right," "front," "back," "inner," and "outer," etc., appearing or about to appear in this document, are based solely on the accompanying drawings and are not intended to specifically limit this utility model.
[0026] See Figure 1 , Figure 1This invention illustrates the specific structure of a ballast leakage protection circuit compatible with mains power, comprising a power supply circuit 1, a step-down circuit 2, a drive circuit 5, an LED circuit 3, and a detection circuit 4. Specifically:
[0027] The input terminal of power supply circuit 1 is connected to the output pin of the power supply terminal. The output terminal of power supply circuit 1 is connected to the input terminal of step-down circuit 2 and the input terminal of LED circuit 3 respectively. It is used to rectify the output power of the power supply terminal to output power to step-down circuit 2 and LED circuit 3.
[0028] The input terminal of the driving circuit 5 is connected to the output terminal of the LED circuit 3, and is used to drive the LED circuit 3;
[0029] The output of step-down circuit 2 is connected to detection circuit 4 and is used to step down the power supply output from power supply circuit 1 to output a reference voltage to detection circuit 4.
[0030] The detection circuit 4 is connected to the output pin of the power supply terminal, the drive circuit 5, and the LED circuit 3 respectively, and is used to control the working state of the drive circuit 5 and the LED circuit 3 according to the real-time voltage between the output pins of the power supply terminal and the reference voltage output by the step-down circuit 2.
[0031] It should be noted that the ballast leakage protection circuit compatible with mains power of this utility model can be applied to both mains power and ballast. Therefore, the power supply end can be the mains power supply end or the ballast power supply end. At the same time, the leakage protection circuit of this utility model can realize leakage protection of the ballast.
[0032] In existing technologies, leakage current protection circuits typically detect the rectified electrical signal to achieve leakage current protection. Unlike existing technologies, this utility model's ballast leakage current protection circuit, compatible with mains power, uses the pre-rectified electrical signal (i.e., the electrical signal between the output pins) as the detection target and voltage factor as the judgment criterion, achieving accurate leakage current detection from a voltage perspective and greatly improving detection accuracy.
[0033] The power supply circuit 1, the step-down circuit 2, the LED circuit 3, the driver circuit 5, and the detection circuit 4 are described in detail below with reference to specific embodiments:
[0034] I. Power Supply Circuit 1
[0035] like Figure 2 As shown, in this embodiment, the power supply circuit 1 includes a first rectifier bridge BD1, a second rectifier bridge BD2, a second capacitor C2, an eighth capacitor C8, and input ports F1, F2, F3, and F4.
[0036] One AC input terminal of the first rectifier bridge BD1 is connected to input port F1, and the other AC input terminal is connected to input port F2. The negative terminal of the DC output is connected to the step-down circuit 2 and the LED circuit 3, and the positive terminal of the DC output is grounded. One end of the second capacitor C2 is connected to input port F1, and the other end is connected to input port F2.
[0037] Similarly, one AC input terminal of the second rectifier bridge BD2 is connected to input port F3, the other AC input terminal is connected to input port F4, the negative DC output terminal is connected to step-down circuit 2 and LED circuit 3, and the positive DC output terminal is grounded; one end of the eighth capacitor C8 is connected to input port F3, and the other end is connected to input port F4.
[0038] When this invention is applied to a ballast, the input ports F1, F2, F3 and F4 can be connected to the four pins of the ballast.
[0039] When this invention is applied to mains power, any two input ports can be selected to connect to two pins of the mains power, for example, input ports F1 and F2, or input ports F3 and F4, or input ports F1 and F3, or input ports F1 and F4, or input ports F2 and F3, or input ports F2 and F4.
[0040] Therefore, the power supply circuit 1 can rectify the output power of the power supply terminal to output a stable power supply to the step-down circuit 2 and the LED circuit 3.
