阅读说明：本技术 可控硅调光驱动电路及其控制方法 (Silicon controlled rectifier dimming driving circuit and control method thereof ) 是由 何婉玥 于 2020-04-17 设计创作，主要内容包括：本发明公开了一种可控硅调光驱动电路及其控制方法,其中,可控硅调光驱动电路,包括：电流调节电路,包括调整管；交流输入经可控硅调光器和整流桥得到输入电压对负载供电,所述电流调节电路的两端分别与输入电压的高低电位端连接；第一控制器,与所述调整管的控制端连接；通过调节调整管的控制端使得电流调节电路产生泄放电流,使得保持输入电流不低于可控硅调光器的维持电流；第二控制器,与所述调整管的控制端连接；采样流经所述电流调节电路的电流,得到电流采样信号,将所述电流采样信号与第一阈值进行比较。本发明使得可控硅调光电路中具有漏电保护功能,无需设置其他检测回路。(The invention discloses a silicon controlled rectifier dimming drive circuit and a control method thereof, wherein the silicon controlled rectifier dimming drive circuit comprises: the current regulating circuit comprises a regulating tube; the alternating current input obtains input voltage through the silicon controlled rectifier dimmer and the rectifier bridge to supply power to the load, and two ends of the current regulating circuit are respectively connected with the high-low potential end of the input voltage; the first controller is connected with the control end of the adjusting pipe; the control end of the adjusting tube is adjusted to enable the current adjusting circuit to generate a leakage current, so that the input current is not lower than the holding current of the silicon controlled rectifier dimmer; the second controller is connected with the control end of the adjusting pipe; the current flowing through the current regulating circuit is sampled to obtain a current sampling signal, and the current sampling signal is compared with a first threshold value. The invention ensures that the silicon controlled rectifier dimming circuit has the leakage protection function without arranging other detection loops.)

1. A thyristor dimming drive circuit comprising:

the current regulating circuit comprises a regulating tube; the alternating current input obtains input voltage through the silicon controlled rectifier dimmer and the rectifier bridge to supply power to the load, and two ends of the current regulating circuit are respectively connected with the high-low potential end of the input voltage;

the first controller is connected with the control end of the adjusting pipe; the control end of the adjusting tube is adjusted to enable the current adjusting circuit to generate a leakage current, so that the input current is not lower than the holding current of the silicon controlled rectifier dimmer;

the second controller is connected with the control end of the adjusting pipe; the current flowing through the current regulating circuit is sampled to obtain a first current sampling signal, the first current sampling signal is compared with a first threshold value, and when the first current sampling signal is lower than the first threshold value, the phenomenon of electric leakage is judged to exist, and then power is not supplied to a load.

2. The thyristor dimming drive circuit of claim 1, wherein: the current regulation circuit comprises an electric leakage detection mode and a working mode, wherein in the electric leakage detection mode, the second controller controls the current regulation circuit, and in the working mode, the first controller controls the current regulation circuit.

3. The triac dimming drive circuit of claim 2, wherein: and under the electric leakage detection mode, the second controller controls an adjusting tube in the current regulating circuit to be switched on for a period of time, the adjusting tube is used as an electric leakage detection interval, the first current sampling signal is compared with the first threshold value, a comparison result is obtained, and whether a main loop containing a load is switched on or whether a rear-stage circuit can supply power to the load is controlled according to the comparison result.

4. The thyristor dimming drive circuit of claim 3, wherein: the second controller comprises a first comparator, two input ends of the first comparator respectively receive the first current sampling signal and the first threshold, and an output end of the first comparator outputs the comparison result.

5. The triac dimming drive circuit of claim 4, wherein: the silicon controlled rectifier dimming driving circuit further comprises a main loop switch, the main loop switch is connected with a load in series, a control end of the main loop switch is connected with an output end of the first comparator, the first current sampling signal is lower than that of the first threshold, the main loop switch is kept in a disconnected state, and the first current sampling signal is higher than that of the first threshold, and the main loop switch is in a connected state.

