LED dimming drive circuit, dimming method and dimming system

Abstract

The present invention provides an LED dimming driving circuit, a dimming method and a dimming system, wherein the LED dimming driving circuit comprises: a reference generation module, a reference selection module and a driving module. The reference generation module can simultaneously generate a dimming reference signal and a reference compensation holding signal, and the reference compensation holding signal can compensate for the difference between the actual reference signal and the expected reference signal caused by the shutdown delay, so as to solve the problem of brightness over-adjustment caused by the shutdown action delay, so as to increase the user's dimming experience.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics, and in particular to an LED dimming drive circuit, a dimming method and a dimming system. Background Art

[0002] As people's requirements for energy saving are getting higher and higher, lamps with dimming function have appeared. The lamp can change the brightness and color of the light to achieve a certain degree of comfort and meet people's requirements for energy saving. The types of lamps with dimming function include bulb lamps, downlights, T-tube lamps, panel lamps, etc.

[0003] However, most households and companies use wall power switches to turn lights on and off, and do not have dimmers on the wall, so they can only dim lights through switches. The existing dimming method uses a control module to detect the on and off of the power switch to achieve dimming, but there is a shutdown delay, resulting in the brightness not being what the user really wants when the light is turned on next time.

[0004] Therefore, the current LED dimming driving circuit has the problem of over-adjustment of brightness due to shutdown delay, that is, the actual brightness of the LED lamp is greater than the expected value, resulting in a poor dimming experience for users. Summary of the invention

[0005] The object of the present invention is to provide an LED dimming drive circuit, a dimming method and a dimming system to solve the problem of over-adjustment of brightness caused by shutdown delay and enhance the user's dimming experience.

[0006] In order to achieve the above-mentioned object and other related objects, the present invention provides an LED dimming drive circuit, comprising:

[0007] A reference generation module, generating a dimming reference signal and a reference compensation holding signal;

[0008] A reference selection module is connected to the reference generation module and is used to select one of the dimming reference signal and the reference compensation holding signal as the reference signal. When the brightness of the LED lamp reaches an expected value, the reference compensation holding signal is selected as the reference signal to compensate the dimming reference signal, so that the brightness of the LED lamp is maintained at the expected brightness value;

[0009] The driving module is connected to the reference selection module and generates a control signal according to the reference signal to adjust the brightness of the LED lamp.

[0010] Optionally, in the LED dimming drive circuit, when the brightness of the LED lamp does not reach an expected brightness value, the dimming reference signal is selected as the reference signal.

[0011] Optionally, in the LED dimming drive circuit, within the same time, the change amount of the dimming reference signal is greater than or equal to the change amount of the reference compensation holding signal.

[0012] Optionally, in the LED dimming drive circuit, the LED dimming drive circuit also includes a detection module, which generates a detection signal based on a sampling signal and a reference signal representing the input voltage. When the sampling signal is less than or equal to the reference signal, and the time duration in this state is greater than or equal to a time threshold, the state of the detection signal output by the detection module is a first level, otherwise the state of the output detection signal is a second level.

[0013] Optionally, in the LED dimming drive circuit, the reference generation module includes:

[0014] A logic signal generating module receives a detection signal, counts the detection signal to obtain a count value, and generates a dimming signal and a compensation signal according to the count value. When the count value is an even number, the logic signal generating module outputs a compensation signal, and controls the reference selection module to select a reference compensation holding signal as a reference signal; when the count value is an odd number, the logic signal generating module outputs a dimming signal, and controls the reference selection module to select a dimming reference signal as a reference signal.

[0015] Optionally, in the LED dimming drive circuit, the reference generation module further includes:

[0016] a dimming reference signal generating module, connected to the logic signal generating module, configured to receive the dimming signal generated by the logic signal generating module and output the dimming reference signal;

[0017] The reference compensation holding signal generating module is connected to the logic signal generating module, and is used for receiving the compensation signal generated by the logic signal generating module and outputting the reference compensation holding signal.

[0018] Optionally, in the LED dimming drive circuit, the reference selection module is respectively connected to the dimming reference signal generating module, the reference compensation holding signal generating module and the logic signal generating module; when the count value is an even number, the logic signal generating module outputs a compensation signal, and controls the reference selection module to select the reference compensation holding signal as the reference signal; when the count value is an odd number, the logic signal generating module outputs a dimming signal, and controls the reference selection module to select the dimming reference signal as the reference signal.

[0019] Optionally, in the LED dimming drive circuit, the brightness of the LED lamp is continuously adjusted by controlling the dimming reference signal to gradually increase or gradually decrease.

[0020] Optionally, in the LED dimming drive circuit, the logic signal generating module further generates a reset signal, and the reset signal resets the dimming reference signal and the reference compensation holding signal to initial values.

[0021] Optionally, in the LED dimming drive circuit, the group of first levels and second levels are used as a group of actions, and the logic signal generating module includes:

[0022] A counter, whose input end is connected to the output end of the detection module, counts the detection signal to obtain a count value;

[0023] A collection module, whose input end is connected to the output end of the detection module, and is used to collect the duration of the second level in each group of actions;

[0024] A third comparator, whose positive input terminal is connected to the output terminal of the acquisition module and whose negative input terminal receives the reference value, is used to compare the second level duration of the above group of actions with the reference value and obtain a time comparison result;

[0025] A storage module is connected to the third comparator and the counter, and is used to store the corresponding relationship between the count value and the time comparison result and the dimming signal, the compensation signal and the reset signal.

[0026] Optionally, in the LED dimming drive circuit, when the count value is an odd number, and when the second level duration of the upper group of actions is greater than or equal to the reference value, the logic signal generating module first outputs a reset signal, then outputs a dimming signal, and controls the dimming reference signal to adjust from an initial value; when the second level duration of the upper group of actions is less than the reference value, the logic signal generating module outputs a dimming signal, and controls the dimming reference signal to continue to adjust based on the dimming reference signal generated by the upper group of actions.

[0027] Optionally, in the LED dimming driving circuit, the dimming reference signal generating module includes:

[0028] A second switch tube, whose control end is connected to the output end of the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0029] A second current source, a second end of which is connected to the first end of the second switch tube, and a first end of which receives a third reference to generate a second current signal;

[0030] a fourth switch tube, whose control end is connected to the output end of the logic signal generating module, receives a reset signal, and is turned off or closed according to the reset signal;

[0031] A second capacitor has a first end connected to the first end of the fourth switch tube and the second end of the second switch tube respectively, and the second current signal charges the second capacitor to generate a dimming reference signal.

[0032] Optionally, in the LED dimming drive circuit, the reference compensation holding signal generating module includes:

[0033] A third switch tube, whose control end is connected to the output end of the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0034] A third current source, a second end of which is connected to the first end of the third switch tube, and a first end of which receives a third reference to generate a third current signal;

[0035] a fifth switch tube, whose control end is connected to the output end of the logic signal generating module, receives a reset signal, and is turned off or closed according to the reset signal;

[0036] A third capacitor, a first end of which is respectively connected to the first end of the fifth switch tube and the second end of the third switch tube, the third current signal charges the third capacitor to generate a reference compensation holding signal, wherein the charging speed of the second capacitor is greater than the charging speed of the third capacitor.

[0037] Optionally, in the LED dimming drive circuit, the reference compensation holding signal generating module includes:

[0038] The reference conversion module has an input end connected to the first end of the second capacitor and an output end connected to the reference selection module, receives the dimming reference signal, and converts it into a reference compensation holding signal.

[0039] Optionally, in the LED dimming driving circuit, the dimming reference signal generating module includes:

[0040] A second switch tube, whose control end is connected to the output end of the logic signal generating module, whose first end is connected to the second current source, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0041] A fourth switch tube, whose control end is connected to the output end of the logic signal generating module, whose second end receives a third reference, receives a reset signal, and is turned off or closed according to the reset signal;

[0042] The second capacitor has a first end connected to the first end of the fourth switch tube and the second end of the second switch tube respectively, and a second end connected to ground. When the dimming signal controls the second switch tube to close, the second capacitor discharges to generate the dimming reference signal.

[0043] Optionally, in the LED dimming drive circuit, the reference compensation holding signal generating module includes:

[0044] A third switch tube, whose control end is connected to the output end of the logic signal generating module, whose first end is connected to the third current source, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0045] a fifth switch tube, whose control end is connected to the output end of the logic signal generating module, whose second end receives a third reference, receives a reset signal, and is turned off or closed according to the reset signal;

[0046] The third capacitor has a first end connected to the first end of the fifth switch tube and the second end of the third switch tube respectively, and a second end connected to ground. When the dimming signal controls the third switch tube to close, the third capacitor discharges to generate the reference compensation holding signal.

[0047] Optionally, in the LED dimming driving circuit, the dimming reference signal generating module includes:

[0048] A second switch tube, whose control end is connected to the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0049] A first pulse module, connected to the first end of the second switch tube, generating a first pulse signal;

[0050] The first digital-to-analog conversion module has a first input end connected to the logic signal generating module to receive the reset signal, and a second input end connected to the second end of the second switch tube to generate a dimming reference signal according to the first pulse signal.

[0051] Optionally, in the LED dimming drive circuit, the reference compensation holding signal generating module includes:

[0052] A third switch tube, whose control end is connected to the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal;

[0053] A second pulse module, connected to the first end of the third switch tube, generating a second pulse signal;

[0054] The second digital-to-analog conversion module has a first input end connected to the logic signal generating module to receive a reset signal, and a second input end connected to the second end of the third switch tube to generate a reference compensation holding signal according to the second pulse signal.

[0055] Optionally, in the LED dimming drive circuit, the pulse frequency generated by the first pulse module is greater than the pulse frequency generated by the second pulse module.

[0056] Optionally, in the LED dimming drive circuit, when the logic signal generating module outputs a reset signal, the first digital-to-analog conversion module and the second digital-to-analog conversion module receive the reset signal and reset the dimming reference signal and the reference compensation hold signal to an initial value.

[0057] Optionally, in the LED dimming drive circuit, the reference selection module includes:

[0058] a sixth switch tube, wherein a control end of the sixth switch tube is connected to the output end of the logic signal generating module to receive the dimming signal, a first end of the sixth switch tube is connected to the dimming reference signal generating module to receive the dimming reference signal, and the sixth switch tube is turned off or on according to the dimming signal to control the output of the dimming reference signal;

[0059] A seventh switch tube, whose control end is connected to the output end of the logic signal generating module, receives the dimming signal, and a first end of the seventh switch tube is connected to the reference compensation holding signal, receives the compensation signal, and is turned off or closed according to the compensation signal to control the output of the reference compensation holding signal.

[0060] In order to achieve the above-mentioned object and other related objects, the present invention also provides a dimming method of an LED dimming drive circuit, comprising:

[0061] generating a dimming reference signal and a reference compensation holding signal;

[0062] Selecting one of the dimming reference signal and the reference compensation holding signal as a reference signal;

[0063] Generate a control signal according to the reference signal for adjusting the brightness of the LED lamp;

[0064] When the brightness of the LED lamp reaches an expected value, the reference compensation holding signal is selected as the reference signal to compensate the dimming reference signal, so that the brightness of the LED lamp is maintained at the expected brightness value.

[0065] Optionally, in the dimming method, when the brightness of the LED lamp does not reach an expected brightness value, the dimming reference signal is selected as the reference signal.

[0066] Optionally, in the dimming method, a change rate of the dimming reference signal is greater than or equal to a change rate of the reference compensation hold signal.

[0067] Optionally, in the dimming method, a detection signal is generated based on a sampling signal representing the input voltage and a reference signal. When the sampling signal representing the input voltage is less than or equal to the reference signal, and the duration of this state is greater than or equal to a time threshold, the state of the detection signal is a first level; otherwise, the state of the detection signal is a second level.

[0068] Optionally, in the dimming method, the detection signal is counted to obtain a count value, and a dimming signal and a compensation signal are generated based on the count value. When the count value is an even number, a compensation signal is generated to select a reference compensation holding signal as a reference signal; when the count value is an odd number, a dimming signal is generated to select a dimming reference signal as a reference signal.

[0069] Optionally, in the dimming method, the dimming reference signal and the reference compensation holding signal are controlled to gradually increase or gradually decrease to continuously adjust the brightness of the LED lamp.

[0070] Optionally, in the dimming method, the group of first levels and second levels are used as a group of actions. When the count value is an odd number and when the duration of the second level of the previous group of actions is greater than or equal to a reference value, a reset signal is first generated to reset the dimming reference signal and the reference compensation hold signal to an initial value, and then a dimming signal is generated, and the dimming reference signal is controlled to be adjusted from the initial value; when the duration of the second level of the previous group of actions is less than the reference value, a dimming signal is generated, and the dimming reference signal is controlled to continue to be adjusted based on the dimming reference signal generated by the previous group of actions.

[0071] Optionally, in the dimming method, the dimming method includes:

[0072] When powered on for the first time, the whole machine dims, starting from the initial value of the dimming reference signal;

[0073] The input voltage is controlled to be less than or equal to the reference value for the first time, and the duration of this state is greater than or equal to the time threshold, and then the input voltage is controlled to be greater than the reference value;

[0074] The whole machine is compensated and maintained, a reference compensation and maintenance signal is selected as a reference signal, and a current corresponding to the reference compensation and maintenance signal is output;

[0075] Determine whether the brightness of the LED lamp is an expected value, and if the brightness of the LED lamp reaches the expected value, end the dimming action; if the brightness of the LED lamp does not reach the expected value, control the input voltage to be less than or equal to the reference value for the second time, and the duration of this state is greater than or equal to the time threshold, and then control the input voltage to be greater than the reference value;

[0076] Compare the duration of the last time the input voltage was greater than the reference value with the benchmark value. If the duration is greater than the benchmark value, return to the step of initial power-on. If the duration is less than or equal to the benchmark value, continue dimming based on the last dimming reference signal, and return to the step of first controlling the input voltage to be less than or equal to the reference value.

[0077] Optionally, in the dimming method, the dimming method is continuous dimming.

[0078] In order to achieve the above object and other related objects, the present invention also provides a dimming system, comprising:

[0079] The LED dimming driving circuit described above generates a control signal according to the sampling signal;

[0080] The power conversion module is connected to the LED dimming drive circuit and controls the brightness of the LED lamp according to the control signal.

[0081] Optionally, in the dimming system, the power conversion module includes a power switch and a sampling resistor, and the power switch and the sampling resistor are connected in series.

[0082] The voltage across the sampling resistor is sampled to obtain the sampling signal.

[0083] Optionally, in the dimming system, the dimming system further includes:

[0084] A power switch, a first end of which is connected to a first end of a power source and is used to control input of an input voltage;

[0085] A rectifier bridge, whose first input end is connected to the second end of the power switch, and whose second input end is connected to the second end of the power supply, rectifies the input voltage, and the first end and the second end of the LED dimming drive circuit are respectively connected to the first output end and the second output end of the rectifier bridge,

[0086] The sampling signal is obtained by sampling the rectified input voltage.

[0087] Optionally, in the dimming system, the dimming system further includes:

[0088] A power switch, a first end of which is connected to a first end of a power source and is used to control input of an input voltage;

[0089] A rectifier bridge, whose first input end is connected to the second end of the power switch, and whose second input end is connected to the second end of the power supply, rectifies the input voltage, the first end of the LED dimming drive circuit is connected to the second end of the power switch, and the second end of the LED dimming drive circuit is connected to the second output end of the rectifier bridge,

[0090] The sampling signal is obtained by sampling the input voltage.

[0091] To summarize, the present invention can simultaneously generate a dimming reference signal and a reference compensation holding signal through a reference generation module, and the difference between an actual reference signal and an expected reference signal caused by a shutdown delay can be compensated by the reference compensation holding signal, thereby solving the problem of over-adjustment of brightness caused by a shutdown action delay, and increasing the user's dimming experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0092] Figure 1 is a schematic block diagram of a dimming system in the prior art;

[0093] Figure 2 It is a working waveform diagram of the dimming system of the prior art;

[0094] Figure 3 is a schematic block diagram of a dimming system of the present invention;

[0095] Figure 4 is a schematic circuit diagram of a dimming system in a first embodiment;

[0096] Figure 5 yes Figure 4 Working waveform diagram of the detection module in;

[0097] Figure 6 is a schematic circuit diagram of a dimming system in a second embodiment;

[0098] Figure 7 is a schematic circuit diagram of a dimming system in a third embodiment;

[0099] Figure 8 is a flow chart of a dimming method according to an embodiment of the present invention.

[0100] Fig. 9 is a partial working waveform diagram of the control module in the first embodiment;

[0101] Fig.10 is a schematic circuit diagram of a dimming system in a fourth embodiment;

[0102] Fig.11 is a schematic circuit diagram of a dimming system in a fifth embodiment;

[0103] Fig.12is a partial working waveform diagram of the control module in the fifth embodiment;

[0104] Fig.13 is a schematic circuit diagram of a dimming system in a sixth embodiment;

[0105] Fig.14 is a partial working waveform diagram of the control module in the sixth embodiment;

[0106] Figure 1-2 middle:

[0107] 010-power switch, 011-rectifier bridge, 02-control module, 03-power conversion module;

[0108] Figure 3 to Figure 14 middle:

[0109] 100 - power switch module, 101 - power switch, 102 - rectifier bridge, 200 - detection module, 300 - control module, 301 - reference generation module, 302 - reference selection module, 303 - drive module, 400 - power conversion module. DETAILED DESCRIPTION

[0110] The LED dimming drive circuit, dimming method and dimming system proposed in the present invention are further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following embodiments. It should be noted that the accompanying drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0111] See also Figure 1 , shows a schematic block diagram of a dimming system in the prior art. The block diagram includes a power switch 010, a rectifier bridge 011, a control module 02 and a power conversion module 03. The input of the AC voltage can be controlled by turning the power switch 010 on and off, and the rectifier bridge 011 is used to rectify the AC input voltage to obtain a DC bus voltage Vbus. The control module 02 detects the DC bus voltage Vbus obtained after rectification by the rectifier bridge 011 to determine whether the power switch 010 is closed, so as to control the magnitude of the LED load current. The power conversion module 03 converts the DC bus voltage Vbus into a suitable DC current to provide energy to the LED load. That is, the dimming method in the prior art is to achieve dimming by detecting the on and off of the power switch by the control module.

[0112] See also Figure 2, shows the working waveform of the dimming system of the prior art. It can be found that when the power switch 010 is in state A (the power switch 010 is closed), the output current Io of the power conversion module 03 will change with time. When the user wants the output current Io to correspond to the reference signal at time point t1, and operates the power switch 010 to turn off, the shutdown action (the power switch 010 is in state B) is actually at time point t2. Therefore, there will be a delay in turning off the power switch, resulting in the brightness when it is turned on next time not being the brightness that the user really wants.

[0113] In order to solve the problem of over-adjustment of brightness caused by shutdown delay and to enhance the user's dimming experience, the present invention provides a dimming system, see Figure 3 to Figure 14 .

[0114] See also Figure 3 The dimming system includes: a power switch module 100, an LED dimming drive circuit and a power conversion module 400. The power switch module 100 includes a power switch 101 and a rectifier bridge 102. The first end of the power switch 101 is connected to the first end of the power supply, and the input voltage is inputted by the on-off control of the power switch 101. The rectifier bridge 102 has a first input end connected to the second end of the power switch 101, and a second input end connected to the second end of the power supply, for rectifying the input voltage.

[0115] The LED dimming driving circuit includes a detection module 200 and a control module 300 , and the control module 300 includes a reference generation module 301 , a reference selection module 302 and a driving module 303 .

[0116] The detection module 200 is connected to the power switch module 100 , and specifically, the detection module 200 is connected between the first output terminal and the second output terminal of the rectifier bridge 102 , that is, the rectified input voltage is sampled to obtain the sampling signal.

[0117] See also Figure 4 The detection module includes: a voltage sampling circuit, a first comparator U1, a second comparator U2, a first reference REF1 (ie, a reference signal REF1), a second reference REF2, a first switch tube Q1, a first capacitor C1 and a first current source I1.

[0118] The voltage sampling circuit is used to sample the input voltage, and includes a first resistor R1 and a second resistor R2. The first end of the first resistor R1 is connected to the first output end of the rectifier bridge 102; the first end of the second resistor R2 is connected to the second end of the first resistor R1, and the second end of the second resistor R2 is connected to the second output end of the rectifier bridge 102 and grounded. The first resistor R1 and the second resistor R2 obtain a sampling signal by voltage division.

[0119] The positive input terminal of the first comparator U1 is connected to the output terminal of the voltage sampling circuit, that is, connected to the second terminal of the first resistor R1, and the negative input terminal thereof receives the reference signal REF1, and the output terminal thereof is connected to the control terminal of the first switch tube Q1. The voltage at the positive input terminal of the first comparator U1 is the sampling signal, and the voltage at the negative input terminal of the first comparator U1 is the reference signal REF1. The sampling signal at the positive input terminal is compared with the reference signal REF1 at the negative input terminal, and a corresponding intermediate signal is output at the output terminal according to the comparison result. If the sampling signal is lower than or equal to the reference signal, and the duration of the state is greater than or equal to the time threshold, the intermediate signal is a low level; if the sampling signal is lower than or equal to the reference signal, and the duration of the state is less than the time threshold, the first intermediate signal is a square wave low level; if the sampling signal is higher than the reference signal, the first intermediate signal is a square wave high level. The time threshold is a value set according to actual needs, and the square wave low level and the square wave high level constitute a square wave signal. For example, when the power switch 101 is closed, the first comparator U1 outputs a square wave signal according to the comparison result between the sampling signal at the positive input terminal and the reference signal REF1 at the negative input terminal, and when the sampling signal is lower than the reference signal REF1, the output signal V U1 is low level; when the sampling signal is higher than the reference signal REF1, the output signal V U1 When the power switch 101 is turned off (i.e., the sampling signal is lower than or equal to the reference signal, and the duration of this state is greater than or equal to the time threshold), the output signal V U1 For low level, see Figure 5 .

[0120] The control end of the first switch tube Q1 is connected to the output end of the first comparator U1, the first end thereof is connected to the first end of the first capacitor C1, and the second end thereof is connected to the second end of the first capacitor C1 and is grounded. The first comparator U1 outputs a high level to close the first switch tube Q1, so that the voltage of the first capacitor C1 is discharged to 0V. The first comparator U1 outputs a low level, the first switch tube Q1 is turned off, so that the first capacitor C1 is charged by the first current source I1.

[0121] The first end of the first capacitor C1 is connected to the output end of the first current source I1 and the positive input end of the second comparator U2. The negative input end of the second comparator U2 receives the second reference REF2. The first end of the first current source I1 receives the power supply voltage VCC. The positive input end voltage of the second comparator U2 is the voltage V C1 , the voltage at its negative input terminal is the second reference REF2, and the second comparator U2 converts the voltage V C1 The detection signal V is compared with the second reference REF2 and output according to the comparison result. U2 When the voltage V C1 When the detection signal V U2 is a first level, which is a high level; when the voltage V C1 When the detection signal V U2 is the second level, which is a low level. Since the sampling signal is less than or equal to the reference signal, and the duration of this state is greater than or equal to the time threshold, the first capacitor C1 is continuously charged, so that its voltage V C1 is higher than the second reference REF2, the second comparator U2 will output a high level (ie, the first level), see Figure 5 , and the sampling signal is greater than the reference signal, and then the duration of the sampling signal being less than or equal to the reference signal is less than the time threshold, and then the sampling signal is greater than the reference signal again, the first capacitor C1 is continuously discharged and charged, and the voltage V C1 For example, when the power switch 101 is closed, that is, the sampling signal is greater than the reference signal, and then the sampling signal is less than or equal to the reference signal, and the duration of this state is less than the time threshold, the first comparator U1 will output a square wave signal, so the first capacitor C1 is continuously discharged and charged, and the voltage V C1The second comparator U2 will output a low level. When the power switch 101 is turned off, that is, the sampling signal is less than or equal to the reference signal, and the duration of this state is greater than the time threshold, the first capacitor C1 is continuously charged, so that its voltage V C1 is higher than the second reference REF2, the second comparator U2 will output a high level, see Figure 5 Therefore, the on / off state of the power switch 101 can be detected by the level of the detection signal output by the second comparator U2, that is, whether the input voltage is lower than the reference value can be detected by the level of the detection signal output by the second comparator U2, for example, whether the input voltage is undervoltage.

[0122] In the second embodiment, see Figure 6 , the first input end of the detection module 200 is connected to the second end of the power switch 101, and the second input end of the detection module 200 is connected to the second output end of the rectifier bridge 102. Or the first input end of the detection module 200 is connected to the second input end of the rectifier bridge 102, and the second input end of the detection module 200 is connected to the second output end of the rectifier bridge 102. That is, the input voltage is sampled to obtain the sampling signal, and the other parts are the same as those in the first embodiment, which will not be repeated here.

[0123] In the third embodiment, see Figure 7 The power conversion module 400 includes a power switch and a sampling resistor, the power switch and the sampling resistor are connected in series, and the positive input terminal of the first comparator U1 of the detection module 200 is connected to the sampling resistor. That is, the voltage across the sampling resistor is sampled to obtain the sampling signal, and the other parts are the same as those in the first embodiment, which will not be repeated here.

[0124] The following is a detailed description taking the input voltage of the detection module 200 as the voltage after the rectifier bridge as an example.

[0125] The control module 300 is connected to the detection module 200 and outputs a PWM control signal according to the detection signal of the detection module 200 to control the power switch of the power conversion module 400, thereby realizing the dimming of the LED.

[0126] Continue reading Figure 4The control module 300 includes a reference generation module 301, a reference selection module 302 and a driving module 303. The reference generation module 301 is connected to the detection module 200, and generates a dimming reference signal and a reference compensation holding signal according to the detection signal output by the detection module 200; the reference selection module 302 is connected to the reference generation module 301, and is used to select one of the dimming reference signal and the reference compensation holding signal as the reference signal R-REF, that is, the reference signal R-REF is the dimming reference signal or the reference compensation holding signal; the driving module 303 is connected to the reference selection module 302, and adjusts the output voltage or current according to the dimming reference signal or the reference compensation holding signal selected by the reference selection module 302.

[0127] The reference generation module 301 includes: a logic signal generation module, whose input end is connected to the output end of the detection module 200 , and generates a dimming signal V1 , a reset signal V2 and a compensation signal V3 according to the detection signal output by the detection module 200 . That is, the first output end, the second output end and the third output end of the logic signal generating module respectively output the dimming signal V1, the reset signal V2 and the compensation signal V3, and its third output end is connected to the reference selection module 302; a dimming reference signal generating module, whose first input end is connected to the first output end of the logic signal generating module, whose second input end is connected to the second output end of the logic signal generating module, and whose output end is connected to the reference selection module 302; the dimming reference signal generating module generates a dimming reference signal according to the dimming signal V1, and whose output end outputs the dimming reference signal; a reference compensation holding signal generating module, whose first input end is connected to the first output end of the logic signal generating module, whose second input end is connected to the second output end of the logic signal generating module, and whose output end is connected to the reference selection module 302; the reference compensation holding signal generating module generates a reference compensation holding signal according to the dimming signal V1, and whose output end outputs the reference compensation holding signal.

[0128] The group of first level and second level is taken as a group of actions, and the logic signal generating module may include: a counter, a collection module, a third comparator and a memory. The input end of the counter is connected to the output end of the detection module 200, and the detection signal is counted to obtain a count value; the collection module, whose input end is connected to the output end of the detection module 200, is used to collect the duration of the second level in each group of actions; the third comparator, whose positive input end is connected to the output end of the collection module, and whose negative input end receives a reference value, is used to compare the duration of the second level of the previous group of actions with the reference value, and obtain a time comparison result (the reference value is set to N seconds, N is a constant greater than 0); the memory, which is connected to the third comparator and the counter, is used to store the corresponding relationship between the count value and the time comparison result and the dimming signal V1, the compensation signal V3 and the reset signal V2.

[0129] When the count value is an odd number, when the second level duration of the previous group action is greater than or equal to the reference value, the logic signal generation module first outputs a reset signal V2, the reset signal V2 resets the dimming reference signal and the reference compensation holding signal to the initial value, and then outputs the dimming signal V1, and controls the dimming reference signal to adjust from the initial value; when the second level duration of the previous group action is less than the reference value, the logic signal generation module outputs the dimming signal V1, and controls the dimming reference signal to continue to adjust based on the dimming reference signal generated by the previous group action. When the count value is an even number, the logic signal generation module outputs a compensation signal V3.

[0130] When the logic signal generating module outputs the compensation signal V3, the reference selecting module 302 selects the reference compensation holding signal as the reference signal R-REF; when the logic signal generating module outputs the dimming signal V1, the reference selecting module 302 selects the dimming reference signal as the reference signal R-REF. Therefore, if the count value is an even number, the reference selecting module 302 selects the reference compensation holding signal as the reference signal R-REF; if the count value is an odd number, the reference selecting module 302 selects the dimming reference signal as the reference signal R-REF.

[0131] See also Figure 8 , the specific steps of dimming include:

[0132] S01: When powered on for the first time, the logic signal generating module outputs a dimming signal V1, the reference selecting module 302 selects a dimming reference signal as a reference signal, and the driving module 303 controls the output current to be adjusted from the initial value of the dimming reference signal;

[0133] S02: For the first time, the control input voltage is less than or equal to the reference value (the reference signal is used to represent the reference value), and the duration of this state is greater than or equal to the time threshold, and then the control input voltage is greater than the reference value;

[0134] S03: Selecting the reference compensation holding signal as the reference signal, the driving module 303 controls the output current to be the current value corresponding to the reference compensation holding signal;

[0135] S04: Determine whether the brightness of the LED lamp is an expected value. If the brightness of the LED lamp reaches the expected value, the dimming action is terminated; if the brightness of the LED lamp does not reach the expected value, proceed to step S05;

[0136] S05: controlling the input voltage to be less than or equal to the reference value for the second time, and the duration of this state is greater than or equal to the time threshold, and then controlling the input voltage to be greater than the reference value;

[0137] S06: Compare the duration of the last time when the input voltage was greater than the reference value with the reference value. If the duration is greater than the reference value, return to step S01; if the duration is less than or equal to the reference value, proceed to step S07:

[0138] S07: The logic signal generating module outputs a dimming signal, and continues dimming based on the dimming reference signal of the previous group, and returns to step S02. The process is repeated until the brightness of the LED lamp reaches the expected value.

[0139] In the first embodiment, the dimming reference signal generating module includes: a second switch tube Q2, a fourth switch tube Q4 and a second capacitor C2. The control end of the second switch tube Q2 is connected to the first output end of the logic signal generating module to receive the dimming signal V1, the first end of the second switch tube Q2 is connected to the second end of the second current source I2, the first end of the second current source I2 receives the third reference REF3 for charging the second capacitor C2, and the third reference REF3 limits the maximum value of the reference for clamping. The second end of the second switch tube Q2 is connected to the first end of the second capacitor C2; the control end of the fourth switch tube Q4 is connected to the second output end of the logic signal generating module to receive the reset signal V2 for controlling the fourth switch tube Q4 to discharge the second capacitor C2, the first end of the second capacitor C2 is connected to the first end of the fourth switch tube, and the second end is connected to the second end of the fourth switch tube.

[0140] The reference compensation holding signal generating module includes: a third switch tube Q3, a fifth switch tube Q5 and a third capacitor C3. The control end of the third switch tube Q3 is connected to the first output end of the logic signal generating module to receive the dimming signal V1, the first end of the third switch tube Q3 is connected to the second end of the third current source I3 to charge the third capacitor C3, the first end of the third current source I3 receives the third reference REF3, the second end of the third switch tube Q3 is connected to the first end of the third capacitor C3; the control end of the fifth switch tube Q5 is connected to the second output end of the logic signal generating module; the reset signal V2 is received to control the fifth switch tube Q5 to discharge the third capacitor C3, the first end of the third capacitor C3 is connected to the first end of the fifth switch tube Q5, and the second end is connected to the second end of the fifth switch tube Q5.

[0141] When the dimming signal V1 outputted from the first output terminal of the logic signal generating module is at a high level (i.e., when the logic signal generating module outputs the dimming signal V1), the second switch tube Q2 and the third switch tube Q3 are closed, so that the second current source I2 can charge the second capacitor C2, and the third current source I3 can charge the third capacitor C3.

[0142] In this embodiment, the charging speeds of the second capacitor C2 and the third capacitor C3 can be adjusted by setting the second current source I2, the third current source I3, the capacitance of the second capacitor C2, and the capacitance of the third capacitor C3, so that the charging speed of the second capacitor C2 is greater than the charging speed of the third capacitor C3. At this time, the voltage V C2 is the dimming reference signal, the voltage V C3 Holds the signal for reference compensation. Fig. 9 When the user wants the output current to correspond to the current value at time t1, the power switch 101 is turned off. The actual turn-off action is actually at time t2 (that is, the difference between time t2 and time t1 is the human body reaction time). Therefore, during the period t1-t2, the voltage V C2 Continue to increase, and the third capacitor C3 has a hysteresis due to charging, and the third capacitor C3 voltage V C3 At time t2, the voltage V of the second capacitor C2 corresponding to time t1 is just reached. C2. Therefore, the required compensation time can be obtained by measuring the human body reaction speed, thereby obtaining the parameter configuration (i.e., the capacitance parameters of the second current source I2, the third current source I3, the second capacitor C2, and the third capacitor C3). Specifically: the required capacitance of the second capacitor C2 and the third capacitor C3 can be obtained by the time point t1 and the time point t2 and the size of the set second current source I2 and the third current source I3, that is, the required capacitance of the second capacitor C2 and the third capacitor C3 can be obtained according to the formula: I = C*du / dt. Alternatively, the size of the second current source I2 and the third current source I3 can be obtained by providing a known second capacitor C2 and a known third capacitor C3.

[0143] When the reset signal V2 outputted from the second output terminal of the logic signal generating module is at a high level (ie, the logic signal generating module outputs the reset signal V2), the fourth switch tube Q4 and the fifth switch tube Q5 are closed, and the voltages of the second capacitor C2 and the third capacitor C3 are discharged.

[0144] The reference selection module 302 is connected to the reference generation module 301 and is used to select a reference signal R-REF. The reference signal R-REF is one of the dimming reference signal and the reference compensation holding signal.

[0145] The reference selection module 302 includes a sixth switch tube Q6 and a seventh switch tube Q7. The control end of the sixth switch tube Q6 is connected to the first output end of the logic signal generation module to receive the dimming signal V1. The first end of the sixth switch tube Q6 is connected to the first end of the fourth switch tube Q4, and the second end is connected to the driving module 303. The control end of the seventh switch tube Q7 is connected to the third output end of the logic signal generation module to receive the compensation signal V3. The first end of the seventh switch tube Q7 is connected to the first end of the third capacitor C3, and the second end is connected to the driving module 303.

[0146] When the first output terminal of the logic signal generating module outputs a high-level dimming signal V1, the sixth switch tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third output terminal of the logic signal generating module outputs a high-level compensation signal V3, the reference compensation holding signal is transmitted to the driving module 303. Fig. 9 The reference signal R-REF is the voltage V of the second capacitor C2 during the period from the initial power-on (the count value is 1) to the actual shutdown of the power switch 101 (time point t2). C2 At time t2, the switch is turned off, the dimming signal V1 turns to a low level, and the output voltage V of the second capacitor C2 stops. C2That is, the dimming reference signal stops being outputted. Next time the power switch 101 is closed (the count value is 2), at time t3, the compensation signal V3 is at a high level, and the reference signal R-REF is switched to the voltage V of the third capacitor C3. C3 , if the voltage V of the third capacitor C3 C3 If the reference signal is the one that the user really expects, the dimming is terminated. Otherwise, the power switch 101 is turned off again after being closed for a period of time, and the compensation signal V3 turns to a low level, and the output of the voltage V of the third capacitor C3 is stopped. C3 , the power switch 101 is closed again (the count value is 3). If the last closing time of the power switch is less than or equal to the reference value, the reference signal R-REF is the dimming reference signal, that is, the reference signal R-REF is the voltage V of the second capacitor C2 last time. C2 Continue to adjust based on the actual situation, and repeat in sequence until the user's expectations are met.

[0147] In the fourth embodiment, the difference from the first embodiment is that the second capacitor C2 and the third capacitor C3 are discharged through a current source, and the principle is the same, which is within the protection scope of the present invention.

[0148] For example, see Fig.10 When the current source is used to discharge the second capacitor C2 and the third capacitor C3 respectively, the dimming reference signal generating module includes: a second switch tube Q2, whose control end is connected to the first output end of the logic signal generating module; receiving the dimming signal V1, a second current source I2, whose first end is connected to the first end of the second switch tube Q2, and whose second end is grounded; a fourth switch tube Q4, whose control end is connected to the second output end of the logic signal generating module, receiving the reset signal V2, whose first end is connected to the second end of the second switch tube Q2, and whose second end receives the third reference; a second capacitor C2, whose first end is respectively connected to the first end of the fourth switch tube Q4 and the second end of the second switch tube Q2, and whose second end is grounded.

[0149] The reference compensation holding signal generating module includes: a third switch tube Q3, whose control end is connected to the first output end of the logic signal generating module; receiving a dimming signal V1, a third current source I3, whose first end is connected to the first end of the third switch tube Q3, and whose second end is grounded; a fifth switch tube Q5, whose control end is connected to the second output end of the logic signal generating module; receiving a reset signal V2, a third capacitor C3, whose first end is respectively connected to the first end of the fifth switch tube Q5 and the second end of the third switch tube Q3, and whose second end is grounded.

[0150] The reference selection module includes: a sixth switch tube Q6, whose control end is connected to the first output end of the logic signal generating module, receives the dimming signal V1, whose first end is connected to the first end of the fourth switch tube Q4, and whose second end is connected to the driving module 303; a seventh switch tube Q7, whose control end is connected to the third output end of the logic signal generating module, receives the compensation signal V3, whose first end is connected to the first end of the third capacitor C3, and whose second end is connected to the driving module 303. The above circuit can discharge the second capacitor C2 and the third capacitor C3 through a current source.

[0151] See also Fig.11 In the fifth embodiment, the dimming reference signal generating module includes: a second switch tube Q2, a fourth switch tube Q4 and a second capacitor C2. The control end of the second switch tube Q2 is connected to the first output end of the logic signal generating module to receive the dimming signal V1, the first end of the second switch tube Q2 is connected to the second end of the second current source I2, the first end of the second current source I2 receives the third reference REF3, and the third reference REF3 limits the maximum value of the reference for clamping. The second end of the second switch tube Q2 is connected to the first end of the second capacitor C2; the control end of the fourth switch tube Q4 is connected to the second output end of the logic signal generating module to receive the reset signal V2. The first end of the second capacitor C2 is connected to the first end of the fourth switch tube, and the second end is connected to the second end of the fourth switch tube.

[0152] The reference compensation holding signal generating module includes: a reference conversion module, whose input end is connected to the first end of the second capacitor C2, and whose output end is connected to the reference selection module 302. The reference conversion module is used to convert the voltage V C2 Stepping is performed to generate a reference compensation hold signal.

[0153] See also Fig.12 , the voltage V of the second capacitor C2 C2 is the dimming reference signal, the voltage V C2 When the user wants the output current to correspond to the current value at time t1, the power switch 101 is turned off. The actual turn-off action is actually at time t2. Therefore, during the period t1-t2, the voltage V C2 The voltage VR2 of the stepped second capacitor C2 continues to increase, and because of the step, the voltage VR2 at time point t2 just reaches the voltage V of the second capacitor C2 corresponding to time point t1. C2 .

[0154] The reference selection module 302 includes a sixth switch tube Q6 and a seventh switch tube Q7. The control end of the sixth switch tube Q6 is connected to the first output end of the logic signal generating module to receive the dimming signal V1. The first end of the sixth switch tube Q6 is connected to the first end of the second capacitor C2, and the second end is connected to the driving module 303. The control end of the seventh switch tube Q7 is connected to the third output end of the logic signal generating module to receive the compensation signal V3. The first end of the seventh switch tube Q7 is connected to the output end of the reference conversion module, and the second end is connected to the driving module 303. When the first output end of the logic signal generating module outputs a high-level dimming signal V1, the sixth switch tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third output end of the logic signal generating module outputs a high-level compensation signal V3, the seventh switch tube Q7 is closed, and the reference compensation holding signal is transmitted to the driving module 303. Continue to refer to Fig.12 The reference signal R-REF is the voltage V of the second capacitor C2 during the period from the initial power-on (the count value is 1) to the actual shutdown of the power switch 101 (time point t2). C2 At time t2, the power switch 101 is turned off, the dimming signal V1 is turned to a low level, and the output voltage V of the second capacitor C2 stops. C2 That is, the dimming reference signal is stopped from being output. When the power switch 101 is closed next time (the count value is 2), at time t3, the compensation signal V3 is high level and the reference signal R-REF is switched to the stepped voltage V of the second capacitor C2. R2 , if the voltage V R2 If the reference signal is the one that the user really expects, the dimming is terminated. Otherwise, the power switch 101 is turned off again after being closed for a period of time, and the compensation signal V3 turns to a low level, and the output voltage V is stopped. R2 , the power switch 101 is closed again (the count value is 3). If the last closing time of the power switch is less than or equal to the reference value, the reference signal R-REF is the dimming reference signal, that is, the reference signal R-REF is the voltage V of the second capacitor C2 last time. C2 The basis continues to be adjusted in sequence until the user's expectations are met.

[0155] See also Fig.13In the sixth embodiment, the reference compensation holding signal generating module includes: a second switch tube Q2, a first pulse module M1 and a first digital-to-analog conversion module. The control end of the second switch tube Q2 is connected to the first output end of the logic signal generating module; the first pulse module M1 is connected to the first end of the second switch tube Q2; the first input end of the first digital-to-analog conversion module is connected to the second output end of the logic signal generating module, the second input end thereof is connected to the second end of the second switch tube Q2, and the output end thereof is connected to the reference selecting module 302.

[0156] The reference compensation holding signal generating module includes: a third switch tube Q3, a second pulse module M2 and a second digital-to-analog conversion module. The control end of the third switch tube Q3 is connected to the first output end of the logic signal generating module; the second pulse module M2 is connected to the first end of the third switch tube Q3; the first input end of the second digital-to-analog conversion module is connected to the second output end of the logic signal generating module, the second input end thereof is connected to the second end of the third switch tube Q3, and the output end thereof is connected to the reference selecting module 302.

[0157] The input end of the logic signal generating module is connected to the output end of the detection module 200 , and the first output end, the second output end and the third output end of the logic signal generating module output a dimming signal V1 , a reset signal V2 and a compensation signal V3 respectively.

[0158] The pulse frequency of the first pulse module M1 is set to be faster than that of the second pulse module M2. When the first output terminal of the logic signal generating module outputs a high-level dimming signal V1, the pulse signal CLK1 generated by the first pulse module M1 is transmitted to the first digital-to-analog conversion module, and the pulse signal CLK2 generated by the second pulse module M2 is transmitted to the second digital-to-analog conversion module. Since the pulse frequency generated by the first pulse module M1 is fast, the slope of the first conversion signal R-R1 corresponding to the first pulse module M1 also changes faster. Fig.14 , it can be found that the slope of the first conversion signal R-R1 corresponding to the first pulse module M1 is greater than the slope of the second conversion signal R-R2 corresponding to the second pulse module M2, so the first conversion signal R-R1 is used as a dimming reference signal, and the second conversion signal R-R2 is used as a reference compensation holding signal. When the user wants the output current to correspond to the current value at time point t1, the power switch 101 is turned off, and the actual turn-off action is actually at time point t2. Therefore, during the period t1-t2, the first conversion signal R-R1 continues to increase, while the second conversion signal R-R2 increases at a slower rate, and the second conversion signal R-R2 just reaches the first conversion signal R-R1 corresponding to time point t1 at time point t2.

[0159] The reference selection module 302 includes a sixth switch tube Q6 and a seventh switch tube Q7. The control end of the sixth switch tube Q6 is connected to the first output end of the logic signal generating module, the first end of the sixth switch tube Q6 is connected to the output end of the first digital-to-analog conversion module, and the second end is connected to the driving module 303. The control end of the seventh switch tube Q7 is connected to the third output end of the logic signal generating module, the first end of the seventh switch tube Q7 is connected to the output end of the second digital-to-analog conversion module, and the second end is connected to the driving module 303. When the first end of the logic signal generating module outputs a high-level dimming signal V1, the sixth switch tube Q6 is closed, and the dimming reference signal is transmitted to the driving module 303; when the third end of the logic signal generating module outputs a high-level compensation signal V3, the reference compensation hold signal is transmitted to the driving module 303. Continue to refer to Fig.14 , the reference signal R-REF is the first conversion signal R-R1 during the period from the initial power-on (the count value is 1) to the actual shutdown of the power switch 101 (time point t2). At time point t2, the power switch 101 is turned off, the dimming signal V1 flips to a low level, and stops outputting the first conversion signal R-R1, that is, stops outputting the dimming reference signal. The next time the power switch 101 is closed (the count value is 2), at time t3, the compensation signal V3 is a high level, switching the reference signal R-REF to the second conversion signal R-R2. If the second conversion signal If R-R2 is the reference signal that the user actually expects, the dimming is terminated. Otherwise, the power switch 101 is turned off again after being closed for a period of time, the compensation signal V3 becomes a low level, the output of the second conversion signal R-R2 is stopped, and the power switch 101 is closed again (the count value is 3). If the last closing time of the power switch is less than or equal to the reference value N, the reference signal R-REF is the dimming reference signal, that is, the reference signal R-REF continues to be adjusted based on the last first conversion signal R-R1, and the cycle is repeated until the user's expectations are met.

[0160] The input end of the driving module 303 is connected to the reference selection module 302, and the output end thereof is connected to the power conversion module 400. The driving module 303 generates a PWM control signal according to the reference signal R-REF selected by the reference selection module 302 to adjust the output current or voltage signal. The power conversion module 400 outputs a DC current or a DC voltage according to the PWM control signal to provide energy to the LED load.

[0161] The LED dimming drive circuit, dimming method and dimming system provided by the present invention can simultaneously generate a dimming reference signal and a reference compensation holding signal through a reference generation module, and the difference between the actual reference signal and the expected reference signal caused by the shutdown delay is compensated by the reference compensation holding signal. Therefore, the LED dimming drive circuit, dimming method and dimming system can solve the problem of over-adjustment of brightness caused by the shutdown action delay, so as to increase the user's dimming experience.

[0162] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. An LED dimming drive circuit, characterized in that: include: A reference generation module generates a dimming reference signal and a reference compensation holding signal, wherein the change amount of the dimming reference signal is greater than or equal to the change amount of the reference compensation holding signal within the same time period; A reference selection module is connected to the reference generation module and is used to select one of the dimming reference signal and the reference compensation holding signal as the reference signal. When the brightness of the LED lamp reaches an expected value, the reference compensation holding signal is selected as the reference signal to compensate the dimming reference signal, so that the brightness of the LED lamp is maintained at the expected brightness value; When the brightness of the LED lamp does not reach the expected brightness value, selecting the dimming reference signal as the reference signal; The driving module is connected to the reference selection module and generates a control signal according to the reference signal to adjust the brightness of the LED lamp.

2. The LED dimming driving circuit according to claim 1, characterized in that: The LED dimming drive circuit also includes a detection module, which generates a detection signal based on a sampling signal representing an input voltage and a reference signal. When the sampling signal is less than or equal to the reference signal and the duration is greater than or equal to a time threshold, the state of the detection signal output by the detection module is a first level; otherwise, the state of the detection signal output is a second level.

3. The LED dimming driving circuit according to claim 2, characterized in that: The reference generation module comprises: A logic signal generating module receives a detection signal, counts the detection signal to obtain a count value, and generates a dimming signal and a compensation signal according to the count value. When the count value is an even number, the logic signal generating module outputs a compensation signal, and controls the reference selection module to select a reference compensation holding signal as a reference signal; when the count value is an odd number, the logic signal generating module outputs a dimming signal, and controls the reference selection module to select a dimming reference signal as a reference signal.

4. The LED dimming driving circuit according to claim 3, characterized in that: The reference generation module further includes: a dimming reference signal generating module, connected to the logic signal generating module, configured to receive the dimming signal generated by the logic signal generating module and output the dimming reference signal; The reference compensation holding signal generating module is connected to the logic signal generating module, and is used for receiving the compensation signal generated by the logic signal generating module and outputting the reference compensation holding signal.

5. The LED dimming driving circuit according to claim 4, characterized in that: The reference selection module is respectively connected to the dimming reference signal generating module, the reference compensation holding signal generating module and the logic signal generating module. When the count value is an even number, the logic signal generating module outputs a compensation signal and controls the reference selection module to select the reference compensation holding signal as the reference signal. When the count value is an odd number, the logic signal generating module outputs a dimming signal and controls the reference selection module to select the dimming reference signal as the reference signal.

6. The LED dimming driving circuit according to claim 5, characterized in that: The brightness of the LED lamp is continuously adjusted by controlling the dimming reference signal to gradually increase or gradually decrease.

7. The LED dimming driving circuit according to claim 3, characterized in that: The logic signal generating module further generates a reset signal, and the reset signal resets the dimming reference signal and the reference compensation holding signal to initial values.

8. The LED dimming driving circuit according to claim 7, characterized in that: A set of first level and second level is used as a set of actions, and the logic signal generating module includes: A counter, whose input end is connected to the output end of the detection module, counts the detection signal to obtain a count value; A collection module, whose input end is connected to the output end of the detection module, and is used to collect the duration of the second level in each group of actions; A third comparator, whose positive input terminal is connected to the output terminal of the acquisition module and whose negative input terminal receives the reference value, is used to compare the second level duration of the above group of actions with the reference value and obtain a time comparison result; A storage module is connected to the third comparator and the counter, and is used to store the corresponding relationship between the count value and the time comparison result and the dimming signal, the compensation signal and the reset signal.

9. The LED dimming driving circuit according to claim 7, characterized in that: When the count value is an odd number, and when the second level duration of the previous group of actions is greater than or equal to the reference value, the logic signal generating module first outputs a reset signal, then outputs a dimming signal, and controls the dimming reference signal to adjust from an initial value; when the second level duration of the previous group of actions is less than the reference value, the logic signal generating module outputs a dimming signal, and controls the dimming reference signal to continue adjusting based on the dimming reference signal generated by the previous group of actions.

10. The LED dimming driving circuit according to claim 4, characterized in that: The dimming reference signal generating module comprises: A second switch tube, whose control end is connected to the output end of the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal; A second current source, a second end of which is connected to the first end of the second switch tube, and a first end of which receives a third reference to generate a second current signal; a fourth switch tube, whose control end is connected to the output end of the logic signal generating module, receives a reset signal, and is turned off or closed according to the reset signal; A second capacitor has a first end connected to the first end of the fourth switch tube and the second end of the second switch tube respectively, and the second current signal charges the second capacitor to generate a dimming reference signal.

11. The LED dimming driving circuit according to claim 10, characterized in that: The reference compensation holding signal generating module comprises: A third switch tube, whose control end is connected to the output end of the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal; A third current source, a second end of which is connected to the first end of the third switch tube, and a first end of which receives a third reference to generate a third current signal; a fifth switch tube, whose control end is connected to the output end of the logic signal generating module, receives a reset signal, and is turned off or closed according to the reset signal; A third capacitor, a first end of which is respectively connected to the first end of the fifth switch tube and the second end of the third switch tube, the third current signal charges the third capacitor to generate a reference compensation holding signal, wherein the charging speed of the second capacitor is greater than the charging speed of the third capacitor.

12. The LED dimming driving circuit according to claim 10, characterized in that: The reference compensation holding signal generating module comprises: The reference conversion module has an input end connected to the first end of the second capacitor and an output end connected to the reference selection module, receives a dimming reference signal, and steps the dimming reference signal to generate a reference compensation holding signal.

13. The LED dimming driving circuit according to claim 4, characterized in that: The dimming reference signal generating module comprises: A second switch tube, whose control end is connected to the output end of the logic signal generating module, whose first end is connected to the second current source, receives the dimming signal, and is turned off or closed according to the dimming signal; A fourth switch tube, whose control end is connected to the output end of the logic signal generating module, whose second end receives a third reference, receives a reset signal, and is turned off or closed according to the reset signal; The second capacitor has a first end connected to the first end of the fourth switch tube and the second end of the second switch tube respectively, and a second end connected to ground. When the dimming signal controls the second switch tube to close, the second capacitor discharges to generate the dimming reference signal.

14. The LED dimming driving circuit according to claim 13, characterized in that: The reference compensation holding signal generating module comprises: A third switch tube, whose control end is connected to the output end of the logic signal generating module, whose first end is connected to the third current source, receives the dimming signal, and is turned off or closed according to the dimming signal; a fifth switch tube, whose control end is connected to the output end of the logic signal generating module, whose second end receives a third reference, receives a reset signal, and is turned off or closed according to the reset signal; The third capacitor has a first end connected to the first end of the fifth switch tube and the second end of the third switch tube respectively, and a second end connected to ground. When the dimming signal controls the third switch tube to close, the third capacitor discharges to generate the reference compensation holding signal.

15. The LED dimming driving circuit according to claim 4, characterized in that: The dimming reference signal generating module comprises: A second switch tube, whose control end is connected to the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal; A first pulse module, connected to the first end of the second switch tube, generating a first pulse signal; The first digital-to-analog conversion module has a first input end connected to the logic signal generating module to receive a reset signal, and a second input end connected to the second end of the second switch tube to generate a dimming reference signal according to the first pulse signal.

16. The LED dimming driving circuit according to claim 15, characterized in that: The reference compensation holding signal generating module comprises: A third switch tube, whose control end is connected to the logic signal generating module, receives the dimming signal, and is turned off or closed according to the dimming signal; A second pulse module, connected to the first end of the third switch tube, generating a second pulse signal; The second digital-to-analog conversion module has a first input end connected to the logic signal generating module to receive a reset signal, and a second input end connected to the second end of the third switch tube to generate a reference compensation holding signal according to the second pulse signal.

17. The LED dimming driving circuit according to claim 16, characterized in that: The pulse frequency generated by the first pulse module is greater than the pulse frequency generated by the second pulse module.

18. The LED dimming driving circuit according to claim 17, characterized in that: When the logic signal generating module outputs a reset signal, the first digital-to-analog conversion module and the second digital-to-analog conversion module receive the reset signal and reset the dimming reference signal and the reference compensation holding signal to initial values.

19. The LED dimming driving circuit according to claim 11, 12, 14 or 16, characterized in that: The benchmark selection module includes: a sixth switch tube, wherein a control end of the sixth switch tube is connected to the output end of the logic signal generating module to receive the dimming signal, a first end of the sixth switch tube is connected to the dimming reference signal generating module to receive the dimming reference signal, and the sixth switch tube is turned off or on according to the dimming signal to control the output of the dimming reference signal; A seventh switch tube, whose control end is connected to the output end of the logic signal generating module, receives the compensation signal, and a first end of the seventh switch tube is connected to the reference compensation hold signal, receives the reference compensation hold signal, and is turned off or closed according to the compensation signal to control the output of the reference compensation hold signal.

20. A dimming method for an LED dimming drive circuit, characterized in that: include: generating a dimming reference signal and a reference compensation holding signal; Selecting one of the dimming reference signal and the reference compensation holding signal as a reference signal; Generate a control signal according to the reference signal for adjusting the brightness of the LED lamp; Wherein, within the same time, the change amount of the dimming reference signal is greater than or equal to the change amount of the reference compensation holding signal, and when the brightness of the LED lamp reaches the expected value, the reference compensation holding signal is selected as the reference signal to compensate the dimming reference signal, so that the brightness of the LED lamp is maintained at the expected brightness value; When the brightness of the LED lamp does not reach the expected brightness value, the dimming reference signal is selected as the reference signal.

21. The dimming method according to claim 20, wherein: The changing rate of the dimming reference signal is greater than or equal to the changing rate of the reference compensation holding signal.

22. The dimming method according to claim 21, wherein: A detection signal is generated based on a sampling signal representing an input voltage and a reference signal. When the sampling signal representing the input voltage is less than or equal to the reference signal for a duration greater than or equal to a time threshold, the state of the detection signal is a first level; otherwise, the state of the detection signal is a second level.

23. The dimming method according to claim 22, wherein: Counting the detection signal to obtain a count value, and generating a dimming signal and a compensation signal according to the count value, and generating a compensation signal when the count value is an even number to select a reference compensation holding signal as a reference signal; When the count value is an odd number, a dimming signal is generated to select the dimming reference signal as the reference signal.

24. The dimming method according to claim 23, wherein: The dimming reference signal and the reference compensation holding signal are controlled to gradually increase or gradually decrease to continuously adjust the brightness of the LED lamp.

25. The dimming method according to claim 23, wherein: A group of first level and second level is used as a group of actions. When the count value is an odd number and when the duration of the second level of the previous group of actions is greater than or equal to the reference value, a reset signal is first generated to reset the dimming reference signal and the reference compensation holding signal to the initial value, and then a dimming signal is generated, and the dimming reference signal is controlled to be adjusted from the initial value; when the duration of the second level of the previous group of actions is less than the reference value, a dimming signal is generated, and the dimming reference signal is controlled to continue to be adjusted based on the dimming reference signal generated by the previous group of actions.

26. The dimming method according to claim 25, characterized in that: The dimming method comprises: When powered on for the first time, the whole machine dims, starting from the initial value of the dimming reference signal; The input voltage is controlled to be less than or equal to the reference value for the first time, and the duration of this state is greater than or equal to the time threshold, and then the input voltage is controlled to be greater than the reference value; The whole machine is compensated and maintained, a reference compensation and maintenance signal is selected as a reference signal, and a current corresponding to the reference compensation and maintenance signal is output; Determine whether the brightness of the LED lamp is an expected value, and if the brightness of the LED lamp reaches the expected value, end the dimming action; if the brightness of the LED lamp does not reach the expected value, control the input voltage to be less than or equal to the reference value for the second time, and the duration of this state is greater than or equal to the time threshold, and then control the input voltage to be greater than the reference value; Compare the duration of the last time the input voltage was greater than the reference value with the benchmark value. If the duration is greater than the benchmark value, return to the step of initial power-on. If the duration is less than or equal to the benchmark value, continue dimming based on the last dimming reference signal, and return to the step of first controlling the input voltage to be less than or equal to the reference value.

27. The dimming method according to claim 20, wherein: The dimming method is continuous dimming.

28. A dimming system, characterized in that: include: The LED dimming drive circuit according to any one of claims 1 to 19, which generates a control signal according to the sampling signal; The power conversion module is connected to the LED dimming drive circuit and controls the brightness of the LED lamp according to the control signal.

29. The dimming system according to claim 28, characterized in that: The power conversion module includes a power switch and a sampling resistor, wherein the power switch and the sampling resistor are connected in series. The voltage across the sampling resistor is sampled to obtain the sampling signal.

30. The dimming system according to claim 28, wherein: The dimming system further comprises: A power switch, a first end of which is connected to a first end of a power source and is used to control input of an input voltage; A rectifier bridge, whose first input end is connected to the second end of the power switch, and whose second input end is connected to the second end of the power supply, rectifies the input voltage, and the first end and the second end of the LED dimming drive circuit are respectively connected to the first output end and the second output end of the rectifier bridge, The sampling signal is obtained by sampling the rectified input voltage.

31. The dimming system according to claim 28, wherein: The dimming system further comprises: A power switch, a first end of which is connected to a first end of a power source and is used to control input of an input voltage; A rectifier bridge, whose first input end is connected to the second end of the power switch, and whose second input end is connected to the second end of the power supply, rectifies the input voltage, the first end of the LED dimming drive circuit is connected to the second end of the power switch, and the second end of the LED dimming drive circuit is connected to the second output end of the rectifier bridge, The sampling signal is obtained by sampling the input voltage.

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