Alternating current state identification circuit based on AC signal detection

By using an AC signal detection-based AC power status recognition circuit, the problem of misjudgment in LED lamp dimming power supply systems during AC power outages is solved, enabling precise power supply mode switching and ensuring stable operation of LED lamps.

CN121968406APending Publication Date: 2026-05-01BOKE DRIVERS CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
BOKE DRIVERS CO LTD
Filing Date
2026-02-04
Publication Date
2026-05-01

AI Technical Summary

Technical Problem

Existing LED dimming power supply systems cannot accurately identify the AC power outage status when there is a sudden AC power failure, which leads to the false triggering of the DC emergency mode and causes abnormal problems such as LED flashback. This is especially true when the power supply is under no-load or light load, the slow release of charge in capacitor CX can cause misjudgment.

Method used

An AC power status identification circuit based on AC signal detection is adopted, including first and second sampling circuits, operational amplifier circuit, reference circuit, comparator circuit and signal amplification circuit. By reducing the down bias resistance value of the second sampling circuit, the AC power off state is accurately detected, and accurate power supply mode switching is achieved.

Benefits of technology

It achieves accurate identification during AC power outages, avoids accidental triggering of DC emergency mode, ensures stable power supply for LED lights, and prevents abnormal phenomena such as LED light flickering.

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Abstract

The invention discloses an alternating current state identification circuit based on AC signal detection, and the circuit comprises a first sampling circuit which is used for sampling the voltage value of alternating current; the second sampling circuit is used for sampling the voltage value of the alternating current; the operational amplifier circuit is used for presetting a voltage value and is used for merging a resistor into a lower bias resistance circuit of the second sampling circuit when the sampling voltage value of the first sampling circuit is greater than the preset voltage value so as to reduce the sampling voltage value of the second sampling circuit; the reference circuit is used for providing a reference voltage value; the comparison circuit is used for comparing the sampling voltage value of the second sampling circuit with a reference voltage value and outputting a comparison signal; and the signal amplification circuit is used for amplifying the comparison signal and sending the comparison signal to the dimming control circuit to enable the dimming control circuit to identify the alternating current state, so that the dimming control circuit more accurately detects the comparison signal of the alternating current turn-off pulse width time output by the comparison circuit, and accurate control switching of alternating current power supply or emergency direct current power supply is realized.
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Description

Technical Field

[0001] This invention relates to the field of LED lamp dimming, specifically to an AC power status recognition circuit based on AC signal detection. Background Technology

[0002] In existing LED dimming power supply systems, switching between AC power and emergency DC power is typically achieved via an AC signal. In practical applications, when the AC power suddenly fails, the power system must recognize the AC power outage and enter DC emergency mode. Therefore, it's crucial to distinguish whether the AC power was properly switched off to avoid mistakenly triggering DC power supply. However, existing LED dimming power supply systems... Figure 1 As shown, with the increased power demand of LED lights leading to a larger power supply, the CX capacitor in the AC EMI circuit needs a larger capacitance value, specifically 1uF or higher. When the power supply is under no-load or light load, and the AC power is switched off, the charge in capacitor CX will slowly dissipate. This causes the AC detection signal circuit to mistakenly interpret the power supply as being in DC emergency mode, thus switching to DC emergency mode and causing abnormal problems such as LED flickering. Summary of the Invention

[0003] This invention overcomes the shortcomings of the prior art and provides an AC power status identification circuit based on AC signal detection.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] An AC power state identification circuit based on AC signal detection, characterized in that: it includes...

[0006] The first sampling circuit is connected to the AC input terminal and is used to sample the voltage value of the AC power.

[0007] The second sampling circuit is connected to the AC input terminal and is used to sample the voltage value of the AC power.

