Lighting circuit and control method thereof

Abstract

The present invention provides a lighting circuit and control method thereof. A busbar of the lighting circuit receives an input signal, which is rectified and adjusted to obtain an input voltage. This input voltage is converted to obtain a control signal. This control signal controls at least one controlled circuit to obtain a reference signal, which is used to configure the operating parameters of the lighting circuit after it is connected to a power-frequency AC power supply. This invention has an extremely high level of integration, greatly simplifies the system, and reduces operating costs.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and in particular to a lighting circuit and a control method thereof. Background Art

[0002] Commercial LED driver power supplies (such as some high-power street lamps) require fine-tuning of the output current or open-circuit protection voltage at a later stage (before the power supply is installed).

[0003] In existing designs, two setting lines are usually added to the output end of the lighting circuit, which are transmitted to the main controller of the lighting circuit through an optocoupler or a wireless module (such as an NFC device) to change the duty cycle of the controller output, thereby fine-tuning the output current or other parameters.

[0004] However, the existing design solutions are extremely expensive and not conducive to large-scale production. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-cost lighting circuit and control method, which solves the problem of high cost and disadvantageous large-scale production of design solutions in the prior art.

[0006] Based on the above objectives, the present invention provides a lighting circuit, comprising:

[0007] The bus receives an input signal, and the input signal is rectified and adjusted to obtain an input voltage;

[0008] a detection circuit, receiving the input voltage, converting the input voltage to output a control signal;

[0009] The reference signal generating circuit receives the control signal and controls at least one controlled circuit in the reference signal generating circuit to output a reference signal, wherein the reference signal is used to configure the operating parameters of the lighting circuit after it is connected to the industrial frequency AC power supply.

[0010] Optionally, at least one diode is further included; the anode of the diode receives the input signal, and the cathode of the diode outputs the input voltage.

[0011] Optionally, it also includes a rectifier bridge, a filter capacitor and a shaping circuit, the input end of the rectifier bridge receives the input signal, the filter capacitor and the rectifier bridge are connected in parallel to output the input voltage, and the shaping circuit is connected to the output end of the rectifier bridge; when the detection circuit receives the input voltage, the shaping circuit generates a pull-down current to adjust the input voltage waveform to obtain the control signal.

[0012] Optionally, the operating parameters include at least one of an input voltage, an output voltage, a power supply voltage, an output current, and a switching frequency when the lighting circuit is a switching circuit.

[0013] Optionally, the reference signal generating circuit further receives a first voltage, and adjusts the first voltage according to the control signal to obtain the reference signal.

[0014] The reference signal generating circuit includes a plurality of controlled circuits, and the plurality of controlled circuits are connected in series or in parallel.

[0015] Optionally, the reference signal generating circuit further includes at least one fuse circuit and a fuse reading circuit.

[0016] The fuse circuit corresponds to the controlled circuit in a one-to-one manner, and the control signal controls whether the fuse circuit is blown;

[0017] The fuse reading circuit is connected to the fuse circuits to read the state of each fuse circuit and thereby control the corresponding controlled circuit.

[0018] Optionally, each of the fuse circuits includes a switch tube and a fuse, and the switch tube and the fuse are connected in series;

[0019] The fuse reading circuit includes at least one hysteresis comparator, each hysteresis comparator corresponds to a corresponding fuse circuit; the input end of the hysteresis comparator is connected to the common connection end of the corresponding fuse and the switching tube, and the output end of the hysteresis comparator is connected to the control end of the corresponding controlled circuit.

[0020] Optionally, the reference signal generating circuit further includes a memory, which stores the reference signal; when the control circuit is powered on next time, the reference signal in the memory is read to configure the operating parameters.

[0021] Optionally, the input signal is a pulse signal, and the reference signal is proportional to the pulse width or duty cycle or specific timing of the pulse signal.

[0022] The present invention also provides a method for controlling a lighting circuit.

[0023] The busbar of the lighting circuit receives an input signal, and the input signal is rectified and adjusted to obtain an input voltage;

[0024] Converting the input voltage to obtain a control signal;

[0025] The control signal controls at least one controlled circuit to obtain a reference signal, and the reference signal is used to configure the operating parameters of the lighting circuit after it is connected to the industrial frequency AC power supply.

[0026] Optionally, at least one diode is used, wherein the anode of the diode receives the input signal and the cathode of the diode outputs the input voltage.

[0027] Optionally, the lighting circuit includes a rectifier bridge, a filter capacitor and a shaping circuit, the input end of the rectifier bridge receives the input signal, the filter capacitor and the rectifier bridge are connected in parallel and output the input voltage, and the shaping circuit is connected to the output end of the rectifier bridge; when the input voltage is detected, the shaping circuit generates a pull-down current to adjust the input voltage waveform to obtain the control signal.

[0028] Optionally, the operating parameters include at least one of an input voltage, an output voltage, a power supply voltage, an output current, and a switching frequency when the lighting circuit is a switching circuit.

[0029] Optionally, the first voltage is adjusted according to the control signal to obtain the reference signal.

[0030] Optionally, the controlled circuit includes multiple controlled circuits, and the multiple controlled circuits are connected in series or in parallel.

[0031] Optionally, a memory is used to store the reference signal; when the lighting circuit is powered on next time, the reference signal in the memory is read to configure the operating parameters.

[0032] Optionally, the input signal is a pulse signal, and the reference signal is proportional to the pulse width or duty cycle or specific timing of the pulse signal.

[0033] Compared with the prior art, the present invention has the following advantages: it detects the input voltage, converts it according to the input voltage, and obtains a control signal; the control signal controls at least one controlled circuit to generate a reference signal. The present invention has a simple system and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram of a first embodiment of a lighting circuit according to the present invention;

[0035] Figure 2 This is a schematic diagram of a second embodiment of a lighting circuit according to the present invention;

[0036] Figure 3 This is a schematic diagram of a third embodiment of a lighting circuit according to the present invention;

[0037] Figure 4 This is a schematic diagram of a reference signal generating circuit embodiment 1;

[0038] Figure 5 This is a schematic diagram of a second embodiment of a reference signal generating circuit;

[0039] Figure 6 This is a schematic diagram of a third embodiment of a reference signal generating circuit;

[0040] Figure 7Schematic diagram of an embodiment for applying a reference signal to set the output current of a lighting circuit. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments and covers any substitution, modification, equivalent method and solution made within the spirit and scope of the present invention.

[0042] In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can also fully understand the present invention without description of these details.

[0043] The present invention is described in more detail in the following paragraphs with reference to the accompanying drawings. It should be noted that the drawings are simplified and not to exact proportions, in order to facilitate and clearly illustrate the embodiments of the present invention.

[0044] like Figure 1 The figure shows a schematic diagram of a first embodiment of a lighting circuit according to the present invention. The lighting circuit includes an input capacitor C00, two diodes, and a control circuit. The anodes of the two diodes are connected to the two ends of the input power supply, and the cathodes of the two diodes are connected. The voltage at the connected terminals is the input voltage VIN obtained by rectifying the input power supply voltage through the two diodes. A specific embodiment of the control circuit is as follows: the control circuit includes a thyristor J1, a first detection circuit U01, and a reference signal circuit U02. The first terminal of thyristor J1 receives the input voltage VIN, and its control terminal is grounded. The second terminal of thyristor J1 is connected to the first capacitor C01 through a first regulator U04. The first capacitor voltage VCC is used to power the lighting circuit, and the first regulator U04 is used to regulate the first capacitor voltage VCC. The first detection circuit U01 detects the voltage at the second terminal of thyristor J1. Since the input voltage VIN is a pulse signal, the voltage at the second terminal of thyristor J1 is also a pulse signal and can represent the pulse signal information of the input voltage VIN. The voltage at the second terminal of thyristor J1 is recorded as the first pulse voltage. The first detection circuit U01 performs conversion based on the detected first pulse voltage V1 and outputs control signals VC1-VCn (n>0). The reference signal generation circuit U02 receives the control signals VC1-VCn and the supply voltage VCC and outputs a reference signal VREF. The reference signal generated in this embodiment is a voltage signal, but the reference signal in the present invention is not limited to voltage signals. In other embodiments, the reference signal generated can also be a current signal or a switching frequency signal.

[0045] The AC input power supply in the embodiment of the present invention is a pulse power supply, and the control signal reflects the pulse width or duty cycle or specific timing information of the pulse power supply. The reference signal obtained according to the control signal is proportional to the pulse width or duty cycle or specific timing of the pulse power supply or has other specific relationships, which can make the setting of the reference signal more flexible. In this embodiment, when a pulse power supply is given, the input voltage can be obtained through the two diodes provided, instead of through the rectifier bridge U00 of the main circuit, thereby avoiding the large capacitor C00 in the main circuit affecting the accuracy of the input voltage VIN detection. When the lighting circuit of the present invention is installed as a finished product, it is connected to an industrial frequency AC power supply, and the industrial frequency AC power supply needs to pass through the rectifier bridge U00 and the large capacitor C00 of the main circuit. The diodes D1 and D2 provided do not affect the operation of the lighting circuit after the finished product is installed. The reference signal generating circuit U02 of the present invention can generate a reference signal VREF by a one-time fuse, or a memory is set to store the reference signal VREF. After the finished lighting circuit is installed, the reference signal VREF adjusts the operating parameters of the lighting circuit, such as the input voltage, output voltage, power supply voltage, output current, and the duty cycle when the lighting circuit is a switching circuit.

[0046] like Figure 2 As shown, it illustrates the principle diagram of the second embodiment of the lighting circuit of the present invention. Figure 1 The difference between the embodiments is only the different ways of obtaining the input voltage VIN. The specific differences are as follows: the rectifier bridge of the main circuit receives the input power supply and obtains the input voltage VIN through the large capacitor C00 and the shaping circuit. The input end of the shaping circuit is connected to the first end of the JEFT tube. It is known that when the AC input power supply is a pulse signal, a smooth input voltage signal will be obtained after filtering by the rectifier circuit and the large capacitor, making it difficult for the detection circuit to accurately detect the pulse width of each pulse signal and the time width between the pulse widths, thereby making it difficult to obtain an ideal reference signal. However, the present invention, by providing a shaping circuit, can generate a pull-down current to pull down the input voltage at the falling edge of the pulse signal, so that the input voltage waveform matches the input power waveform, that is, the input voltage is also a series of pulse signals and is consistent or close to the absolute value of the input power pulse signal (in practice, it is difficult to achieve that the input voltage waveform is completely consistent with the absolute value of the input power), or, the signal waveform adjusted by the shaping circuit contains input power information.

[0047] like Figure 3 As shown, the schematic diagram of the third embodiment of the lighting circuit of the present invention is shown. Figure 1The difference between the embodiments is only the different ways of obtaining the input voltage VIN. The specific differences are as follows: the rectifier bridge of the main circuit acts as a rectifier circuit, receives the AC input power AC, and obtains the input voltage VIN through the large capacitor C00 and the shaping circuit. The shaping circuit is connected in parallel at both ends of the rectifier bridge. The present invention sets a shaping circuit to generate a pull-down current to pull down the input voltage at the falling edge of the pulse signal, so that the input voltage waveform matches the input power waveform, that is, the input voltage is also a series of pulse signals and the absolute value is consistent or close to the input power pulse signal (in practice, it is difficult to achieve that the input voltage waveform is completely consistent with the absolute value of the input power), or the signal waveform adjusted by the shaping circuit contains input power information. Since the load at the output end of the lighting circuit is capacitive, it will generate a negative current in the bus voltage, which will affect the shaping circuit. Therefore, a high-voltage diode needs to be connected in series on the bus. The shaping circuit designed in this way is more complicated than that of the second embodiment.

[0048] Figure 2 、 Figure 3 In the illustrated embodiment, after the lighting circuit is plugged into the industrial frequency AC power supply, the shaping circuit does not affect the operation of the lighting circuit. The input voltage obtained after rectification and filtering of the industrial frequency AC power supply drives the lighting circuit to operate. The reference signal set before the industrial frequency AC power supply is plugged in adjusts the operating parameters of the lighting circuit.

[0049] like Figure 4As shown in the figure, a schematic diagram of the first embodiment of the reference signal generation circuit according to the present invention is shown, which includes at least one fuse circuit, a fuse reading circuit, and at least one controlled circuit. The fuse reading circuit includes at least one hysteresis comparator, and each fuse circuit, hysteresis comparator, and controlled circuit correspond to each other. A certain fuse circuit includes a fuse Fk and a switching transistor M10k. The fuse Fk and the switching transistor M10k are connected in series. The first end of the fuse circuit is connected to a first capacitor C01, and its second end is grounded. The control terminal of the switching transistor M10k receives a corresponding control signal VCk. The input terminal of each hysteresis comparator U20k is connected to the common connection terminal of the fuse Fk and the switching transistor M10k in the corresponding fuse circuit, where 0 < k <= n, and n represents the number of fuse circuits. The output terminal of each hysteresis comparator U20k is connected to a corresponding controlled circuit. Each controlled circuit includes a switching transistor M20k and a resistor Rk connected in parallel. The control terminal of the switching transistor M20k is connected to the output terminal of the corresponding hysteresis comparator M20k. The various controlled circuits are connected in series to form a first series circuit. The first end of the first series circuit receives a given first voltage VB, and its second end is grounded. The connection terminal between two controlled circuits is used as the output terminal of the reference signal generation circuit to output a reference signal. Since there may be a situation where the fuse is not completely blown after programming, or there may be a situation where the switching transistor in the fuse circuit needs to be turned off but is not completely turned off, a hysteresis comparator is used to read the programming state of the fuse. When the voltage at the common connection terminal of the fuse and the switching transistor is close to zero, the hysteresis comparator outputs a signal indicating that the fuse is blown; when the voltage at the common connection terminal of the fuse and the switching transistor is close to the voltage of the first capacitor, the hysteresis comparator outputs a signal indicating that the fuse is not blown. Using a hysteresis comparator can improve the anti-interference performance of the fuse programming result. The present invention can also use other circuit structures to read the programming state of the fuse, not limited to using a hysteresis comparator to implement. Since the fuse is programmed once and irreversible, after the lighting circuit finished product is installed, the reference signal obtained by one-time programming is used to set the working parameters of the lighting circuit.

[0050] As Figure 5 As shown in the figure, a schematic diagram of the second embodiment of the reference signal generation circuit according to the present invention is shown, which includes a plurality of controlled circuits (U1 to Un) and a memory U201. The plurality of controlled circuits are connected in series to form a series circuit. One end of the series circuit receives a first voltage VB, and the other end is grounded. A certain controlled circuit Uk includes a switching transistor Mk and a resistor Rk connected in parallel, where 1 < k < n. Each control signal VC1 to VCn controls a corresponding switching transistor respectively. The common connection terminal between two controlled circuits is used as the output terminal of the reference signal generation circuit to output a reference signal VREF. The memory U201 stores the reference signal VREF. After the lighting circuit finished product is installed, the control circuit reads the initialization information in the memory U201 to obtain the reference signal VREF to set the working parameters of the lighting circuit.

[0051] As Figure 6 As shown in Figure 6 , a schematic diagram of the third embodiment of the reference signal generation circuit according to the present invention is illustrated, which includes a plurality of controlled circuits and a memory U201. The plurality of controlled circuits are connected in parallel to form a parallel circuit. Its first end receives a first current I0, and its second end is grounded. The output end of the parallel circuit outputs a reference signal VREF, and the memory U201 stores the reference signal VREF. The first current I0 is obtained according to a first voltage VB. A certain controlled circuit includes a series-connected switching transistor Mk and a resistor Rk, where 1 < k < n, and each control signal VC1 to VCn controls a corresponding switching transistor respectively. After the lighting circuit is installed as a finished product, the lighting circuit reads the information in the memory U201 to obtain the reference signal VREF to set the operating parameters of the lighting circuit.

[0052] Figure 7 A schematic diagram of an embodiment of the present invention for setting the output current of a lighting circuit using a reference signal is illustrated, which includes a first operational amplifier U03, an adjustment transistor M0, a sampling circuit Rc, and a first regulator U04. The first input terminal of the first operational amplifier U03 receives the reference signal VREF, the second input terminal receives an output current sampling signal VCS, and the output terminal is connected to the control terminal of the adjustment transistor M0. The first end of the adjustment transistor M0 is connected to the LED load, and the second end is grounded through a sampling resistor Rcs. The reference signal VREF in this embodiment is used to control the output current of the lighting circuit.

[0053] Although the above embodiments are separately described and elaborated, for some common technologies involved, in the view of those of ordinary skill in the art, substitutions and integrations can be made between the embodiments. For the content not clearly recorded in one of the embodiments, reference can be made to another embodiment with relevant records.

[0054] The above-described embodiments do not constitute a limitation on the protection scope of this technical solution. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the above embodiments shall be included within the protection scope of this technical solution.

Claims

1. A lighting circuit, characterized in that: include, The bus receives an input signal, and the input signal is rectified and adjusted to obtain an input voltage; a detection circuit, receiving the input voltage, converting the input voltage to output a control signal; The reference signal generating circuit receives the control signal and controls at least one controlled circuit in the reference signal generating circuit to output a reference signal, wherein the reference signal is used to configure the operating parameters of the lighting circuit after it is connected to the industrial frequency AC power supply.

