WO2019233489A1

WO2019233489A1 - Dimmable led driving circuit and control method

Info

Publication number: WO2019233489A1
Application number: PCT/CN2019/090443
Authority: WO
Inventors: 牟在鑫; 张攀
Original assignee: 美芯晟科技（北京）有限公司
Priority date: 2018-06-08
Filing date: 2019-06-06
Publication date: 2019-12-12

Abstract

The present invention provides a dimmable LED driving circuit and a control method. The circuit comprises: a silicon controlled dimmer, a bleeder current circuit and an LED circuit. The bleeder current circuit provides a current demanded, when an input voltage does not reach the breakover voltage of the LED circuit, by the silicon controlled dimmer. The dimmable LED driving circuit further comprises a silicon controlled shear wave angle detection circuit and a bleeder current control circuit. After the silicon controlled dimmer is turned on, the silicon controlled shear wave angle detection circuit obtains a first electrical parameter signal representing a silicon controlled shear wave angle; the bleeder current control circuit compares the first electrical parameter signal with a first threshold and controls the bleeder current circuit according to the comparison result; and besides, an output current compensating circuit is additionally arranged to compare the electrical parameter signal with a second threshold and to control the current of the LED circuit according to the comparison result.

Description

一种可调光LED驱动电路及控制方法Dimmable LED driving circuit and control method

优先权声明：本申请要求2018年6月8日提交的申请号为201810590181.6的中国申请，2018年6月15日提交的申请号为201810623766.3的中国申请，以及2018年7月23日提交的申请号为201810812820.9的中国申请的优先权，其全部内容以引用方式并入本申请中。Priority statement: This application requires the Chinese application with application number 201810590181.6 filed on June 8, 2018, the Chinese application with application number 201810623766.3 filed on June 15, 2018, and the application number filed on July 23, 2018 The priority of the Chinese application for 201810812820.9 is incorporated herein by reference in its entirety.

技术领域Technical field

本申请涉及LED驱动电路领域，尤其涉及一种可调光LED驱动电路及控制方法。The present application relates to the field of LED driving circuits, and in particular, to a dimmable LED driving circuit and a control method.

背景技术Background technique

LED驱动通常采用线性驱动方式，具有结构简单，EMI(Electro-Magnetic Interference，电磁干扰)小，并可兼容大部分可控硅调光器实现调光等优势。但是，线性LED驱动在配合可控硅调光器使用时，为了维持可控硅导通，必须要有泄放(bleeder)电流电路。而泄放电流电路需要在特定时间段内运行以维持可控硅调光器的导通状态，这无疑会增加***的损耗，降低***的效率，而无法提高***的应用功率。LED drive usually adopts linear drive method, with simple structure, small EMI (Electro-Magnetic Interference, electromagnetic interference), and can be compatible with most SCR dimmers to achieve dimming and other advantages. However, when a linear LED driver is used with a thyristor dimmer, in order to maintain the thyristor on, a bleeder current circuit is required. The bleeder current circuit needs to be operated within a certain period of time to maintain the on-state of the thyristor dimmer, which will undoubtedly increase the loss of the system, reduce the efficiency of the system, and fail to increase the applied power of the system.

另外，可控硅调光器会将输入电压的波形进行导通角切波，从而产生切向的输出电压波形。当可控硅调光器的导通角度较小，即，可控硅调光器切波后输出的峰值电压接近LED灯的导通电压时，可控硅调光器的切波会出现严重的不对称(例如，切波后的峰值电压会非周期性的大于或小于输出LED电压)，从而导致LED灯出现闪灯问题。如图2所示，V _LED表示LED灯的导通电压。由于可控硅调光器10的切波的不对称性，不同时间周期内的切波后的峰值电压会在V _LED的上下波动(例如，第一个周期内，切波后的峰值电压 Vin_pk1大于V _LED，而在第二个周期内，切波后的峰值电压Vin_pk2小于V _LED)，从而导致LED灯的电流I _LED产生剧烈变化。当该电流变化的频率小于人眼的识别频率时，即出现人眼可见的闪灯现象。 In addition, the thyristor dimmer conducts the conduction angle tangent waveform of the input voltage waveform, thereby generating a tangential output voltage waveform. When the conduction angle of the TRIAC dimmer is small, that is, the peak voltage of the TRIAC dimmer after the wave is cut is close to the on-voltage of the LED lamp, the shear wave of the TRIAC dimmer will be severe. (For example, the peak voltage after the shear wave will be greater or less than the output LED voltage aperiodically), which causes the LED lamp to flash. As shown in Figure 2, V _LED represents the on-voltage of the LED lamp. Due to the asymmetry of the shear wave of the TRIAC dimmer 10, the peak voltage after the shear wave in different time periods will fluctuate up and down the V _LED (for example, the peak voltage after the shear wave Vin_pk1 during the first period) It is greater than V _LED , and in the second period, the peak voltage Vin_pk2 after cutting is smaller than V _LED ), which causes the current I _{LED of the} LED lamp to change drastically. When the frequency of the current change is less than the recognition frequency of the human eye, a flashing phenomenon visible to the human eye occurs.

发明内容Summary of the Invention

为了解决上述问题，本发明提出了一种可调光LED驱动电路及控制方法。In order to solve the above problems, the present invention provides a dimmable LED driving circuit and a control method.

一方面本发明提出了一种可调光LED驱动电路，包括：可控硅调光器、泄放电流电路、LED电路；所述泄放电流电路提供在输入电压未达到所述LED电路的导通电压时所述可控硅调光器所需的电流；所述可调光LED驱动电路还包括：可控硅切波角度检测电路和泄放电流控制电路；所述可控硅调光器导通后，所述可控硅切波角度检测电路获取表征可控硅切波角度的第一电参数信号；所述泄放电流控制电路将所述第一电参数信号与第一阈值进行比较，来控制所述泄放电流电路。In one aspect, the present invention provides a dimmable LED driving circuit, including: a thyristor dimmer, a bleeder current circuit, and an LED circuit; the bleeder current circuit provides a guide when the input voltage does not reach the LED circuit. The current required by the TRIAC dimmer when voltage is applied; the dimmable LED driving circuit further includes: a TRIAC cut-wave angle detection circuit and a bleed current control circuit; the TRIAC dimmer After being turned on, the thyristor cut-wave angle detection circuit obtains a first electrical parameter signal representing the thyristor cut-angle; the bleeder current control circuit compares the first electrical parameter signal with a first threshold value To control the bleeder current circuit.

优选地，所述泄放电流控制电路在检测到所述第一电参数信号大于第一阈值，控制所述泄放电流电路关断，停止提供泄放电流。Preferably, when the bleeder current control circuit detects that the first electrical parameter signal is greater than a first threshold, the bleeder current control circuit controls the bleeder current circuit to be turned off and stops supplying the bleeder current.

优选地，所述泄放电流控制电路将表征流过所述LED电路电流的第二电参数与第三阈值进行比较，当所述第一电参数信号小于所述第一阈值且所述第二电参数信号小于所述第三阈值时，所述泄放电流控制电路控制所述泄放电流电路开启，提供泄放电流。Preferably, the bleeder current control circuit compares a second electrical parameter representing a current flowing through the LED circuit with a third threshold value, when the first electrical parameter signal is smaller than the first threshold value and the second When the electrical parameter signal is less than the third threshold, the bleeder current control circuit controls the bleeder current circuit to be turned on to provide a bleeder current.

优选地，所述第一电参数信号对应于输入电压在一个周期内从所述可控硅调光器的起始导通切波角度开始到周期结束期间的平均值。Preferably, the first electrical parameter signal corresponds to an average value of the input voltage during a period from the start of the TRIAC dimmer to the end of the period.

优选地，所述可控硅切波角度检测电路包括积分电路，所述积分电路用于对输入电压积分，从而提供所述第一电参数信号。Preferably, the thyristor cut-wave angle detection circuit includes an integration circuit, and the integration circuit is configured to integrate an input voltage to provide the first electrical parameter signal.

优选地，所述第一电参数信号对应于在一个第二电参数信号采样周期内的参考电压平均值，所述第二电参数信号表征流过所述LED电路的电流。Preferably, the first electrical parameter signal corresponds to an average value of a reference voltage within a sampling period of the second electrical parameter signal, and the second electrical parameter signal represents a current flowing through the LED circuit.

优选地，所述可控硅切波角度检测电路包括第一运算放大器U1和采样积分电路，所述第一运算放大器U1的正向输入端接第二电参数信号，第一运算放大器U1的反向输入端接第五阈值，第一运算放大器U1的输出端与采样积分电路相连，并且采样积分电路上接参考电压，采样积分电路的输出端接泄放电流控制电路用于将运算处理后的第一电参数信号输入泄放电流控制电路。Preferably, the thyristor cut-wave angle detection circuit includes a first operational amplifier U1 and a sampling integration circuit. A positive input terminal of the first operational amplifier U1 is connected to a second electrical parameter signal. A fifth threshold is connected to the input. The output of the first operational amplifier U1 is connected to the sampling and integrating circuit, and the reference voltage is connected to the sampling and integrating circuit. The output of the sampling and integrating circuit is connected to the bleeder current control circuit for applying the processed The first electrical parameter signal is input to a bleeder current control circuit.

优选地，所述第一电参数信号对应于以输入电压上升沿为开始并以第二电参数信号下降沿为结束所确定的一个采样周期内的参考电压平均值，所述第二电参数信号表征流过所述LED电路的电流。Preferably, the first electrical parameter signal corresponds to an average value of a reference voltage within a sampling period determined starting with a rising edge of the input voltage and ending with a falling edge of the second electrical parameter signal, and the second electrical parameter signal Characterizes the current flowing through the LED circuit.

优选地，所述可控硅切波角度检测电路包括第二运算放大器U2、第三运算放大器U3、第一脉冲产生电路A1、第二脉冲产生电路A2、RS触发器以及采样积分电路，所述第二运算放大器U2的正向输入端接输入电压采样信号，第二运算放大器U2的反向输入端接用于提供上升沿采集起始阈值的第六阈值，第三运算放大器U3的反向输入端接第二电参数信号，第三运算放大器U3的正向输入端接用于提供下降沿采集结束阈值的第七阈值，第二运算放大器U2和第三运算放大器U3的输出分别接第一脉冲产生电路A1和第二脉冲产生电路A2的输入，所述第一脉冲产生电路A1和第二脉冲产生电路A2的输出分别接RS触发器的S端和R端，脉冲电路检测到运算放大器产生的翻转信号时向RS触发器输入脉冲信号，RS触发器的输出与采样积分电路相连接，并且采样积分电路上接参考电压，采样积分电路输出端接泄放电流控制电路用于将运算处理后的第一电参数信号输入泄放电流控制电路。Preferably, the thyristor cut-wave angle detection circuit includes a second operational amplifier U2, a third operational amplifier U3, a first pulse generating circuit A1, a second pulse generating circuit A2, an RS trigger, and a sampling integration circuit. The forward input terminal of the second operational amplifier U2 is connected to the input voltage sampling signal, the reverse input terminal of the second operational amplifier U2 is connected to the sixth threshold for providing a rising edge acquisition start threshold, and the reverse input of the third operational amplifier U3. Terminate the second electrical parameter signal, the forward input of the third operational amplifier U3 is terminated to provide a seventh threshold for the falling edge acquisition end threshold, and the outputs of the second operational amplifier U2 and the third operational amplifier U3 are connected to the first pulse, respectively. The inputs of the generating circuit A1 and the second pulse generating circuit A2. The outputs of the first pulse generating circuit A1 and the second pulse generating circuit A2 are respectively connected to the S and R terminals of the RS flip-flop. The pulse circuit detects the When the signal is inverted, a pulse signal is input to the RS flip-flop. The output of the RS flip-flop is connected to the sampling and integrating circuit, and the sampling and integrating circuit is connected to a reference voltage to sample and integrate. Output termination bleeder current circuit for controlling a first electrical input signal parameter after the bleeder current arithmetic processing control circuit.

优选地，还包括：输出电流补偿电路，所述输出电流补偿电路将所述第一电参数信号与第二阈值进行比较，来控制流过所述LED电路的电流；其中，第二阈值小于第一阈值并且表明可控硅调光器切波后的输入电压的峰值电压接近LED电路的导通电压。Preferably, it further comprises: an output current compensation circuit that compares the first electrical parameter signal with a second threshold value to control the current flowing through the LED circuit, wherein the second threshold value is smaller than the first threshold value. A threshold value also indicates that the peak voltage of the input voltage of the TRIAC dimmer is close to the on-voltage of the LED circuit.

优选地，所述输出电流补偿电路包括第一跨导放大器；所述第一跨导放大器用于在第一电参数信号小于所述第二阈值时，所述输出电流补偿电路输出电流，以减小流经LED电路的电流的峰值电流。Preferably, the output current compensation circuit includes a first transconductance amplifier; the first transconductance amplifier is configured to output a current when the first electrical parameter signal is less than the second threshold, so as to reduce the current Peak current of small current flowing through the LED circuit.

优选地，所述输出电流补偿电路还包括第二跨导放大器；所述第二跨导放大器用于在第一电参数信号小于第四阈值时，限制所述第一跨导放大器的输出电流；其中所述第二阈值大于所述第四阈值。Preferably, the output current compensation circuit further includes a second transconductance amplifier; the second transconductance amplifier is configured to limit an output current of the first transconductance amplifier when a first electrical parameter signal is less than a fourth threshold; Wherein the second threshold is greater than the fourth threshold.

优选地，所述泄放电流控制电路包括第一比较放大器对所述第一阈值和第一电参数信号进行比较；第二比较放大器对第三阈值和第二电参数信号进行比较。Preferably, the bleeder current control circuit includes a first comparison amplifier to compare the first threshold value and a first electrical parameter signal; a second comparison amplifier compares a third threshold value and a second electrical parameter signal.

优选地，所述泄放电流电路包括电流源和开关电路；所述电流源和所述开关电路串联连接，所述开光电路在所述泄放电流控制电路的控制下泄放开启或泄放关断。Preferably, the bleeder current circuit includes a current source and a switch circuit; the current source and the switch circuit are connected in series, and the open-light circuit is bleed on or bleed off under the control of the bleed current control circuit. .

优选地，所述第一阈值、所述第二阈值、所述第三阈值和所述第四阈值可以为电流阈值、电压阈值、时间阈值中的任一阈值。Preferably, the first threshold, the second threshold, the third threshold, and the fourth threshold may be any one of a current threshold, a voltage threshold, and a time threshold.

第二方面，本发明还提出了一种控制方法，包括：可控硅调光器导通后，获取电参数表征可控硅切波角度的第一电参数信号电参数；输入电压是整流桥对流经所述可控硅调光器的交流电进行整流后的全波整流电压并且作为LED电路的驱动电压；其中，泄放电流电路提供在所述输入电压未达到所述LED电路的导通电压时所述可控硅调光器所需的电流；泄放将所述电参数第一电参数信号与第一阈值进行比较，来控制泄放电流电路。In a second aspect, the present invention also provides a control method, including: after the thyristor dimmer is turned on, obtaining a first electric parameter signal electric parameter representing the thyristor cut angle of the electric parameter; the input voltage is a rectifier bridge The full-wave rectified voltage after rectifying the alternating current flowing through the thyristor dimmer is used as the driving voltage of the LED circuit; wherein the bleeder current circuit provides that the input voltage does not reach the on-voltage of the LED circuit The current required by the thyristor dimmer; the bleed compares the first electrical parameter signal of the electrical parameter with a first threshold to control the bleed current circuit.

优选地，还包括：当所述第一电参数信号大于所述第一阈值时，泄放关断泄放电流。Preferably, the method further includes: when the first electrical parameter signal is greater than the first threshold, the bleeder turns off the bleeder current.

优选地，还包括：当所述第一电参数信号小于所述第一阈值时，检测所述第一电参数信号是否小于第二阈值；其中，所述第二阈值小于所述第一阈值并且表明可控硅调光器切波后的输入电压的峰值电压接近LED电路的导通电压；当检测所述第一电参数信号大于所述第二阈值时，保持所述LED电路流过的峰值电流不变；当检测所述第一电参数信号小于所述第二阈值时，减小所述LED电路流过的峰值电流。在一些实施例中，所述第一电参数信号小于所述第二阈值的情况表明所述可控硅调光器切波后的输入电压的峰值电压接近LED电路的导通电压。Preferably, it further comprises: when the first electrical parameter signal is smaller than the first threshold, detecting whether the first electrical parameter signal is smaller than a second threshold; wherein the second threshold is smaller than the first threshold and It indicates that the peak voltage of the input voltage of the TRIAC dimmer is close to the on-voltage of the LED circuit; when the first electrical parameter signal is detected to be greater than the second threshold value, the peak value of the LED circuit flow is maintained The current does not change; when it is detected that the first electrical parameter signal is less than the second threshold, the peak current flowing through the LED circuit is reduced. In some embodiments, a case where the first electrical parameter signal is smaller than the second threshold indicates that a peak voltage of the input voltage after the thyristor dimmer is cut is close to a turn-on voltage of the LED circuit.

优选地，还包括：泄放检测第二电参数，判断第二电参数是否小于第三阈值；其中，所述第二电参数是流过所述LED电路的电流；当所述第二电参数小于所述第三阈值时，泄放电路提供泄放电流；当所述第二电参数大于所述第三阈值时，泄放电路停止提供泄放电流。Preferably, the method further includes: detecting a second electrical parameter by bleed to determine whether the second electrical parameter is less than a third threshold; wherein the second electrical parameter is a current flowing through the LED circuit; when the second electrical parameter is When less than the third threshold, the bleeder circuit provides a bleeder current; when the second electrical parameter is greater than the third threshold value, the bleeder circuit stops providing a bleeder current.

优选地，所述第一电参数信号对应于一个周期内输入电压从所述可控硅调光器的起始导通切波角度开始到周期结束期间的平均值。Preferably, the first electrical parameter signal corresponds to an average value of an input voltage during a period from a start-on switching wave angle of the thyristor to a period end.

本发明通过控制泄放电流的开启和关断，提高了线性可控硅LED驱动电路的效率和稳定性，同时解决或改善可控硅调光器小角度闪烁的问题。The invention improves the efficiency and stability of the linear thyristor LED driving circuit by controlling the opening and closing of the bleeder current, and at the same time solves or improves the problem of small-angle flicker of the thyristor dimmer.

附图说明BRIEF DESCRIPTION OF THE DRAWINGS

图1为现有技术中可调光LED驱动电路图；FIG. 1 is a driving circuit diagram of a dimmable LED in the prior art;

图2为现有技术中可调光LED驱动电路的可控硅调光器导通较小时Ics电流、LED电流的波形图；FIG. 2 is a waveform diagram of Ics current and LED current when the thyristor dimmer of the dimmable LED driving circuit in the prior art is relatively small;

图3为本发明一个周期的整流后的输入电压Vin与可控硅调光器的导通切波角度关系；FIG. 3 is a relationship between a rectified input voltage Vin and a turn-on and cut-off angle of a thyristor according to a period of the present invention; FIG.

图4为现有技术中可调光LED驱动电路的泄放电流造成的功率损耗示意图；4 is a schematic diagram of power loss caused by a leakage current of a dimmable LED driving circuit in the prior art;

图5为本发明实施例提供的一种可调光LED驱动电路图；5 is a circuit diagram of a dimmable LED driving circuit according to an embodiment of the present invention;

图6为本发明实施例提供的泄放电流电路开启或关闭时功率损耗示意图；6 is a schematic diagram of power loss when a bleeder current circuit is turned on or off according to an embodiment of the present invention;

图7为本发明实施例提供的一种可控硅切波角度检测电路示意图；FIG. 7 is a schematic diagram of a thyristor cut angle detection circuit according to an embodiment of the present invention; FIG.

图8为本发明实施例提供的一种控制泄放电流的泄放电流控制电路示意图；8 is a schematic diagram of a bleed current control circuit for controlling a bleed current according to an embodiment of the present invention;

图9A、9B和9C为本发明实施例提供的三种Ics电流、ILED电流与可控硅调光器切波角度的关系示意图；9A, 9B, and 9C are schematic diagrams of the relationship between three types of Ics current, ILED current, and the cutting wave angle of a TRIAC dimmer according to an embodiment of the present invention;

图10为本发明实施例提供的可控硅切波角度检测电路降低Ics的峰值电流时对应的泄放电流示意图；FIG. 10 is a schematic diagram of a bleeder current when a thyristor cut-wave angle detection circuit according to an embodiment of the present invention reduces the peak current of Ics;

图11为本发明实施例提供的一种解决闪灯的输出电流补偿电路示意图；FIG. 11 is a schematic diagram of an output current compensation circuit for solving a flash lamp according to an embodiment of the present invention; FIG.

图12为本发明实施例提供的一种改善小角度闪灯的输出电流补偿电路示意图；12 is a schematic diagram of an output current compensation circuit for improving a small-angle flash lamp according to an embodiment of the present invention;

图13为本发明实施例提供的一种泄放电流的控制方法流程图；13 is a flowchart of a method for controlling a bleed current according to an embodiment of the present invention;

图14为本发明实施例提供的另一种可调光LED驱动电路图；14 is a circuit diagram of another dimmable LED driving circuit according to an embodiment of the present invention;

图15为本发明检测第二电参数信号实施例电路图；15 is a circuit diagram of an embodiment of detecting a second electrical parameter signal according to the present invention;

图16为本发明实施例提供的又一种可调光LED驱动电路图；FIG. 16 is another circuit diagram of a dimmable LED driving circuit according to an embodiment of the present invention; FIG.

图17为本发明检测输入电压及第二电参数信号实施例的电路图；17 is a circuit diagram of an embodiment of detecting an input voltage and a second electrical parameter signal according to the present invention;

图18为本发明检测输入电压及第二电参数信号实施例的波形图。18 is a waveform diagram of an embodiment of detecting an input voltage and a second electrical parameter signal according to the present invention.

具体实施方式Detailed ways

为使本发明实施例的技术方案以及优点表达的更清楚，下面通过附图和实施例，对本发明的技术方案做进一步的详细描述。In order to make the technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention are described in further detail below with reference to the accompanying drawings and embodiments.

图1是一种可调光LED驱动电路，其包括：AC电源、可控硅调光器10、整流桥、泄放电流电路20、LED电路30、功率控制电路40、MOS管50和采样电阻Rcs。在该电路中，可控硅调光器10和整流桥的输入端串联连接，并且由AC电源供电。整流桥的一个输出端接地，另一个输出端连接输入电压 Vin；整流桥的输出端提供全波整流电压，作为输入电压Vin，所述输入电压作为驱动LED电路的驱动电压。FIG. 1 is a dimmable LED driving circuit, which includes: AC power supply, thyristor dimmer 10, rectifier bridge, bleeder current circuit 20, LED circuit 30, power control circuit 40, MOS tube 50, and sampling resistor Rcs. In this circuit, the TRIAC dimmer 10 and the input terminal of the rectifier bridge are connected in series and are powered by an AC power source. One output terminal of the rectifier bridge is grounded, and the other output terminal is connected to the input voltage Vin; the output terminal of the rectifier bridge provides a full-wave rectified voltage as the input voltage Vin, and the input voltage is used as the driving voltage for driving the LED circuit.

LED电路30、MOS管50和采样电阻Rcs依次串联，LED电路30的另一端连接输入电压Vin，采样电阻Rcs的另一端接地；泄放电流电路20的一端连接输入电压Vin，其另一端接地；功率控制电路40的第一输入端连接基准电压VREF，其第二输入端连接在MOS管50和电阻Rcs中间，其输出端连接在MOS管50的栅极。在一个例子中，LED电路30包括串联的LED灯和与之并联的电阻电容电路。The LED circuit 30, the MOS tube 50 and the sampling resistor Rcs are connected in series. The other end of the LED circuit 30 is connected to the input voltage Vin and the other end of the sampling resistor Rcs is grounded. One end of the bleeder current circuit 20 is connected to the input voltage Vin and the other end is grounded. A first input terminal of the power control circuit 40 is connected to the reference voltage VREF, a second input terminal thereof is connected between the MOS tube 50 and the resistor Rcs, and an output terminal thereof is connected to the gate of the MOS tube 50. In one example, the LED circuit 30 includes LED lamps connected in series and a resistor-capacitor circuit connected in parallel.

在一些实施例中，对可控硅调光器10的切波可以用角度来表征。图3示意了经过可控硅调光器10切波后的一个周期的输入电压Vin，其中θ1为最小的起始导通切波角度，导通切波可能发生在θ1-π之间的任意角度。θ2是可控硅调光器的起始导通切波角度的一个可能示例，且θ1<θ2。π-θ1和π-θ2为分别为θ1和θ2角度下的可控硅调光器的导通宽度。输入电压Vin的最大值Vpeak出现在π/2的角度。In some embodiments, the tangent to the TRIAC dimmer 10 may be characterized by an angle. Figure 3 shows the input voltage Vin during a period after the TRIAC dimmer 10 cuts, where θ1 is the smallest initial conduction cut angle, and the conduction cut may occur at any arbitrary angle between θ1-π angle. θ2 is a possible example of the initial conduction shear wave angle of the TRIAC dimmer, and θ1 <θ2. π-θ1 and π-θ2 are the conduction widths of the TRIAC dimmers at the angles of θ1 and θ2, respectively. The maximum value Vpeak of the input voltage Vin appears at an angle of π / 2.

当可控硅调光器10导通后(例如，图4中θ1-π之间的任意角度)，需要有一定的电流来维持其导通(例如，图4中Itriac表示可控硅调光器中的电流导通情况)。在输入电压Vin未达到LED电路30的导通电压V _LED前(例如，图4中θ1-θ2之间)，LED电路30未导通，因此通过增加泄放电流电路20来提供一个电流(即，此时Ibleeder不为0)，使可控硅调光器10导通；在输入电压Vin到达LED电路30的导通电压后(例如，图4中θ2-θ’之间)，LED电路30导通，电路会产生电流，这时可控硅调光器10需要的电流可以由LED电路30的电流(即图4中的Ics)来替代。另外在输入电压Vin小于LED电路30的导通电压时(例如，图4中θ’之后到周期结束的区间)，LED电路30也不能导通，此时可控硅调光器10也需要泄放电流电路20来提供电流(即，此时Ibleeder不为0)。由于泄放电流电路20产生的泄放电流不是负载电流，会造成大量损耗。图4示例性地示意了一种电路损耗情况。如图4所示，在一个周期内，电路总的损耗为Ptotal＝PA+PB+PC。其中PA及PC为泄放电流造成的损耗(对应图4中的Pbloss)，PB为线性LED驱动固有的损耗，即输入电压与LED电压压差产生的损耗。与开始导通直至输入电压Vin大于LED电路30的导通电压这一阶段的损耗PA相比，输入电压Vin减小直至小于LED电路30的导通电压这一阶段泄放电流的损耗PC较大。在本申请的一些实施例中，可以通过减小泄放电流在PC阶段的损耗(例如，关闭或减小PC阶段的泄放电流)，以达到降低电路功耗的目的。 After the TRIAC dimmer 10 is turned on (for example, any angle between θ1-π in FIG. 4), a certain current is required to maintain its conduction (for example, Itriac in FIG. 4 represents TRIAC dimming Current in the device). Before the input voltage Vin does not reach the turn-on voltage V _LED of the LED circuit 30 (for example, between θ1 and θ2 in FIG. 4), the LED circuit 30 is not turned on, so a current is provided by increasing the bleeder current circuit 20 (ie At this time, Ibleeder is not 0), so that the TRIAC dimmer 10 is turned on; after the input voltage Vin reaches the turn-on voltage of the LED circuit 30 (for example, between θ2-θ 'in FIG. 4), the LED circuit 30 When the circuit is turned on, a current is generated. At this time, the current required by the TRIAC dimmer 10 may be replaced by the current of the LED circuit 30 (that is, Ics in FIG. 4). In addition, when the input voltage Vin is smaller than the turn-on voltage of the LED circuit 30 (for example, the interval after θ ′ to the end of the cycle in FIG. 4), the LED circuit 30 cannot be turned on. At this time, the thyristor dimmer 10 also needs to be discharged. The current-discharging circuit 20 supplies a current (that is, Ibleeder is not 0 at this time). Since the bleed current generated by the bleed current circuit 20 is not a load current, a large amount of loss is caused. FIG. 4 exemplarily illustrates a circuit loss situation. As shown in Figure 4, in a period, the total loss of the circuit is Ptotal = PA + PB + PC. Among them, PA and PC are losses caused by the bleed current (corresponding to Pbloss in FIG. 4), and PB is the inherent loss of linear LED driving, that is, the loss caused by the difference between the input voltage and the LED voltage. Compared with the loss PA at the stage where the input voltage Vin is started until the input voltage Vin is greater than the on-voltage of the LED circuit 30, the loss PC at the stage where the input voltage Vin decreases until it is less than the on-voltage of the LED circuit 30 is larger. . In some embodiments of the present application, the loss of the bleed current in the PC stage (for example, turning off or reducing the bleed current in the PC stage) can be used to achieve the purpose of reducing the power consumption of the circuit.

图5为本发明实施例提供的一种可调光LED驱动电路图。如图5所示，在可调光LED驱动电路上，增加了可控硅切波角度检测电路60和泄放电流控制电路70。其中，可控硅切波角度检测电路60的输入端连接输入电压Vin，输出端连接泄放电流控制电路70的第一输入端；然后泄放电流控制电路70的第二输入端连接在MOS管50的漏极和电阻Rcs之间，其输出端连接在泄放电流电路20。FIG. 5 is a circuit diagram of a dimmable LED driving circuit according to an embodiment of the present invention. As shown in FIG. 5, a thyristor cut-wave angle detection circuit 60 and a bleeder current control circuit 70 are added to the dimmable LED driving circuit. The input terminal of the thyristor cut-wave angle detection circuit 60 is connected to the input voltage Vin, and the output terminal is connected to the first input terminal of the bleed current control circuit 70; and the second input terminal of the bleed current control circuit 70 is connected to the MOS tube. An output terminal of the drain of 50 and the resistor Rcs is connected to the bleeder current circuit 20.

在可控硅调光器10导通后，交流电源电压Vac经可控硅调光器10导通角切波后，以全波整流电压的方式提供给可控硅切波角度检测电路60。在一些实施例中，可控硅切波角度检测电路60可以检测可控硅调光器10的起始导通切波角度θ。泄放电流控制电路70可以根据所述检测到的起始导通切波角度θ控制泄放电流电路20的工作状态。具体地，可控硅切波角度检测电路60可以检测一个与所述起始导通切波角度θ对应的电参数信号Vout，并将所述电参数信号Vout发送给泄放电流控制电路70。After the thyristor dimmer 10 is turned on, the AC power supply voltage Vac is turned on by the thyristor dimmer 10 and turned on and then provided to the thyristor cut angle detection circuit 60 as a full-wave rectified voltage. In some embodiments, the thyristor cut-wave angle detection circuit 60 may detect the initial on-cut tangent angle θ of the thyristor 10. The bleeder current control circuit 70 may control the working state of the bleeder current circuit 20 according to the detected initial on-cutting wave angle θ. Specifically, the thyristor cut-wave angle detection circuit 60 may detect an electrical parameter signal Vout corresponding to the initial conduction cut-wave angle θ, and send the electrical parameter signal Vout to the bleeder current control circuit 70.

电参数信号Vout可以表征可控硅切波角度。在一个例子中，电参数信号Vout可以表示为输入电压Vin在一个周期内从可控硅调光器10的起始导通切波角度开始到周期结束期间的平均值。在一个周期中，所述起始导通切波角度θ越大，其对应的电参数信号Vout就越小。The electrical parameter signal Vout can characterize the SCR shear wave angle. In one example, the electrical parameter signal Vout can be expressed as an average value of the input voltage Vin from the start of the TRIAC dimmer 10 to the end of the period during the period from the start of the TRIAC dimmer 10 to the cut-on angle. In one period, the larger the initial conduction cut-off angle θ is, the smaller the corresponding electrical parameter signal Vout is.

在LED电路30导通前，泄放电流控制电路70在接收到可控硅切波角度检测电路60输出的电参数信号Vout后，根据其内部设置的第一(电压)阈值，将电参数信号Vout与第一阈值进行比较。所述第一阈值同样对应于一个起始切波角度阈值(也叫做第一角度阈值)。当电参数信号Vout小于第一阈值时(即，起始导通切波角度θ大于第一角度阈值时)，泄放电流控制电路70开启泄放电流电路20的导通，提供泄放电流；当电参数信号Vout大于第一阈值时(即，起始导通切波角度θ小于所述第一角度阈值时)，泄放电流控制电路70关断泄放电流电路20，停止提供泄放电流，以达到降低功耗的作用。Before the LED circuit 30 is turned on, the bleeder current control circuit 70 receives the electrical parameter signal Vout output from the thyristor cut-wave angle detection circuit 60, and converts the electrical parameter signal according to a first (voltage) threshold value set therein. Vout is compared with a first threshold. The first threshold value also corresponds to an initial shear wave angle threshold value (also referred to as a first angle threshold value). When the electrical parameter signal Vout is smaller than the first threshold value (that is, when the initial conduction shear wave angle θ is greater than the first angle threshold value), the bleeder current control circuit 70 turns on the bleeder current circuit 20 to provide a bleeder current; When the electrical parameter signal Vout is greater than a first threshold value (that is, when the initial conduction cut-off angle θ is smaller than the first angle threshold value), the bleeder current control circuit 70 turns off the bleeder current circuit 20 and stops supplying the bleeder current To achieve the effect of reducing power consumption.

优选地，当电参数信号Vout大于第一阈值时，可以先关断泄放电流，延迟一定时间(例如，1ms)后再开启泄放电流电路20。更优选地，再次开启的泄放电流电路20可以提供一个较小的泄放电流。这里所说的较小的泄放电流时相对于关断前的泄放电流来说的。所述较小的泄放电流的幅值可以与关断前的泄放电流的幅值成一定的比例。所述比例可以是0.1,0.2,0.5,或者其他0-1之间的任意数值。Preferably, when the electrical parameter signal Vout is greater than the first threshold, the bleeder current may be turned off first, and the bleeder current circuit 20 may be turned on after a delay (for example, 1 ms). More preferably, the bleeder current circuit 20 turned on again can provide a smaller bleeder current. The smaller bleeder current mentioned here is relative to the bleeder current before shutdown. The magnitude of the smaller bleeder current may be proportional to the magnitude of the bleeder current before shutdown. The ratio can be 0.1, 0.2, 0.5, or any other value between 0-1.

优选地，当电参数信号Vout大于第一阈值时，泄放电流电路20可以直接提供一个较小的泄放电流。Preferably, when the electrical parameter signal Vout is larger than the first threshold, the bleeder current circuit 20 can directly provide a smaller bleeder current.

图6为泄放电流电路开启或关闭时功率损耗示意图。图6示意有两个半波，左边的半波对应于可控硅调光器10处于最大导通宽度情况下的损耗情况，该损耗为PA+PB。右边的半波对应于可控硅调光器10处于任意导通宽度的情况，其时的损耗为PB1+PC。Figure 6 is a schematic diagram of the power loss when the bleeder current circuit is turned on or off. FIG. 6 shows that there are two half-waves, and the left half-wave corresponds to the loss of the thyristor 10 at the maximum conduction width, and the loss is PA + PB. The half-wave on the right corresponds to the case where the TRIAC dimmer 10 is at any conduction width, and the loss at this time is PB1 + PC.

所述第一阈值可以是由用户根据特定的规则进行设定的。例如，所述第一阈值可以与可调光LED驱动电路在不同时间段的损耗有关。特别地，泄放电流控制电路70中设置的第一阈值可以使得可调光LED驱动电路基本满足公式(1)的要求，即：The first threshold may be set by a user according to a specific rule. For example, the first threshold may be related to the loss of the dimmable LED driving circuit in different time periods. In particular, the first threshold value set in the bleeder current control circuit 70 can make the dimmable LED driving circuit basically meet the requirements of formula (1), that is:

PA+PB≥PB1+PC (1)PA + PB≥PB1 + PC (1)

如果PB1较大，条件(1)不满足时，则需要考虑关闭泄放电流电路20，或者降低其电流损耗。If PB1 is large and the condition (1) is not satisfied, it is necessary to consider closing the bleeder current circuit 20 or reducing its current loss.

在一个例子中，第一阈值对应于输入电压Vin在一个可控硅调光器10具有第一起始导通切波角度的周期内从第一起始导通切波角度开始到周期结束期间的平均值；其中，在可控硅调光器10具有该第一起始导通切波角度的周期内线性LED驱动的损耗(PA部分)和泄放电流电路20在未调整输出电流的情况下的电路损耗(PB部分)之和与在具有最小起始导通切波角度的周期内线性LED驱动的损耗(PB1部分)和输入电压Vin未达到所述LED电路30的导通电压前泄放电流电路的电路损耗(PC部分)之和相当。也就是说此时设置的第一阈值即为临界值，如果第一阈值对应的平均值大于这个临界值，则电路就不能起到降低功耗的作用。In one example, the first threshold value corresponds to an average of the input voltage Vin during a period in which the thyristor dimmer 10 has a first starting on-cut angle from the first starting on-cut angle to the end of the period Where the thyristor dimmer 10 has the first starting on-cut angle and the linear LED driving loss (PA part) and the circuit of the bleeder current circuit 20 without adjusting the output current The sum of the loss (part PB) and the loss (part PB1) of the linear LED drive during the period with the smallest initial on-cutting angle and the input voltage Vin does not reach the on-voltage of the LED circuit 30 before the current is discharged. The sum of the circuit losses (PC part) is equivalent. In other words, the first threshold value set at this time is a critical value. If the average value corresponding to the first threshold value is greater than this critical value, the circuit cannot play a role in reducing power consumption.

在一个实施例中，如图7所示提供的一种可控硅切波角度检测电路60，包括积分电路。在一个例子中，积分电路由电阻Rset1、电阻Rset2和电容Cset1构成。电阻Rset1和电阻Rset2构成分压电路连接在Vin和地之间，电容Cset1和电阻Rset2并联。图7所述电路，首先将Vin通过电阻Rset1及Rset2分压以产生泄放控制电路可以处理的电压，电容Cset1将上述电压进行积分滤波，所产生的Vout即为输入电压Vin从所述可控硅调光器10的起始导通切波角度开始到周期结束期间等比例缩小后的平均值。In one embodiment, as shown in FIG. 7, a thyristor shear wave angle detection circuit 60 includes an integration circuit. In one example, the integrating circuit is composed of a resistor Rset1, a resistor Rset2, and a capacitor Cset1. The resistor Rset1 and the resistor Rset2 form a voltage dividing circuit connected between Vin and the ground, and the capacitor Cset1 and the resistor Rset2 are connected in parallel. The circuit in FIG. 7 first divides Vin through resistors Rset1 and Rset2 to generate a voltage that the bleed control circuit can handle. The capacitor Cset1 integrates and filters the above voltage, and the generated Vout is the input voltage Vin from the controllable voltage. The average value of the silicon dimmer 10 is proportionally reduced during the period from the start of the on-cut angle to the end of the period.

可选地，在可控硅切波角度检测电路60中，可在电阻Rset1和电阻Rset2的两电阻中间节点到电容Cset1之间加一个电阻Rset3，使电参数信号Vout的纹波更好。Optionally, in the thyristor cut-wave angle detection circuit 60, a resistor Rset3 can be added between the two intermediate nodes of the resistor Rset1 and the resistor Rset2 to the capacitor Cset1, so that the ripple of the electrical parameter signal Vout is better.

输入电压Vin输入到可控硅切波角度检测电路60时，可控硅切波角度检测电路60通过电阻电容串并联的方式检测可控硅调光器10的切波角度，从而将可控硅调光器10的起始导通切波角度θ转化为一个具体的电参数信号Vout。可控硅调光器10的初始电压值可以通过调整电阻Rset1和电阻Rset2 的电阻比例灵活设置，且电容Cset1的电容越大电参数信号Vout的纹波越小。在电阻电容参数确定的情况下，电参数信号Vout的电压随着可控硅调光器10的起始导通切波角度θ的增大而逐渐减小，由公式(2)可得到：When the input voltage Vin is input to the thyristor cut-wave angle detection circuit 60, the thyristor cut-wave angle detection circuit 60 detects the tangent angle of the thyristor dimmer 10 by means of a resistor-capacitor series-parallel connection, thereby converting the thyristor 10 The initial on-cut angle θ of the dimmer 10 is converted into a specific electrical parameter signal Vout. The initial voltage value of the TRIAC dimmer 10 can be flexibly set by adjusting the resistance ratio of the resistors Rset1 and Rset2, and the larger the capacitance of the capacitor Cset1 is, the smaller the ripple of the electrical parameter signal Vout is. When the resistance and capacitance parameters are determined, the voltage of the electrical parameter signal Vout gradually decreases with the increase of the initial conduction shear wave angle θ of the TRIAC dimmer 10, which can be obtained from formula (2):

其中，交流电压Vac＝Vpeak·sinθ，Vpeak表示交流电源的电压最大值，θ表示可控硅调光器10的输入电压起始导通切波角度。Wherein, the AC voltage Vac = Vpeak · sin θ, Vpeak represents the maximum voltage of the AC power source, and θ represents the initial conduction cut-off angle of the input voltage of the TRIAC dimmer 10.

优选地，第一阈值以电压阈值VREF1为例，则可控硅调光器10起始导通角阈值θth(即第一角度阈值)由公式(2)反推可得：Preferably, the first threshold value is taken as an example of the voltage threshold value VREF1, and then the initial conduction angle threshold value θth (that is, the first angle threshold value) of the TRIAC dimmer 10 can be deduced from formula (2):

根据公式(3)可知，第一阈值确定了可控硅调光器10导通角度阈值θth。当可控硅调光器10起始导通角度θ<θth时，泄放电流控制电路70关断泄放电流电路20的导通，停止提供泄放电流；当可控硅起始导通角度θ>θth时，泄放电流控制电路70开启泄放电流电路20的导通，提供泄放电流。According to formula (3), it can be known that the first threshold value determines the conduction angle threshold value θth of the thyristor 10. When the thyristor dimmer 10 has an initial conduction angle θ <θth, the bleeder current control circuit 70 turns off the conduction of the bleeder current circuit 20 and stops supplying the bleeder current; When θ> θth, the bleeder current control circuit 70 turns on the bleeder current circuit 20 to provide a bleeder current.

可选地，泄放电流可以为可变电流，当可控硅调光器10起始导通角θ<θth时，泄放电流电路20停止提供泄放电流，经过特定延迟时间后，再提供一个较小的泄放电流。Alternatively, the bleeder current may be a variable current. When the thyristor dimmer 10 has an initial conduction angle θ <θth, the bleeder current circuit 20 stops supplying the bleeder current, and then supplies the bleeder current after a specific delay time A smaller bleeder current.

可选地，泄放电流可以为可变电流，当可控硅调光器10起始导通角θ<θth时，泄放电流电路20提供一个较小的泄放电流，以实现可控硅调光器10关断后对母线放电。Optionally, the bleeder current may be a variable current. When the thyristor dimmer 10 has an initial conduction angle θ <θth, the bleeder current circuit 20 provides a smaller bleeder current to realize the thyristor. After the dimmer 10 is turned off, the bus is discharged.

在控制泄放电流的一个实施例中，泄放电流控制电路70接收到电参数信号Vout大于第一阈值，控制泄放电流电路20关断，停止提供泄放电流；此时由于LED电路30导通，泄放电流控制电路70开始接收到采样电阻Rcs的电压Vcs，该电压表征流过所述LED电路30的电流，下文将电压Vcs称为电参数信号Vcs；然后与内置的第三阈值进行比较，当电参数信号Vout小于第一阈值且电压Vcs小于第三阈值时，泄放电流控制电路70控制泄放电流电路20开启，提供泄放电流。In one embodiment of controlling the bleeder current, the bleeder current control circuit 70 receives the electrical parameter signal Vout that is greater than the first threshold, and controls the bleeder current circuit 20 to turn off, and stops supplying the bleeder current; On, the bleeder current control circuit 70 starts to receive the voltage Vcs of the sampling resistor Rcs, which characterizes the current flowing through the LED circuit 30. The voltage Vcs is hereinafter referred to as the electrical parameter signal Vcs; In comparison, when the electrical parameter signal Vout is less than the first threshold value and the voltage Vcs is less than the third threshold value, the bleeder current control circuit 70 controls the bleeder current circuit 20 to turn on to provide a bleeder current.

如图14所示，可控硅切波角度检测电路60的实施例不仅上述一种通过检测输入电压Vin得到表征可控硅切波角度电参数信号Vout的实施例，还可以通过检测电参数信号Vcs得到电参数信号Vout。为加以区分本段说明将电参数信号Vcs以及电参数信号Vout分别命名为第一电参数信号Vout以及第二电参数信号Vcs。图14中可控硅切波角度检测电路60的输入接MOS管50的源极和电阻Rcs之间的公共端，可控硅切波角度检测电路60的输出分别与输出电流补偿电路80及泄放电流控制电路70相接，第一电参数信号Vout对应于在一个第二电参数信号Vcs采样周期内的参考电压平均值，所述第二电参数信号Vcs表征流过所述LED电路30的电流。As shown in FIG. 14, an embodiment of the thyristor cut-wave angle detection circuit 60 is not only the above-mentioned embodiment obtained by detecting the input voltage Vin to characterize the thyristor cut-angle electrical parameter signal Vout, but also can be detected by detecting the electrical parameter signal. Vcs gets the electrical parameter signal Vout. To distinguish this paragraph, the electrical parameter signal Vcs and the electrical parameter signal Vout are named as the first electrical parameter signal Vout and the second electrical parameter signal Vcs, respectively. The input of the thyristor cut-wave angle detection circuit 60 in FIG. 14 is connected to the common terminal between the source of the MOS tube 50 and the resistor Rcs, and the output of the thyristor cut-wave angle detection circuit 60 and the output current compensation circuit 80 and the leakage are respectively The discharge current control circuit 70 is connected. The first electrical parameter signal Vout corresponds to an average value of the reference voltage in a sampling period of the second electrical parameter signal Vcs. The second electrical parameter signal Vcs represents the current flowing through the LED circuit 30. Current.

检测第二电参数信号实施例的电路如图15所示，图15中的可控硅切波角度检测电路60包括第一运算放大器U1和采样积分电路61，所述第一运算放大器U1的正向输入端接第二电参数信号Vcs，第一运算放大器U1的反向输入端接第五阈值，可控硅切波角度检测电路60对大于第五阈值的第二电参数信号Vcs进行采样，第一运算放大器U1的输出端与采样积分电路61相连，并且采样积分电路61上接参考电压，采样积分电路61的输出端接泄放电流控制电路70用于将运算处理后的第一电参数信号Vout输入泄放电流控制电路70。优选地，第一运算放大器U1的输出端与采样积分电路61的输入端之间还设有串联设置的两个非门。两个非门之间的公共端与采样积分电路61中的其中一个开关的控制端相连，与采样积分电路61相连的非门的输出端与采样积分电路61中的另一个开关的控制端相连，串联设置的两个开关一端上接参考电压另一端接地，两个开关公共端接积分电阻，积分电阻与地之间还设有积分电容。第一运算放大器U1根据第二电参数信号Vcs与第五阈值的比较结果控制采样积分电路61的充放电时间进而得到表征可控硅切波角度的第一电参数信号Vout。通过检测电参数信号Vcs来获取表征可控硅切波角度电参数信号Vout的方式提高了检测准确度，同时采样过程更为简便可靠。A circuit for detecting a second electrical parameter signal embodiment is shown in FIG. 15. The thyristor cut angle detection circuit 60 in FIG. 15 includes a first operational amplifier U1 and a sampling integration circuit 61. A second electrical parameter signal Vcs is connected to the input, a fifth threshold is connected to the inverting input of the first operational amplifier U1, and the thyristor cut angle detection circuit 60 samples a second electrical parameter signal Vcs that is greater than the fifth threshold. The output terminal of the first operational amplifier U1 is connected to the sampling integration circuit 61, and the sampling integration circuit 61 is connected to a reference voltage, and the output terminal of the sampling integration circuit 61 is connected to the bleeder current control circuit 70 for applying the first electrical parameter after the operation processing. The signal Vout is input to the bleeder current control circuit 70. Preferably, two NOT gates arranged in series are further provided between the output terminal of the first operational amplifier U1 and the input terminal of the sampling integration circuit 61. The common terminal between the two NOT gates is connected to the control terminal of one switch in the sampling integration circuit 61, and the output terminal of the NOT gate connected to the sampling integration circuit 61 is connected to the control terminal of the other switch in the sampling integration circuit 61. One end of the two switches arranged in series is connected to the reference voltage and the other end is grounded. The two switches are commonly terminated with an integration resistor, and an integration capacitor is also provided between the integration resistor and the ground. The first operational amplifier U1 controls the charging and discharging time of the sampling and integration circuit 61 according to the comparison result between the second electrical parameter signal Vcs and the fifth threshold to obtain a first electrical parameter signal Vout that characterizes the thyristor cut angle. By detecting the electrical parameter signal Vcs to obtain the thyristor-cut angle electrical parameter signal Vout, the detection accuracy is improved, and the sampling process is simpler and more reliable.

如图16所示，可控硅切波角度检测电路60的实施例还可以通过同时检测输入电压Vin以及第二电参数信号Vcs得到电参数信号Vout。图16中可控硅切波角度检测电路60的输入不仅与MOS管50的源极和电阻Rcs之间的公共端相连，还与LED驱动电路的电压母线相连用于采集输入电压Vin。第一电参数信号Vout对应于以输入电压Vin上升沿为开始并以第二电参数信号Vcs下降沿为结束所确定的一个采样周期内的参考电压平均值。As shown in FIG. 16, in the embodiment of the thyristor cut-wave angle detection circuit 60, the electrical parameter signal Vout can also be obtained by simultaneously detecting the input voltage Vin and the second electrical parameter signal Vcs. The input of the thyristor cut-wave angle detection circuit 60 in FIG. 16 is not only connected to the common terminal between the source of the MOS tube 50 and the resistor Rcs, but also connected to the voltage bus of the LED driving circuit for collecting the input voltage Vin. The first electrical parameter signal Vout corresponds to an average value of the reference voltage within a sampling period determined starting from a rising edge of the input voltage Vin and ending with a falling edge of the second electrical parameter signal Vcs.

检测输入电压及第二电参数信号实施例的电路如图17所示，图17中可控硅切波角度检测电路60包括第二运算放大器U2、第三运算放大器U3、第一脉冲产生电路A1、第二脉冲产生电路A2、RS触发器以及采样积分电路61，所述第二运算放大器U2的正向输入端接输入电压采样信号Vdect，第二运算放大器U2的反向输入端接用于提供上升沿采集起始阈值的第六阈值，第三运算放大器U3的反向输入端接第二电参数信号Vcs，第三运算放大器U3的正向输入端接用于提供下降沿采集结束阈值的第七阈值，第二运算放大器U2和第三运算放大器U3的输出分别接第一脉冲产生电路A1和第二脉冲产生电路A2的输入，所述第一脉冲产生电路A1和第二脉冲产生电路A2的输出分别接RS触发器的S端和R端，脉冲电路检测到运算放大器产生的翻转信号时向RS触发器输入脉冲信号，RS触发器的输出与采样积分电路相连接，并且采样积分电路上接参考电压。具体地，当检测到输入电压Vin达到上升沿阈值时第二运算放大器U2产生第一翻转信号X1，第一脉冲产生电路A1检测到第一翻转信号X1向RS触发器输入第一脉冲信号Y1，同样地，当检测到第二电参数信号Vcs达到下降沿阈值时第三运算放大器U3产生第二翻转信号X2，第二脉冲产生电路A2检测到第二翻转信号X2向RS触发器输入第二脉冲信号Y2。进一步由图17及图18的波形可知，RS触发器的Q端和

端分别与采样积分电路61中两个开关的控制端相连，串联设置的两个开关一端上接参考电压另一端接地，两个开关公共端接积分电阻，积分电阻与地之间还设有积分电容。采样积分电路61输出端接泄放电流控制电路70用于将运算处理后的第一电参数信号Vout输入泄放电流控制电路70。由图18可知，本实施例中的可控硅切波角度检测电路60检测角度范围较大，能够检测到可控硅导通θ1开始至第二电参数信号Vcs关断之间任意时刻角度，并且同时检测输入电压Vin及第二电参数信号Vcs，提高了检测角度的精准性，保证后续泄放电路控制的稳定性。 A circuit for detecting an input voltage and a second electrical parameter signal is shown in FIG. 17. In FIG. 17, the thyristor angle detection circuit 60 includes a second operational amplifier U2, a third operational amplifier U3, and a first pulse generating circuit A1. A second pulse generating circuit A2, an RS flip-flop, and a sampling integration circuit 61, the forward input terminal of the second operational amplifier U2 is connected to the input voltage sampling signal Vdect, and the reverse input terminal of the second operational amplifier U2 is used to provide The sixth threshold of the rising edge acquisition start threshold, the reverse input terminal of the third operational amplifier U3 is connected to the second electrical parameter signal Vcs, and the forward input terminal of the third operational amplifier U3 is used to provide the first threshold of the falling edge acquisition end threshold. Seven thresholds. The outputs of the second operational amplifier U2 and the third operational amplifier U3 are connected to the inputs of the first pulse generating circuit A1 and the second pulse generating circuit A2, respectively. The outputs are respectively connected to the S and R ends of the RS flip-flop. When the pulse circuit detects the inversion signal generated by the operational amplifier, the pulse signal is input to the RS flip-flop. The output and sampling product of the RS flip-flop are Circuit connected to the reference voltage and the sampling integration circuit. Specifically, when it is detected that the input voltage Vin reaches the rising edge threshold, the second operational amplifier U2 generates a first flip signal X1, and the first pulse generating circuit A1 detects that the first flip signal X1 inputs a first pulse signal Y1 to the RS flip-flop, Similarly, when it is detected that the second electrical parameter signal Vcs reaches the falling edge threshold, the third operational amplifier U3 generates a second flip signal X2, and the second pulse generating circuit A2 detects that the second flip signal X2 inputs a second pulse to the RS flip-flop. Signal Y2. Further from the waveforms in FIG. 17 and FIG. 18, it can be seen that the Q-side of the RS flip-flop and

The two terminals are connected to the control terminals of two switches in the sampling and integration circuit 61 respectively. One end of the two switches connected in series is connected to the reference voltage and the other end is grounded. The two switches are commonly connected to the integral resistor. capacitance. The output terminal of the sampling and integration circuit 61 is connected to the bleeder current control circuit 70 for inputting the first electrical parameter signal Vout after the operation processing to the bleeder current control circuit 70. As can be seen from FIG. 18, the thyristor cut-wave angle detection circuit 60 in this embodiment has a larger detection angle range, and can detect the angle at any time between the start of the thyristor θ1 and the turning off of the second electrical parameter signal Vcs. In addition, the input voltage Vin and the second electrical parameter signal Vcs are detected at the same time, which improves the accuracy of the detection angle and ensures the stability of subsequent bleeder circuit control.

图8示意了一种泄放电流控制电路70的一种结构，该电路结构侧重在解决LED电路30导通后的泄放电流控制，当然，还可以采取其它形式的或者更为复杂的电路。泄放电流控制电路70包括对所述第一阈值和第一电参数信号进行比较的第一比较放大器、对第三阈值和电参数信号Vcs进行比较的第二比较放大器。泄放电流控制电路70还可以包括逻辑门电路(在图中示意为与门)，根据第一比较放大器和第二比较放大器的比较结果控制泄放电流电路20。该电路中两个比较放大器的输出端都连接到与门的两个输入端上，其中第一比较放大器的正向输入端输入第一阈值，其反向输入端连接电参数信号Vout，第二比较放大器的正向输入端输入第三阈值，反向输入端输入电参数信号Vcs；与门根据两个比较器输出的电平来控制泄放电流电路20的关断和开启。FIG. 8 illustrates a structure of a bleeder current control circuit 70. The circuit structure focuses on solving the bleeder current control after the LED circuit 30 is turned on. Of course, other forms or more complicated circuits may be adopted. The bleeder current control circuit 70 includes a first comparison amplifier that compares the first threshold value and the first electrical parameter signal, and a second comparison amplifier that compares the third threshold value and the electrical parameter signal Vcs. The bleed current control circuit 70 may further include a logic gate circuit (illustrated as an AND gate in the figure), and controls the bleed current circuit 20 according to a comparison result between the first comparison amplifier and the second comparison amplifier. The output ends of the two comparison amplifiers in this circuit are connected to the two input ends of the AND gate. The positive input end of the first comparison amplifier is input with the first threshold value, and the reverse input end of the first comparison amplifier is connected with the electrical parameter signal Vout. The positive input terminal of the comparison amplifier inputs a third threshold value, and the reverse input terminal inputs an electrical parameter signal Vcs; the AND gate controls the turning off and opening of the bleeder current circuit 20 according to the levels of the outputs of the two comparators.

当电参数信号Vout大于第一阈值时，意味着起始导通角小，第一比较放大器输出低电平，此时与门关断泄放电流电路20的导通，停止提供泄放电流；当电参数信号Vout小于第一阈值时，意味着起始导通角大，第一比较放大器输出高电平，且当电参数信号Vcs大于第三阈值时，第二比较放大器输出低电平，此时与门关断泄放电流电路20的导通，停止提供泄放电流；当电参数信号Vout小于第一阈值时，第一比较放大器输出高电平，且当电参数信号Vcs小于第三阈值时，第二比较放大器输出高电平，此时与门开启泄放电流电路20的导通，提供泄放电流。When the electrical parameter signal Vout is greater than the first threshold value, it means that the initial conduction angle is small, and the first comparison amplifier outputs a low level. At this time, the gate is turned off to turn off the bleeder current circuit 20 and stop supplying the bleeder current. When the electrical parameter signal Vout is less than the first threshold value, it means that the initial conduction angle is large, the first comparison amplifier outputs a high level, and when the electrical parameter signal Vcs is greater than a third threshold value, the second comparison amplifier outputs a low level, At this time, the AND gate turns off the conduction of the bleeder current circuit 20 and stops supplying the bleeder current; when the electrical parameter signal Vout is smaller than the first threshold, the first comparison amplifier outputs a high level, and when the electrical parameter signal Vcs is smaller than the third At the threshold value, the second comparison amplifier outputs a high level, and at this time, the AND gate opens the bleeder current circuit 20 to provide a bleeder current.

可选地，如果当可控硅调光器10导通后，泄放电流控制电路70接收的电参数信号Vcs始终小于第三阈值时，即使电参数信号Vout大于第一阈值，泄放电流控制电路70始终开启所述泄放电流电路20，来提供泄放电流。Optionally, if the electrical parameter signal Vcs received by the bleed current control circuit 70 is always smaller than the third threshold after the thyristor dimmer 10 is turned on, the bleed current control is performed even if the electrical parameter signal Vout is greater than the first threshold. The circuit 70 always turns on the bleeder current circuit 20 to provide a bleeder current.

可选地，泄放电流电路20中所用的NMOS管，可以为NPN/PNP以及PMOS等开关管。Optionally, the NMOS tube used in the bleeder current circuit 20 may be a switching tube such as NPN / PNP and PMOS.

在上述可调光LED驱动电路中，通过可控硅切波角度检测电路60输出电参数信号Vout后，泄放电流控制电路70比较电参数信号Vout大于第一阈值时，控制泄放电流电路20停止提供泄放电流，来提高***的工作效率；当电参数信号Vout小于第一阈值且电参数信号Vcs小于第三阈值时，控制泄放电流电路20再次提供泄放电流，以保证***的稳定性。In the above-mentioned dimmable LED driving circuit, after the electrical parameter signal Vout is output through the thyristor cut angle detection circuit 60, the bleeder current control circuit 70 controls the bleeder current circuit 20 when the electrical parameter signal Vout is greater than a first threshold value. Stop providing the bleeder current to improve the working efficiency of the system; when the electrical parameter signal Vout is less than the first threshold and the electrical parameter signal Vcs is less than the third threshold, the bleeder current circuit 20 is controlled to supply the bleeder current again to ensure the stability of the system Sex.

对于交流供电的可调光LED驱动电路中，可控硅调光器10切波后输入的峰值电压Vin_pk接近输出LED灯电压V _LED一定范围时(Vin_pk-V _LED＜△V，此时对应可控硅调光器处于小角度的情况)，可控硅调光器10切波出现严重不对称现象，造成闪灯；而如果可控硅调光器10切波后输入的峰值电压Vin_pk与LED灯电压V _LED的差值大于等于该范围(Vin_pk-V _LED≥△V)，则可控硅调光器10就不会出现这种严重不对称现象，也就不会出现闪灯。所以在可控硅调光器10切波后的输入峰值电压Vin_pk与LED灯电压V _LED的差值大于等于该范围(Vin_pk-V _LED≥△V)时就将LED电流下降至零或者较低值，则可以解决或改善闪灯的问题。在一些实施例中，所述△V的取值可以由用户输入确定。所述△V可以是一个固定的电压值，也可以取决于LED灯的导通电压V _LED(例如，△V可以是V _LED的一个固定或者可变的比例)。 For an AC-powered dimmable LED drive circuit, when the TRIAC dimmer 10 cuts the input peak voltage Vin_pk close to the output LED lamp voltage V _{LED within} a certain range (Vin_pk-V _LED <△ V, the corresponding In the case where the TRIAC dimmer is at a small angle), the thyristor dimmer 10 has a severe asymmetry in the cutting wave, causing flashing; and if the thyristor dimmer 10 is cutting, the input peak voltage Vin_pk and the LED The difference between the lamp voltage V _LED is greater than or equal to this range (Vin_pk-V _LED ≥ △ V), then the thyristor dimmer 10 will not have such a serious asymmetry phenomenon, and there will be no flashing light. Therefore, when the difference between the input peak voltage Vin_pk and the LED lamp voltage V _LED after the TRIAC dimmer 10 is cut, the LED current will be reduced to zero or lower when the difference is greater than or equal to this range (Vin_pk-V _LED ≥ △ V). Value, you can solve or improve the flashing problem. In some embodiments, the value of ΔV may be determined by user input. The ΔV may be a fixed voltage value, or may depend on the on-voltage V _LED of the LED lamp (for example, ΔV may be a fixed or variable ratio of V _LED ).

为了解决上述问题，本发明在可控硅切波角度检测电路60和功率控制电路40之间增加一个输出电流补偿电路80，并将功率控制电路40的输入端改为与输出电流补偿电路80的输出端连接。可控硅切波角度检测电路60的输出端连接输出电流补偿电路80的第一输入端。In order to solve the above problem, the present invention adds an output current compensation circuit 80 between the thyristor cut-wave angle detection circuit 60 and the power control circuit 40, and changes the input end of the power control circuit 40 to the output current compensation circuit 80. Output connection. The output terminal of the thyristor cut-wave angle detection circuit 60 is connected to the first input terminal of the output current compensation circuit 80.

在输出电流补偿电路80接收到可控硅切波角度检测电路60输出的电参数信号Vout时，根据其内部设置的第二阈值，将电参数信号Vout与第二阈值进行比较。当电参数信号Vout小于第二阈值，意味着切波后输入的峰值电压可能接近输出LED灯电压V _LED一定范围，输出电流补偿电路80控制LED电路30的电流逐渐减小；电参数信号Vout越小，则输出电流补偿电路80调整控制LED电路30的电流的幅度越大，直到Vin_pk-V _LED≥△V时，输出电流补偿电路将LED电路30的峰值电流降为零，或者降低到一个较小值，此时，可解决闪灯或很大程度上改善闪灯。 When the output current compensation circuit 80 receives the electrical parameter signal Vout output from the thyristor cut-wave angle detection circuit 60, the electrical parameter signal Vout is compared with the second threshold according to a second threshold value set therein. When the electrical parameter signal Vout is less than the second threshold value, it means that the peak voltage input after the cutting wave may be close to a certain range of the output LED lamp voltage V _LED , and the output current compensation circuit 80 controls the current of the LED circuit 30 to gradually decrease; the more the electrical parameter signal Vout The smaller, the output current compensation circuit 80 adjusts the amplitude of the current of the LED circuit 30 to be larger, until Vin_pk-V _LED ≥ △ V, the output current compensation circuit reduces the peak current of the LED circuit 30 to zero, or to a lower value. A small value, at this time, can solve the flash or greatly improve the flash.

优选地，功率控制电路40的反向输入端改为与输出电流补偿电路80的输出端连接，实现由功率控制电路40来控制Ics峰值电流的下降斜率。Preferably, the reverse input terminal of the power control circuit 40 is connected to the output terminal of the output current compensation circuit 80 instead, so that the power control circuit 40 can control the falling slope of the peak current of Ics.

优选地，泄放电流控制电路70第二输入端连接在MOS管50和采样电阻Rcs中间，实现泄放电流控制电路70实时检测电参数信号Vcs，当电参数信号Vcs小于其内部设置的第三阈值时，泄放电流电路20一直提供电流，以维持可控硅调光器10导通。Preferably, the second input terminal of the bleeder current control circuit 70 is connected between the MOS tube 50 and the sampling resistor Rcs, so that the bleeder current control circuit 70 detects the electrical parameter signal Vcs in real time. When the threshold value is reached, the bleeder current circuit 20 always provides current to keep the TRIAC dimmer 10 on.

其中，Ics峰值电流表示经过采样电阻Rcs的输出电流，电参数信号Vcs表征流过LED电路(30)的电流，且Vcs＝Ics*Rcs。The Ics peak current represents the output current through the sampling resistor Rcs, the electrical parameter signal Vcs represents the current flowing through the LED circuit (30), and Vcs = Ics * Rcs.

在一个实施例中，如图9A、9B和9C所示提供三种可控硅调光器10切波角度、Ics电流与I _LED电流的关系。图9A、9B和9C中的可控硅调光器10切波角度θ分别为θ1、θ2和θ3，切波后输入的峰值电压分别为Vin_pk1′、Vin_pk2′、V _LED+△V。且切波角度θ1<θ2<θ3，切波后的输入峰值电压Vin_pk1′>Vin_pk2′>V _LED+△V。 In one embodiment, as shown in FIGS. 9A, 9B, and 9C, three kinds of thyristor dimmers 10 are provided with the relationship of the cut angle, the Ics current, and the I _LED current. The cutting wave angles θ of the TRIAC dimmer 10 in FIGS. 9A, 9B, and 9C are θ1, θ2, and θ3, respectively, and the peak voltages input after the cutting are Vin_pk1 ′, Vin_pk2 ′, and V _LED + △ V. And the shear wave angle θ1 <θ2 <θ3, the input peak voltage Vin_pk1 ′> Vin_pk2 ′> V _LED + △ V after the shear wave.

当可控硅切波角度检测电路60检测到可控硅调光器10的切波角度θ到达第二阈值所设定的θ1(如图9A所示，切波角度θ小于或等于θ1时，Ics峰值电流恒为Ipk1)时，输出电流补偿电路80开始减小Ics的峰值电流，并且随着可控硅调光器10的切波角度θ的逐渐增大，Ics的峰值电流持续下降(如图9B所示，Ics峰值电流下降至Ipk2，Ipk2<Ipk1)，此时LED的电流也随着Ics峰值电流的下降而下降；当可控硅切波角度检测电路60检测到可控硅调光器10的起始切波角度θ增大至θ3(如图9C所示，此时可控硅调光器10切波后输入的峰值电压V _LED+△V)时，输出电流补偿电路80会将Ics的峰值电流下降至零。如果Ics的峰值电流在输入电压Vin仍大于LED导通电压V _LED之前降为零，则可解决闪灯问题；如果Ics的峰值电流在输入电压Vin小于LED导通电压V _LED之后降为较小值，则可很大程度上改善小角度闪灯问题。 When the thyristor tangent angle detection circuit 60 detects that the tangent angle θ of the thyristor dimmer 10 reaches θ1 set by the second threshold (as shown in FIG. 9A, the tangent angle θ is less than or equal to θ1, When the peak current of Ics is constant Ipk1), the output current compensation circuit 80 starts to reduce the peak current of Ics, and as the cutting angle θ of the thyristor dimmer 10 gradually increases, the peak current of Ics continues to decrease (such as As shown in FIG. 9B, the peak Ics current decreases to Ipk2, and Ipk2 <Ipk1). At this time, the LED current also decreases as the peak Ics current decreases; when the thyristor cut-wave angle detection circuit 60 detects the thyristor dimming, When the initial shear wave angle θ of the modulator 10 increases to θ3 (as shown in FIG. 9C, at this time, the peak voltage V _LED + △ V input after the TRIAC dimmer 10 is cut), the output current compensation circuit 80 will Reduce the peak current of Ics to zero. If the peak current of Ics drops to zero before the input voltage Vin is still greater than the LED turn-on voltage V _LED , the flashing problem can be solved; if the peak current of Ics drops to a smaller value after the input voltage Vin is less than the LED turn-on voltage V _LED Value can greatly improve the problem of small-angle flashing.

在一个实施例中，如图10所示提供的可控硅切波角度检测电路60降低Ics的峰值电流时对应的泄放电流，在Ics的峰值电流开始逐渐下降时，泄放电流控制电路70实时检测电参数信号V _CS，当电参数信号V _CS小于第三阈值后，泄放电流电路20一直提供电流，以维持可控硅调光器10的导通。 In one embodiment, the thyristor cut-wave angle detection circuit 60 provided in FIG. 10 provides a corresponding bleeder current when the peak current of Ics is reduced. When the peak current of Ics starts to gradually decrease, the bleeder current control circuit 70 The electrical parameter signal V _{CS is} detected in real time. When the electrical parameter signal V _{CS is} less than the third threshold, the bleeder current circuit 20 always provides current to maintain the conduction of the thyristor 10.

在解决闪灯问题的一个实施例中，如图11所示，本发明提出了一种输出电流补偿电路80，包括第一跨导放大器GM和补偿电阻Rcomp。该电路中第一跨导放大器输出端通过单向导通的二极管和补偿电阻Rcomp连接到MOS管的漏极，其正向输入端输入第二阈值，反向输入端耦合用于接收可控硅切波角度检测电路60产生的电参数信号Vout。In an embodiment for solving the flashing problem, as shown in FIG. 11, the present invention provides an output current compensation circuit 80 including a first transconductance amplifier GM and a compensation resistor Rcomp. The output of the first transconductance amplifier in this circuit is connected to the drain of the MOS transistor through a unidirectional diode and a compensation resistor Rcomp. Its forward input is input with a second threshold, and its reverse input is coupled to receive the thyristor. The electrical parameter signal Vout generated by the wave angle detection circuit 60.

输出电流补偿电路80检测输入到第一跨导放大器反向输入端的电参数信号Vout的电压值。如果电参数信号Vout的电压值减小到第二阈值，则第一跨导放大器的输出端开始输出一个补偿电流Icomp，该补偿电流Icomp会在补偿电阻Rcomp上产生一个补偿电压Vcomp(Vcomp＝Icomp×Rcomp)，从而减小Ics的峰值电流。如果电参数信号Vout继续减小，则补偿电流Icomp逐渐增大，Ics峰值电流逐渐减小，LED电流也逐渐下降。如果电参数信号Vout减小到某一设定量(也即图9C中切波角度为θ3度，可控硅调光器10切波后输入的峰值电压为V _LED+△V)，补偿电压Vcomp增加到与功率控制电路40 中VREF相等时，Ics的峰值电流下降至零，LED电路30上的电流也下降至零，使得可控硅调光器10未出现严重不对称之前将LED电流下降至零，从而实现解决闪灯问题。 The output current compensation circuit 80 detects a voltage value of the electrical parameter signal Vout input to the inverting input terminal of the first transconductance amplifier. If the voltage value of the electrical parameter signal Vout decreases to a second threshold value, the output of the first transconductance amplifier starts to output a compensation current Icomp, and the compensation current Icomp will generate a compensation voltage Vcomp (Vcomp = Icomp) on the compensation resistor Rcomp. × Rcomp), thereby reducing the peak current of Ics. If the electrical parameter signal Vout continues to decrease, the compensation current Icomp gradually increases, the peak current Ics gradually decreases, and the LED current also gradually decreases. If the electrical parameter signal Vout is reduced to a certain set amount (that is, the cutting wave angle in FIG. 9C is θ3 degrees, and the peak voltage input after the TRIAC dimmer 10 is cut is V _LED + △ V), the compensation voltage When Vcomp increases to be equal to VREF in the power control circuit 40, the peak current of Ics drops to zero, and the current on the LED circuit 30 also drops to zero, so that the TRIAC dimmer 10 reduces the LED current before serious asymmetry occurs. To zero, so as to solve the problem of flashing lights.

在改善小角度闪灯问题的一个实施例中，如图12所示，本发明提出了另一种输出电流补偿电路80，包括第一跨导放大器、第二跨导放大器和补偿电阻Rcomp。第一跨导放大器正向输入端输入第二阈值，其反向输入端和第二跨导放大器正向输入端连接以接收电参数信号Vout，第二跨导放大器反向输入端输入第四阈值；第一跨导放大器GM1的输出端经一个单向(输出方向)导通的二极管后，第二跨导放大器GM2的输出端经另一个相反方向(输入方向)单向导通的二极管后，耦合在一起，然后经补偿电阻Rcomp耦合到MOS管50的漏极；其中第二阈值大于第四阈值。当电参数信号Vout下降至第四阈值后，第二跨导放大器开始限制第一跨导放大器的输出电流，从而将Ics限制在一个较小值，从而实现很大程度上改善小角度闪灯问题。In an embodiment for improving the problem of small-angle flashing, as shown in FIG. 12, the present invention proposes another output current compensation circuit 80 including a first transconductance amplifier, a second transconductance amplifier, and a compensation resistor Rcomp. The first transconductance amplifier has a second threshold input at its positive input, its reverse input is connected to the second transconductance amplifier's forward input to receive the electrical parameter signal Vout, and the second transconductance amplifier's reverse input has its fourth threshold. ; The output of the first transconductance amplifier GM1 is coupled by a unidirectional (output direction) diode, and the output of the second transconductance amplifier GM2 is coupled by another unidirectional diode in the opposite direction (input direction). Together, and then coupled to the drain of the MOS transistor 50 via the compensation resistor Rcomp; wherein the second threshold is greater than the fourth threshold. When the electrical parameter signal Vout drops to the fourth threshold, the second transconductance amplifier begins to limit the output current of the first transconductance amplifier, thereby limiting Ics to a smaller value, thereby achieving a large improvement in the problem of small-angle flashing. .

可选地，上述提到的第一阈值、第二阈值、第三阈值和第四阈值可以为电流阈值、电压阈值、时间阈值等等中的任一阈值。Optionally, the aforementioned first threshold, second threshold, third threshold, and fourth threshold may be any one of a current threshold, a voltage threshold, a time threshold, and the like.

图13为本发明实施例提供的一种控制方法流程图。如图13所示，本发明还提供了一种控制方法，具体步骤包括：FIG. 13 is a flowchart of a control method according to an embodiment of the present invention. As shown in FIG. 13, the present invention further provides a control method. The specific steps include:

步骤S1302，可控硅调光器导通后；Step S1302, after the thyristor dimmer is turned on;

步骤S1302，获取电参数信号Vout，其中所述电参数信号Vout对应于输入电压Vin从所述可控硅调光器10的起始导通切波角度开始到周期结束期间的平均值，输入电压Vin是整流桥对流经所述可控硅调光器10的交流电整流后得到的全波整流电压，输入电压Vin是LED电路的驱动电压；Step S1302, obtaining an electrical parameter signal Vout, wherein the electrical parameter signal Vout corresponds to an average value of the input voltage Vin from the start of the TRIAC dimmer 10 to the end of the period, and the input voltage Vin is a full-wave rectified voltage obtained by rectifying the AC power flowing through the TRIAC dimmer 10, and the input voltage Vin is the driving voltage of the LED circuit;

步骤S1303，泄放电流控制电路70将电参数信号Vout与第一阈值进行比较，来控制泄放电流电路20；当电参数信号Vout大于所述第一阈值时，执行步骤S1304；当电参数信号Vout小于第一阈值时，执行步骤S1305；Step S1303: The bleeder current control circuit 70 compares the electrical parameter signal Vout with a first threshold value to control the bleeder current circuit 20. When the electrical parameter signal Vout is greater than the first threshold value, step S1304 is performed; when the electrical parameter signal When Vout is less than the first threshold, step S1305 is performed;

在一个例子中，第一阈值对应于输入电压Vin在一个可控硅调光器10具有第一起始导通切波角度的周期内从第一起始导通切波角度开始到周期结束期间的平均值；其中，在可控硅调光器10具有该第一起始导通切波角度的周期内线性LED驱动的损耗和泄放电流电路20在未调整输出电流的情况下的电路损耗之和与在具有最小起始导通切波角度的周期内线性LED驱动的损耗和输入电压Vin未达到所述LED电路30的导通电压前泄放电流电路的电路损耗之和相当。In one example, the first threshold value corresponds to an average of the input voltage Vin during a period in which the thyristor dimmer 10 has a first starting on-cut angle from the first starting on-cut angle to the end of the period Where the sum of the losses of the linear LED drive and the bleeder current circuit 20 in the period when the thyristor dimmer 10 has the first initial on-cut angle is The sum of the losses of the linear LED drive and the circuit losses of the bleeder current circuit before the input voltage Vin does not reach the turn-on voltage of the LED circuit 30 during the period with the smallest initial on-cut angle.

步骤S1304，泄放电流控制电路70关断泄放电流电路20的导通，停止提供泄放电流，然后执行步骤S1301；Step S1304, the bleeder current control circuit 70 turns off the conduction of the bleeder current circuit 20, stops supplying the bleeder current, and then executes step S1301;

步骤S1305，输出电流补偿电路80检测电参数信号Vout是否小于第二阈值；Step S1305, the output current compensation circuit 80 detects whether the electrical parameter signal Vout is less than a second threshold value;

步骤S1306，当输出电流补偿电路80检测输入电压Vout大于第二阈值时，输出电流补偿电路80保持输出电流的峰值电流不变，执行步骤S1308；Step S1306, when the output current compensation circuit 80 detects that the input voltage Vout is greater than the second threshold, the output current compensation circuit 80 keeps the peak current of the output current unchanged, and executes step S1308;

步骤S1307，当输出电流补偿电路80检测输入电压Vout小于第二阈值时，输出电流补偿电路80减小输出电流的峰值电流，执行步骤S1308；In step S1307, when the output current compensation circuit 80 detects that the input voltage Vout is less than the second threshold, the output current compensation circuit 80 reduces the peak current of the output current, and executes step S1308;

步骤S1308，泄放电流控制电路70检测电参数信号Vcs，判断所述电参数信号Vcs是否小于第三阈值；所述电参数信号Vcs对应于流过所述LED电路(30)的电流；Step S1308, the bleeder current control circuit 70 detects the electrical parameter signal Vcs, and determines whether the electrical parameter signal Vcs is less than a third threshold; the electrical parameter signal Vcs corresponds to the current flowing through the LED circuit (30);

步骤S1309，当电参数信号Vcs小于第三阈值时，泄放电流控制电路70开启泄放电流电路20的导通，提供泄放电流，然后执行步骤S1308；In step S1309, when the electrical parameter signal Vcs is less than the third threshold, the bleed current control circuit 70 turns on the bleed current circuit 20 to provide a bleed current, and then executes step S1308;

步骤S1310，当电参数信号Vcs大于第三阈值时，泄放电流控制电路70关断泄放电流电路20的导通，停止提供泄放电流。然后执行步骤S1301。In step S1310, when the electrical parameter signal Vcs is greater than the third threshold, the bleeder current control circuit 70 turns off the conduction of the bleeder current circuit 20 and stops supplying the bleeder current. Then step S1301 is executed.

其中，该方法中步骤S1303将将电参数信号Vout与第一阈值进行比较，其实也就是对可控硅调光器10的起始导通角度θ和第一阈值决定的导通角度θth进行比较。Wherein, step S1303 in the method compares the electrical parameter signal Vout with the first threshold value, which is actually comparing the starting conduction angle θ of the thyristor 10 with the conduction angle θth determined by the first threshold value. .

优选地，步骤S1304中当可控硅调光器切波的起始导通角度θ小于第一阈值决定的起始导通角度θth时，泄放电流电路20提供一个较小的泄放电流。Preferably, in step S1304, when the starting conduction angle θ of the TRIAC dimmer switch is smaller than the starting conduction angle θth determined by the first threshold, the bleeder current circuit 20 provides a smaller bleeder current.

优选地，步骤S1304中当可控硅调光器切波的起始导通角度θ小于第一阈值决定的起始导通角度θth时，可以先关断泄放电流，延迟1ms后再开启泄放电流电路20，提供一个较小的泄放电流。Preferably, in step S1304, when the initial conduction angle θ of the thyristor dimmer switch is smaller than the initial conduction angle θth determined by the first threshold, the bleeder current may be turned off first, and the bleeder may be turned on after a delay of 1 ms. The bleeder circuit 20 provides a smaller bleeder current.

需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者装置不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者装置所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者装置中还存在另外的相同要素。It should be noted that in this article, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations There is any such actual relationship or order among them. Moreover, the terms "including," "including," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or device that includes a series of elements includes not only those elements but also those that are not explicitly listed Or other elements that are inherent to this process, method, article, or device. Without more restrictions, the elements defined by the sentence "including a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

以上所述的具体实施方式，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施方式而已，并不用于限定本发明的保护范围，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。The specific embodiments described above further describe the objectives, technical solutions, and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. The scope of protection, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be included in the scope of protection of the present invention.

Claims

一种可调光LED驱动电路，包括：可控硅调光器(10)、泄放电流电路(20)、LED电路(30)，所述泄放电流电路(20)提供在输入电压(Vin)未达到所述LED电路(30)的导通电压时所述可控硅调光器(10)所需的电流，其特征在于，还包括：可控硅切波角度检测电路(60)和泄放电流控制电路(70)，其中A dimmable LED driving circuit includes a silicon controlled dimmer (10), a bleeder current circuit (20), and an LED circuit (30). The bleeder current circuit (20) provides an input voltage (Vin The current required by the thyristor dimmer (10) when the on-voltage of the LED circuit (30) is not reached, further comprising: a thyristor cut-wave angle detection circuit (60) and Bleed Current Control Circuit (70), where

所述可控硅调光器(10)导通后，所述可控硅切波角度检测电路(60)获取表征可控硅切波角度的第一电参数信号(Vout)，After the thyristor dimmer (10) is turned on, the thyristor cut-wave angle detection circuit (60) obtains a first electrical parameter signal (Vout) that characterizes the thyristor cut-wave angle,

所述泄放电流控制电路(70)将所述第一电参数信号(Vout)与第一阈值进行比较，来控制所述泄放电流电路(20)。The bleeder current control circuit (70) compares the first electrical parameter signal (Vout) with a first threshold to control the bleeder current circuit (20).
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述泄放电流控制电路(70)在检测到所述第一电参数信号(Vout)大于第一阈值，控制所述泄放电流电路(20)关断，停止提供泄放电流。The dimmable LED driving circuit according to claim 1, wherein the bleeder current control circuit (70) controls the bleeder when it detects that the first electrical parameter signal (Vout) is greater than a first threshold value. The current-discharging circuit (20) is turned off and stops supplying a bleeder current.
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述泄放电流控制电路(70)将表征流过所述LED电路(30)电流的第二电参数(Vcs)与第三阈值进行比较，当所述第一电参数信号(Vout)小于所述第一阈值且所述第二电参数信号(Vcs)小于所述第三阈值时，所述泄放电流控制电路(70)控制所述泄放电流电路(20)开启，提供泄放电流。The dimmable LED driving circuit according to claim 1, characterized in that the bleeder current control circuit (70) will characterize the second electrical parameter (Vcs) and the first electrical parameter (Vcs) of the current flowing through the LED circuit (30). Three thresholds are compared. When the first electrical parameter signal (Vout) is smaller than the first threshold and the second electrical parameter signal (Vcs) is smaller than the third threshold, the bleeder current control circuit (70 ) Controlling the bleeder current circuit (20) to open to provide a bleeder current.
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述第一电参数信号(Vout)对应于输入电压(Vin)在一个周期内从所述可控硅调光器(10)的起始导通切波角度开始到周期结束期间的平均值。The dimmable LED driving circuit according to claim 1, wherein the first electrical parameter signal (Vout) corresponds to the input voltage (Vin) from the thyristor dimmer (10) within a period. ) Is the average value from the start of the cut-on angle to the end of the period.
根据权利要求1或4所述的可调光LED驱动电路，其特征在于，所述可控硅切波角度检测电路(60)包括积分电路，所述积分电路用于对输入电压(Vin)积分，从而提供所述第一电参数信号(Vout)。The dimmable LED driving circuit according to claim 1 or 4, wherein the thyristor cut-wave angle detection circuit (60) comprises an integration circuit, and the integration circuit is configured to integrate an input voltage (Vin) To provide the first electrical parameter signal (Vout).
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述第一电参数信号(Vout)对应于在一个第二电参数信号(Vcs)采样周期内的参考电压平均值，所述第二电参数信号(Vcs)表征流过所述LED电路(30)的电流。The dimmable LED driving circuit according to claim 1, wherein the first electrical parameter signal (Vout) corresponds to an average value of a reference voltage in a sampling period of the second electrical parameter signal (Vcs), and The second electrical parameter signal (Vcs) characterizes a current flowing through the LED circuit (30).
根据权利要求6所述的可调光LED驱动电路，其特征在于，所述可控硅切波角度检测电路(60)包括第一运算放大器U1和采样积分电路(61)，所述第一运算放大器U1的正向输入端接第二电参数信号(Vcs)，第一运算放大器U1的反向输入端接第五阈值，第一运算放大器U1的输出端与采样积分电路(61)相连，并且采样积分电路(61)上接参考电压，采样积分电路(61)的输出端接泄放电流控制电路(70)用于将运算处理后的第一电参数信号(Vout)输入泄放电流控制电路(70)。The dimmable LED driving circuit according to claim 6, wherein the thyristor cut-wave angle detection circuit (60) comprises a first operational amplifier U1 and a sampling integration circuit (61), and the first operation The forward input of the amplifier U1 is connected to the second electrical parameter signal (Vcs), the reverse input of the first operational amplifier U1 is connected to the fifth threshold, and the output of the first operational amplifier U1 is connected to the sampling integration circuit (61), and The sampling integration circuit (61) is connected to a reference voltage, and the output terminal of the sampling integration circuit (61) is connected to a bleeder current control circuit (70) for inputting the first electrical parameter signal (Vout) after the operation processing to the bleeder current control circuit. (70).
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述第一电参数信号(Vout)对应于以输入电压(Vin)上升沿为开始并以第二电参数信号(Vcs)下降沿为结束所确定的一个采样周期内的参考电压平均值，所述第二电参数信号(Vcs)表征流过所述LED电路(30)的电流。The dimmable LED driving circuit according to claim 1, wherein the first electrical parameter signal (Vout) corresponds to starting with a rising edge of an input voltage (Vin) and starting with a second electrical parameter signal (Vcs) The falling edge is an average value of the reference voltage within a determined sampling period, and the second electrical parameter signal (Vcs) represents a current flowing through the LED circuit (30).
根据权利要求8所述的可调光LED驱动电路，其特征在于，所述可控硅切波角度检测电路(60)包括第二运算放大器U2、第三运算放大器U3、第一脉冲产生电路A1、第二脉冲产生电路A2、RS触发器以及采样积分电路(61)，所述第二运算放大器U2的正向输入端接输入电压采样信号(Vdect)，第二运算放大器U2的反向输入端接用于提供上升沿采集起始阈值的第六阈值，第三运算放大器U3的反向输入端接第二电参数信号(Vcs)，第三运算放大器U3的正向输入端接用于提供下降沿采集结束阈值的第七阈值，第二运算放大器U2和第三运算放大器U3的输出分别接第一脉冲产生电路A1和第二脉冲产生电路A2的输入，所述第一脉冲产生电路A1和第二脉冲产生电路A2的输出分别接RS触发器的S端和R端，脉冲电路检测到运算放大器产生的翻转信号时向RS触发器输入脉冲信号，RS触发器的输出与采样积分电路 (61)相连接，并且采样积分电路(61)上接参考电压，采样积分电路(61)输出端接泄放电流控制电路(70)用于将运算处理后的第一电参数信号(Vout)输入泄放电流控制电路(70)。10、根据权利要求1所述的可调光LED驱动电路，其特征在于，还包括：输出电流补偿电路(80)，所述输出电流补偿电路(80)将所述第一电参数信号(Vout)与第二阈值进行比较，来控制流过所述LED电路(30)的电流；其中，第二阈值小于第一阈值并且表明可控硅调光器切波后的输入电压的峰值电压接近LED电路的导通电压(V _LED)。 The dimmable LED driving circuit according to claim 8, characterized in that the thyristor cut-wave angle detection circuit (60) comprises a second operational amplifier U2, a third operational amplifier U3, and a first pulse generating circuit A1. A second pulse generating circuit A2, an RS flip-flop, and a sampling integration circuit (61), a forward input terminal of the second operational amplifier U2 is connected to an input voltage sampling signal (Vdect), and a reverse input terminal of the second operational amplifier U2; Connected to the sixth threshold for providing a rising edge acquisition start threshold, the inverting input of the third operational amplifier U3 is connected to the second electrical parameter signal (Vcs), and the positive input of the third operational amplifier U3 is connected to provide the falling Along the seventh threshold of the acquisition end threshold, the outputs of the second operational amplifier U2 and the third operational amplifier U3 are connected to the inputs of the first pulse generation circuit A1 and the second pulse generation circuit A2, respectively. The output of the two pulse generating circuit A2 is respectively connected to the S and R ends of the RS flip-flop. When the pulse circuit detects the inverted signal generated by the operational amplifier, the pulse signal is input to the RS flip-flop. The output and sampling of the RS flip-flop The sub-circuit (61) is connected, and the reference voltage is connected to the sampling integration circuit (61), and the output terminal of the sampling integration circuit (61) is connected to the bleeder current control circuit (70) for processing the first electrical parameter signal ( Vout) input bleeder current control circuit (70). 10. The dimmable LED driving circuit according to claim 1, further comprising: an output current compensation circuit (80), wherein the output current compensation circuit (80) converts the first electrical parameter signal (Vout ) Compared with a second threshold to control the current flowing through the LED circuit (30); wherein the second threshold is smaller than the first threshold and indicates that the peak voltage of the input voltage after the TRIAC dimmer is close to the LED The on-voltage of the circuit (V _LED ).
根据权利要求10所述的可调光LED驱动电路，其特征在于，所述输出电流补偿电路(80)包括第一跨导放大器；所述第一跨导放大器用于在第一电参数信号(Vout)小于所述第二阈值时，所述输出电流补偿电路(80)输出电流，以减小流经LED电路的电流的峰值电流。The dimmable LED driving circuit according to claim 10, characterized in that the output current compensation circuit (80) comprises a first transconductance amplifier; the first transconductance amplifier is used for the first electrical parameter signal ( When Vout) is less than the second threshold, the output current compensation circuit (80) outputs a current to reduce a peak current of a current flowing through the LED circuit.
根据权利要求11所述的可调光LED驱动电路，其特征在于，所述输出电流补偿电路(80)还包括第二跨导放大器；所述第二跨导放大器用于在第一电参数信号(Vout)小于第四阈值时，限制所述第一跨导放大器的输出电流；其中所述第二阈值大于所述第四阈值。The dimmable LED driving circuit according to claim 11, characterized in that the output current compensation circuit (80) further comprises a second transconductance amplifier; the second transconductance amplifier is used for the first electrical parameter signal (Vout) is less than a fourth threshold, limiting the output current of the first transconductance amplifier; wherein the second threshold is greater than the fourth threshold.
根据权利要求2所述的可调光LED驱动电路，其特征在于，所述泄放电流控制电路(70)包括第一比较放大器对所述第一阈值和第一电参数信号(Vout)进行比较；第二比较放大器对第三阈值和第二电参数信号(Vcs)进行比较。The dimmable LED driving circuit according to claim 2, wherein the bleeder current control circuit (70) comprises a first comparison amplifier to compare the first threshold value and a first electrical parameter signal (Vout). ; The second comparison amplifier compares the third threshold value and the second electrical parameter signal (Vcs).
根据权利要求1所述的可调光LED驱动电路，其特征在于，所述泄放电流电路(20)包括电流源和开关；所述电流源和所述开关电路串联连接，所述开关电路在所述泄放电流控制电路(70)的控制下泄放开启或泄放关断。The dimmable LED driving circuit according to claim 1, wherein the bleeder current circuit (20) comprises a current source and a switch; the current source and the switch circuit are connected in series, and the switch circuit is at Under the control of the bleed current control circuit (70), the bleed is turned on or the bleed is turned off.
根据权利要求1-14之一所述的可调光LED驱动电路，其特征在于，所述第一阈值、所述第二阈值、所述第三阈值和所述第四阈值可以为电流阈值、电压阈值、时间阈值中的任一阈值。The dimmable LED driving circuit according to claim 1, wherein the first threshold value, the second threshold value, the third threshold value, and the fourth threshold value are current threshold values, Either voltage threshold or time threshold.
一种控制方法，其特征在于，包括：A control method, comprising:

可控硅调光器(10)导通后，获取表征可控硅切波角度的第一电参数信号(Vout)；After the thyristor dimmer (10) is turned on, a first electrical parameter signal (Vout) representing the thyristor cutting wave angle is obtained;

由泄放电流电路(20)提供在输入电压(Vin)未达到LED电路(30)的导通电压时所述可控硅调光器(10)所需的电流，其中，所述输入电压(Vin)是经整流桥对流经所述可控硅调光器(10)的交流电进行整流后的全波整流电压并且作为所述LED电路的驱动电压；以及The current required by the TRIAC dimmer (10) when the input voltage (Vin) does not reach the on-voltage of the LED circuit (30) is provided by a bleeder current circuit (20), wherein the input voltage ( Vin) is a full-wave rectified voltage rectified by alternating current flowing through the thyristor dimmer (10) via a rectifier bridge and used as a driving voltage of the LED circuit; and

由泄放电流控制电路(70)将所述第一电参数信号(Vout)与第一阈值进行比较，并根据比较结果控制所述泄放电流电路(20)。A bleeder current control circuit (70) compares the first electrical parameter signal (Vout) with a first threshold, and controls the bleeder current circuit (20) according to the comparison result.
根据权利要求16所述的控制方法，其特征在于，还包括：The control method according to claim 16, further comprising:

当所述第一电参数信号(Vout)大于所述第一阈值时，泄放电流电路(20)关断泄放电流。When the first electrical parameter signal (Vout) is greater than the first threshold, the bleeder current circuit (20) turns off the bleeder current.
根据权利要求16所述的控制方法，其特征在于，还包括：The control method according to claim 16, further comprising:

当所述第一电参数信号(Vout)小于所述第一阈值时，检测所述第一电参数信号(Vout)是否小于第二阈值，其中，所述第二阈值小于所述第一阈值；When the first electrical parameter signal (Vout) is smaller than the first threshold, detecting whether the first electrical parameter signal (Vout) is smaller than a second threshold, wherein the second threshold is smaller than the first threshold;

当检测所述第一电参数信号(Vout)大于所述第二阈值时，保持所述LED电路(30)流过的峰值电流不变；以及When detecting that the first electrical parameter signal (Vout) is greater than the second threshold, keeping the peak current flowing through the LED circuit (30) unchanged; and

当检测所述第一电参数信号(Vout)小于所述第二阈值时，减小所述LED电路(30)流过的峰值电流。When the first electrical parameter signal (Vout) is detected to be less than the second threshold, the peak current flowing through the LED circuit (30) is reduced.
根据权利要求18所述的控制方法，其特征在于，还包括：The control method according to claim 18, further comprising:

泄放电流控制电路(70)检测第二电参数(Vcs)，并判断第二电参数(Vcs)是否小于第三阈值，其中，所述第二电参数(Vcs)表征流过所述LED电路(30)的电流；The bleeder current control circuit (70) detects a second electrical parameter (Vcs), and determines whether the second electrical parameter (Vcs) is less than a third threshold, wherein the second electrical parameter (Vcs) represents a flow through the LED circuit (30) the current;

当所述第二电参数(Vcs)小于所述第三阈值时，泄放电流电路提供泄放电流；以及When the second electrical parameter (Vcs) is less than the third threshold, a bleed current circuit provides a bleed current; and

当所述第二电参数(Vcs)大于所述第三阈值时，泄放电流电路停止提供泄放电流。When the second electrical parameter (Vcs) is greater than the third threshold, the bleeder current circuit stops providing a bleeder current.
根据权利要求18所述的控制方法，其特征在于，所述第一电参数信号(Vout)对应于一个周期内输入电压(Vin)从所述可控硅调光器(10)的起始导通切波角度开始到周期结束期间的平均值。The control method according to claim 18, characterized in that the first electrical parameter signal (Vout) corresponds to an input voltage (Vin) from a start guide of the thyristor (10) in one cycle. The average value of the pass-cut wave angle from the beginning to the end of the period.