CN114630470A - Leakage protection circuit, driving circuit and leakage detection method - Google Patents
Leakage protection circuit, driving circuit and leakage detection method Download PDFInfo
- Publication number
- CN114630470A CN114630470A CN202210178974.3A CN202210178974A CN114630470A CN 114630470 A CN114630470 A CN 114630470A CN 202210178974 A CN202210178974 A CN 202210178974A CN 114630470 A CN114630470 A CN 114630470A
- Authority
- CN
- China
- Prior art keywords
- voltage
- bus voltage
- signal
- control signal
- state
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
- G01R31/52—Testing for short-circuits, leakage current or ground faults
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
Disclosed are a leakage protection circuit, a driving circuit and a leakage detection method, wherein the leakage protection circuit includes: the input detection module is used for generating a first control signal according to the direct-current bus voltage and a first preset voltage; the bypass module is connected between the direct-current bus voltage and the ground, the input end of the bypass module receives a first control signal, and when the first control signal is effective, the bypass module generates a bypass current sampling signal; the input detection module generates a second control signal representing the voltage state of the direct-current bus according to the direct-current bus voltage and the bypass current sampling signal. According to the embodiment of the invention, whether the voltage input state of the direct current bus is normal is judged by simultaneously detecting whether the bypass current sampling signal and the direct current bus voltage reach the threshold value within the preset time.
Description
Technical Field
The present disclosure relates to power electronics related field, and in particular, to a leakage protection circuit, a driving circuit, and a leakage detection method.
Background
The LED lamp is more and more applied in the field of illumination, such as being applied to classrooms, shopping malls, office buildings and the like, wherein the LED lamp comprises a fluorescent lamp, and two ends of the fluorescent lamp are respectively connected with commercial power through a zero line and a live wire. When the device is installed, one end is usually installed firstly, then the other end is installed, if an operator carelessly touches hands or other parts of a body to the electrode at the other end when the one end is installed, a human body and a power grid form a loop to cause electric shock, and the problem is solved by adding electric leakage protection at present.
However, as the requirement for energy saving is higher and higher, the LED driving circuit of the fluorescent lamp with the leakage protection function also needs to be dimmed to adapt to different environments and requirements.
In the prior art, an LED driving circuit with leakage protection and dimming functions detects that the input has leakage phenomenon, and controls the LED driving circuit to be in a closed state; and detecting that the input is not electric shock, the LED drive circuit works normally, and the LED lamp is lightened.
The existing input detection method can sample alternating current input voltages at different moments by detecting bus pull-down current behind a rectifier bridge circuit, and judge whether a current leakage phenomenon exists or not by identifying voltage amplitude or speed change. If the LED driving circuit is connected to a trailing edge dimmer (trailing edge dimmer), input detection is started immediately after power-on, voltage change is detected, and the first sampling time T1 and the second sampling time T2 may be at a trailing edge critical point (see fig. 1a), which may result in an erroneous determination that the input voltage amplitude or rate change is too large, and thus an electrical leakage phenomenon is considered, and thus an erroneous protection occurs.
In another existing input detection method, a detected direct current bus voltage Vbus Is compared with a preset voltage Vr, a detection current Is generated when the direct current bus voltage Is greater than the preset voltage, and then whether a current leakage phenomenon occurs Is determined by comparing the detection current with the preset current Ir. If the LED driving circuit Is connected to a leading edge dimmer (leading edge dimmer), input detection Is started immediately after power-on, and the leading edge turn-on voltage Is very high (see fig. 1b), so that the detection current Is greater than the preset current Ir, and thus electric leakage Is not caused by misunderstanding, which may cause an electric shock accident.
Disclosure of Invention
In view of the above, an object of the present invention is to provide a leakage protection circuit, a driving circuit and a leakage detection method, which can avoid the problem of electric shock caused by the accidental contact of a human body during the installation of a load in case of an input abnormality, so as to improve the safety during the installation and removal of the load.
According to a first aspect of the present invention, there is provided a leakage protection circuit comprising: the input detection module is connected between the direct current bus voltage and the ground and generates a first control signal according to the direct current bus voltage and a first preset voltage; the bypass module is connected between the direct-current bus voltage and the ground, the input end of the bypass module receives the first control signal, and when the first control signal is effective, the bypass module generates a bypass current sampling signal; and the input detection module generates a second control signal representing the voltage state of the direct-current bus according to the direct-current bus voltage and the bypass current sampling signal.
Preferably, when the first control signal is valid, and when both the bypass current sampling signal and the dc bus voltage meet a preset condition, it is determined that the dc bus voltage state is normal; and when any one of the bypass current sampling signal and the direct current bus voltage does not meet a preset condition, judging that the state of the direct current bus voltage is abnormal.
Preferably, when the difference between the dc bus voltage at the first moment and the dc bus voltage at the second moment is smaller than a first threshold, and the bypass current sampling signal at the second moment is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the difference value between the direct current bus voltage at the first moment and the direct current bus voltage at the second moment is larger than or equal to a first threshold value and/or the bypass current sampling signal at the second moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal, wherein the first moment is different from the second moment.
Preferably, when the dc bus voltage is greater than a third threshold and the bypass current sampling signal at the present time is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the direct current bus voltage is smaller than or equal to a third threshold value and/or the bypass current sampling signal at the current moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal.
Preferably, when the dc bus voltage is greater than the first preset voltage, the input detection module generates a first control signal, where the first control signal is a pulse signal.
Preferably, when the first control signal is valid, entering a leakage detection state; and when the first control signal is invalid, the leakage detection state is exited.
Preferably, when the second control signal represents that the voltage state of the direct current bus is normal, the driving module is controlled to work; and when the second control signal represents that the voltage state of the direct current bus is abnormal, controlling the driving module to be closed.
Preferably, the voltage state of the direct current bus comprises a normal state, a leakage state and a poor contact state.
Preferably, the input detection module comprises a pulse generation unit and an input detection unit, wherein the pulse generation unit is configured to generate the first control signal according to a dc bus voltage and a first preset voltage; the input detection unit is used for generating the second control signal according to the direct-current bus voltage and the bypass current sampling signal within a preset time when the first control signal is kept effective.