6. The triac dimming drive circuit of claim 4 or 5, wherein: the silicon controlled rectifier dimming driving circuit further comprises a rear-stage circuit, the rear-stage circuit receives input voltage and supplies power to a load through the rear-stage circuit, the rear-stage circuit is a switch topology circuit or a linear driving circuit, and a control end of the rear-stage circuit is connected with an output end of the first comparator.

7. The triac dimming drive circuit of claim 4, wherein: the silicon controlled rectifier dimming driving circuit further comprises an input voltage detection circuit, the input voltage detection circuit samples the input voltage in a leakage detection interval, and when the input voltage reaches a second threshold value, the first comparator compares the current sampling signal with the first threshold value.

8. The triac dimming drive circuit of claim 7, wherein: in the leakage detection mode, the adjusting tube is in a complete conduction state; in the working mode, the adjusting pipe works in a linear state or an off state.

9. The triac dimming drive circuit of claim 8, wherein: and in the leakage detection mode, when the input voltage reaches a second threshold value, controlling the adjusting tube to be in a complete conduction state.

10. The triac dimming drive circuit of claim 8, wherein: the first controller receives the second current sampling signal, and the second current sampling signal is adjusted to approach a third threshold value representing a reference value of the main loop output current.

Technical Field

The invention relates to the technical field of power electronics, in particular to a silicon controlled rectifier dimming driving circuit and a control method thereof.

Background

In a thyristor dimming driving circuit, a thyristor regulator (Traic Dimmer) performs dimming through phase control adjustment, that is, the output current is adjusted by changing the magnitude of a conduction phase angle to realize dimming. In the conduction process of the silicon controlled regulator, a maintaining current for maintaining the operation of the silicon controlled regulator is required to be achieved. When the output current to the load is small, the total input current of the power supply is easily lower than the maintaining current of the silicon controlled rectifier, so that a bleeder circuit is usually required to be arranged, and when the output current to the load is small, the bleeder circuit generates the bleeder current to improve the total input current, thereby satisfying the maintaining current of the silicon controlled rectifier, and ensuring the normal work of the driving circuit and the realization of the dimming function.

As shown in fig. 1, an active bleeder circuit of the prior art is illustrated. The input current is sampled through the resistor R02, and the leakage current iblr is controlled, so that a sampling signal representing the total input current is not less than VREF0, and the conduction of the thyristor is ensured. The bleeder circuit comprises a resistor R01 and a switch tube M00 which are mutually connected in series, the bleeder circuit is controlled by an operational amplifier U04, the operational amplifier U04 respectively receives a sampling signal representing input total current and VREF0, and the sampling signal and the VREF0 are compared to control the switch tube M00.

However, the related art triac dimming driving circuit does not have a leakage protection function. In the process of installing the load, partial connection may occur in the process of installing the load, and if a human body is contacted carelessly at this time, electric shock is easy to occur, and the operation safety is influenced. Especially in the case of double-end input, one end is generally inserted into the lamp holder and then the other end, and since the operator needs to hold the end of the lamp tube by hand, the operator may touch the conductive metal at the end, which is prone to electric shock.

However, in the prior art, there is no protection circuit and structure for solving the technical problem.

Disclosure of Invention

The invention aims to provide a silicon controlled dimming driving circuit with a leakage protection function and a control method thereof, which are used for solving the technical problem that the leakage protection cannot be realized in the prior art so as to improve the safety.

In order to achieve the above object, the present invention provides a thyristor dimming driving circuit, including:

the current regulating circuit comprises regulating tubes which are mutually connected in series; the alternating current input obtains input voltage through the silicon controlled rectifier dimmer and the rectifier bridge to supply power to the load, and two ends of the current regulating circuit are respectively connected with the high-low potential end of the input voltage;

the first controller is connected with the control end of the adjusting pipe; the control end of the adjusting tube is adjusted to enable the current adjusting circuit to generate a leakage current, so that the input current is not lower than the holding current of the silicon controlled rectifier dimmer;

the second controller is connected with the control end of the adjusting pipe; the current flowing through the current regulating circuit is sampled to obtain a current sampling signal, the first current sampling signal is compared with a first threshold value, when the first current sampling signal is lower than the first threshold value, the phenomenon of electric leakage is judged to exist, and then power is not supplied to a load.