2. The lighting circuit according to claim 1, wherein: The device further comprises at least one diode; an anode of the diode receives the input signal, and a cathode of the diode outputs the input voltage.

3. The lighting circuit according to claim 1, wherein: It also includes a rectifier bridge, a filter capacitor and a shaping circuit, wherein the input end of the rectifier bridge receives the input signal, the filter capacitor and the rectifier bridge are connected in parallel to output the input voltage, and the shaping circuit is connected to the output end of the rectifier bridge; When the detection circuit receives the input voltage, the shaping circuit generates a pull-down current to adjust the input voltage waveform to obtain the control signal.

4. The lighting circuit according to claim 1, wherein: The operating parameters include at least one of an input voltage, an output voltage, a power supply voltage, an output current, and a switching frequency when the lighting circuit is a switching circuit.

5. The lighting circuit according to claim 1, wherein: The reference signal generating circuit further receives a first voltage and adjusts the first voltage according to the control signal to obtain the reference signal.

6. The lighting circuit according to claim 5, characterized in that: The reference signal generating circuit includes a plurality of controlled circuits, and the plurality of controlled circuits are connected in series or in parallel.

7. The lighting circuit according to claim 6, characterized in that: The reference signal generating circuit further includes at least one fuse circuit and a fuse reading circuit, The fuse circuit corresponds to the controlled circuit in a one-to-one manner, and the control signal controls whether the fuse circuit is blown; The fuse reading circuit is connected to the fuse circuits to read the state of each fuse circuit and thereby control the corresponding controlled circuit.

8. The lighting circuit according to claim 7, characterized in that: Each of the fuse circuits includes a switch tube and a fuse, wherein the switch tube and the fuse are connected in series; The fuse reading circuit includes at least one hysteresis comparator, each hysteresis comparator corresponds to a corresponding fuse circuit; the input end of the hysteresis comparator is connected to the common connection end of the corresponding fuse and the switching tube, and the output end of the hysteresis comparator is connected to the control end of the corresponding controlled circuit.

9. The lighting circuit according to claim 5, characterized in that: The reference signal generating circuit further includes a memory for storing the reference signal; when the control circuit is powered on next time, the reference signal in the memory is read to configure the operating parameters.

10. The lighting circuit according to claim 1, characterized in that: The input signal is a pulse signal, and the reference signal is proportional to the pulse width or duty cycle or specific timing of the pulse signal.

11. A method for controlling a lighting circuit, characterized in that: The busbar of the lighting circuit receives an input signal, and the input signal is rectified and adjusted to obtain an input voltage; Converting the input voltage to obtain a control signal; The control signal controls at least one controlled circuit to obtain a reference signal, and the reference signal is used to configure the operating parameters of the lighting circuit after it is connected to the industrial frequency AC power supply.

12. The method for controlling a lighting circuit according to claim 11, wherein: At least one diode is used, wherein the anode of the diode receives the input signal and the cathode of the diode outputs the input voltage.

13. The method for controlling a lighting circuit according to claim 11, wherein: The lighting circuit includes a rectifier bridge, a filter capacitor and a shaping circuit, wherein the input end of the rectifier bridge is connected to the input signal, the filter capacitor and the rectifier bridge are connected in parallel and output the input voltage, and the shaping circuit is connected to the output end of the rectifier bridge; When the input voltage is detected, the shaping circuit generates a pull-down current to adjust the input voltage waveform to obtain the control signal.

14. The method for controlling a lighting circuit according to claim 11, wherein: The operating parameters include at least one of an input voltage, an output voltage, a power supply voltage, an output current, and a switching frequency when the lighting circuit is a switching circuit.

15. The method for controlling a lighting circuit according to claim 11, wherein: The first voltage is adjusted according to the control signal to obtain the reference signal.

16. The method for controlling a lighting circuit according to claim 11, wherein: The controlled circuit includes multiple controlled circuits, and the multiple controlled circuits are connected in series or in parallel.

17. The method for controlling a lighting circuit according to claim 11, wherein: A memory is used to store the reference signal; when the lighting circuit is powered on next time, the reference signal in the memory is read to configure the operating parameters.

18. The method for controlling a lighting circuit according to claim 11, wherein: The input signal is a pulse signal, and the reference signal is proportional to the pulse width or duty cycle or specific timing of the pulse signal.

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