Preferably, the input detection unit includes: the voltage detection unit generates a voltage detection signal according to the divided voltage of the direct-current bus voltage and a first reference voltage; the current detection unit generates a current detection signal according to the bypass current sampling signal and a second reference voltage; and the latch unit generates a second control signal according to the first control signal, the voltage detection signal and the current detection signal.
Preferably, the pulse generating unit includes a first resistor, a second resistor, a first comparator, a timer, a logic or gate, a first monostable pulse unit, and a second monostable pulse unit: the first resistor and the second resistor are connected between the direct current bus voltage and the ground in series, and a first node between the first resistor and the second resistor outputs a first voltage; a first input end of the first comparator is connected with the first node, a second input end of the first comparator receives a first preset voltage, and an output end of the first comparator outputs a first comparison signal; the input end of the first monostable pulse unit receives a first comparison signal, and the first monostable pulse unit generates a second pulse signal; the timer is used for generating a clock signal; the logic or gate is respectively connected with the output end of the first monostable pulse unit and the timer, and generates a first logic signal according to a first comparison signal and a clock signal; the second monostable pulse unit generates a first control signal according to the first logic signal.
Preferably, the voltage detection unit includes a first resistor, a second resistor, a subtractor, a sample-and-hold unit, and a second comparator, wherein the first resistor and the second resistor are connected in series between the dc bus voltage and ground, and a first node between the first resistor and the second resistor outputs a first voltage; sampling and maintaining the divided voltage of the direct current bus voltage by using a maintaining unit when the first control signal triggers the edge; the subtracter is respectively connected with the second comparator and the sampling holding unit, receives the divided voltage of the direct current bus voltage and the first voltage, and outputs a difference voltage between the divided voltage of the direct current bus voltage and the first voltage; the first input end of the second comparator receives the difference voltage, the second input end of the second comparator receives the first reference voltage, and the output end of the second comparator outputs a second comparison signal as a voltage detection signal.
Preferably, the voltage detection unit includes a first resistor, a second resistor, and a second comparator, wherein the first resistor and the second resistor are connected in series between the dc bus voltage and ground, and a first node between the first resistor and the second resistor outputs a divided voltage of the dc bus voltage; the first input end of the second comparator receives the divided voltage of the direct current bus voltage, the second input end of the second comparator receives the first reference voltage, and the output end of the second comparator outputs a second comparison signal as a voltage detection signal.
Preferably, the current detection unit includes a third comparator and a third monostable pulse unit; the first input end of the third comparator receives the bypass current sampling signal, the second input end of the third comparator receives the second reference voltage, and the output end of the third comparator outputs a third comparison signal;
the third comparison signal outputs a current detection signal via a third monostable pulse unit.
Preferably, the latch unit comprises a logic and gate, a judgment module and an RS flip-flop; the input end of the logic AND gate is respectively connected with the voltage detection unit and the current detection unit, and generates a second logic signal according to the voltage detection signal and the current detection signal; the judging module judges whether the second logic signal is high level or not continuously for multiple times according to the first control signal so as to generate a detection signal; the set end of the RS trigger is connected with the judging unit, the reset end of the RS trigger is grounded, and the output end of the RS trigger outputs a second control signal.
Preferably, when the judging unit continuously judges that the second logic signal is at a high level for multiple times, the output detection signal is at a high level, which represents that the voltage state of the direct current bus is normal; and when the second logic signal is at a low level in the continuous multiple judgment process, the output detection signal is at a low level, and the abnormal state of the direct current bus voltage is represented.
Preferably, the bypass module comprises a reference generation unit, an operational amplifier, a first transistor and a third resistor, wherein the reference generation unit generates a reference signal according to the first control signal; the first transistor and the third resistor are connected between the direct current bus voltage and the ground in series, and a second node between the first transistor and the third resistor outputs the bypass current sampling signal; the first end of the operational amplifier receives the reference signal, the second end is connected with the second node, and the output end is connected with the control end of the first transistor.
Preferably, the first output end and the second output end of the dc bus voltage are the first output end and the second output end of the rectifier bridge, respectively.
Preferably, the input end of the rectifier bridge is respectively connected with a first diode and a second diode, and the first diode and the second diode provide the direct current bus voltage.
According to another aspect of the present invention, there is provided a driving circuit including: the leakage protection circuit as described above; and the driving module is connected with the leakage protection circuit and receives a second control signal, when the state of the direct current bus is abnormal, the second control signal controls the driving module not to supply power to the load, and when the state of the direct current bus is normal, the second control signal controls the driving module to supply power to the load.
According to a third aspect of the present invention, there is provided a leakage detecting method including: generating a first control signal according to the direct current bus voltage and a first preset voltage; generating a bypass current sampling signal when the first control signal is active; and generating a second control signal representing the voltage state of the direct current bus according to the direct current bus voltage and the bypass current sampling signal.
Preferably, when the first control signal is valid, and when both the bypass current sampling signal and the dc bus voltage meet a preset condition, it is determined that the dc bus voltage state is normal; and when any one of the bypass current sampling signal and the direct current bus voltage does not meet a preset condition, judging that the state of the direct current bus voltage is abnormal.
Preferably, when the difference between the dc bus voltage at the first moment and the dc bus voltage at the second moment is smaller than a first threshold, and the bypass current sampling signal at the second moment is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the difference value between the direct current bus voltage at the first moment and the direct current bus voltage at the second moment is larger than or equal to a first threshold value and/or the bypass current sampling signal at the second moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal, wherein the first moment is different from the second moment.
Preferably, when the dc bus voltage is greater than a third threshold and the bypass current sampling signal at the present time is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the direct current bus voltage is smaller than or equal to a third threshold value and/or the bypass current sampling signal at the current moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal.
Preferably, when the dc bus voltage is greater than the first preset voltage, a first control signal is generated, and the first control signal is a pulse signal.