Optionally, the thyristor dimming driving circuit includes a leakage detection mode and a working mode, the second controller controls the current adjusting circuit in the leakage detection mode, and the first controller controls the current adjusting circuit in the working mode.

Optionally, in the leakage detection mode, the second controller controls the adjusting tube in the current adjusting circuit to be turned on for a period of time, as a leakage detection interval, compares the first current sampling signal with the first threshold, obtains a comparison result, and controls whether the main loop including the load is turned on or whether the post-stage circuit enables power supply to the load according to the comparison result.

Optionally, the second controller includes a first comparator, two input ends of the first comparator respectively receive the first current sampling signal and the first threshold, and an output end of the first comparator outputs the comparison result.

Optionally, the silicon controlled rectifier dimming driving circuit further includes a main loop switch, the main loop switch is connected in series with the load, a control end of the main loop switch is connected to an output end of the first comparator, the main loop switch keeps a disconnected state when the current sampling signal is lower than the first threshold, and the main loop switch is in a connected state when the current sampling signal is higher than the first threshold.

Optionally, the silicon controlled rectifier dimming driving circuit further includes a back-stage circuit, the back-stage circuit receives input voltage, the load is powered through the back-stage circuit, the back-stage circuit is a switching topology circuit or a linear driving circuit, and a control end of the back-stage circuit is connected with an output end of the first comparator.

Optionally, the scr dimming driving circuit further includes an input voltage detection circuit, the input voltage detection circuit samples the input voltage in a leakage detection interval, and when the input voltage reaches a second threshold, the first comparator compares the current sampling signal with the first threshold.

Optionally, in the leakage detection mode, the adjusting tube is in a complete conduction state; in the working mode, the adjusting pipe works in a linear state or an off state.

Optionally, in the leakage detection mode, when the input voltage reaches the second threshold, the adjusting tube is controlled to be in a complete conduction state.

Optionally, a second resistor is connected in series in the main loop, the second resistor samples the output current flowing through the main loop to obtain a second current sampling signal representing the output current flowing through the main loop, and the first controller receives the second current sampling signal and adjusts the second current sampling signal to approach a third threshold representing the reference value of the output current of the main loop.

Optionally, a third resistor is disposed between the adjusting tube and the ground terminal, the second resistor samples a current flowing through the adjusting tube to obtain the first sampling signal, the first controller and the second controller respectively receive the first sampling signal, and in the leakage detection mode, the second controller compares the first sampling signal with the first threshold; in the working mode, the first sampling signal is adjusted to approach a fourth threshold value, so that the output current of the main loop is higher than the holding current of the thyristor.

Another technical solution of the present invention is to provide a method for controlling a thyristor dimming driving circuit, including the steps of:

after the power is on, entering a leakage detection mode, enabling an adjusting tube in a current adjusting circuit to be conducted, sampling current flowing through the current adjusting circuit to obtain a first current sampling signal, comparing the first current sampling signal with a first threshold value, obtaining a comparison result, and controlling whether a main loop containing a load is conducted or whether a rear-stage circuit can supply power to the load according to the comparison result;

when the first current sampling signal is lower than the first threshold, the main loop switch is kept in an off state, or a rear-stage circuit is not enabled, and when the first current sampling signal is higher than the first threshold, the main loop switch is in an on state, or the rear-stage circuit is enabled to supply power to a load, so that the main loop switch enters a working mode.

Optionally, the current regulation circuit is controlled by the second controller in the leakage detection mode, and controlled by the first controller in the working mode.

