CN111970793B

CN111970793B - LED driving circuit, control method thereof and LED driving device

Info

Publication number: CN111970793B
Application number: CN202010737875.5A
Authority: CN
Inventors: 叶美盼; 林星宇
Original assignee: Hangzhou Silan Microelectronics Co Ltd
Current assignee: Hangzhou Silan Microelectronics Co Ltd
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2023-07-21
Anticipated expiration: 2040-07-28
Also published as: CN111970793A

Abstract

Disclosed is an LED driving circuit including: the leakage protection circuit detects whether a leakage phenomenon exists and generates a leakage control signal; and the dimming circuit is connected with the leakage protection circuit, receives the leakage control signal, and performs dimming according to the leakage control signal when no leakage phenomenon exists, and stops dimming according to the leakage control signal when the leakage phenomenon exists. According to the LED driving circuit provided by the embodiment of the invention, when the leakage detection is carried out and the leakage phenomenon exists, the leakage protection circuit controls the intermittent conduction of the bypass module to carry out the leakage detection and protection, and when the leakage phenomenon does not exist, the dimming module controls the conduction or the disconnection of the bypass module to carry out the transmission of dimming data and power so as to realize the dimming.

Description

LED driving circuit, control method thereof and LED driving device

Technical Field

The present application relates to the field of power electronics, and in particular, to an LED driving circuit, a control method thereof, and an LED driving device.

Background

The LED lamp is increasingly used in the field of illumination, such as in classrooms, shops, office buildings, etc., including fluorescent lamps, and two ends of the fluorescent lamp are respectively connected to the mains supply through a zero line and a fire wire. When in installation, one end is usually installed first, and then the other end is installed, if an operator carelessly touches hands or other parts of the body with the electrode at the other end when one end is installed, a loop is formed between the human body and the power grid, electric shock is caused, and the problem is solved by adding an electric leakage protection circuit.

An existing LED driving circuit 100 with a leakage protection function includes a leakage protection circuit 101 and a power conversion circuit 102, as shown in fig. 1. The LED driving circuit 100 obtains an ac input voltage from an external power source 110, obtains a dc bus voltage VH after rectifying by a rectifier bridge 120, and converts the dc bus voltage VH to generate a dc output voltage, thereby driving an external load 130, such as an LED lamp. When the leakage protection circuit 101 detects that an electric shock condition is input, it controls the LED driving circuit 100 to be in an off state; when the leakage protection circuit 101 detects that the input is not shocked, the LED driving circuit 100 operates normally, and the LED lamp is turned on.

However, as the energy-saving requirement is higher and higher, the LED driving circuit of the fluorescent lamp with the leakage protection function also needs to be dimmed so as to adapt to different environments and requirements. Because the LED driving circuit of the fluorescent lamp with the leakage protection function has only two ends input, namely a zero line input end and a fire wire input end, and no other ports are used for dimming.

In addition, the existing dimming technology can solve the dimming input at two ends of the fluorescent lamp, but has no leakage protection function.

An existing LED driver circuit 200 with dimming functionality includes an LED dimming circuit and a power conversion circuit 202. As shown in fig. 2, the LED dimming circuit includes a bypass circuit 203, a zero crossing detection circuit 204, a data sampling circuit 205, and an MCU module 206. Rectifier bridge 120 rectifies the output signal of dimmer 140 to produce a dc bus voltage VH, which is zero-cross detected by zero-cross detection circuit 204 to produce a zero-cross detection signal; the data sampling circuit 205 samples the bus dc voltage VH to generate a data sampling signal, the MCU module 206 generates a bypass control signal according to the zero-crossing detection signal and the data sampling signal, the bypass control signal is used to control the bypass circuit 203 to be turned on and off, when the bypass switch is turned on, the external power supply 110, the dimmer 140 and the bypass circuit 203 form a conductive loop, and when the bypass switch is turned off, the conductive loop is turned off. The MCU module 206 also parses the dimming data transmitted by the dimmer according to the data sampling signal, thereby generating different pulse width modulation signals PWM, and adjusting the magnitude of the LED output current.

Accordingly, further improvements in LED driving circuits for fluorescent lamps are desired, while solving the problem of leakage and the problem of dimming.

Disclosure of Invention

In view of the foregoing, an object of the present invention is to provide an LED driving circuit, a control method thereof, and an LED driving device, which can realize both leakage protection and dimming.

According to an aspect of the present invention, there is provided an LED driving circuit including: the leakage protection circuit detects whether a leakage phenomenon exists and generates a leakage control signal; and the dimming circuit is connected with the leakage protection circuit, receives the leakage control signal, and performs dimming according to the leakage control signal when no leakage phenomenon exists, and stops dimming according to the leakage control signal when the leakage phenomenon exists.

Preferably, the leakage protection circuit generates a leakage detection signal and judges whether a leakage phenomenon exists according to the voltage of the direct current bus with dimming data.

Preferably, the dimming circuit generates a leakage current according to the leakage detection signal when the leakage detection is performed and the leakage phenomenon exists, analyzes dimming data from the direct current bus voltage when the leakage phenomenon does not exist, and generates a pulse width modulation signal according to the dimming data.

Preferably, the dimming circuit includes: the bypass module is connected with the leakage protection circuit and receives a leakage detection signal; the dimming module is connected with the bypass module and generates a pulse width modulation signal and a bypass control signal according to the voltage of the direct current bus; when the leakage detection is carried out and the leakage phenomenon exists, the bypass module generates leakage current according to the leakage detection signal, and when the leakage phenomenon does not exist, the bypass module generates bypass current according to the bypass control signal.

Preferably, the leakage protection circuit multiplexes the bypass module to perform leakage detection, and when the leakage detection is performed and a leakage phenomenon exists, the leakage detection signal controls the bypass module to conduct intermittently; and when no leakage phenomenon exists, the bypass control signal controls the bypass module to be switched on or off.

Preferably, the dimming module is further connected to the leakage protection circuit, receives a leakage control signal, and performs dimming when no leakage occurs according to the leakage control signal, and stops dimming when the leakage occurs.

Preferably, the bypass module comprises a second transistor, a first diode, a second resistor and a third resistor, wherein the second transistor and the third resistor are connected in series between a first output terminal and a second output terminal of the direct current bus voltage; the grid electrode of the second transistor is connected with a second output end of the direct current bus voltage through a second resistor; the anode of the first diode is connected with the leakage protection circuit, and the cathode of the first diode is connected with the grid electrode of the second transistor; the anode of the second diode is connected with the dimming module, and the cathode of the second diode is connected with the grid electrode of the second transistor; the first node between the second transistor and the third resistor outputs a sampling signal of the leakage current or a sampling signal of the bypass current.

Preferably, when the leakage phenomenon exists, the leakage detection signal controls the second transistor to be intermittently conducted, and the power supply, the second transistor and the third resistor form a leakage current loop.

Preferably, when no leakage exists, the bypass control signal controls the second transistor to be turned on and off, and the power supply, the second transistor and the third resistor form a bypass loop.

Preferably, the dimming circuit further comprises: the high-voltage starting module is connected with the leakage protection circuit and the bypass module and generates a power supply voltage according to the voltage of the direct-current bus; and when no leakage phenomenon exists, the high-voltage starting module supplies power to the dimming module according to the leakage control signal.