Preferably, when the first control signal is valid, entering a leakage detection state; and when the first control signal is invalid, the leakage detection state is exited.
Preferably, when the second control signal represents that the voltage state of the direct current bus is normal, the driving module is controlled to work; and when the second control signal represents that the voltage state of the direct current bus is abnormal, controlling a driving module to be closed.
Preferably, the dc bus voltage state includes any one of a normal state, a leakage state, and a poor contact state.
According to the embodiment of the invention, whether the input state of the voltage of the direct current bus is normal or not is judged by detecting whether the bypass current sampling signal and the voltage of the direct current bus reach the threshold value or not within the preset time, so that the problem of electric shock caused by the fact that a human body is in mistaken contact during the installation of a load under the condition of abnormal input can be avoided, and the safety in the process of assembling and disassembling the load is improved.
Furthermore, by sampling the bypass current, the misjudgment caused by over-low direct current bus voltage with poor contact can be avoided; and meanwhile, by detecting a bypass current sampling signal and detecting the voltage of a direct-current bus, the problem of mistaken switching when the front-cut light modulator is subjected to electric shock can be avoided, and the problem of mistaken protection during normal work of the rear-cut light modulator can also be avoided.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings.
Fig. 1a and 1b respectively show waveforms of a prior art LED driving circuit;
fig. 2 shows a schematic circuit diagram of a drive circuit to which a leakage protection circuit provided by a first embodiment of the present invention is applied;
fig. 3 is a circuit diagram of an input detection module of the leakage protection circuit according to the first embodiment of the present invention;
fig. 4 shows a circuit diagram of a pulse generating unit provided by the first embodiment of the present invention;
fig. 5 shows a circuit diagram of an input detection unit provided by the first embodiment of the present invention;
fig. 6 is a circuit diagram of an input detection unit provided according to a second embodiment of the present invention;
fig. 7 is a circuit diagram showing a bypass module of the leakage protection circuit provided in the first embodiment of the present invention;
fig. 8 is a waveform diagram of a pulse generating unit provided by an embodiment of the invention when an alternating current is input;
fig. 9 is a waveform diagram of a pulse generating unit provided by an embodiment of the invention when a direct current is input;
FIG. 10 illustrates a waveform diagram of a bypass module provided by an embodiment of the present invention;
fig. 11 is a waveform diagram of an input detection unit provided in the first embodiment of the present invention when the dc bus voltage is normal;
fig. 12 is a waveform diagram of an input detection unit according to a first embodiment of the present invention when an electric shock occurs;
fig. 13 is a waveform diagram of an input detection unit according to a second embodiment of the present invention when there is a poor contact between dc bus voltages;
fig. 14 is a waveform diagram of an input detection unit provided in the second embodiment of the present invention when the dc bus voltage state is normal;
fig. 15 is a waveform diagram of an input detecting unit according to a second embodiment of the present invention when an electric shock occurs;
fig. 16 is a schematic circuit diagram showing a drive circuit to which a leakage protection circuit provided by a third embodiment of the present invention is applied;
fig. 17 is a flowchart illustrating a leakage detection method according to an embodiment of the present invention.
Detailed Description
Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the various figures, like elements are identified with the same or similar reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale.
Fig. 2 shows a schematic circuit diagram of a drive circuit to which a leakage protection circuit of a first embodiment of the present invention is applied; as shown in fig. 2, the driving circuit includes a rectifier bridge 110, a leakage protection circuit 120, and a driving module 130. The driver circuit supplies power to a load 140, wherein the load 140 may be a capacitive load or a purely resistive load, for example, the load 140 is an LED load.
The first input end of the rectifier bridge 110 is connected to the live line L of the ac power supply line via the fuse Rfu, and the second input end is connected to the neutral line N of the ac power supply line, for rectifying the ac input voltage Vin. The first output terminal of the rectifier bridge 110 is connected to the second output terminal of the rectifier bridge 110 via the leakage protection circuit 120 and the driving module 130, respectively. Specifically, a first end of the leakage protection circuit 120 is connected to a first output end of the rectifier bridge 110, a second end is connected to a second output end of the rectifier bridge 110, and a third end is connected to the driving module 130; the driving module 130 is connected between the first output terminal and the second output terminal of the rectifier bridge 110, and is connected to the leakage protection circuit 120; the load 140 is connected in parallel between the first output terminal and the second output terminal of the driving module 130.
The phenomenon that a human body is electrically shocked is equivalent to the phenomenon that a resistor Rb is connected in series with a live wire L or a zero wire N of an alternating current power supply line, and the resistance Rb of the human body is more than 500 ohms generally.
In this embodiment, after the leakage protection circuit 120 starts to operate, it enters a leakage detection state, and sends an enable signal indicating invalidity to the driving module 130, where the invalid enable signal controls the driving module 130 to turn off, and does not supply power to the load 140; when the leakage protection circuit 120 determines that the leakage phenomenon exists, the leakage determination is repeated until the leakage phenomenon is determined not to exist; when the leakage protection circuit 120 determines that there is no leakage, it sends an enable signal representing valid to the driving module 130; the enable signal asserted at this time controls the driving module 130 to be turned on to supply power to the load 140.
In this embodiment, the leakage protection circuit 120 includes an input detection module 121 and a bypass module 122, where the input detection module 121 is configured to generate a first control signal Ctrl1 representing a detection state according to the dc bus voltage Vbus and the first preset voltage Vr1 within a preset time period when the first control signal is asserted, and enter a leakage detection state according to the first control signal Ctrl 1.
In this embodiment, when the dc bus voltage Vbus is greater than the first preset voltage Vr1, the input detection module 121 generates a first control signal Ctrl1, where the first control signal Ctrl1 is a pulse signal. When the first control signal Ctrl1 is valid, entering a leakage detection state, the bypass module 122 generates a bypass current sampling signal Vs; the input detection module 121 obtains a bypass current sampling signal Vs from the bypass module 122, and generates a second control signal Ctrl2 representing a voltage state of the dc bus according to the bypass current sampling signal Vs and a dc bus voltage Vbus within a preset time period in which a first control signal is maintained to be valid, where the voltage state of the dc bus includes a normal state and an abnormal state, and the abnormal state includes an electric leakage state and a poor contact state; when the first control signal Ctrl1 is inactive, the leakage detection state is exited.