Optionally, the first controller is connected with the control end of the adjusting pipe; the control end of the adjusting tube is adjusted to enable the current adjusting circuit to generate a leakage current, so that the input current is not lower than the holding current of the silicon controlled rectifier dimmer; the second controller is connected with the control end of the adjusting pipe; the current flowing through the current regulating circuit is sampled to obtain a current sampling signal, the first current sampling signal is compared with a first threshold value, when the current sampling signal is lower than the first threshold value, the phenomenon of electric leakage is judged to exist, and then power is not supplied to a load.

Compared with the prior art, the technical scheme of the invention has the following advantages: the invention reuses the current regulating circuit in the silicon controlled rectifier dimming circuit, sets a leakage detection mode and a working mode by differently controlling the current regulating circuit, completes leakage detection after electrification and then enters the working mode, and the current regulating circuit realizes the discharge function in the working mode. The invention multiplexes the current regulating circuit as the part for detecting the electric leakage, thereby having the function of electric leakage protection in the silicon controlled rectifier dimming circuit without arranging other detecting loops.

Drawings

Fig. 1 is a schematic structural diagram of a prior art thyristor dimming driving circuit;

fig. 2 is a schematic structural diagram of a thyristor dimming driving circuit according to a first embodiment of the invention;

FIG. 3 is a schematic diagram of a first comparator;

fig. 4 is a schematic structural diagram of a second embodiment of the thyristor dimming driving circuit according to the invention.

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.

In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale, which is only used for convenience and clarity to assist in describing the embodiments of the present invention.

As shown in fig. 2, the basic structure of the thyristor dimming driving circuit of the present invention is illustrated, and the basic structure includes:

the current regulating circuit comprises a regulating tube M00 and a first resistor R01 which are mutually connected in series; the alternating current input obtains an input voltage Vin through a silicon controlled dimmer U02 and a rectifier bridge U01 to supply power to a load, and two ends of the current regulating circuit are respectively connected with a high-potential end and a low-potential end of the input voltage Vin; the first resistor R01 is an optional component and can be used for limiting current;

the first controller is connected with the control end of the adjusting pipe M00; the control end of the adjusting tube M00 is adjusted to enable the current adjusting circuit to generate the leakage current iblr, so that the input current is not lower than the holding current of the silicon controlled dimmer;

the second controller is connected with the control end of the adjusting pipe M00; the current flowing through the current regulating circuit is sampled to obtain a first current sampling signal Vs1, the first current sampling signal Vs1 is compared with a first threshold Vth1 within a period of time after power-on, and when the first current sampling signal Vs1 is lower than the first threshold Vth1, the phenomenon of electric leakage is judged to exist, and then power is not supplied to a load.

The silicon controlled rectifier dimming driving circuit comprises a leakage detection mode and a working mode, the second controller controls the current adjusting circuit in the leakage detection mode, and the first controller controls the current adjusting circuit in the working mode.

In the leakage detection mode, the second controller controls the regulating tube M00 in the current regulating circuit to be turned on for a period of time, as a leakage detection interval t1, compares the first current sampling signal Vs1 with the first threshold Vth1, obtains a comparison result, and controls whether a main loop including a load is turned on or whether a post-stage circuit U03 enables power supply to the load according to the comparison result. The comparison is performed by a first comparator, referring to fig. 3, which illustrates a first comparator Comp1, included in the second controller, two inputs of the first comparator Comp1 respectively receive the first current sampling signal Vs1 and the first threshold Vth1, and an output of the first comparator outputs the comparison result Vctrl. The leakage detection interval t1 may be a period of continuous conduction or a period of intermittent conduction, and leakage detection is implemented in this interval.

The silicon controlled rectifier dimming driving circuit further comprises a main loop switch M01, the main loop switch M01 is connected with a load in series, a control end of the main loop switch M01 is connected with an output end of the first comparator Comp1, when the first current sampling signal Vs1 is lower than the first threshold Vth1, the main loop switch M01 keeps in a disconnected state, and when the first current sampling signal Vs1 is higher than the first threshold Vth1, the main loop switch M01 is in a connected state.