Preferably, the high-voltage starting module comprises a first transistor, a voltage stabilizing tube, a first resistor, a third diode, a fourth diode, a first capacitor and a first switch, wherein the first resistor and the voltage stabilizing tube are connected in series between a first output end and a second output end of the direct-current bus voltage; the grid electrode of the first transistor is connected with a second node between the first resistor and the voltage stabilizing tube; the anode of the third diode is connected with the second output end of the direct current bus voltage through the first capacitor, and the cathode of the third diode is connected with the grid electrode of the first transistor; the anode of the fourth diode is connected with the node between the first transistor and the second transistor, and the cathode of the fourth diode is connected with the anode of the third diode; a third node between the third diode and the fourth diode outputs a supply voltage, and the third node is connected with the dimming module through the first switch; the control end of the first switch receives the leakage control signal and is closed and opened according to the leakage control signal.

Preferably, when the leakage detection is performed and the leakage phenomenon exists, the leakage detection signal controls the second transistor to be intermittently conducted, and the power supply source, the first transistor, the second transistor and the third resistor form a leakage current loop.

Preferably, when no leakage exists, the bypass control signal controls the second transistor to be turned on and off, and the power supply, the first transistor, the second transistor and the third resistor form a bypass loop.

Preferably, the power supply forms a power supply loop with the first transistor, the fourth diode and the first capacitor.

Preferably, the dimming module includes: the voltage detection unit is used for generating a bypass control signal according to the voltage of the direct current bus, and the bypass control signal controls the on and off of the bypass module; the data acquisition unit is used for generating a data signal according to the voltage of the direct current bus; and the control unit is connected with the data acquisition unit and is used for generating a pulse width modulation signal according to the data signal.

Preferably, the voltage detection unit includes a first comparator, a second comparator, a third operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second switch, and a third switch; the fifth resistor and the sixth resistor are connected in series between the first output end and the second output end of the direct current bus voltage; the first input end of the first comparator is connected with a node between the fifth resistor and the sixth resistor, the second input end receives a first reference voltage, and the output end outputs a second control signal; the first input end of the second comparator is connected with a node between the fifth resistor and the sixth resistor, the second input end receives the second reference voltage, and the output end outputs a third control signal; the first input end of the third operational amplifier receives the bypass current sampling signal from the bypass module, the second input end receives a third reference voltage through a seventh resistor and a second switch, and is connected with the second output end of the DC bus voltage through a fourth resistor, and receives a fourth reference voltage through the third switch, and the output end outputs a bypass control signal; the second control signal controls the closing and opening of the second switch, and the third control signal controls the closing and opening of the third switch.

Preferably, the leakage protection circuit includes: the voltage sampling module is used for obtaining direct current bus voltage and sampling the direct current bus voltage to obtain sampling voltage; the leakage flow control module is connected with the voltage sampling module and is used for generating a sampling control signal and a leakage detection signal according to the sampling voltage and the reference voltage; the leakage judging module is connected with the voltage sampling module and the leakage flow control module and is used for acquiring a first sampling voltage at a first sampling time and a second sampling voltage at a second sampling time according to the sampling control signal, judging whether a leakage phenomenon exists or not and generating a leakage control signal according to the first sampling voltage and the second sampling voltage, wherein the first sampling time is earlier than the second sampling time.

Preferably, the leakage current control module generates the leakage current detection signal when or after the dc bus voltage is greater than a reference voltage.

Preferably, the leakage current linearly rises to a preset current value or linearly falls after rising for a preset time.

Preferably, the leakage current curve rises to a preset current value or the curve falls after the curve rises for a preset time.

Preferably, the first sampling timing is before the generation of the leakage current or when the generation of the leakage current starts, and the second sampling timing is before the linear decrease of the leakage current.

Preferably, the first sampling timing and the second sampling timing are during a linear rise of the leakage current.

Preferably, when the second sampling voltage is less than or equal to the first sampling voltage, there is a leakage phenomenon; when the second sampling voltage is larger than the first sampling voltage, no leakage phenomenon exists.

Preferably, when the second sampling voltage is less than or equal to the sum of the first sampling voltage and a preset bias voltage, a leakage phenomenon exists; when the second sampling voltage is larger than the sum of the first sampling voltage and a preset bias voltage, no leakage phenomenon exists.

Preferably, when the power is on, the leakage protection circuit detects whether a leakage phenomenon exists, and when the leakage phenomenon does not exist, the dimming circuit works normally; when the leakage phenomenon exists, the dimming circuit does not work, and the leakage detection is repeated until the leakage phenomenon does not exist.

According to a second aspect of the present invention, there is provided a control method of an LED driving circuit, comprising: detecting whether an electric leakage phenomenon exists or not and generating an electric leakage control signal; when no leakage occurs, dimming is started according to the leakage control signal, and when leakage occurs, dimming is stopped according to the leakage control signal.

Preferably, the control method further includes: and generating a leakage detection signal, and judging whether a leakage phenomenon exists according to the direct current bus voltage with the dimming data.

Preferably, the control method further includes: when the electric leakage detection is carried out or the electric leakage phenomenon exists, the electric leakage is generated according to the electric leakage detection signal, when the electric leakage phenomenon does not exist, the dimming data are analyzed from the direct current bus voltage, and the pulse width modulation signal is generated according to the dimming data so as to carry out dimming.

Preferably, the control method further includes: when no leakage phenomenon exists, generating a bypass control signal according to the voltage of the direct current bus; and generating a bypass current according to the bypass control signal; the current path of the leakage current is the same as the current path of the bypass current.

Preferably, the control method further includes: generating a power supply voltage according to the DC bus voltage; and controlling power supply according to the electric leakage control signal so as to control whether dimming is performed, when no electric leakage exists, performing power supply according to the electric leakage control signal so as to start dimming, and when electric leakage detection is performed and the electric leakage exists, stopping power supply according to the electric leakage control signal so as to stop dimming.

Preferably, the step of dimming includes: generating a data signal according to the DC bus voltage; and generating a pulse width modulated signal based on the data signal.

Preferably, the step of detecting whether the leakage phenomenon exists comprises: obtaining a direct current bus voltage, and sampling the direct current bus voltage to obtain a sampling voltage; generating a sampling control signal and a leakage detection signal according to the sampling voltage and the reference voltage; and acquiring a first sampling voltage at a first sampling time and a second sampling voltage at a second sampling time according to the sampling control signal, judging whether an electric leakage phenomenon exists or not and generating an electric leakage control signal according to the first sampling voltage and the second sampling voltage, wherein the first sampling time is earlier than the second sampling time.

Preferably, the leakage detection signal is generated when or after the dc bus voltage is greater than a reference voltage.

Preferably, when the power is just on, detecting whether the electric leakage phenomenon exists, and when the electric leakage phenomenon does not exist, dimming; when the leakage phenomenon exists, the dimming is stopped, and the leakage detection is repeated until the leakage phenomenon does not exist.

According to a third aspect of the present invention, there is provided an LED driving device comprising: a dimmer, the first input end of which is connected with the first alternating current input end, and generates alternating current input voltage with dimming data based on dimming action; the first input end of the rectifier bridge is connected with the first output end of the dimmer, the second input end of the rectifier bridge is connected with the second end of the alternating current input, and the rectifier bridge is used for rectifying the alternating current input voltage with dimming data so as to output direct current bus voltage with the dimming data; the LED driving circuit and the power conversion circuit are connected with the dimming circuit and used for converting the DC bus voltage into DC output voltage according to the pulse width modulation signal output by the LED driving circuit and supplying power to a load.