[0041] II. Step-down circuit 2
[0042] like Figure 2 As shown, in this embodiment, the step-down circuit 2 includes a step-down chip U2, an eleventh diode D11, a twelfth diode D12, a third inductor L3, a fourth inductor L4, a sixteenth capacitor C16, a seventeenth capacitor C17, a second polarity capacitor CE2, a third polarity capacitor CE3, a fourth polarity capacitor CE4, a fortieth resistor R40, a forty-first resistor R41, and a current-limiting resistor RS1, wherein:
[0043] The ground pin GND of the step-down chip U2 is connected to the negative terminal of the twelfth diode D12. The clock pin SCL and the power supply pin VCC are respectively connected to the negative terminal of the eleventh diode D11. The open-drain pin DRAIN is connected to the power supply circuit 1 through the third inductor L3. The chip select pin CS is connected to the negative terminal of the twelfth diode D12 through the current limiting resistor RS1.
[0044] The positive terminal of the twelfth diode D12 is grounded, and the negative terminal is connected to the detection circuit 4 through the fourth inductor L4 and to the negative terminal of the eleventh diode D11 through the seventeenth capacitor C17. The positive terminal of the eleventh diode D11 is connected to the detection circuit 4.
[0045] One end of the 40th resistor R40 is connected to the detection circuit 4, and the other end is grounded. The 40th resistor R40, the 16th capacitor C16, and the second polarity capacitor CE2 are connected in parallel.
[0046] The forty-first resistor R41 is connected in parallel with the third inductor L3; the positive terminal of the fourth polarity capacitor CE4 is connected to the open-drain pin DRAIN, and the negative terminal is grounded; the positive terminal of the third polarity capacitor CE3 is connected to power supply circuit 1, and the negative terminal is grounded.
[0047] It should be noted that when connected to mains power, whether it is a single-ended input to input ports F1 and F2, a single-ended input to input ports F3 and F4, or a dual-ended input, the voltage after rectification by the first rectifier bridge DB1 and the second rectifier bridge DB2 is 310VDC, which is consistent with the working state of the step-down chip U2. Therefore, the step-down chip U2 can work normally, playing the role of step-down constant current, and supplying a constant reference voltage to the detection circuit 4.
[0048] In other embodiments, voltage reduction can be achieved using voltage divider resistors.
[0049] like Figure 3 As shown, in this embodiment, the step-down circuit 2 includes a voltage divider resistor group (first resistor R1, second resistor R2, third resistor R3, fourth resistor R4, and fifth resistor R5), a first capacitor C1, and a first Zener diode D1; wherein, one end of the first resistor R1 is connected to the power supply circuit 1, and the other end is grounded through the second resistor R2, the third resistor R3, the fourth resistor R4, and the fifth resistor R5 in sequence. The fifth resistor R5 is connected in parallel with the first capacitor C1 and the first Zener diode D1, respectively. The positive terminal of the first Zener diode D1 is grounded, and the negative terminal is connected to the detection circuit 4.
[0050] Therefore, the step-down circuit 2 can step down the power supply output from the power supply circuit 1 and convert it into a 5V reference voltage for use by the detection circuit 4.
[0051] In other embodiments, different numbers and resistance values of resistors can be selected for voltage reduction according to actual needs.
[0052] like Figure 4 As shown, in this embodiment, the voltage divider resistor group includes four resistors connected in series (second resistor R2, third resistor R3, fourth resistor R4 and fifth resistor R5).
[0053] Therefore, in applications, different step-down circuits 2 can be used to step down the power output of power supply circuit 1 according to actual needs, and no restrictions are imposed here.
[0054] III. LED Circuit 3
[0055] like Figure 2As shown, in this embodiment, the LED circuit 3 includes a plurality of light-emitting diodes (LED1...LEDN) connected in series.
[0056] IV. Drive Circuit 5
[0057] This utility model provides a ballast leakage protection circuit compatible with mains power, which can be applied to both mains power and ballast. When the power supply circuit 1 is connected to the ballast, the drive circuit 5 does not work; when the power supply circuit 1 is connected to mains power, the drive circuit 5 works to drive the LED circuit 3.