Specifically, in a leakage detection state, when both the bypass current sampling signal Vs and the direct current bus voltage Vbus meet a preset condition, it is determined that the direct current bus voltage state is normal; and when any one of the bypass current sampling signal Vs and the direct current bus voltage Vbus does not meet a preset condition, judging that the direct current bus voltage state is abnormal, such as an electric leakage state or a poor contact state. The preset conditions are, for example, that the dc bus voltage Vbus has a change in magnitude smaller than a threshold value and that the bypass current sampling signal Vs reaches a threshold value.
Specifically, the preset conditions are that the difference between the direct current bus voltage Vbus1 at the first time and the direct current bus voltage Vbus2 at the second time is smaller than a first threshold, the bypass current sampling signal Vs2 at the second time is larger than a second threshold, and the first time is different from the second time. When the difference value between the direct current bus voltage Vbus1 at the first moment and the direct current bus voltage Vbus2 at the second moment is smaller than a first threshold value, and the bypass current sampling signal Vs at the second moment is larger than a second threshold value, judging that the direct current bus voltage state is normal; and when the difference value between the direct current bus voltage Vbus1 at the first moment and the direct current bus voltage Vbus2 at the second moment is larger than or equal to a first threshold value, and/or the bypass current sampling signal Vs at the second moment is smaller than or equal to a second threshold value, judging that the state of the direct current bus voltage is abnormal, wherein the first moment is different from the second moment.
The bypass module 122 is connected between the dc bus voltage and ground, an input end of the bypass module receives the first control signal Ctrl1, and when the first control signal Ctrl1 is valid, the bypass module 122 generates a bypass current sampling signal Vs.
In this embodiment, when the first control signal Ctrl1 is asserted, the bypass module enters a dc bus voltage detection state, and generates a bypass current according to the first control signal Ctrl1, where the pull-down current is a slow change of a linear or parabolic shape on the rising edge and the falling edge if the dc bus voltage Vbus is high enough.
The input detection module 121 further generates a second control signal Ctrl2 representing the voltage state of the dc bus according to the dc bus voltage Vbus and the bypass current sampling signal Vs.
When the second control signal Ctrl2 represents that the dc bus voltage is normal, controlling the driving module 130 to work normally; when the second control signal Ctrl2 indicates that the dc bus voltage is abnormal, the driving module 130 is controlled to be turned off, and the leakage detection is continued.
According to the leakage protection circuit and the driving circuit provided by the embodiment of the invention, whether the voltage input state of the direct current bus is normal or not is judged by detecting whether the bypass current sampling signal and the direct current bus voltage reach the threshold value or not within the preset time, so that the problem of electric shock caused by mistaken contact of a human body in the process of installing a load under the condition of abnormal input can be avoided, and the safety in the process of installing and disassembling the load is improved.
Furthermore, by sampling the bypass current, the misjudgment caused by the over-low voltage of the direct current bus with poor contact can be avoided; and meanwhile, by detecting a bypass current sampling signal and detecting the voltage of a direct-current bus, the problem of mistaken switching when the front-cut light modulator is subjected to electric shock can be avoided, and the problem of mistaken protection during normal work of the rear-cut light modulator can also be avoided.
Referring to fig. 3, the input detection module 121 includes a pulse generation unit 1211 and an input detection unit.
The pulse generating unit 1211 is configured to generate a first control signal Ctrl1 according to the dc bus voltage Vbus and a first preset voltage Vr 1.
In this embodiment, referring to fig. 4, the pulse generating unit 1211 includes a first resistor R1, a second resistor R2, a first comparator C1, a timer, a logic or gate, a first one-shot pulse unit, and a second one-shot pulse unit. The first resistor R1 and the second resistor R2 are connected in series between the dc bus voltage Vbus and ground, and a first node between the first resistor R1 and the second resistor R2 outputs a first voltage Va. A first input end of the first comparator C1 is connected with the first node, a second input end receives a first preset voltage, and an output end outputs a first comparison signal Vc 1; the input end of the first monostable pulse unit receives a first comparison signal Vc1, the output end of the first monostable pulse unit outputs a second pulse signal, and the second pulse signal periodically resets the timer. The timer is used for generating a clock signal; the logic OR gate is respectively connected with the output end of the first monostable pulse unit and the timer, and generates a first logic signal according to the first comparison signal and the clock signal; the second one-shot pulse unit generates a first control signal Ctrl1 according to the first logic signal.
Referring to fig. 8, the input terminal of the rectifier bridge 110 receives an ac input voltage Vac, and the first comparator C1 outputs a high level when a first voltage Va representing the dc bus voltage Vbus exceeds a first preset voltage Vr1, and otherwise outputs a low level. The first control signal Ctrl1 is a pulse signal having a certain pulse width.
Referring to fig. 9, the input terminal of the rectifier bridge 110 receives the dc bus voltage Vdc, the first comparator C1 outputs a high level or a low level, and the timer cannot be periodically reset. The period of the clock signal output by the timer is larger than the period of the alternating current input voltage. When the first voltage Va representing the dc bus voltage Vbus exceeds the first preset voltage Vr1, the first comparator C1 outputs a high level, and the period of the first control signal Ctrl1 is determined by the period of the clock signal.
When the first control signal Ctrl1 output by the input detection unit is valid, the second control signal Ctrl2 is generated according to the dc bus voltage Vbus and the bypass current sampling signal Vs within a preset time period in which the first control signal Ctrl1 remains valid.
Referring to fig. 5, in the present embodiment, the input detection unit includes a voltage detection unit 1212, a current detection unit 1213, and a latch unit 1214.
The voltage detection unit 1212 is configured to generate a voltage detection signal according to the dc bus voltage Vbus and the first reference voltage Vref 1; the current detection unit 1213 is configured to generate a current detection signal according to the bypass current sampling signal Vs and the second reference voltage Vref 2; the latch unit 1214 generates the second control signal Ctrl2 according to the first control signal, the voltage detection signal, and the current detection signal.