Preferably, the power conversion circuit comprises a diode and a power conversion module, wherein the anode of the diode is connected with the first output end of the direct current bus voltage, and the cathode of the diode is connected with the power conversion module; the power conversion module is used for converting the direct-current bus voltage into direct-current output voltage according to the pulse width modulation signal and supplying power to a load.

Preferably, the dimmer further comprises a second input terminal, the second input terminal of the dimmer is connected with the second input terminal of the alternating current input, and the second output terminal of the dimmer is connected with the second input terminal of the rectifier bridge.

According to the LED driving circuit provided by the embodiment of the invention, when the leakage phenomenon exists, the bypass module is intermittently conducted to perform leakage protection, and when the leakage phenomenon does not exist, the bypass module is conducted and turned off to perform dimming data and power transmission so as to realize dimming.

Further, the leakage protection circuit performs leakage detection by detecting leakage current generated by the bypass module, and the leakage protection circuit realizes leakage protection by using the bypass module in a time-sharing manner.

The LED driving circuit provided by the embodiment of the invention can realize the detection of electric leakage, high-voltage starting and power supply and bypass control through the transistors in the bypass module controlled by time division multiplexing, so that the dimming of the LED is realized, the circuit is simple, and the cost is reduced.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings.

Fig. 1 shows a schematic circuit diagram of a prior art LED driving device with a leakage protection circuit.

Fig. 2 shows a schematic circuit diagram of a prior art LED driving device with dimming function.

Fig. 3 shows a schematic circuit diagram of an LED driving device according to a first embodiment of the present invention.

FIG. 4 shows a schematic circuit diagram of the bypass module of FIG. 3;

fig. 5 shows a schematic circuit diagram of an LED driving device according to a second embodiment of the present invention

Fig. 6 shows a schematic circuit diagram of the dimmer circuit of fig. 5;

fig. 7 shows a schematic circuit diagram of the leakage protection circuit in fig. 5 and a schematic configuration diagram of the dimming circuit.

Fig. 8 shows a signal waveform diagram when the LED driving circuit provided by the embodiment of the present invention does not have a leakage phenomenon.

Fig. 9 shows a signal waveform diagram when the LED driving circuit for leakage protection is connected in parallel to both ends of the normal LED driving circuit, and a leakage phenomenon exists;

fig. 10 shows a signal waveform diagram when an LED driving circuit and a dimmer are connected in series and a leakage phenomenon exists in the LED driving circuit according to an embodiment of the present invention.

Fig. 11 shows a schematic circuit diagram of an LED driving device according to a third embodiment of the present invention.

Fig. 12 shows a schematic circuit diagram of an LED driving device according to a fourth 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. The same reference numbers will be used throughout the drawings to refer to the same or like parts. For clarity, the various features of the drawings are not drawn to scale.

Fig. 3 shows a schematic circuit diagram of an LED driving device of a first embodiment of the present invention. The LED driving apparatus includes a dimmer 140, a rectifier bridge 120, an LED driving circuit 300, and a power conversion circuit 150. The dimmer 140 obtains an ac input voltage from the external ac power source 110 (i.e., a power supply source), and outputs the ac input voltage with dimming data based on a dimming operation. The rectifier bridge 120 rectifies the ac input voltage with dimming data to output the dc bus voltage VH with dimming data. The LED driving circuit 300 performs dimming according to the dc bus voltage VH with dimming data, and the power conversion circuit 150 steps down the dc bus voltage VH to obtain a dc output voltage, thereby driving the external load 130, such as an LED lamp.

In this embodiment, the dimmer 140 includes a first input terminal and a first output terminal, wherein the first input terminal is connected to the ac input first terminal or the power supply terminal (i.e., the first terminal of the external ac power source 110), and generates the ac input voltage with dimming data based on the dimming operation. The rectifier bridge 120 is, for example, a full-wave rectifier circuit for rectifying an ac input voltage into a dc bus voltage VH. The rectifier bridge 120 has a first input terminal connected to a first output terminal of the dimmer 140 and a second input terminal connected to an ac input second terminal (i.e., a second terminal of the external ac power source 110). The first output terminal of the rectifier bridge 120 is a high voltage terminal, and the second output terminal is a low voltage terminal. The second output is for example grounded.

As shown in fig. 3, the LED driving circuit 300 includes a leakage protection circuit 301 and a dimming circuit 302. Wherein, the leakage protection circuit 301 detects whether there is a leakage phenomenon and generates a leakage control signal; the dimming circuit 302 is connected to the leakage protection circuit 301, receives the leakage control signal, controls the dimming circuit 302 to start dimming when there is no leakage phenomenon, and controls the dimming circuit 302 to stop dimming when there is a leakage phenomenon.

Specifically, the leakage protection circuit 301 is connected between the first output terminal and the second output terminal of the rectifier bridge 120. The leakage protection circuit 301 generates a leakage detection signal based on the dc bus voltage VH with the dimming data, and determines whether or not there is a leakage phenomenon based on the dc bus voltage VH. The power conversion circuit 150 is configured to step down the dc bus voltage VH to obtain a dc output voltage. A first input of the power conversion circuit 150 is connected to a first output of the rectifier bridge 120, a second input of the power conversion circuit 150 is connected to a second output of the rectifier bridge 120, and the power conversion circuit 150 is configured to supply power to an external load 130 (e.g., an LED lamp). The power conversion circuit 150 may be implemented by a switching power supply or a linear constant current control circuit. For example, the power conversion circuit 150 may be implemented using switching power supplies of various topologies such as Buck (Buck) topology, buck-BOOST (Buck-BOOST) topology, FLYBACK (FLYBACK) topology, etc.

The dimming circuit 302 is connected between the first output terminal and the second output terminal of the rectifier bridge 120 and connected with the leakage protection circuit 301, generates a leakage current according to a leakage detection signal when a leakage detection or a leakage phenomenon exists, and parses dimming data from the dc bus voltage VH when a leakage phenomenon does not exist, generates a pulse width modulation signal PWM according to the dimming data, and generates a bypass control signal according to the dc bus voltage VH. In this embodiment, the leakage current linearly increases to a preset current value or linearly decreases after a preset time is maintained.

In a preferred embodiment, the leakage current curve rises to a predetermined current value or the curve falls after a predetermined time.

In this embodiment, the dimming circuit 302 includes a bypass module 303 and a dimming module 304. The bypass module 303 is connected to the leakage protection circuit 301, and is configured to generate a leakage current according to the leakage detection signal when the leakage detection is performed and a leakage phenomenon exists; the dimming module 304 is connected to the bypass module, and generates a pulse width modulation signal PWM and a bypass control signal according to the dc bus voltage VH, and the bypass module 303 is further configured to generate a bypass current according to the bypass control signal when no leakage occurs.

In this embodiment, the dimming module 304 parses the dimming data signal from the dc bus voltage VH, generates a pulse width modulation signal PWM according to the dimming data signal, and receives the pulse width modulation signal PWM from the third input terminal of the power conversion circuit 150, and supplies power to the external load 130 according to the pulse width modulation signal PWM.

Wherein, the leakage protection circuit 301 multiplexes the bypass module 303 to perform leakage detection, when the leakage detection is performed and a leakage phenomenon exists, the leakage detection signal output by the leakage protection circuit 301 controls the bypass module 303 to be intermittently turned on, and the dimming module 304 stops dimming according to the leakage control signal; when no leakage occurs, the dimming module 304 starts dimming according to the leakage control signal, and the bypass control signal output by the dimming module 304 controls the bypass module 303 to be turned on or off, so as to transmit dimming data or power.