[0058] like Figure 2 As shown, in this embodiment, the driving circuit 5 includes a driving chip U1, a second inductor L2, a thirteenth diode D13, a tenth capacitor C10, an eighteenth polarity capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, an eighth resistor R8, a seventeenth resistor R17, an eighteenth resistor R18, and a forty-first resistor R41. Wherein:
[0059] The overvoltage protection pin OVP of the driver chip U1 is grounded through the forty-first resistor R41; the power input pin VIN is connected to the positive terminal of LED circuit 3 through the eighth resistor R8; the open-drain pin DRAIN is connected to the positive terminal of LED circuit 3 through the thirteenth diode D13 and to the negative terminal of LED circuit 3 through the second inductor L2; the compiler pin ISP is grounded through the seventeenth resistor R17 and the eighteenth resistor R18 respectively.
[0060] One end of the twentieth capacitor C20 is connected to the positive terminal of LED circuit 3, and the other end is grounded;
[0061] The positive terminal of the eighteenth polarity capacitor C18 is connected to the positive terminal of LED circuit 3, the negative terminal of the eighteenth polarity capacitor C18 is connected to the negative terminal of LED circuit 3 and detection circuit 4, and is grounded through the tenth capacitor C10. The eighteenth polarity capacitor C18 and the nineteenth capacitor C19 are connected in parallel.
[0062] Therefore, when connected to mains power, the LED circuit can be driven by constant current through the driver chip U1 to ensure that the LED circuit can be used normally.
[0063] V. Detection Circuit 4
[0064] like Figure 2 As shown, the detection circuit 4 includes two bandpass filter modules 41, a comparison module 42 and a switch module 43. The comparison module 42 is provided with two real-time sampling terminals and two reference sampling terminals. The two sets of output pins of the bandpass filter module 41, the real-time sampling terminal, the reference sampling terminal and the power supply terminal correspond one-to-one.
[0065] The bandpass filter module 41 is connected to a corresponding set of output pins to filter the output power supply between the corresponding set of output pins;
[0066] The real-time sampling terminal is connected to the corresponding bandpass filter module 41 to detect the real-time voltage between a set of corresponding output pins;
[0067] The reference sampling terminal is connected to the output terminal of step-down circuit 2 to obtain the reference voltage;
[0068] The output of the comparison module 42 is connected to the switch module 43 and is used to control the on / off state of the switch module 43 according to the real-time voltage and the reference voltage.
[0069] Therefore, through the cooperation between the bandpass filter module 41, the comparison module 42 and the switching module 43, the switching module 43 can accurately switch on and off according to the real-time voltage between the output pins and the reference voltage of the step-down circuit 2, with high precision.
[0070] The bandpass filter module 41, the comparator module 42, and the switch module 43 are described in detail below:
[0071] (1) Bandpass filter module
[0072] The bandpass filter module 41 includes two diodes connected in series in opposite directions, and the real-time sampling terminal of the comparator module 42 is connected between the two diodes.
[0073] like Figure 2 As shown, in this embodiment, one bandpass filter module 41 includes a fourth diode D4 and a fifth diode D5; the other bandpass filter module 42 includes a ninth diode D9 and a tenth diode D10. Wherein:
[0074] The positive terminal of the fourth diode D4 is connected to the input port F1, the negative terminal of the fourth diode D4 is connected to the negative terminal of the fifth diode D5, and the positive terminal of the fifth diode D5 is connected to the input port F2.
[0075] Similarly, the positive terminal of the ninth diode D9 is connected to the input port F3, the negative terminal of the ninth diode D9 is connected to the negative terminal of the tenth diode D10, and the positive terminal of the tenth diode D10 is connected to the input port F4.
[0076] During operation, a real-time sampling terminal A can be set between the fourth diode D4 and the fifth diode D5, and another real-time sampling terminal B can be set between the ninth diode D9 and the tenth diode D10.
[0077] Therefore, by setting real-time sampling terminals A and B, the real-time voltage between the output pins can be effectively detected, thereby obtaining the power supply status between the output pins in real time.