In this embodiment, the voltage detection unit 1212 includes a first resistor R1, a second resistor R2, a subtractor, a sample-and-hold unit, and a second comparator C2, the first resistor R1 and the second resistor R2 are connected in series between the dc bus voltage Vbus and the ground, and a first node between the first resistor R1 and the second resistor R2 outputs the first voltage Va. The sampling and holding unit is used for sampling and holding the divided voltage Vsh of the direct current bus voltage when the first control signal Ctrl1 triggers an edge, the triggering edge is a rising edge for example, the subtracter is respectively connected with the second comparator C2 and the sampling and holding unit, receives the divided voltage Vsh of the direct current bus voltage and the first voltage Va, and outputs a difference voltage Vx between the divided voltage Vsh of the direct current bus voltage and the first voltage Va, and the Vx is Vsh-Va. The second comparator C2 has a first input terminal receiving the difference voltage Vx, a second input terminal receiving the first reference voltage Vref1, and an output terminal outputting a second comparison signal Vc2 as a voltage detection signal. When the difference voltage Vx is smaller than the first reference voltage Vref1 (i.e., Vx < Vref1), the second comparison signal Vc2 is at a high level, and conversely, the second comparison signal Vc2 is at a low level.
The current detecting unit 1213 includes a third comparator C3 and a third one-shot pulse unit, wherein the third comparator C3 has a first input terminal receiving the bypass current sampling signal Vs, a second input terminal receiving the second reference voltage Vref2, and an output terminal outputting a third comparison signal Vc3, and outputs a current detection signal Vd via the third one-shot pulse unit, where the current detection signal Vd is a narrow pulse width square wave. If the dc bus voltage Vbus is sufficiently high, the current detection unit 1213 can detect the bypass current sampling signal Vs. Specifically, when the bypass current sampling signal Vs is greater than the second reference voltage Vref2 (i.e., Vs > Vref2), the second comparison signal Vc3 output by the third comparator C3 is at a high level, and a narrow-pulse-width square wave is output by the third one-shot pulse.
The latch unit 1214 includes a logic and gate, a judgment module, and an RS flip-flop. The input terminals of the logic and gate are respectively connected to the voltage detection unit 1212 and the current detection unit 1213, and generate a second logic signal according to the voltage detection signal and the current detection signal. The judging module continuously judges whether the second logic signal is high level for a plurality of times according to the first control signal Ctrl1 to generate a detection signal; when the second logic signal is continuously judged to be at a high level for multiple times, the detection signal is at a high level, and the input is represented to be normal; and if the second logic signal is at low level in the continuous multiple judgment process, the detection signal is at low level, and the input abnormity is represented. The set end of the RS trigger is connected with the judging unit, the reset end of the RS trigger is grounded, and the output end of the RS trigger outputs a second control signal Ctrl 2.
Referring to fig. 11, if the dc bus voltage is normal, when the first control signal Ctrl1 is asserted, the divided voltage Vsh of the dc bus voltage is always less than or equal to Va, so the difference voltage Vx is low, and the second comparison signal Vc2 output by the second comparator C2 is always high. Meanwhile, the bypass current rises in a linear or parabolic curve, and the current detection signal Vd is output when the bypass current sampling signal Vs reaches the second reference voltage Vref 2. The voltage detection signal Vc2 and the current detection signal Vd are simultaneously at a high level a plurality of times in succession, and the second control signal Ctrl2 is locked at a high level.
Referring to fig. 12, if an electric shock occurs, which is equivalent to an impedance of the input series connection of 500 Ω or more, the bypass current will pull down the dc bus voltage Vbus, when the first control signal Ctrl1 is asserted, the input divided voltage Vsh will be greater than the first voltage Va, the difference voltage Vx will be greater than the first reference voltage Vref1, and the second comparison signal Vc2 output by the second comparator C2 will appear low level, which determines that there is a leakage phenomenon.
Referring to fig. 13, if the dc bus voltage Vbus is low due to poor contact of the dc bus voltage, for example, when the input voltage is just power-on, and the first control signal Ctrl1 is valid, the bypass current sampling signal Vs cannot reach the second reference voltage Vref2 because the input voltage is too low, and therefore the current detection signal Vd is not output, the latch unit clears the previous detection signal, and restarts to lock the second control signal Ctrl2 after several times of normal operations.
Referring to fig. 7, the bypass module 122 includes a reference generation unit, an operational amplifier, and a first transistor Q1 and a third resistor R3, wherein the reference generation unit generates a reference signal having a rising edge or a falling edge in a linear or parabolic shape according to a first control signal Ctrl 1. The first transistor Q1 and the third resistor R3 are connected in series between the dc bus voltage Vbus and ground, and a second node between the first transistor Q1 and the third resistor R3 outputs the bypass current sampling signal Vs. The operational amplifier has a first terminal receiving the reference signal, a second terminal connected to the second node, and an output terminal connected to the control terminal of the first transistor Q1. Referring to fig. 10, when the first control signal Ctrl1 is active, if the dc bus voltage Vbus is sufficiently high, the bypass current sampling signal Vs follows the reference signal change, and its rising edge and falling edge change slowly in a linear or parabolic manner. The maximum value of the bypass current is also determined by the reference signal.
Fig. 6 is a circuit diagram of an input detection unit according to a second embodiment of the present invention. Compared to the first embodiment, the voltage detecting unit 1212 includes only the first resistor R1, the second resistor R2, and the second comparator C2.
The first resistor R1 and the second resistor R2 are connected in series between the dc bus voltage Vbus and ground, and a first node between the first resistor R1 and the second resistor R2 outputs a first voltage Va.
The second comparator C2 has a first input terminal receiving the first voltage Va, a second input terminal receiving the first reference voltage Vref1, and an output terminal outputting the second comparison signal Vc2 as a voltage detection signal.