Specifically, the leakage protection circuit 301 determines whether there is a leakage phenomenon according to the dc bus voltage VH, and if there is a leakage phenomenon, repeatedly performs leakage detection until it is determined that there is no leakage phenomenon; when no leakage occurs, the dimming module 304 provides the power conversion circuit 150 with a pulse width modulation signal PWM, which is used to control the on and off of the main switching tube in the power conversion circuit 150, and controls the magnitude of the output current by changing the duty ratio of the pulse width modulation signal PWM, so as to adjust the brightness of the LED lamp 130.

The power conversion circuit 150 includes a diode D0 and a power conversion module 151, wherein an anode of the diode D0 is connected to a first output terminal of the dc bus voltage VH (i.e., a first output terminal of the rectifier bridge 120), and a cathode is connected to the power conversion module 151, mainly for blocking dc, to prevent the sine wave voltage from being capacitively filtered. In this embodiment, the leakage protection circuit 301 and the dimming circuit 302 are connected in sequence between the rectifier bridge 120 and the power conversion circuit 150.

Fig. 4 shows a schematic circuit diagram of the bypass module of fig. 3. As shown in fig. 4, referring to fig. 4, the bypass module 303 includes a second transistor Q2, a first diode D1, a second diode D2, a second resistor R2, and a third resistor R3. Wherein the second transistor Q2 and the third resistor R3 are connected in series between the first output terminal and the second output terminal of the dc bus voltage VH. The gate of the second transistor Q2 is connected to the second output terminal of the dc bus voltage VH through a second resistor R2. The anode of the first diode D1 is connected to the leakage protection circuit 301, and the cathode is connected to the gate of the second transistor Q2. The anode of the second diode D2 is connected to the dimming module 304, and the cathode is connected to the gate of the second transistor Q2. Wherein, the second output terminal of the DC bus voltage VH is grounded to GND. The second transistor Q2 is turned on or off according to the leakage detection signal or the bypass control signal. When the leakage detection is performed (for example, when the circuit is just powered on) and a leakage phenomenon exists, the leakage detection signal controls the second transistor Q2 to be intermittently conducted, and a leakage current loop is formed by the power supply, the second transistor Q2 and the third resistor R3; when no leakage phenomenon exists, the bypass control signal controls the second transistor Q2 to be conducted, and the power supply, the second transistor Q2 and the third resistor R3 form a bypass loop.

According to the LED driving circuit provided by the embodiment of the invention, when the leakage detection is carried out and the leakage phenomenon exists, the bypass module is intermittently conducted to carry out leakage protection, and when the leakage phenomenon does not exist, the bypass module is conducted or turned off to carry out the transmission of dimming data and power so as to realize dimming.

Fig. 5 shows a schematic circuit diagram of an LED driving device according to a second embodiment of the present invention. In comparison with the first embodiment of the present invention, the dimming circuit 302 further includes a high voltage start module 308, where the high voltage start module 308 is connected to the leakage protection circuit 301 and the bypass module 303, and is configured to generate the supply voltage Vcc according to the dc bus voltage VH, and control whether to supply power to the dimming module 304 according to the leakage control signal.

The leakage protection circuit 301 multiplexes the bypass module 303 to perform leakage detection, when the leakage detection is performed and a leakage phenomenon exists, the leakage detection signal output by the leakage protection circuit 301 controls the bypass module 303 to be intermittently conducted, the leakage control signal controls the power supply path between the high-voltage starting module 308 and the dimming module 304 to be turned off, and the dimming module 304 and the power conversion circuit 150 do not work; when it is determined that the leakage phenomenon does not exist, the bypass control signal output by the dimming module 304 controls the bypass module 303 to be turned on or off, so as to transmit dimming data or power, and the leakage control signal controls the power supply path between the high voltage starting module 308 and the dimming module 304 to be turned on, so that the dimming module 304 and the power conversion circuit 150 work normally.

The bypass module 303 and the high voltage starting module 308 are connected between the first output end and the second output end of the dc bus voltage VH (i.e., between the first output end and the second output end of the rectifier bridge 120), the bypass module 303 is connected with the leakage protection circuit 301 and the dimming module 304, receives a leakage detection signal generated by the leakage protection circuit 301 and a bypass control signal generated by the dimming module 304, and controls the bypass module 303 to be turned on or turned off according to the leakage detection signal or the bypass control signal.

Specifically, when the leakage detection (when power is just on) is performed and there is a leakage phenomenon, the leakage detection signal output by the leakage protection circuit 301 controls the bypass module 303 to be intermittently turned on; when no leakage occurs, the bypass control signal output by the dimming module 304 controls the bypass module 303 to be turned on or off.

The high voltage starting module 308 is connected between the first output terminal and the second output terminal of the dc bus voltage VH (i.e., between the first output terminal and the second output terminal of the rectifier bridge 120) for generating a supply voltage according to the dc bus voltage VH, and is connected to the leakage protection circuit 301 for controlling whether to supply power to the dimming module 304 according to a leakage control signal generated by the leakage protection circuit 301.

Fig. 6 shows a schematic circuit diagram of the dimming module of fig. 5. As shown in fig. 6, the dimming module 304 includes a voltage detection unit 305, a data acquisition unit 306, and a control unit 307. The voltage detection unit 305, the data acquisition unit 306 and the control unit 307 are all powered by a high voltage start module 308.

The voltage detection unit 305 receives the dc bus voltage VH, and generates a bypass control signal according to the dc bus voltage VH, where the bypass control signal is used to control on and off of the bypass module 303.

The data acquisition unit 306 acquires the dc bus voltage VH, and samples the dc bus voltage VH to obtain a data signal. The data signal is transmitted to the control unit 307 for processing to realize the functions of dimming, color temperature adjustment, grouping management and the like of the lamp.

The control unit 307 is connected to the data acquisition unit 305 and receives data signals. The control unit 307 obtains dimming data generated by the dimmer 140 according to the data signal, thereby generating different pulse width modulation signals PWM, controlling the magnitude of the output current or voltage generated by the power conversion circuit 150, and realizing the functions of dimming the LED lamp 130.

The control unit 307 may provide multiple PWM signals to control dimming of multiple LED lamps according to dimming requirements.

Fig. 7 shows a schematic circuit diagram of the leakage protection circuit in fig. 5 and a schematic structure diagram of the dimming circuit. As shown in fig. 7, the leakage protection circuit 301 includes a voltage sampling module 309, a leakage current control module 310, and a leakage determination module 311.

The voltage sampling module 309 is configured to sample the dc bus voltage VH to obtain a sampling voltage Vs.

In this embodiment, the voltage sampling module 309 includes a first end to a third end, where the first end and the second end of the voltage sampling module 309 are respectively connected to a first output end and a second output end of the dc bus voltage VH; the third terminal of the voltage sampling module 309 is connected to the leakage current control module 310 and the leakage current judging module 311, respectively, for providing the sampling voltage Vs characterizing the dc bus voltage VH to the leakage current control module 310 and the leakage current judging module 311.

The leakage current control module 310 is connected to the voltage sampling module 309, and is configured to generate a sampling control signal and a leakage detection signal according to the sampling voltage Vs and a reference voltage, so as to control generation of leakage current. Specifically, the leakage current control module 122 is electrically connected to the third terminal of the voltage sampling module 121, and receives the sampling voltage Vs.