[0008] The operational amplifier circuit is connected to the first sampling circuit and the second sampling circuit respectively. It has a preset voltage value and is used to add a resistor to the lower bias resistor circuit of the second sampling circuit when the sampling voltage value of the first sampling circuit is greater than the preset voltage value, thereby reducing the total lower bias resistor value and thus reducing the sampling voltage value of the second sampling circuit.

[0009] A reference circuit is used to provide a reference voltage value;

[0010] The comparison circuit is connected to the second sampling circuit and the reference circuit respectively, and is used to compare the sampled voltage value of the second sampling circuit and the reference voltage value, and output a comparison signal;

[0011] The signal amplification circuit is connected to the comparator circuit and the dimming control circuit respectively. It is used to amplify the comparison signal and send it to the dimming control circuit so that the dimming control circuit can identify the AC power status.

[0012] The AC power status identification circuit based on AC signal detection as described above is characterized in that: the AC live wire input terminal is connected to the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the input terminals of the first sampling circuit and the second sampling circuit respectively; the AC neutral wire input terminal is connected to the positive terminal of diode D6, and the negative terminal of diode D6 is connected to the input terminals of the first sampling circuit and the second sampling circuit respectively.

[0013] The AC signal detection-based AC power state identification circuit described above is characterized in that: the first sampling circuit includes a resistor R1, one end of which is connected to the negative terminals of diodes D1 and D6 respectively; resistor R1 is connected in sequence to resistors R2 and R3 and then to one end of capacitor C2, one end of resistor R4, and one end of resistor R5 respectively; the other end of resistor R5 is connected to one end of capacitor C3 and an operational amplifier circuit respectively; and the other ends of capacitor C2, resistor R4, and capacitor C3 are grounded respectively.

[0014] The AC signal detection-based AC state identification circuit described above is characterized in that: the second sampling circuit includes a resistor R7, one end of which is connected to the negative terminals of diode D1 and diode D6 respectively, and the other end of the resistor R7 is connected to resistors R8 and R9 in sequence, and then connected to the operational amplifier circuit, one end of capacitor C5, one end of resistor R10 and the comparator circuit respectively, and the other ends of capacitor C5 and resistor R10 are grounded respectively.

[0015] The AC signal detection-based AC state identification circuit described above is characterized in that: the operational amplifier circuit includes an operational amplifier U1, pin 1 of the operational amplifier U1 is connected to the first sampling circuit, pin 2 of the operational amplifier U1 is connected to one end of capacitor C4 and one end of resistor R6 respectively, the other end of resistor R6 is connected to the second sampling circuit, and pin 3 of the operational amplifier U1 and the other end of capacitor C4 are grounded respectively.

[0016] The AC signal detection-based AC power status identification circuit described above is characterized in that: the reference circuit includes a resistor R11, one end of which is connected to the VCC power supply, and the other end of which is connected to the comparator circuit and the negative terminal of the Zener diode ZD1, while the positive terminal of the Zener diode ZD1 is grounded.

[0017] The AC signal detection-based AC state identification circuit described above is characterized in that: the comparison circuit includes a transistor Q1, the emitter of transistor Q1 is connected to the second sampling circuit, the base of transistor Q1 is connected to the reference circuit, and the collector of transistor Q1 is connected to the signal amplification circuit.

[0018] The AC signal detection-based AC power status identification circuit described above is characterized in that: the signal amplification circuit includes an optocoupler U2, pin 1 of which is connected to the VCC power supply through resistor R13, pin 2 of which is connected to the collector of transistor Q2, the base of transistor Q2 is connected to one end of resistor R12 and one end of capacitor C6 respectively, the other end of resistor R12 is connected to the comparator circuit, the emitter of transistor Q2 and the other end of capacitor C6 are grounded respectively, and pins 3-4 of optocoupler U2 are connected to the dimming control circuit respectively.