In this embodiment, when both the bypass current sampling signal Vs and the dc bus voltage Vbus satisfy a preset condition, it is determined that the dc bus voltage is normal; and when any one of the bypass current sampling signal Vs and the direct current bus voltage Vbus does not meet the preset condition, judging that the input is abnormal and the electric leakage phenomenon possibly exists. The preset condition is, for example, whether the bypass current sampling signal Vs and the dc bus voltage Vbus reach the threshold value at the same time.
Specifically, the preset conditions are that the bypass current sampling signal Vs at the third time reaches the second threshold and the dc bus voltage Vbus at the third time reaches the third threshold. When the direct current bus voltage Vbus is greater than a third threshold value and a bypass current sampling signal Vs at the current moment is greater than a second threshold value, judging that the direct current bus voltage state is normal; and when the direct current bus voltage Vbus is smaller than or equal to a third threshold value and/or the bypass current sampling signal Vs at the current moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal.
The present embodiment is applicable to a driving circuit for dimming using a back-cut dimmer.
Referring to fig. 14, when the first control signal Ctrl1 is asserted, the voltage detection signal Vc2 and the current detection signal Vd are simultaneously at a high level for multiple consecutive times, and the second control signal Ctrl2 is locked at a high level, so as to determine that the dc bus voltage is normal.
Referring to fig. 15, when an electric shock occurs, the bypass current is generated, which may cause the dc bus voltage Vbus to drop, so that when the current detection signal Vd is asserted, the first voltage Va is less than the first reference voltage Vref1, and the second comparison signal Vc2 output by the second comparator C2 is at a low level, which may determine that the electric shock occurs.
Fig. 16 shows a circuit diagram of a drive circuit to which a leakage protection circuit according to a third embodiment of the present invention is applied. Compared with the driving circuit of the leakage protection circuit shown in fig. 2, the first terminal of the leakage protection circuit 120 is connected to the input terminal of the rectifier bridge 110 through the first diode D1 and the second diode D2.
Specifically, the first diode D1 is connected between a first input terminal of the rectifier bridge 110 and a first terminal of the leakage protection circuit 120; the second diode D2 is connected between the second input terminal of the rectifier bridge 110 and the first terminal of the leakage protection circuit 120.
The rest of the driving circuit in the third embodiment is the same as that in the first embodiment, and is not described again here.
Fig. 17 is a flowchart illustrating a leakage detection method according to an embodiment of the present invention. Referring to fig. 17, the leakage detecting method includes the following steps.
In step S101, a first control signal is generated according to the dc bus voltage and a first preset voltage.
In step S102, a bypass current sampling signal is generated when the first control signal is active.
In step S103, a second control signal representing a voltage state of the dc bus is generated according to the dc bus voltage and the bypass current sampling signal.
In this embodiment, when the dc bus voltage Vbus is greater than the first preset voltage Vr1, the input detection module 121 generates the first control signal Ctrl1, and the first control signal Ctrl1 is a pulse signal. When the first control signal Ctrl1 is valid, entering a leakage detection state, and the bypass module 122 generating a bypass current sampling signal Vs; the input detection module 121 obtains a bypass current sampling signal Vs from the bypass module 122, and generates a second control signal Ctrl2 representing a voltage state of the dc bus according to the bypass current sampling signal Vs and the dc bus voltage Vbus within a preset time period in which the first control signal Ctrl1 is maintained to be valid, where the voltage state of the dc bus includes a normal state and an abnormal state, and the abnormal state includes a leakage state and a poor contact state; when the first control signal Ctrl1 is inactive, the leakage detection state is exited.
Specifically, in the dc bus voltage detection state, when both the bypass current sampling signal Vs and the dc bus voltage Vbus satisfy a preset condition, it is determined that the dc bus voltage state is normal; and when any one of the bypass current sampling signal Vs and the direct current bus voltage Vbus does not meet a preset condition, judging that the direct current bus voltage state is abnormal, such as an electric leakage state or a poor contact state. The preset conditions are, for example, that the amplitude change of the direct current bus voltage Vbus is smaller than a threshold value at different moments and the bypass current sampling signal Vs reaches the threshold value. Specifically, the difference between the dc bus voltage at the first time and the dc bus voltage at the second time is smaller than a first threshold, and the bypass current sampling signal at the second time is greater than a second threshold, so that the dc bus voltage is determined to be in a normal state, where the first time is different from the second time.
In a preferred embodiment, the preset condition is, for example, whether the bypass current sampling signal Vs and the dc bus voltage Vbus reach a threshold value at the same time. Specifically, the bypass current sampling signal Vs at the third time reaches the second threshold and the dc bus voltage Vbus at the third time reaches the third threshold.
According to the leakage detection method provided by the embodiment of the invention, whether the voltage input state of the direct current bus is normal is judged by detecting whether the bypass current sampling signal and the direct current bus voltage reach the threshold value within the preset time, so that the problem of electric shock caused by mistaken contact of a human body in the process of installing a load under the condition of abnormal input can be avoided, and the safety in the process of installing and disassembling the load is improved.
Furthermore, by sampling the bypass current, the misjudgment caused by the over-low voltage of the direct current bus with poor contact can be avoided; and meanwhile, by detecting a bypass current sampling signal and detecting the voltage of a direct-current bus, the problem of mistaken switching when the front-cut light modulator is subjected to electric shock can be avoided, and the problem of mistaken protection during normal work of the rear-cut light modulator can also be avoided.
Embodiments of the invention are described above, and these embodiments do not set forth any exhaustive details or limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. The scope of the invention should be determined from the following claims.
Claims (28)
1. An earth leakage protection circuit, comprising:
the input detection module is connected between the direct current bus voltage and the ground and generates a first control signal according to the direct current bus voltage and a first preset voltage;
the bypass module is connected between the direct-current bus voltage and the ground, the input end of the bypass module receives the first control signal, and when the first control signal is effective, the bypass module generates a bypass current sampling signal;
and the input detection module generates a second control signal representing the voltage state of the direct-current bus according to the direct-current bus voltage and the bypass current sampling signal.