In this embodiment, the leakage current control module 310 generates the leakage current detection signal when or after the dc bus voltage VH is greater than the reference voltage.

The bypass module 303 generates a leakage current according to the leakage detection signal. The change rate of the leakage current is controllable, and the slope of the leakage current is controlled to reach a desired value. The bypass module 303 can generate any leakage current according to the leakage detection signal, i.e. can control the slope of the leakage current. The leakage current may be linear or may be a gentle parabolic. When the leakage current linearly changes, the leakage current linearly rises to a preset current value or linearly falls after rising for a preset time; when the leakage current is in a gentle parabola, the leakage current curve rises to a preset current value or the curve rises and maintains the curve to fall after the preset time.

The rate of change (i.e., slope) of the sampled voltage Vs at the time of leakage may be greater than, less than, or equal to the rate of change (i.e., slope) at the time of no leakage.

The leakage judging module 311 is configured to obtain a first sampling voltage Vs1 at a first sampling time and obtain a second sampling voltage Vs2 at a second sampling time according to the sampling control signal; and judging whether a leakage phenomenon exists according to the first sampling voltage Vs1 and the second sampling voltage Vs2, wherein the first sampling time is earlier than the second sampling time, and the first sampling time and the second sampling time are before the end of the leakage current Ileak.

In this embodiment, the first sampling timing is before the generation of the leakage current Ileak or when the generation of the leakage current Ileak starts, and the second sampling timing is before the linear decrease of the leakage current Ileak.

In a preferred embodiment, the first sampling instant and the second sampling instant are during a linear rise of the leakage current Ileak, and the first sampling instant is earlier than the second sampling instant.

Specifically, when no leakage phenomenon exists, the leakage human body resistance is 0 ohm, and at the moment, vs2 is more than Vs1; when the leakage phenomenon exists, the leakage human body resistance is larger than 500 ohms, and at the moment, vs2 is less than or equal to Vs1. Therefore, whether the electric leakage phenomenon exists or not can be judged by comparing the magnitudes of the first sampling voltage Vs1 and the second sampling voltage Vs2, namely, when Vs2 > Vs1, the electric leakage phenomenon does not exist; when Vs2 is less than or equal to Vs1, the leakage phenomenon exists.

The leakage judging module 311 is further configured to generate a leakage control signal Ctrl1 according to the sampling control signal and the sampling voltage Vs; the leakage control signal Ctrl1 is used to control the on/off of the power supply path between the high voltage start module 308 and the dimming module 304. When the leakage detection is performed and the leakage phenomenon is judged to exist, the leakage control signal Ctrl1 controls the power supply path between the high-voltage starting module 308 and the dimming module 304 to be turned off; when it is determined that no leakage exists, the power supply path between the high voltage starting module 308 and the dimming module 304 is controlled to be conducted.

Referring to fig. 7, the bypass module 303 includes a second transistor Q2, a first diode D1, a second diode D2, a second resistor R2, and a third resistor R3. Wherein the first transistor Q1, the second transistor Q2 and the third resistor R3 are connected in series between the first output terminal and the second output terminal of the dc bus voltage VH. The first node between the second transistor Q2 and the third resistor R3 outputs a leakage current sampling signal or a bypass current sampling signal, and the gate of the second transistor Q2 is connected to the second output terminal of the dc bus voltage VH through the second resistor R2. The anode of the first diode D1 is connected to the leakage current control module 310, and the cathode is connected to the gate of the second transistor Q2. The anode of the second diode D2 is connected to the voltage detection unit 305, and the cathode is connected to the gate of the second transistor Q2. Wherein the second output terminal of the dc bus voltage VH is grounded. The second transistor Q2 is turned on or off according to the leakage detection signal or the bypass control signal. When the circuit is just started to be electrified and when a leakage phenomenon exists, the leakage detection signal controls the second transistor Q2 to be intermittently conducted, and a leakage current loop is formed by the power supply, the first transistor Q1, the second transistor Q2 and the third resistor R3; when no leakage occurs, the bypass control signal controls the second transistor Q2 to be turned on, and the power supply, the first transistor Q1, the second transistor Q2 and the third resistor R3 form a bypass loop, and at this time, the bypass module 303 multiplexes the first transistor in the high voltage starting module 308 to realize the bypass function.

The high voltage start-up module 308 includes a first transistor Q1, a voltage regulator Z1, a first resistor R1, a third diode D3, a fourth diode D4, a first capacitor C1, and a first switch K1. The first resistor R1 and the regulator tube Z1 are connected in series between the first output terminal and the second output terminal of the dc bus voltage VH. The gate of the first transistor Q1 is connected to a second node between the first resistor R1 and the regulator tube Z1. The anode of the third diode D3 is connected to ground through the first capacitor C1, and the cathode is connected to the gate of the first transistor Q1. The anode of the fourth diode D4 is connected to the node between the first transistor Q1 and the second transistor Q2, and the cathode is connected to the anode of the third diode D3. The power supply forms a power supply loop with the first transistor Q1, the fourth diode D4 and the first capacitor C1, a third node between the anode of the third diode D3 and the cathode of the fourth diode D4 outputs a power supply voltage Vcc for supplying power to the dimming module 304, and the third node is connected to the dimming module 304 through the first switch K1. The control end of the first switch K1 is connected to the leakage judging module 311, receives a leakage control signal Ctrl1 output by the leakage judging module 311, and controls the on and off of the power supply path between the high voltage starting module 308 and the dimming module 304 according to the leakage control signal Ctrl 1.

The gate voltage of the first transistor Q1 is stabilized at Vz1 through the first resistor R1 and the voltage stabilizing tube Z1, the first transistor Q1 works in a linear region, the fourth diode D4 is conducted, the cathode of the fourth diode D4 outputs a power supply voltage Vcc, so that when the circuit is started, a starting voltage can be quickly established, and Vcc=Vz1-V _Q1gs Vd4, wherein Vz1 is the voltage across the voltage regulator Z1, V _Q1gs The gate-source voltage of the first transistor Q1, vd4 is the voltage across the fourth diode D4. When the dc bus voltage VH reaches the trough, that is, when the voltage value of the dc bus voltage VH is low, the power supply voltage Vcc is maintained through the first capacitor C1, and meanwhile, the power supply voltage Vcc is fed back to the gate of the first transistor Q1 through the third diode D3, so as to ensure that the first transistor Q1 has enough gate voltage to operate in the linear region to maintain the normal operation of Q1.

The leakage current control module 310 is connected to the gate of the second transistor Q2 through the first diode D1, and generates a leakage current detection signal to control the on state of the second transistor Q2. The dimming module 304 is connected to the gate of the second transistor Q2 through the second diode D2, and generates a bypass control signal to control the on state of the second transistor Q2. When both the leakage detection signal and the bypass control signal are low, the second transistor Q2 is turned off. When the anode voltage of the first diode D1 is higher than the anode voltage of the second diode D2, the leakage detection signal controls the conduction state of the second transistor Q2 to perform leakage detection; when the anode voltage of the second diode D2 is higher than the anode voltage of the first diode D1, the bypass control signal controls the on state of the second transistor Q2. When the second transistor Q2 is turned on, the bypass module 303 is turned on, and the ac input power, the dimmer 140 and the bypass module 303 form a conductive loop. When the second transistor Q2 is turned off, the bypass module 303 is turned off, and the conductive loop is turned off, so that dimming data and power are transmitted, and dimming is achieved.

The voltage detection unit 305 includes a first comparator U1, a second comparator U2, a third operational amplifier U3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a second switch K2, and a third switch K3. The fifth resistor R5 and the sixth resistor R6 are connected in series between the first output terminal and the second output terminal of the dc bus voltage VH, and a fourth node between the fifth resistor R5 and the sixth resistor R6 outputs a divided voltage signal corresponding to the dc bus voltage VH. The first input end of the first comparator U1 receives the voltage division signal, the second input end receives the first reference voltage Vref1, and the output end outputs a second control signal Ctrl2, wherein the second control signal Ctrl2 controls the second switch K2 to be closed or opened. The first input end of the second comparator U2 is connected with a fourth node between the fifth resistor R5 and the sixth resistor R6, the second input end receives the second reference voltage Vref2, and the output end outputs a third control signal Ctrl3, wherein the third control signal Ctrl3 controls the third switch K3 to be closed or opened. The first input terminal of the third operational amplifier U3 is connected to the first node between the second transistor Q2 and the third resistor R3, receives a sampling signal of leakage current or bypass current, the second input terminal receives the third reference voltage Vref3 through the seventh resistor R7 and the second switch K2, while the second input terminal is connected to ground (the second terminal of the dc bus voltage VH) through the fourth resistor R4, while the second input terminal receives the fourth reference voltage Vref4 through the third switch K3, the output terminal outputs a bypass control signal, and is connected to the anode of the second diode D2, and the bypass control signal controls the operating state of the second transistor Q2 through the second diode D2. The first input terminal of the first comparator U1 is an inverting input terminal, and the second input terminal is a non-inverting input terminal, but is not limited thereto. The first input terminal of the second comparator U2 is an inverting input terminal, and the second input terminal is a non-inverting input terminal, but is not limited thereto. The first input terminal of the third operational amplifier U3 is an inverting input terminal, and the second input terminal is a non-inverting input terminal, but is not limited thereto.

As shown in fig. 7, when power-on is started, the leakage protection circuit 301 controls the second transistor Q2 to be intermittently turned on through the first diode D1, at this time, the first switch K1 is turned off, the dimming module 304 and the power conversion circuit 150 do not operate, the anode of the second diode D2 is at a low level, and the leakage current control module 310 controls the second transistor Q2 to be turned on according to the leakage detection signal, so as to generate the leakage current Ileak. The leakage judging module 311 controls the leakage judging module 311 to obtain the first sampling voltage Vs1 from the voltage sampling module 309 before the leakage control module 310 generates the leakage current Ileak or when the leakage current Ileak starts to generate; the sampling control signal controls the leakage judging module 311 to acquire the second sampling voltage Vs2 from the voltage sampling module 309 before the leakage current Ileak linearly decreases. When Vs2 > Vs1, there is no leakage phenomenon, and then the leakage detection signal is at a low level, i.e. the anode of the first diode D1 is always at a low level, and the leakage control signal Ctrl1 generated by the leakage judging module 311 controls the first switch K1 to be closed, so as to supply power to the dimming module 304. When Vs2 is less than or equal to Vs1, a leakage phenomenon exists, a leakage control signal Ctrl1 controls the first switch K1 to be disconnected, the leakage detection signal is a pulse square wave, and the second transistor Q2 is controlled to be intermittently conducted until no leakage phenomenon is detected.

In normal operation, i.e. when there is no leakage phenomenon, the leakage control signal Ctrl1 controls K1 to be closed, the anode voltage of the first diode D1 is at a low level, the second transistor Q2 is controlled by the bypass control signal output by the third operational amplifier U3, the high level maintenance time of the bypass control signal is the same as the high level maintenance time of the second control signal Ctrl2, the bypass control signal controls the current flowing through the second transistor Q2 and the on and off of the second transistor Q2, so as to perform the transmission of dimming data, the power transmission and the power supply path of the dimmer, and the dimming module 304 normally works. .

Referring to fig. 8, when the second control signal Ctrl2 generated at the output end of the first comparator U1 is at a high level, the second switch K2 is closed, the voltage at the positive input end of the third operational amplifier U3 is Vref3×r4/(r4+r7), the first transistor Q1 and the second transistor Q2 are controlled to operate in a linear region, and the current flowing through the first transistor Q1 and the second transistor Q2 is Vref3×r4/((r4+r7) ×r3). At this time, the dimmer 140 generates dimming data, and the bypass module 303 is turned on for transmission of the dimming data.

Similarly, when the third control signal Ctrl3 output from the second comparator U2 controls the bypass module 303 to be turned on during the chopping period of the dimmer 140 (i.e. when the dimmer 140 is turned off), the dimmer 140 is powered, and the ac input power source, the dimmer and the bypass module form a power supply loop. That is, when the third control signal Ctrl3 is at a high level, the third switch K3 is turned on to control the first transistor Q1 and the second transistor Q2 to operate in the linear region, and the current flowing through the first transistor Q1 and the second transistor Q2 is Vref4/R3.

The different values of the currents flowing through the first transistor Q1 and the second transistor Q2 are set at different stages to have different impedances of the bypass module 303, and the different values can be used for power supply of the dimmer and transmission of dimming data.

When the second control signal Ctrl2 and the third control signal Ctrl3 are both at low level, the second transistor Q2 is turned off, and the first transistor Q1 operates in the linear region and continues to output the supply voltage Vcc. At this point, the bypass module 303 is turned off for power transfer.

According to the LED driving circuit provided by the embodiment of the invention, when leakage detection is carried out and a leakage phenomenon exists, the bypass module is intermittently conducted to carry out leakage judgment, meanwhile, the power supply path between the high-voltage starting module and the dimming module is turned off to carry out leakage protection, when no leakage exists, the bypass module is conducted, the alternating current input power supply, the dimmer and the bypass module form a conductive loop, and the power supply of the dimmer and the transmission of dimming data are realized; when no electric leakage exists, the bypass module is turned off, power transmission is achieved, and therefore dimming of the LED lamp is achieved.

Further, the leakage protection circuit performs leakage detection by detecting leakage current generated by the bypass module, and the leakage protection circuit multiplexes the bypass module to realize leakage protection.

When the LED driving circuit with leakage protection is connected in parallel to two ends of the normal LED driving circuit (the LED driving circuit without leakage protection), the dimmer 140 can work normally, the waveform of the dc bus voltage VH carries the dimming information, as shown in fig. 9, the second sampling voltage Vs2 obtained at time t2 is smaller than the first sampling voltage Vs1 obtained at time t1, and the LED driving circuit with leakage protection is always subjected to leakage protection until Vs2 > Vs1.

When the single LED driving circuit is connected in series with the dimmer 140, only the leakage protection circuit 301 is operated, and neither the dimming module 304 nor the power conversion circuit 150 is operated, as shown in fig. 10, the waveform of the dc bus voltage VH does not have dimming information, and only a leakage loop can be generated through the internal capacitance of the dimmer 140. When the leakage protection is performed, if the second sampling voltage Vs2 obtained at the time t2 is smaller than the first sampling voltage Vs1 obtained at the time t1, the leakage protection is performed until Vs2 > Vs1.

Fig. 11 shows a schematic circuit diagram of an LED driving device according to a third embodiment of the present invention. In comparison with the first embodiment of the present invention, the dimmer 140 further includes a second input terminal, the second input terminal of the dimmer 140 is connected to the second ac input terminal, and the second output terminal of the dimmer is connected to the second input terminal of the rectifier bridge.

According to the LED driving circuit provided by the embodiment of the invention, when the leakage detection is carried out and the leakage phenomenon exists, the bypass module is intermittently conducted to carry out the leakage protection, and when the leakage phenomenon does not exist, the bypass module is conducted, the alternating current input power supply, the dimmer and the bypass module form a conductive loop, so that the power supply of the dimmer and the transmission of dimming data are realized; when no electric leakage exists, the bypass module is turned off, power transmission is achieved, and therefore dimming of the LED lamp is achieved.

Fig. 12 shows a schematic circuit diagram of an LED driving device according to a fourth embodiment of the present invention. In comparison with the second embodiment of the present invention, the dimmer 140 further includes a second input terminal, the second input terminal of the dimmer 140 is connected to the second ac input terminal, and the second output terminal of the dimmer is connected to the second input terminal of the rectifier bridge.

According to the LED driving circuit provided by the embodiment of the invention, when an electric leakage phenomenon exists, the bypass module is intermittently conducted to perform electric leakage judgment, meanwhile, the power supply path between the high-voltage starting module and the dimming module is turned off to perform electric leakage protection, and when no electric leakage exists, the bypass module is conducted, the alternating current input power supply, the dimmer and the bypass module form a conductive loop, so that the power supply of the dimmer and the transmission of dimming data are realized; when no electric leakage exists, the bypass module is turned off, power transmission is achieved, and therefore dimming of the LED lamp is achieved.

Embodiments of the invention are described above without exhaustive details, nor without limiting the invention to the precise 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 modifications as are suited to the particular use contemplated. The scope of the invention should be determined by the following claims.

Claims

1. An LED driving circuit, comprising:

the leakage protection circuit detects whether a leakage phenomenon exists and generates a leakage control signal;

the dimming circuit is connected with the leakage protection circuit and receives the leakage control signal, when no leakage phenomenon exists, the dimming circuit performs dimming according to the leakage control signal, and when the leakage phenomenon exists, the dimming circuit stops dimming according to the leakage control signal;

the leakage protection circuit is arranged between a first output end and a second output end of the rectifier bridge;

the dimming circuit includes:

The bypass module is connected with the leakage protection circuit and receives a leakage detection signal;

the dimming module is connected with the bypass module and generates a pulse width modulation signal and a bypass control signal according to the voltage of the direct current bus;

when the leakage detection is carried out and the leakage phenomenon exists, the bypass module generates leakage current according to the leakage detection signal, and when the leakage phenomenon does not exist, the bypass module generates bypass current according to the bypass control signal.

2. The LED driving circuit of claim 1, wherein the leakage protection circuit generates a leakage detection signal and determines whether a leakage phenomenon exists according to a dc bus voltage with dimming data.

3. The LED driving circuit of claim 2, wherein the dimming circuit generates a leakage current according to the leakage detection signal when the leakage detection is performed and the leakage phenomenon is present, and parses dimming data from the dc bus voltage when the leakage phenomenon is not present, and generates the pulse width modulation signal according to the dimming data.

4. The LED driving circuit according to claim 1, wherein the leakage protection circuit multiplexes the bypass module to perform leakage detection, and the leakage detection signal controls intermittent conduction of the bypass module when the leakage detection is performed and a leakage phenomenon exists; and when no leakage phenomenon exists, the bypass control signal controls the bypass module to be switched on or off.

5. The LED driving circuit of claim 1, wherein the dimming module is further connected to the leakage protection circuit, receives a leakage control signal, and performs dimming when there is no leakage and stops dimming when there is leakage according to the leakage control signal.

6. The LED driving circuit of claim 5, wherein the bypass module comprises a second transistor, a first diode, a second resistor, and a third resistor,

the second transistor and the third resistor are connected in series between the first output end and the second output end of the direct current bus voltage;

the grid electrode of the second transistor is connected with a second output end of the direct current bus voltage through a second resistor;

the anode of the first diode is connected with the leakage protection circuit, and the cathode of the first diode is connected with the grid electrode of the second transistor;

the anode of the second diode is connected with the dimming module, and the cathode of the second diode is connected with the grid electrode of the second transistor;

the first node between the second transistor and the third resistor outputs a sampling signal of the leakage current or a sampling signal of the bypass current.

7. The LED driving circuit of claim 6, wherein the leakage detection signal controls the second transistor to be intermittently turned on when there is a leakage phenomenon, and the power supply forms a leakage current loop with the second transistor and the third resistor.

8. The LED driving circuit of claim 6, wherein the bypass control signal controls the second transistor to be turned on and off when there is no leakage, and the power supply forms a bypass loop with the second transistor and the third resistor.

9. The LED driving circuit of claim 1, wherein the dimming circuit further comprises:

the high-voltage starting module is connected with the leakage protection circuit and the bypass module and generates a power supply voltage according to the voltage of the direct-current bus;

and when no leakage phenomenon exists, the high-voltage starting module supplies power to the dimming module according to the leakage control signal.

10. The LED driving circuit of claim 9, wherein the high voltage start-up module comprises a first transistor, a voltage regulator, a first resistor, a third diode, a fourth diode, a first capacitor, and a first switch,

the first resistor and the voltage stabilizing tube are connected in series between a first output end and a second output end of the direct current bus voltage;

the grid electrode of the first transistor is connected with a second node between the first resistor and the voltage stabilizing tube;

the anode of the third diode is connected with the second output end of the direct current bus voltage through the first capacitor, and the cathode of the third diode is connected with the grid electrode of the first transistor;

The anode of the fourth diode is connected with the node between the first transistor and the second transistor, and the cathode of the fourth diode is connected with the anode of the third diode;

a third node between the third diode and the fourth diode outputs a supply voltage, and the third node is connected with the dimming module through the first switch;

the control end of the first switch receives the leakage control signal and is closed and opened according to the leakage control signal.

11. The LED driving circuit of claim 10, wherein the leakage detection signal controls the second transistor to be intermittently turned on when the leakage detection is performed and the leakage phenomenon occurs, the power supply forming a leakage current loop with the first transistor, the second transistor, and the third resistor.

12. The LED driving circuit of claim 10, wherein the bypass control signal controls the second transistor to be turned on and off when there is no leakage, and the power supply forms a bypass loop with the first transistor, the second transistor and the third resistor.

13. The LED driving circuit of claim 10, wherein the power supply forms a power supply loop with the first transistor, the fourth diode and the first capacitor.

14. The LED driving circuit according to claim 1 or 10, wherein the dimming module comprises:

The voltage detection unit is used for generating a bypass control signal according to the voltage of the direct current bus, and the bypass control signal controls the on and off of the bypass module;

the data acquisition unit is used for generating a data signal according to the voltage of the direct current bus;

and the control unit is connected with the data acquisition unit and is used for generating a pulse width modulation signal according to the data signal.

15. The LED driving circuit according to claim 14, wherein the voltage detecting unit includes a first comparator, a second comparator, a third operational amplifier, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a second switch, and a third switch;

the fifth resistor and the sixth resistor are connected in series between the first output end and the second output end of the direct current bus voltage;

the first input end of the first comparator is connected with a node between the fifth resistor and the sixth resistor, the second input end receives a first reference voltage, and the output end outputs a second control signal;

the first input end of the second comparator is connected with a node between the fifth resistor and the sixth resistor, the second input end receives the second reference voltage, and the output end outputs a third control signal;

the first input end of the third operational amplifier receives the bypass current sampling signal from the bypass module, the second input end receives a third reference voltage through a seventh resistor and a second switch, and is connected with the second output end of the DC bus voltage through a fourth resistor, and receives a fourth reference voltage through the third switch, and the output end outputs a bypass control signal;

The second control signal controls the closing and opening of the second switch, and the third control signal controls the closing and opening of the third switch.

16. The LED driving circuit according to claim 3, wherein the leakage protection circuit includes:

the voltage sampling module is used for obtaining direct current bus voltage and sampling the direct current bus voltage to obtain sampling voltage;

the leakage flow control module is connected with the voltage sampling module and is used for generating a sampling control signal and a leakage detection signal according to the sampling voltage and the reference voltage;

the leakage judging module is connected with the voltage sampling module and the leakage flow control module and is used for acquiring a first sampling voltage at a first sampling time and a second sampling voltage at a second sampling time according to the sampling control signal, judging whether a leakage phenomenon exists or not and generating a leakage control signal according to the first sampling voltage and the second sampling voltage, wherein the first sampling time is earlier than the second sampling time.

17. The LED driving circuit of claim 16, wherein the leakage current control module generates the leakage current detection signal when or after the dc bus voltage is greater than a reference voltage.

18. The LED driving circuit of claim 16, wherein the leakage current linearly rises to a preset current value or linearly falls after a preset time period.

19. The LED driving circuit of claim 16, wherein the leakage current curve rises to a predetermined current value or the curve falls after a predetermined time.

20. The LED driving circuit according to claim 16, wherein the first sampling timing is before the generation of the leakage current or when the generation of the leakage current starts, and the second sampling timing is before the linear decrease of the leakage current.

21. The LED driving circuit of claim 16, wherein the first sampling instant and the second sampling instant are during a linear rise of the leakage current.

22. The LED driving circuit according to claim 16, wherein when the second sampling voltage is less than or equal to the first sampling voltage, a leakage phenomenon exists;

when the second sampling voltage is larger than the first sampling voltage, no leakage phenomenon exists.

23. The LED driving circuit according to claim 16, wherein a leakage phenomenon exists when the second sampling voltage is less than or equal to a sum of the first sampling voltage and a preset bias voltage;

When the second sampling voltage is larger than the sum of the first sampling voltage and a preset bias voltage, no leakage phenomenon exists.

24. The LED driving circuit according to claim 1, wherein the leakage protection circuit detects whether or not there is a leakage phenomenon upon power-up, and the dimming circuit operates normally when there is no leakage phenomenon; when the leakage phenomenon exists, the dimming circuit does not work, and the leakage detection is repeated until the leakage phenomenon does not exist.

25. A control method of the LED driving circuit according to any one of claims 1 to 24, comprising:

detecting whether an electric leakage phenomenon exists or not and generating an electric leakage control signal;

when no leakage occurs, dimming is started according to the leakage control signal, and when leakage occurs, dimming is stopped according to the leakage control signal.

26. The control method according to claim 25, characterized by further comprising:

and generating a leakage detection signal, and judging whether a leakage phenomenon exists according to the direct current bus voltage with the dimming data.

27. The control method according to claim 26, characterized by further comprising:

when the electric leakage detection is carried out or the electric leakage phenomenon exists, the electric leakage is generated according to the electric leakage detection signal, when the electric leakage phenomenon does not exist, the dimming data are analyzed from the direct current bus voltage, and the pulse width modulation signal is generated according to the dimming data so as to carry out dimming.

28. The control method according to claim 27, characterized by further comprising:

when no leakage phenomenon exists, generating a bypass control signal according to the voltage of the direct current bus; and

generating a bypass current according to the bypass control signal;

the current path of the leakage current is the same as the current path of the bypass current.

29. The control method according to claim 25, characterized by further comprising:

generating a power supply voltage according to the DC bus voltage; and

controlling the power supply according to the leakage control signal, thereby controlling whether dimming is performed,

and when the electric leakage detection is carried out and the electric leakage phenomenon exists, the power supply is stopped according to the electric leakage control signal to stop dimming.

30. The method of claim 25, wherein the step of dimming comprises:

generating a data signal according to the DC bus voltage; and

generating a pulse width modulation signal according to the data signal.

31. The control method according to claim 27, characterized in that the step of detecting whether or not there is an electric leakage phenomenon includes:

obtaining a direct current bus voltage, and sampling the direct current bus voltage to obtain a sampling voltage;

Generating a sampling control signal and a leakage detection signal according to the sampling voltage and the reference voltage;

and acquiring a first sampling voltage at a first sampling time and a second sampling voltage at a second sampling time according to the sampling control signal, judging whether an electric leakage phenomenon exists or not and generating an electric leakage control signal according to the first sampling voltage and the second sampling voltage, wherein the first sampling time is earlier than the second sampling time.

32. The control method according to claim 31, wherein the leakage detection signal is generated when or after the dc bus voltage is greater than a reference voltage.

33. The control method according to claim 31, wherein the leakage current linearly rises to a preset current value or linearly falls after a preset time is maintained.

34. The control method according to claim 31, wherein the leakage current curve rises to a predetermined current value or the curve falls after the curve rises for a predetermined time.

35. The control method according to claim 31, characterized in that the first sampling timing is before the generation of the leakage current or when the generation of the leakage current starts, and the second sampling timing is before the linear decrease of the leakage current.

36. The control method according to claim 31, characterized in that the first sampling instant and the second sampling instant are during a linear rise of the leakage current.

37. The control method according to claim 31, characterized in that when the second sampling voltage is less than or equal to the first sampling voltage, there is a leakage phenomenon;

38. The control method according to claim 31, wherein when the second sampling voltage is less than or equal to a sum of the first sampling voltage and a preset bias voltage, a leakage phenomenon exists;

39. The control method according to claim 25, wherein upon power-up, whether or not there is a leakage phenomenon is detected, and when there is no leakage phenomenon, dimming is performed; when the leakage phenomenon exists, the dimming is stopped, and the leakage detection is repeated until the leakage phenomenon does not exist.

40. An LED driving device, comprising:

a dimmer, the first input end of which is connected with the first alternating current input end, and generates alternating current input voltage with dimming data based on dimming action;

The first input end of the rectifier bridge is connected with the first output end of the dimmer, the second input end of the rectifier bridge is connected with the second end of the alternating current input, and the rectifier bridge is used for rectifying the alternating current input voltage with dimming data so as to output direct current bus voltage with the dimming data;

the LED driving circuit according to any one of claims 1 to 24, and

the power conversion circuit is connected with the dimming circuit and used for converting the voltage of the direct-current bus into direct-current output voltage according to the pulse width modulation signal output by the LED driving circuit and supplying power to a load;

the leakage protection circuit is arranged between the first output end and the second output end of the rectifier bridge.

41. The LED driving apparatus as recited in claim 40, wherein the power conversion circuit comprises a diode and a power conversion module,

the anode of the diode is connected with the first output end of the direct current bus voltage, and the cathode of the diode is connected with the power conversion module;

the power conversion module is used for converting the direct-current bus voltage into direct-current output voltage according to the pulse width modulation signal and supplying power to a load.

42. The LED driving apparatus according to claim 40, wherein the dimmer further comprises a second input terminal, the second input terminal of the dimmer being connected to the ac input second terminal, the second output terminal of the dimmer being connected to the second input terminal of the rectifier bridge.