[0078] (2) Comparison Module
[0079] like Figure 2As shown, in this embodiment, the comparison module 42 includes a first comparator U1A, a second comparator UIB, a second switch Q2, and a third switch Q3. One input terminal of the first comparator U1A is connected to a real-time sampling terminal of the comparison module 42, and the other input terminal of the first comparator U1A is connected to a reference sampling terminal of the comparison module 42. The first comparator U1A controls the on / off state of the second switch Q2 based on the real-time voltage detected by the real-time sampling terminal and the reference voltage obtained by the reference sampling terminal. One input terminal of the second comparator UIB is connected to another real-time sampling terminal of the comparison module 42, and the other input terminal of the second comparator UIB is connected to another reference sampling terminal of the comparison module 42. The second comparator UIB controls the on / off state of the third switch Q3 based on the real-time voltage detected by the other real-time sampling terminal and the reference voltage obtained by the other reference sampling terminal. The second switch Q2, the third switch Q3, and the switch module 43 are connected sequentially. The on / off states of the second switch Q2 and the third switch Q3 control the on / off state of the switch module 43, and the on / off state of the switch module 43 controls the operating state of the drive circuit 5 and the LED circuit 3.
[0080] It should be noted that when the second switch Q2 and the third switch Q3 are turned on, the switch module 43 is turned on, so that the drive circuit 5 is not working and the power supply circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop, and the LED circuit 3 is working; when the second switch Q2 and / or the third switch Q3 are turned off, the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4.
[0081] Further, see Figure 5 The control electrode of the second switch Q2 is connected to the output terminal of the first comparator U1A, the first electrode of the second switch Q2 is connected to the output terminal of the step-down circuit 2, and the second electrode of the second switch Q2 is connected to the first electrode of the third switch Q3; the control electrode of the third switch Q3 is connected to the output terminal of the second comparator UIB, and the second electrode of the third switch Q3 is connected to the switch module 43.
[0082] For example, when both the first comparator U1A and the second comparator UIB output a low level, the second switch Q2, the third switch Q3 and the switch module 43 are turned on, so that the power supply circuit 1, the LED circuit 3 and the detection circuit 4 form an LED loop and the LED circuit 3 works.
[0083] When the first comparator U1A outputs a high level and the second comparator UIB outputs a low level, the second switch Q2 is turned off, the third switch Q3 is turned on, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4.
[0084] When the first comparator U1A outputs a low level and the second comparator UIB outputs a high level, the second switch Q2 is turned on, the third switch Q3 is turned off, and the switch module 43 is turned off, so that the LED circuit 3 is disconnected from the detection circuit 4.
[0085] When both the first comparator U1A and the second comparator UIB output a high level, the second switch Q2, the third switch Q3, and the switch module 43 are disconnected, so that the LED circuit 3 is disconnected from the detection circuit 4.
[0086] It should be noted that the output levels of the first comparator U1A and the second comparator UIB can affect the on / off states of the second switch Q2 and the third switch Q3, but the specific logic can be set according to the actual situation. For example, it can be set so that the second switch Q2 is turned on when the first comparator U1A outputs a low level; or it can be set so that the second switch Q2 is turned on when the first comparator U1A outputs a high level.
[0087] Furthermore, the comparison module 42 also includes a first voltage divider resistor group 421, a second voltage divider resistor group 422, a third voltage divider resistor group 423, and a fourth voltage divider resistor group 424; one input terminal of the first comparator U1A is connected to a real-time sampling terminal of the comparison module 42 through the first voltage divider resistor group 421, and the other input terminal of the first comparator U1A is connected to a reference sampling terminal of the comparison module 42 through the second voltage divider resistor group 422; one input terminal of the second comparator UIB is connected to another real-time sampling terminal of the comparison module 42 through the third voltage divider resistor group 423, and the other input terminal of the second comparator UIB is connected to another reference sampling terminal of the comparison module 42 through the fourth voltage divider resistor group 424.
[0088] It should be noted that in practical applications, different numbers and resistance values of voltage divider resistors can be set according to requirements to form the first voltage divider resistor group 421, the second voltage divider resistor group 422, the third voltage divider resistor group 423 and the fourth voltage divider resistor group 424.
[0089] like Figure 2 As shown, in this embodiment, the first voltage divider resistor group 421 includes the twenty-sixth resistor R26 and the twenty-seventh resistor R27 connected in series; the second voltage divider resistor group 422 includes the twenty-fifth resistor R25 and the twenty-ninth resistor R29 connected in series; the third voltage divider resistor group 423 includes the thirty-seventh resistor R37 and the thirty-eighth resistor R38 connected in series; and the fourth voltage divider resistor group 424 includes the twenty-fourth resistor R24 and the twenty-eighth resistor R28 connected in series.
[0090] (3) Switching module
[0091] like Figure 2As shown, in this embodiment, the switch module 43 includes a first switch Q1. The control terminal of the first switch Q1 is connected to the output terminal of the comparison module 42. One terminal of the first switch Q1 is connected to the drive circuit 5 and the LED circuit 3, and the other terminal of the first switch Q1 is connected to the power supply circuit 1.
[0092] Therefore, when the first switch Q1 is turned on, the power supply circuit 1, the LED circuit 3 and the detection circuit 4 form an LED circuit and the LED circuit 3 works; when the first switch Q1 is turned off, the LED circuit 3 is disconnected from the detection circuit 4.
[0093] Based on the circuit structure of the comprehensive bandpass filter module 41, the comparator module 42, and the switch module 43, it can be seen that... Figure 2 In the example shown:
[0094] The non-inverting input of the first comparator U1A is connected to the step-down circuit 2 through the 25th resistor R25 and grounded through the 29th resistor R29. The inverting input of the first comparator U1A is connected to a real-time sampling terminal A through the 26th resistor R26 and grounded through the 27th resistor R27. The output of the first comparator U1A is connected to the gate of the second switch Q2.
[0095] The non-inverting input of the second comparator U1B is connected to the step-down circuit 2 through the twenty-fourth resistor R24 and grounded through the twenty-eighth resistor R28. The inverting input of the second comparator U1B is connected to another real-time sampling terminal B through the thirty-seventh resistor R37 and grounded through the thirty-eighth resistor R38. The output of the second comparator U1B is connected to the gate of the third switch Q3.
[0096] The source of the second switch Q2 is connected to the step-down circuit 2, the drain of the second switch Q2 is connected to the source of the third switch Q3, the drain of the third switch Q3 is connected to the control terminal of the first switch Q1, one output terminal of the first switch Q1 is connected to the LED circuit 3, and the other terminal is grounded.
[0097] Furthermore, the detection circuit 4 also includes an anti-interference module 44, and the comparison module 42 and the switch module 43 are connected through the anti-interference module 44.
[0098] like Figure 2 As shown, in this embodiment, the anti-interference module 44 includes a 30th resistor R30, a 32nd resistor R32, and an RC circuit (with a 33rd resistor R33 and a 13th capacitor C13 connected in parallel); the 30th resistor R30 is connected in series between the comparator module 42 and the switch module 43; one end of the 32nd resistor R32 is connected to the switch module 43, and the other end is connected to the power supply circuit (i.e., ground); one end of the RC circuit is connected to the comparator module 42, and the other end is connected to the power supply circuit (i.e., ground).
[0099] Therefore, the anti-interference module 44 can isolate the comparison module 42 from the switch module 43, avoid interference to the switch module 43, and improve the accuracy of the switch module 43.
[0100] The following is a further description Figure 2 The leakage current detection principle of the embodiment shown is as follows:
[0101] 1. Connecting the ballast
[0102] When the ballast is input, a real-time voltage difference exists between input ports F1 and F2. This real-time voltage, after being divided by resistors R26 (26th resistor) and R27 (27th resistor), is greater than the 5V voltage division of the first comparator U1A (where 5V is a vague concept, and this voltage can change depending on the output power supply). The first comparator U1A outputs a low level, thus turning on the second switch Q2. Similarly, a real-time voltage difference exists between input ports F3 and F4. This real-time voltage, after being divided by resistors R37 (37th resistor) and R38 (38th resistor), is greater than the voltage division of the second comparator U1A. The 5V voltage is divided by the second comparator U1B, causing the second comparator U1B to output a low level, thus turning on the third switch Q3. The 5V voltage enters the control terminal of the first switch Q1 through the second switch Q2 and the third switch Q3. At this time, the first switch Q1 is turned on, so that the output power of the power supply circuit 1 flows from the negative DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the LED circuit 3, the first switch Q1, and finally back to the positive DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED circuit, thereby lighting up the LED circuit 3. At this time, the negative terminal of the LED circuit 3 is pulled to ground by the first switch Q1. At this time, the open-drain pin DRAIN of the driver chip U1 is equivalent to ground, and the driver chip U1 does not meet the working conditions and does not participate in the operation.
[0103] When one end of the lamp tube detaches, there is no voltage difference between input ports F1 and F2, or F3 and F4. At this time, the second switch Q2 or the third switch Q3 will not conduct. Since one of them is not conducting, there is no voltage or current at the control electrode of the first switch Q1. The first switch Q1 will be in the off state, thus cutting off the LED circuit. This makes it safe for installers to touch the other end, thus preventing leakage.
[0104] II. Connecting to mains power
[0105] When connected to AC mains power, power supply circuit 1 can operate normally with either single-ended or double-ended inputs. When AC mains power is input to input ports F1 and F2, or F3 and F4, the input voltage depends on the actual design and can be wide voltage, narrow voltage, or single voltage, etc. The following explanation uses 220V / 50HZ to illustrate the working principle:
[0106] When connected to AC power, the voltage input path is through input ports F1 and F2, or input ports F3 and F4, or combinations of input ports F1, F2, F3, and F4 (e.g., input from F1 and F3, or F1 and F4, or F2 and F3, or F2 and F4). Regardless of the method, it is input through two pins. In this case, the second switch Q2 or the third switch Q3 is not conducting. Since one is not conducting, there is no voltage or current at the control electrode of the first switch Q1, and the first switch Q1 is in the off state. Thus, the first switch Q1 does not work, which does not affect the operation of the driver chip U1. The output power of the power supply circuit 1 flows from the negative DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 through the first inductor L1, the LED circuit 3, the second inductor L2, the open-drain pin DRAIN, the driver chip U1, and the compiler pin ISP, and finally returns to the positive DC output terminals of the first rectifier bridge BD1 and the second rectifier bridge BD2 to form an LED circuit, so that the LED circuit 3 lights up normally.
[0107] In summary, this utility model's ballast leakage protection circuit compatible with mains power uses the electrical signal between the output pins before rectification as the detection target, and combines the real-time voltage between the output pins of the power supply end with the reference voltage, using voltage factors as the judgment basis to achieve accurate leakage detection from a voltage perspective, greatly improving the accuracy of detection, thereby effectively controlling the on / off state of the LED circuit, playing a role in preventing leakage, and ensuring human safety. Furthermore, this utility model's ballast leakage protection circuit compatible with mains power introduces control components such as comparators and switching transistors, realizing layer-by-layer comparison of electrical signals and flexible switching of the circuit, thereby more accurately controlling the on / off state of the LED circuit with high accuracy.
[0108] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications are also considered to be within the protection scope of this utility model.
Claims
1. A ballast leakage protection circuit compatible with mains power, characterized in that, It includes power supply circuit, step-down circuit, driver circuit, LED circuit and detection circuit; The input terminal of the power supply circuit is connected to the output pin of the power supply terminal, and the output terminal of the power supply circuit is connected to the input terminal of the step-down circuit and the input terminal of the LED circuit respectively, for rectifying the output power of the power supply terminal to output power to the step-down circuit and the LED circuit. The input terminal of the driving circuit is connected to the output terminal of the LED circuit, and is used to drive the LED circuit. The output terminal of the step-down circuit is connected to the detection circuit, and is used to step down the power supply output by the power supply circuit to output a reference voltage to the detection circuit. The detection circuit is connected to the output pin of the power supply terminal, the driving circuit, and the LED circuit respectively, and is used to control the working state of the driving circuit and the LED circuit according to the real-time voltage between the output pins of the power supply terminal and the reference voltage output by the step-down circuit.
2. The ballast leakage protection circuit compatible with mains power as described in claim 1, characterized in that, The detection circuit includes two bandpass filter modules, a comparison module and a switching module. The comparison module is provided with two real-time sampling terminals and two reference sampling terminals. The two sets of output pins of the bandpass filter module, the real-time sampling terminals, the reference sampling terminals and the power supply terminal correspond one-to-one. The bandpass filter module is connected to a corresponding set of output pins to filter the output power between the corresponding set of output pins; The real-time sampling terminal is connected to the corresponding bandpass filter module to detect the real-time voltage between a corresponding set of output pins; The reference sampling terminal is connected to the output terminal of the step-down circuit to obtain the reference voltage; The output of the comparison module is connected to the switching module and is used to control the on / off state of the switching module according to the real-time voltage and the reference voltage.
3. The ballast leakage protection circuit compatible with mains power as described in claim 2, characterized in that, The bandpass filter module includes two diodes connected in series with opposite phases, and the real-time sampling terminal of the comparison module is connected between the two diodes.
4. The ballast leakage protection circuit compatible with mains power as described in claim 2, characterized in that, The switching module includes a first switch, the control terminal of the first switch is connected to the output terminal of the comparison module, one terminal of the first switch is connected to the driving circuit and the LED circuit, and the other terminal of the first switch is connected to the power supply circuit.
5. The ballast leakage protection circuit compatible with mains power as described in claim 2, characterized in that, The comparison module includes a first comparator, a second comparator, a second switch, and a third switch; One input terminal of the first comparator is connected to a real-time sampling terminal of the comparison module, and the other input terminal of the first comparator is connected to a reference sampling terminal of the comparison module. The first comparator is used to control the on / off state of the second switch according to the real-time voltage detected by the real-time sampling terminal and the reference voltage obtained by the reference sampling terminal. One input terminal of the second comparator is connected to another real-time sampling terminal of the comparison module, and the other input terminal of the second comparator is connected to another reference sampling terminal of the comparison module. The second comparator is used to control the on / off state of the third switch according to the real-time voltage detected by the other real-time sampling terminal and the reference voltage obtained by the other reference sampling terminal. The second switch, the third switch, and the switch module are connected in sequence. The on / off state of the second switch and the third switch controls the on / off state of the switch module, and the on / off state of the switch module controls the working state of the drive circuit and the LED circuit.
6. The ballast leakage protection circuit compatible with mains power as described in claim 5, characterized in that, When the second and third switches are turned on, the switch module is turned on, so that the drive circuit is not working and the power supply circuit, LED circuit and detection circuit form an LED loop, and the LED circuit is working; When the second switch and / or the third switch are turned off, the switch module is disconnected, thereby disconnecting the LED circuit from the detection circuit.
7. The ballast leakage protection circuit compatible with mains power as described in claim 5, characterized in that, The control electrode of the second switch is connected to the output terminal of the first comparator, the first electrode of the second switch is connected to the output terminal of the step-down circuit, and the second electrode of the second switch is connected to the first electrode of the third switch. The control electrode of the third switch is connected to the output terminal of the second comparator, and the second electrode of the third switch is connected to the switch module.
8. The ballast leakage protection circuit compatible with mains power as described in claim 5, characterized in that, The comparison module further includes a first voltage divider resistor group, a second voltage divider resistor group, a third voltage divider resistor group, and a fourth voltage divider resistor group; One input terminal of the first comparator is connected to a real-time sampling terminal of the comparison module through the first voltage divider resistor group, and the other input terminal of the first comparator is connected to a reference sampling terminal of the comparison module through the second voltage divider resistor group; One input terminal of the second comparator is connected to another real-time sampling terminal of the comparison module through the third voltage divider resistor group, and the other input terminal of the second comparator is connected to another reference sampling terminal of the comparison module through the fourth voltage divider resistor group.
9. The ballast leakage protection circuit compatible with mains power as described in claim 2, characterized in that, The detection circuit also includes an anti-interference module, and the comparison module and the switch module are connected through the anti-interference module.
10. The ballast leakage protection circuit compatible with mains power as described in claim 1, characterized in that, When the power supply circuit is connected to the ballast, the drive circuit does not work; When the power supply circuit is connected to AC power, the driving circuit operates to drive the LED circuit.