2. The leakage protection circuit of claim 1, wherein when the first control signal is valid, and when both the bypass current sampling signal and the dc bus voltage satisfy a preset condition, the dc bus voltage is determined to be in a normal state; and when any one of the bypass current sampling signal and the direct current bus voltage does not meet a preset condition, judging that the state of the direct current bus voltage is abnormal.
3. The earth leakage protection circuit according to claim 1 or 2, wherein when a difference between the dc bus voltage at a first time and the dc bus voltage at a second time is smaller than a first threshold, and the bypass current sampling signal at the second time is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the difference value between the direct current bus voltage at the first moment and the direct current bus voltage at the second moment is larger than or equal to a first threshold value and/or the bypass current sampling signal at the second moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal, wherein the first moment is different from the second moment.
4. The earth leakage protection circuit according to claim 1 or 2, wherein when the dc bus voltage is greater than a third threshold and the bypass current sampling signal at the present time is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the direct current bus voltage is smaller than or equal to a third threshold value and/or the bypass current sampling signal at the current moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal.
5. The earth leakage protection circuit of claim 1, wherein the input detection module generates a first control signal when the dc bus voltage is greater than the first predetermined voltage, and the first control signal is a pulse signal.
6. The earth leakage protection circuit of claim 5, wherein when the first control signal is asserted, entering an earth leakage detection state; and when the first control signal is invalid, the leakage detection state is exited.
7. The earth leakage protection circuit of claim 1, wherein when the second control signal indicates that the voltage state of the dc bus is normal, the driving module is controlled to operate; and when the second control signal represents that the voltage state of the direct current bus is abnormal, controlling the driving module to be closed.
8. The earth leakage protection circuit of claim 7, wherein the dc bus voltage state comprises any one of a normal state, a leakage state, and a bad contact state.
9. The earth leakage protection circuit of claim 1, wherein the input detection module comprises a pulse generation unit and an input detection unit,
the pulse generating unit is used for generating the first control signal according to the direct-current bus voltage and a first preset voltage;
the input detection unit is used for generating the second control signal according to the direct-current bus voltage and the bypass current sampling signal within a preset time when the first control signal is kept effective.
10. The leakage protection circuit of claim 9, wherein the input detection unit comprises:
the voltage detection unit generates a voltage detection signal according to the divided voltage of the direct-current bus voltage and a first reference voltage;
the current detection unit generates a current detection signal according to the bypass current sampling signal and a second reference voltage;
and the latch unit generates a second control signal according to the first control signal, the voltage detection signal and the current detection signal.
11. The leakage protection circuit of claim 10, wherein the pulse generating unit comprises a first resistor, a second resistor, a first comparator, a timer, a logic or gate, a first monostable pulse unit, and a second monostable pulse unit:
the first resistor and the second resistor are connected between the direct current bus voltage and the ground in series, and a first node between the first resistor and the second resistor outputs a first voltage;
a first input end of the first comparator is connected with the first node, a second input end of the first comparator receives a first preset voltage, and an output end of the first comparator outputs a first comparison signal;
the input end of the first monostable pulse unit receives a first comparison signal, and the first monostable pulse unit generates a second pulse signal;
the timer is used for generating a clock signal;
the logic OR gate is respectively connected with the output end of the first monostable pulse unit and the timer and generates a first logic signal according to a first comparison signal and a clock signal;
the second monostable pulse unit generates a first control signal according to the first logic signal.
12. The earth leakage protection circuit of claim 10, wherein the voltage detection unit comprises a first resistor, a second resistor, a subtractor, a sample-and-hold unit, and a second comparator,
the first resistor and the second resistor are connected between the direct current bus voltage and the ground in series, and a first node between the first resistor and the second resistor outputs a first voltage;
the sampling and holding unit samples and holds the divided voltage of the direct current bus voltage when the first control signal triggers the edge;
the subtracter is respectively connected with the second comparator and the sampling holding unit, receives the divided voltage of the direct current bus voltage and the first voltage, and outputs a difference voltage between the divided voltage of the direct current bus voltage and the first voltage;
the first input end of the second comparator receives the difference voltage, the second input end of the second comparator receives the first reference voltage, and the output end of the second comparator outputs a second comparison signal serving as a voltage detection signal.
13. The leakage protection circuit of claim 10, wherein the voltage detection unit comprises a first resistor, a second resistor, and a second comparator,
the first resistor and the second resistor are connected between the direct current bus voltage and the ground in series, and a first node between the first resistor and the second resistor outputs the divided voltage of the direct current bus voltage;
the first input end of the second comparator receives the divided voltage of the direct current bus voltage, the second input end of the second comparator receives the first reference voltage, and the output end of the second comparator outputs a second comparison signal as a voltage detection signal.
14. The earth leakage protection circuit according to claim 12 or 13, wherein the current detection unit includes a third comparator and a third one-shot pulse unit;
the first input end of the third comparator receives the bypass current sampling signal, the second input end of the third comparator receives a second reference voltage, and the output end of the third comparator outputs a third comparison signal;
the third comparison signal outputs a current detection signal via a third monostable pulse unit.
15. The leakage protection circuit of claim 12 or 13, wherein the latch unit comprises a logic and gate, a judgment module and an RS flip-flop;
the input end of the logic AND gate is respectively connected with the voltage detection unit and the current detection unit, and generates a second logic signal according to the voltage detection signal and the current detection signal;
the judging module judges whether the second logic signal is high level or not continuously for multiple times according to the first control signal so as to generate a detection signal;
the set end of the RS trigger is connected with the judging unit, the reset end of the RS trigger is grounded, and the output end of the RS trigger outputs a second control signal.
16. The earth leakage protection circuit of claim 15, wherein when the determining unit determines the second logic signal to be at a high level for a plurality of times, the output detection signal is at a high level, indicating that the dc bus voltage is normal; and when the second logic signal is at a low level in the continuous multiple judgment process, the output detection signal is at a low level, and the abnormal state of the direct current bus voltage is represented.