Besides controlling the conducting state of the main circuit switch M01, the main circuit switch M01 may be omitted, or, in the case of keeping the main circuit switch M01, the subsequent circuit U03 may be controlled to control whether to supply power to the load, that is, the scr dimming driving circuit further includes the subsequent circuit U03, the subsequent circuit U03 receives the input voltage Vin and supplies power to the load through the subsequent circuit U03, the subsequent circuit is a switching topology circuit or a linear driving circuit, and a control terminal of the subsequent circuit is connected to the output terminal of the first comparator. The switching topology circuit can adopt buck, boost and other types of topologies.

The thyristor dimming driving circuit further comprises an input voltage detection circuit, wherein the input voltage detection circuit samples the input voltage Vin in a leakage detection interval, and when the input voltage Vin reaches a second threshold Vth2, or a sampling signal of the input voltage is compared with a corresponding reference voltage, the first comparator Comp1 compares the current sampling signal with the first threshold.

In the leakage detection mode, the adjusting tube is in a complete conduction state; in the working mode, the adjusting pipe works in a linear state or an off state. In the leakage detection mode, when the input voltage reaches a second threshold Vth2, the adjusting tube is controlled to be in a complete conduction state.

The second resistor R02 is connected in series in the main loop, the second resistor R02 samples the output current flowing through the main loop to obtain a second current sampling signal VS2 which represents the output current flowing through the main loop, and the first controller receives the second current sampling signal VS2 and makes the second current sampling signal approach a third threshold Vth3 which represents the reference value of the output current of the main loop by adjustment.

As shown in fig. 4, a second embodiment of the present invention is illustrated, wherein the second embodiment is different from the first embodiment mainly in the arrangement of the sampling resistor. A third resistor R03 is arranged between the adjusting tube M00 and a ground terminal, the current flowing through the adjusting tube M00 is sampled through the third resistor R03 to obtain the first sampling signal, the first controller and the second controller respectively receive the first sampling signal, and in a leakage detection mode, the second controller compares the first sampling signal with the first threshold Vth 1; in the working mode, the first sampling signal is adjusted to approach a fourth threshold Vth4, so that the output current of the main loop is higher than the holding current of the thyristor.

Another technical solution of the present invention is to provide a method for controlling a thyristor dimming driving circuit, including the steps of:

after the power is on, entering a leakage detection mode, enabling an adjusting tube in a current adjusting circuit to be conducted, sampling current flowing through the current adjusting circuit to obtain a current sampling signal, comparing the current sampling signal with the first threshold value, obtaining a comparison result, and controlling whether a main loop containing a load is conducted or whether a rear-stage circuit can supply power to the load according to the comparison result;

when the current sampling signal is lower than the first threshold value, the main loop switch is kept in an off state, or a rear-stage circuit is not enabled, and when the current sampling signal is higher than the first threshold value, the main loop switch is in an on state, or the rear-stage circuit is enabled to supply power to a load, so that the main loop switch enters a working mode.

The invention comprises a leakage detection mode and a working mode, wherein in the leakage detection mode, the second controller controls the current regulating circuit, and in the working mode, the first controller controls the current regulating circuit.

The first controller is connected with the control end of the adjusting pipe; the control end of the adjusting tube is adjusted to enable the current adjusting circuit to generate a leakage current, so that the input current is not lower than the holding current of the silicon controlled rectifier dimmer; the second controller is connected with the control end of the adjusting pipe; the current flowing through the current regulating circuit is sampled to obtain a current sampling signal, the current sampling signal is compared with a first threshold value within a period of time after the current sampling signal is electrified, and when the current sampling signal is lower than the first threshold value, the phenomenon of electric leakage is judged to exist, and then power is not supplied to a load.

Although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.

The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.