[0019] The beneficial effects of this invention are:

[0020] This invention comprises a first sampling circuit, a second sampling circuit, an operational amplifier circuit, a reference circuit, and a comparator circuit. When the operational amplifier circuit detects that the AC voltage value sampled by the first sampling circuit is greater than a preset voltage value, a resistor is connected in parallel to the lower bias resistor circuit of the second sampling circuit. This reduces the total lower bias resistor value, thereby reducing the sampling voltage value of the second sampling circuit. This shortens the pulse width of the voltage signal of the second sampling circuit when the AC power is turned off, allowing the dimming control circuit to more accurately detect the comparison signal of the AC power off pulse width output of the comparator circuit, the reference circuit, and the second sampling circuit. This enables precise control switching between AC power supply and emergency DC power supply. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of existing technology;

[0022] Figure 2 This is the circuit diagram of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0024] 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.

[0025] like Figure 2 As shown, an AC power status identification circuit based on AC signal detection includes:

[0026] The first sampling circuit 1 is connected to the AC input terminal and is used to sample a stable AC voltage value;

[0027] The second sampling circuit 2 is connected to the AC input terminal and is used to sample the voltage value of the AC power.

[0028] Operational amplifier circuit 3 is connected to the first sampling circuit 1 and the second sampling circuit 2 respectively. It has a preset voltage value. When the sampling voltage value of the first sampling circuit 1 is greater than the preset voltage value, the circuit 3 operates and a resistor is connected in parallel, thereby reducing the downward bias resistance value of the second sampling circuit 2 and reducing the sampling voltage value of the second sampling circuit 2.

[0029] Reference circuit 4 is used to provide a reference voltage value;

[0030] The comparison circuit 5 is connected to the second sampling circuit 2 and the reference circuit 4 respectively, and is used to compare the sampled voltage value of the second sampling circuit 2 and the reference voltage value, and output a comparison signal.

[0031] The signal amplification circuit 6 is connected to the comparator circuit 5 and the dimming control circuit respectively. It is used to amplify the comparison signal and send it to the dimming control circuit so that the dimming control circuit can identify the AC power status.

[0032] The dimming control circuit presets the AC power off pulse width time value. Based on the comparison signal amplified by the signal amplification circuit 6, it detects the AC power off pulse width time when the AC power is off and compares it with the preset AC power off pulse width time value. This enables precise identification of the AC power off state or AC power failure state, thereby achieving precise control and switching between AC power supply and emergency DC power supply.

[0033] During operation, the first sampling circuit 1 samples the AC voltage value and sends it to the operational amplifier circuit 3. When the operational amplifier circuit 3 detects that the AC voltage value sampled by the first sampling circuit 1 is greater than a preset voltage value, the operational amplifier circuit 3 operates by adding a resistor, thereby reducing the total value of the down-bias resistance of the second sampling circuit 2, thus reducing the sampled voltage value of the second sampling circuit 2 and shortening the time for the voltage of the second sampling circuit 2 to drop to the reference voltage under the high voltage input state at the AC input terminal. After the comparison circuit 5 compares the sampled voltage value of the second sampling circuit 2 with the reference voltage value, it outputs a comparison signal, which is amplified by the signal amplification circuit 6 and sent to the dimming control circuit. The dimming control circuit then detects the AC power off pulse width time when the AC power is turned off based on the comparison signal amplified by the signal amplification circuit 6, and compares it with the preset AC power off pulse width time value to accurately identify the AC power off state or AC power failure state.

[0034] like Figure 2As shown, the AC live wire input terminal is connected to the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the input terminal of the first sampling circuit 1 and the input terminal of the second sampling circuit 2 respectively; the AC neutral wire input terminal is connected to the positive terminal of diode D6, and the negative terminal of diode D6 is connected to the input terminal of the first sampling circuit 1 and the input terminal of the second sampling circuit 2 respectively. Diodes D1 and D2 are configured to prevent current from flowing in reverse.

[0035] In practical applications, when the first sampling circuit 1 samples the AC signal from the AC input terminal, the AC signal sampled by the resistors R1, R2, R3, R4 and capacitor C2 in the first sampling circuit 1 is then filtered by the resistor R5 and capacitor C3 to obtain a stable sampling voltage value, which is then sent to the operational amplifier circuit 3.

[0036] Operational amplifier circuit 3 is used to control the lower bias resistance value of second sampling circuit 2 through the electrical signal of first sampling circuit 1. When operational amplifier U1 in operational amplifier circuit 3 detects that the sampling voltage value of first sampling circuit 1 is greater than the preset voltage value, that is, when the AC input terminal is in a high voltage input state, resistor R6 and capacitor C4 in operational amplifier circuit 3 are connected to second sampling circuit 2, thereby reducing the total lower bias resistance value of second sampling circuit 2;

[0037] After resistor R6 and capacitor C4 are connected to the second sampling circuit 2, when the second sampling circuit 2 samples the AC signal from the AC input terminal, the AC signal sampled by resistors R7, R8, R9, R10, capacitor C5, and the connected resistors R6 and capacitor C4 in the second sampling circuit 2 is divided to obtain an AC voltage signal value and sent to one of the input terminals of the comparison circuit 5.

[0038] Reference circuit 4 provides a stable reference voltage value to comparator circuit 5. Reference circuit 4 draws power from VCC and obtains a stable reference voltage value through resistor R11 and Zener diode ZD1, which is then sent to another input terminal of comparator circuit 5.

[0039] In comparator circuit 5, the emitter of transistor Q1 receives the AC voltage signal value output from the second sampling circuit 2, while the base of transistor Q1 receives the reference voltage value output from the reference circuit 4. The comparison yields a periodic signal, which is then sent to the signal amplification circuit. Specifically, comparator circuit 5 outputs a high-level signal when the sampled voltage value of the second sampling circuit 2 is greater than the reference voltage value; and outputs a low-level signal when the sampled voltage value of the second sampling circuit 2 is less than the reference voltage value.

[0040] The signal amplification circuit 6 amplifies the comparison signal output from the comparator circuit 5 and outputs it to the dimming control circuit to identify the state of the AC power. When the comparator circuit 5 outputs a high level, transistor Q2 is turned on, and optocoupler U2 operates to output an amplified signal to the dimming control circuit. When the comparator circuit 5 outputs a low level, transistor Q2 is turned off, and optocoupler U2 does not operate.

[0041] In this case, when the AC voltage at the AC input terminal increases, the voltage of the second sampling circuit 2 also increases accordingly. This makes the time it takes for the voltage of the second sampling circuit 2 to drop to the reference voltage longer during the AC power-off process. Therefore, the first sampling circuit 1 is configured such that when the AC voltage increases by a preset value, a resistor is added in parallel through the operational amplifier circuit 3 to reduce the total downward bias resistance of the second sampling circuit 2, thereby reducing the sampling voltage value of the second sampling circuit 2. This shortens the time it takes for the voltage of the second sampling circuit 2 to drop to the reference voltage during the AC power-off process, allowing the dimming control circuit to more accurately detect the comparison signal of the AC power-off pulse width time output by the comparison circuit 5 comparing the reference circuit and the second sampling circuit 2, thus achieving precise control switching between AC power supply and emergency DC power supply.

[0042] 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. An AC power state identification circuit based on AC signal detection, characterized in that: Including The first sampling circuit (1) is connected to the AC input terminal and is used to sample the voltage value of the AC power. The second sampling circuit (2) is connected to the AC input terminal and is used to sample the voltage value of the AC power. The operational amplifier circuit (3) is connected to the first sampling circuit (1) and the second sampling circuit (2) respectively. It has a preset voltage value and is used to connect a resistor to the lower bias resistor circuit of the second sampling circuit (2) when the sampling voltage value of the first sampling circuit (1) is greater than the preset voltage value, thereby reducing the total lower bias resistor value and reducing the sampling voltage value of the second sampling circuit (2). Reference circuit (4) is used to provide a reference voltage value; The comparison circuit (5) is connected to the second sampling circuit (2) and the reference circuit (4) respectively, and is used to compare the sampling voltage value of the second sampling circuit (2) and the reference voltage value, and output a comparison signal; The signal amplification circuit (6) is connected to the comparison circuit (5) and the dimming control circuit respectively, and is used to amplify the comparison signal and send it to the dimming control circuit so that the dimming control circuit can identify the AC power status.

2. The AC power status identification circuit based on AC signal detection according to claim 1, characterized in that: The AC live wire input terminal is connected to the positive terminal of diode D1, and the negative terminal of diode D1 is connected to the input terminal of the first sampling circuit (1) and the input terminal of the second sampling circuit (2) respectively; the AC neutral wire input terminal is connected to the positive terminal of diode D6, and the negative terminal of diode D6 is connected to the input terminal of the first sampling circuit (1) and the input terminal of the second sampling circuit (2) respectively.

3. The AC power status identification circuit based on AC signal detection according to claim 2, characterized in that: The first sampling circuit (1) includes a resistor R1. One end of the resistor R1 is connected to the negative terminals of diode D1 and diode D6 respectively. The resistor R1 is connected to resistor R2 and resistor R3 in sequence and then connected to one end of capacitor C2, one end of resistor R4 and one end of resistor R5 respectively. The other end of the resistor R5 is connected to one end of capacitor C3 and operational amplifier circuit (3) respectively. The other end of capacitor C2, the other end of resistor R4 and the other end of capacitor C3 are grounded respectively.

4. The AC power status identification circuit based on AC signal detection according to claim 2, characterized in that: The second sampling circuit (2) includes a resistor R7. One end of the resistor R7 is connected to the negative terminals of diode D1 and diode D6 respectively. The other end of the resistor R7 is connected to resistor R8 and resistor R9 in sequence and then connected to the operational amplifier circuit (3), one end of capacitor C5, one end of resistor R10 and comparator circuit (5) respectively. The other end of capacitor C5 and the other end of resistor R10 are grounded respectively.

5. The AC power status identification circuit based on AC signal detection according to claim 1, characterized in that: The operational amplifier circuit (3) includes an operational amplifier U1. Pin 1 of the operational amplifier U1 is connected to the first sampling circuit (1). Pin 2 of the operational amplifier U1 is connected to one end of capacitor C4 and one end of resistor R6 respectively. The other end of resistor R6 is connected to the second sampling circuit (2). Pin 3 of the operational amplifier U1 and the other end of capacitor C4 are grounded respectively.

6. The AC power status identification circuit based on AC signal detection according to claim 1, characterized in that: The reference circuit (4) includes a resistor R11. One end of the resistor R11 is connected to the VCC power supply, and the other end of the resistor R11 is connected to the comparator circuit (5) and the negative terminal of the Zener diode ZD1. The positive terminal of the Zener diode ZD1 is grounded.

7. The AC power status identification circuit based on AC signal detection according to claim 1, characterized in that: The comparator circuit (5) includes a transistor Q1. The emitter of transistor Q1 is connected to the second sampling circuit (2), the base of transistor Q1 is connected to the reference circuit (4), and the collector of transistor Q1 is connected to the signal amplification circuit (6).

8. The AC power status identification circuit based on AC signal detection according to claim 1, characterized in that: The signal amplification circuit (6) includes an optocoupler U2. Pin 1 of the optocoupler U2 is connected to the VCC power supply through resistor R13. Pin 2 of the optocoupler U2 is connected to the collector of transistor Q2. The base of transistor Q2 is connected to one end of resistor R12 and one end of capacitor C6 respectively. The other end of resistor R12 is connected to the comparator circuit (5). The emitter of transistor Q2 and the other end of capacitor C6 are grounded respectively. Pins 3-4 of the optocoupler U2 are connected to the dimming control circuit respectively.