17. The leakage protection circuit of claim 1, wherein the bypass module comprises a reference generation unit, an operational amplifier, and a first transistor and a third resistor,
the reference generation unit generates a reference signal according to the first control signal;
the first transistor and the third resistor are connected between the direct current bus voltage and the ground in series, and a second node between the first transistor and the third resistor outputs the bypass current sampling signal;
the first end of the operational amplifier receives the reference signal, the second end is connected with the second node, and the output end is connected with the control end of the first transistor.
18. The leakage protection circuit of claim 1 wherein the first and second outputs of the dc bus voltage are first and second outputs of a rectifier bridge, respectively.
19. The leakage protection circuit of claim 1, wherein a first diode and a second diode are connected to the input terminals of the rectifier bridge, respectively, and provide the dc bus voltage.
20. A driver circuit, comprising:
the earth leakage protection circuit of any one of claims 1-19;
and the driving module is connected with the leakage protection circuit and receives a second control signal, when the state of the direct current bus is abnormal, the second control signal controls the driving module not to supply power to the load, and when the state of the direct current bus is normal, the second control signal controls the driving module to supply power to the load.
21. An electrical leakage detection method, comprising:
generating a first control signal according to the direct current bus voltage and a first preset voltage;
generating a bypass current sampling signal when the first control signal is active;
and generating a second control signal representing the voltage state of the direct-current bus according to the direct-current bus voltage and the bypass current sampling signal.
22. The electrical leakage detection method according to claim 21, wherein when the first control signal is valid, and when both the bypass current sampling signal and the dc bus voltage satisfy a preset condition, it is determined that the dc bus voltage state is normal; and when any one of the bypass current sampling signal and the direct current bus voltage does not meet a preset condition, judging that the state of the direct current bus voltage is abnormal.
23. A leakage detecting method according to claim 21 or 22, wherein when a difference between the dc bus voltage at a first time and the dc bus voltage at a second time is smaller than a first threshold, and the bypass current sampling signal at the second time is greater than a second threshold, it is determined that the dc bus voltage state is normal; and when the difference value between the direct current bus voltage at the first moment and the direct current bus voltage at the second moment is larger than or equal to a first threshold value and/or the bypass current sampling signal at the second moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal, wherein the first moment is different from the second moment.
24. The leakage detection method according to claim 21 or 22, wherein when the dc bus voltage is greater than a third threshold value and the bypass current sampling signal at the present time is greater than a second threshold value, it is determined that the dc bus voltage state is normal; and when the direct current bus voltage is smaller than or equal to a third threshold value and/or the bypass current sampling signal at the current moment is smaller than or equal to a second threshold value, judging that the direct current bus voltage state is abnormal.
25. The electrical leakage detection method according to claim 21, wherein a first control signal is generated when the dc bus voltage is greater than the first preset voltage, and the first control signal is a pulse signal.
26. The electrical leakage detection method of claim 25, wherein when the first control signal is asserted, entering a leakage detection state; and when the first control signal is invalid, the leakage detection state is exited.
27. A leakage detection method according to claim 21, wherein when the second control signal indicates that the dc bus voltage is in a normal state, the driving module is controlled to operate; and when the second control signal represents that the voltage state of the direct current bus is abnormal, controlling a driving module to be closed.
28. A leakage detecting method according to claim 27, wherein the dc bus voltage state includes any one of a normal state, a leakage state, and a poor contact state.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210178974.3A CN114630470A (en) | 2022-02-25 | 2022-02-25 | Leakage protection circuit, driving circuit and leakage detection method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210178974.3A CN114630470A (en) | 2022-02-25 | 2022-02-25 | Leakage protection circuit, driving circuit and leakage detection method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114630470A true CN114630470A (en) | 2022-06-14 |
Family
ID=81899943
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210178974.3A Pending CN114630470A (en) | 2022-02-25 | 2022-02-25 | Leakage protection circuit, driving circuit and leakage detection method |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114630470A (en) |
-
2022
- 2022-02-25 CN CN202210178974.3A patent/CN114630470A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110113841B (en) | LED driving circuit with silicon controlled rectifier dimmer, circuit module and control method | |
| US10890606B2 (en) | Detection circuit for an active discharge circuit of an X-capacitor, related active discharge circuit, integrated circuit and method | |
| US10845397B2 (en) | Systems and methods for detecting load coupling and for detecting a load type | |
| KR20100016599A (en) | Bulb type detector for dimmer circuit and resistance and short circuit detection | |
| US20150137783A1 (en) | Method, Apparatus and System For Controlling An Electrical Load | |
| CN110768207A (en) | Leakage protection circuit and drive circuit | |
| CN111987692B (en) | Leakage protection circuit, control method thereof and driving circuit | |
| CN111090016A (en) | Silicon controlled rectifier dimmer detection device, circuit and detection method thereof | |
| TW201901641A (en) | Displaying device and protecting circuit thereof | |
| US8487570B2 (en) | Method and device for operating an electric drive with the aid of a phase angle control | |
| CN114630470A (en) | Leakage protection circuit, driving circuit and leakage detection method | |
| CN210247109U (en) | Real-time detection LED drive circuit | |
| CN101098579B (en) | Limited current circuit of digital inverter for LCD backlight | |
| CN112449466A (en) | Linear LED drive circuit, power switch detection method and dimming control method | |
| CN111969551B (en) | Leakage protection circuit, control method thereof and driving circuit | |
| CN218003674U (en) | Flash-off state detection circuit and electronic device | |
| CN109901474B (en) | Control system, control circuit and control method | |
| WO2019057518A1 (en) | Power delivery apparatus | |
| EP2950620B1 (en) | Universal digital dimmer | |
| CN114615775A (en) | LED driving device, driving circuit and driving method thereof | |
| CN210071058U (en) | Liquid level detection system and detector thereof | |
| JP2011106987A (en) | Electricity source and method for determining useful life of capacitor | |
| CN112888104A (en) | LED drive circuit, drive controller and control method thereof | |
| EP0566996A2 (en) | Programmable controller with erroneous input prevention control circuit | |
| CN111970793B (en) | LED driving circuit, control method thereof and LED driving device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |