CN108848598B

CN108848598B - Bleeder module for silicon controlled rectifier dimmer, LED driving circuit and driving method

Info

Publication number: CN108848598B
Application number: CN201811007066.8A
Authority: CN
Inventors: 杨林伟; 王曙光; 陈晓亮
Original assignee: Xiamen Biyi Micro Electronic Technique Co ltd
Current assignee: Xiamen Biyi Micro Electronic Technique Co ltd
Priority date: 2018-08-31
Filing date: 2018-08-31
Publication date: 2024-04-12
Anticipated expiration: 2038-08-31
Also published as: CN108848598A

Abstract

The invention discloses a bleeder module, an LED driving circuit and a driving method for a silicon controlled rectifier dimmer, wherein the bleeder module comprises a bleeder circuit bleeder current control circuit; the bleeder circuit is coupled with the direct current bus and provides a current bleeder path for the work of the silicon controlled rectifier dimmer, and the bleeder circuit comprises a power tube; the bleeder current control circuit is provided with an input end and an output end, wherein the input end of the bleeder current control circuit is coupled with the direct current bus for obtaining the bus voltage, the output end of the bleeder current control circuit is coupled with the control end of the power tube, and the bleeder current control circuit selectively controls the power tube according to the state of the bus voltage so that the bleeder circuit outputs pulse current as bleeder current, wherein the pulse current comprises a plurality of continuous current pulses. The invention provides the pulse current as the bleeder current, and the current is intermittently provided with a certain frequency, pulse width and amplitude, so that the power consumption can be furthest saved and the efficiency can be improved under the condition of maintaining the normal working of the silicon controlled rectifier dimmer.

Description

Bleeder module for silicon controlled rectifier dimmer, LED driving circuit and driving method

Technical Field

The invention belongs to the technical field of power electronics, relates to a silicon controlled rectifier dimmer, and in particular relates to a bleeder module for the silicon controlled rectifier dimmer, an LED driving circuit and an LED driving method thereof.

Background

Silicon controlled dimming is a currently commonly used dimming method. The silicon controlled rectifier dimmer adopts a phase control method to realize dimming, namely, the silicon controlled rectifier dimmer is controlled to be conducted every half period of the sine wave, and the same conduction phase angle is obtained. The magnitude of the conduction phase angle can be changed by adjusting the chopping phase of the silicon controlled rectifier dimmer, so that the dimming is realized.

Silicon controlled dimmers have been commonly used to dim incandescent lamps, and with the popularity of LED light sources, more and more LED driving circuits employ silicon controlled dimmers as dimming means. However, the system efficiency of the existing LED driving circuit is still to be improved, and it is difficult to be compatible with all the scr dimmers.

Referring to fig. 1, the unidirectional silicon controlled rectifier, also called a thyristor, is shown in fig. 1-a, and may be divided into four silicon regions P, N, P, N and A, K, G. The figure is cut in half as shown in fig. 1-b, and it can be easily understood that a unidirectional silicon controlled transistor is composed mainly of a PNP transistor and an NPN transistor as shown in fig. 1-c.

When the positive voltage V is applied to the anode-cathode (a-K), the transistor Q2 is turned on in the forward direction as long as the gate G is turned on to trigger the power supply Vg, the transistor Q2 is turned on at the moment Q1 just like a load connected to the collector of Q1 is turned on with the positive electrode of the power supply, and then Q1 is turned on under the pull current of Q2, at this time, since C is charged, even if the trigger power supply Vg of the gate is turned off, Q1 and Q2 can maintain the on state under the interaction, and Q1 and Q2 are turned off again only after the power supply voltage V becomes relatively small.

Compared with unidirectional thyristors, the bidirectional thyristors are in principle the biggest difference in that they can be turned on in two directions, and instead of having anode and cathode portions, they are represented by T1 and T2, the schematic structure is shown in fig. 3-a, if they are divided into fig. 3-b without considering the difference of G-level, it can be seen that two unidirectional thyristors are connected in opposite parallel, as shown in fig. 3-c.

Referring to fig. 4, fig. 4 discloses a schematic diagram of a scr dimmer. The silicon controlled dimmer turned on requires a large current, but maintains on without requiring a large current, and the dimmer turned off has a process requiring time according to the characteristics of the transistor, without abrupt change, as shown in table 1.

TABLE 1 silicon controlled dimmer on-off condition table

As shown in fig. 5, the conventional scr dimmer control circuit is controlled by a constant current IL, has no segmentation distinction, can adjust the size of IL only by adjusting a resistor R1, is difficult to be compatible with all dimmers, and has low efficiency. The conventional scheme drive waveforms are shown in fig. 6.

The existing scheme mainly has the following defects: (1) relatively low efficiency; (2) The bleed current can only be adjusted through R1, and R1 is fixed, and the current is not adjustable, and is difficult to be compatible with all dimmers.

In view of this, there is an urgent need to design an LED driving circuit so as to overcome the above-mentioned drawbacks of the existing LED driving circuit.

Disclosure of Invention

The technical problems to be solved by the invention are as follows: the bleeder module for the silicon controlled rectifier light modulator provides pulse current as bleeder current, so that power consumption can be saved, and efficiency can be improved.

Meanwhile, the invention provides the LED driving circuit which can save power consumption and improve efficiency.

In addition, the invention also provides an LED driving method which can save power consumption and improve efficiency.

A bleeder module for a thyristor dimmer, comprising:

the bleeder circuit is coupled with the direct current bus and provides a current bleeder path for the work of the silicon controlled rectifier dimmer, and the bleeder circuit comprises a power tube;

The bleeder current control circuit is provided with an input end and an output end, wherein the input end of the bleeder current control circuit is coupled with the direct current bus for obtaining the bus voltage, the output end of the bleeder current control circuit is coupled with the control end of the power tube, and the bleeder current control circuit selectively controls the power tube according to the state of the bus voltage so that the bleeder circuit outputs pulse current as bleeder current, and the pulse current comprises a plurality of continuous current pulses.

As one embodiment of the present invention, when it is detected that the bus voltage jumps from less than the predetermined threshold voltage to greater than the predetermined threshold voltage, the bleeder circuit outputs a pulse current as the bleeder current until the bus voltage rises to the load driving voltage.

As one embodiment of the present invention, a bleed-off current control circuit includes:

the timer is used for detecting the opening position time of the silicon controlled rectifier dimmer;

the detector is coupled with the direct current bus and the timer and is used for acquiring whether the variation trend of the bus voltage after the thyristor dimmer is started accords with an expected judgment signal or not;

and the controller is coupled with the timer and the detector and is used for judging whether the silicon controlled rectifier dimmer is normally started according to feedback results of the detector and the timer, and further adjusting one or more of the frequency, the pulse width or the amplitude of the pulse current to enable the pulse current to reach the minimum current for normally starting the corresponding silicon controlled rectifier dimmer.

As an embodiment of the present invention, the adjusting one or more of the frequency, the pulse width, or the amplitude of the pulse current includes:

if the detector detects that the thyristor dimmer can be normally started in N continuous periods, the amplitude of the bleeder current is reduced according to a given proportion, or the pulse width is reduced or the frequency is reduced to reduce the average value of the bleeder current; then continuously detecting whether the silicon controlled rectifier dimmer can be normally started or not in N continuous periods; if the silicon controlled dimmer can be normally started in N continuous periods, continuously reducing the amplitude of the discharge current according to a given proportion or reducing the pulse width or reducing the frequency; and the like, until the detector detects that the thyristor dimmer cannot be normally started in N continuous periods, increasing the amplitude or pulse width or frequency of the release current to a value which can normally start the thyristor dimmer last time, and keeping unchanged, wherein the period is a period of the rectified power supply, N is more than or equal to 2, and N is a natural number;

if the detector detects that the silicon controlled dimmer cannot be normally started in N continuous periods, increasing the amplitude of the bleeder current or increasing the pulse width or increasing the frequency according to a given proportion to increase the average value of the bleeder current; then continuously detecting whether the silicon controlled rectifier dimmer can be normally started or not in N continuous periods; if the silicon controlled dimmer cannot be normally started in N continuous periods, continuously increasing the amplitude of the discharge current according to a given proportion or increasing the pulse width or increasing the frequency; and the like, and the amplitude, pulse width and frequency of the bleeder current are kept unchanged until the detector detects that the thyristor dimmer can be normally started in N continuous periods.

As one embodiment of the present invention, the bleeding module is used for an LED driving circuit, the bleeding current control circuit further includes an LED on detection unit for detecting whether the LED lamp is turned on, and the controller controls according to feedback results of the LED on detection unit, the timer and the detector:

if the LED lamp is started at the starting moment of the silicon controlled rectifier dimmer, no bleeder current is needed at the moment, after the LED lamp is closed, a low-frequency or low-pulse-width pulse current is provided to ensure that the bus voltage can change along with the mains supply, and after the bus voltage is further reduced to a threshold voltage, the bleeder current is provided to reset the silicon controlled rectifier dimmer;

if the LED lamp is not started at the moment of starting the silicon controlled rectifier dimmer, and the starting position of the silicon controlled rectifier dimmer is more than 50% T, providing pulse current with low frequency or low pulse width to ensure that the bus voltage can change along with the mains supply, and providing release current to reset the silicon controlled rectifier dimmer after the bus voltage is further reduced to a threshold voltage, wherein T is the period of the rectified power supply;

if the silicon controlled rectifier dimmer is started at the moment, the LED lamp is not started, the starting position of the silicon controlled rectifier dimmer is smaller than 50% T, then the bleeder current is provided at the moment, after the LED lamp is started, the bleeder current is stopped being provided, after the LED lamp is closed, the low-frequency or low-pulse-width pulse current is provided to ensure that the bus voltage can follow the change of the mains supply, and after the bus voltage is further reduced to a threshold voltage, the bleeder current is provided to reset the silicon controlled rectifier dimmer.

As an embodiment of the invention, the LED on detection unit includes a zeroth comparator, a first input terminal of the zeroth comparator is coupled to a reference voltage, and a second input terminal of the zeroth comparator is coupled to the constant current control circuit.

As an embodiment of the present invention, the controller includes a switch, a charging current source, a discharging current source, a fourth comparator, a fifth comparator, a sixth comparator, an SR flip-flop, and a sixth capacitor, where the controller is coupled to a power amplifier, and an output end of the power amplifier is coupled to the power tube, where:

the first end of the change-over switch can be switched between the charging current source and the discharging current source, and the output end of the SR trigger sends a signal to the change-over switch; the second end of the change-over switch is respectively connected with the first end of the sixth capacitor, the non-inverting input end of the fourth comparator, the inverting input end of the fifth comparator and the inverting input end of the sixth comparator;

the inverting input end of the fourth comparator is connected with the second reference voltage, and the output end of the fourth comparator is connected with the SR trigger; the second end of the sixth capacitor is grounded; the non-inverting input end of the fifth comparator is connected with a third reference voltage, and the output end of the fifth comparator is connected with an SR trigger;

The non-inverting input end of the sixth comparator is connected with a reference voltage, the output end of the sixth comparator is connected with an enabling port of the first power amplifier, the non-inverting input end of the first power amplifier is connected with a fourth reference voltage, the fourth reference voltage determines the amplitude of the discharge current, and the inverting input end of the first power amplifier is connected with the first end of the first resistor and the source electrode of the first power tube; the output end of the operational amplifier is connected with the grid electrode of the first power tube, the source electrode of the first power tube is connected with the bus voltage, and the second end of the first resistor is grounded;

generating a triangular wave signal by charging and discharging the sixth capacitor, and then comparing the triangular wave signal with a reference voltage to generate a pulse signal, wherein the pulse signal controls the generation of a discharge current; wherein the pulse width is adjusted by adjusting the magnitude of the reference voltage; adjusting any one or more of the charge and discharge current of the triangular wave signal, the capacitance, the second reference voltage and the third reference voltage to adjust the frequency; and adjusting the fourth reference voltage to adjust the amplitude.

As one embodiment of the present invention, the detector includes a first switch, a second switches, a+1 capacitors, and gates, a comparators, where a is an integer greater than or equal to 1;

the first ends of the first switch and each second switch are respectively connected with the second end of the third resistor; the second ends of the first switches are respectively connected with the inverting input ends of the comparators, the second ends of the second switches are respectively connected with the non-inverting input ends of the different comparators, the second ends of the second switches are respectively connected with the first ends of the different capacitors, and the second ends of the capacitors are grounded; the output end of each comparator is connected with the input end of the AND gate, and the output end of the AND gate provides a judging signal.

An LED driving circuit comprising:

a silicon controlled rectifier light modulator is provided with a light source, coupling to a mains supply;

a rectifying circuit connected in series with the thyristor dimmer, rectifying the mains supply;

the constant current control circuit is coupled with the rectifying circuit, and is connected with the LED lamp in series to provide a constant current source for the LED lamp; and

the above-mentioned bleeder module.

A method of driving an LED with a thyristor dimmer, comprising: a pulsed current is selectively output as a bleed current according to a state of the bus voltage, wherein the pulsed current comprises a plurality of consecutive current pulses.

As an embodiment of the present invention, further comprising:

detecting the starting position of the silicon controlled rectifier dimmer;

detecting whether the silicon controlled rectifier dimmer is normally started;

and adjusting one or more of the frequency, the pulse width or the amplitude of the pulse current according to the information of whether the silicon controlled rectifier dimmer is normally started or not and the starting position information of the silicon controlled rectifier dimmer, so that the pulse current reaches the minimum current of the corresponding silicon controlled rectifier dimmer which is normally started.

The invention has the beneficial effects that: the invention provides a bleeder module for a Silicon Controlled Rectifier (SCR) dimmer, an LED driving circuit and a driving method thereof, which provide pulse current as bleeder current, intermittently provide current with certain frequency, pulse width and amplitude, and can maximally save power consumption and improve efficiency under the condition of maintaining normal operation of the SCR dimmer. In addition, the bleeder module, the LED driving circuit and the driving method thereof provided by the invention can be compatible with all the silicon controlled dimmers, and can control the starting of the silicon controlled dimmers according to the pulse currents with different amplitudes or different pulse widths generated by different silicon controlled dimmers, so that the efficiency of different systems can be improved to the greatest extent and all the silicon controlled dimmers can be compatible.

Drawings

Fig. 1 is a schematic diagram of a unidirectional thyristor structure.

Fig. 2 is a schematic diagram of the operation of the unidirectional silicon controlled rectifier.

Fig. 3 is a schematic diagram of a structure of a bidirectional thyristor.

Fig. 4 is a schematic diagram of a thyristor dimmer principle.

Fig. 5 is a schematic diagram of a conventional scr dimmer circuit.

Fig. 6 is a conventional driving waveform diagram of a conventional scr dimming circuit.

Fig. 7 is a circuit diagram of an LED driving circuit according to an embodiment of the present invention.

Fig. 8 is a timing diagram illustrating operation of an LED driving circuit according to an embodiment of the present invention.

Fig. 9 is another circuit diagram of an LED driving circuit according to an embodiment of the present invention.

Fig. 10 is a circuit schematic of a detector in an LED driving circuit according to an embodiment of the present invention.

Fig. 11 is a schematic diagram of a detector in an LED driving circuit according to an embodiment of the present invention.

Fig. 12 is a schematic diagram of a counter in an LED driving circuit according to an embodiment of the present invention.

Fig. 13 is a functional block diagram of a controller according to an embodiment of the present invention.

Fig. 14 is a flow chart of a controller for adjusting pulse current according to an embodiment of the invention.

Fig. 15 is a circuit diagram of a pulse width modulation circuit in an LED driving circuit according to an embodiment of the present invention.

Fig. 16 is a schematic diagram of a pulse width modulation circuit in an LED driving circuit according to an embodiment of the present invention.

Fig. 17 is a schematic diagram of a normal waveform detected by a detector in an LED driving circuit according to an embodiment of the present invention in the fifth embodiment.

Fig. 18 is a schematic diagram of an abnormal waveform detected by a detector in an LED driving circuit according to an embodiment of the present invention in the fifth embodiment.

Fig. 19 is a timing diagram of a controller in a bleeder current control circuit according to an embodiment of the present invention.

FIG. 20 is a timing diagram of a controller in a bleeder current control circuit according to an embodiment of the present invention.

Fig. 21 is a circuit schematic of a controller in a bleed-current control circuit according to an embodiment of the present invention in a sixth embodiment.

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it should be understood that these descriptions are merely intended to illustrate further features and advantages of the invention, and are not limiting of the claims of the invention.

The description of this section is intended to be illustrative of only a few exemplary embodiments and the invention is not to be limited in scope by the description of the embodiments. It is also within the scope of the description and claims of the invention to interchange some of the technical features of the embodiments with other technical features of the same or similar prior art.

The term "coupled" or "connected" in the specification includes both direct and indirect connections, such as through some active, passive, or electrically conductive medium. "plurality" means two or more.

Example 1

Referring to fig. 7, the present invention discloses a bleeder module for a scr dimmer, comprising: a bleeder circuit 5, a bleeder current control circuit 9. The bleeder circuit 5 is coupled to the dc bus, the bleeder circuit 5 provides a current bleeder path for the operation of the triac dimmer 8, and the bleeder circuit 5 includes a power tube Q1. The bleeder current control circuit 9 has an input end and an output end, wherein the input end of the bleeder current control circuit 9 is coupled with a direct current bus for acquiring a bus voltage, the output end of the bleeder current control circuit 9 is coupled with the control end of the power tube Q1, and the bleeder current control circuit 9 selectively controls the power tube Q1 according to the state of the bus voltage so that the bleeder circuit 5 outputs a pulse current as a bleeder current, wherein the pulse current comprises a plurality of continuous current pulses. Specifically, the bleeder current control circuit 9 includes a pulse width modulation signal generating circuit 91 and a power amplifier EA1, wherein an input end of the pulse width modulation signal generating circuit 91 is coupled to the dc bus, an output end of the pulse width modulation signal generating circuit 91 provides a pulse width modulation signal PWM, a first end of the power amplifier EA1 is coupled to an output end of the pulse width modulation signal generating circuit 91 for receiving the PWM signal, a second end of the power amplifier EA1 is coupled to the bleeder circuit 5, and an output end of the power amplifier EA1 is coupled to a control end of the power transistor Q1. The pulse current is realized by a pulse width modulation signal PWM input by a power amplifier EA 1. See in particular fig. 8 the pulsed current of the T2-T3 segment of the bleed current Ibld, which comprises a plurality of successive current pulses.

In one embodiment of the present invention, when it is detected that the bus voltage jumps from less than the predetermined threshold voltage to greater than the predetermined threshold voltage, the bleeder circuit outputs a pulse current as the bleeder current until the bus voltage rises to the load driving voltage.

The working principle of the bleeder current control circuit of the invention is as follows:

[ working time-series diagrams ]

Referring to FIG. 8 and Table 1, the working period T is divided into intervals of T0-T2, T2-T3, T3-T4, T4-T5, T5-T0; maintaining the T5 state in the interval of T0-T2; in the interval of T2-T3, the TRIAC is started; in the interval of T3-T4, the LED lamp is conducted; in the interval of T4-T5, the LED lamp is turned off; in the interval of T5-T0, VBUS < VF1.

In the sections T4-T5, the VBUS voltage can be ensured to be changed along with the mains supply, and the thyristor dimmer is not required to be completely started, so that pulse current with very low frequency and pulse width can be given.

In the sections T5 to T0, since VBUS is already low, it is necessary to turn on the scr dimmer completely, so that the scr dimmer can be reset at the normal zero crossing point of the bus voltage before the rectification, and therefore, the dimmer is driven with a large current to turn on.

Table 2 working time schedule

Referring to fig. 9, in the present embodiment, the bleed-off current control circuit 9 includes: the timer 1, the detector 2 and the controller 3, wherein the controller 3 is respectively connected with the detector 2 and the timer 1.

The timer 1 is configured to detect a time position when the triac dimmer is turned on, and feed back the acquired information to the detector and the controller.

The detector 2 is coupled to the timer and the dc bus, and is configured to obtain a time position when the thyristor dimmer is turned on and a bus voltage VBUS, further detect whether the thyristor dimmer is normally turned on according to a time position when the thyristor dimmer is turned on and a variation trend of the bus voltage VBUS, and feed back a detected result to the controller.

The controller 3 is respectively connected with the detector 2 and the timer 1, and is used for adaptively controlling the bleeder current according to the information of whether the silicon controlled rectifier dimmer is normally started or not and the starting position information of the silicon controlled rectifier dimmer.

In one embodiment, the bleed current comprises a pulsed current comprising a continuous plurality of current pulses. The controller 3 adjusts the amplitude or the pulse width or the frequency of the pulse current according to the information of whether the dimmer is normally turned on, so that the pulse current reaches the minimum current of the corresponding silicon controlled rectifier dimmer which is normally turned on. Specifically, in one cycle, the controller 3 is configured to drive the triac dimmer by a pulse current of a predetermined fixed amplitude, frequency and pulse width; and the method can also be used for adjusting the amplitude or the pulse width or the frequency of the pulse current according to the detection result after knowing that the thyristor dimmer is not normally started, so that the pulse current reaches the minimum current of the corresponding thyristor dimmer which is normally started.

The means for adjusting one or more of the frequency, pulse width or amplitude of the pulsed current comprises:

if the detector detects that the thyristor dimmer can be normally started in N continuous periods, the amplitude of the bleeder current is reduced according to a given proportion, or the pulse width is reduced or the frequency is reduced to reduce the average value of the bleeder current; then continuously detecting whether the silicon controlled rectifier dimmer can be normally started or not in N continuous periods; if the silicon controlled dimmer can be normally started in N continuous periods, continuously reducing the amplitude of the discharge current according to a given proportion or reducing the pulse width or reducing the frequency; and the like, until the detector detects that the thyristor dimmer cannot be normally started in N continuous periods, the amplitude or pulse width or frequency of the bleeder current is increased to a value which can normally start the thyristor dimmer last time, and then the thyristor dimmer is kept unchanged, wherein the period is a period of the rectified power supply, N is more than or equal to 2, and N is a natural number.

The bleeder module is used for the LED drive circuit, the bleeder current control circuit can also include the LED and open the detecting element for detect the LED lamp whether open. The controller controls according to feedback results of the LED on detection unit, the timer and the detector:

(1) If the LED lamp is started at the starting moment of the silicon controlled rectifier dimmer, no bleeder current is needed at the moment, after the LED lamp is closed, a low-frequency or low-pulse-width pulse current is provided to ensure that the bus voltage can change along with the mains supply, and after the bus voltage is further reduced to a threshold voltage, the bleeder current is provided to reset the silicon controlled rectifier dimmer;

(2) If the LED lamp is not started at the moment of starting the silicon controlled rectifier dimmer, and the starting position of the silicon controlled rectifier dimmer is more than 50% T, providing pulse current with low frequency or low pulse width to ensure that the bus voltage can change along with the mains supply, and providing release current to reset the silicon controlled rectifier dimmer after the bus voltage is further reduced to a threshold voltage, wherein T is the period of the rectified power supply;

(3) If the silicon controlled rectifier dimmer is started at the moment, the LED lamp is not started, the starting position of the silicon controlled rectifier dimmer is smaller than 50% T, then the bleeder current is provided at the moment, after the LED lamp is started, the bleeder current is stopped being provided, after the LED lamp is closed, the low-frequency or low-pulse-width pulse current is provided to ensure that the bus voltage can follow the change of the mains supply, and after the bus voltage is further reduced to a threshold voltage, the bleeder current is provided to reset the silicon controlled rectifier dimmer.

In one embodiment of the present invention, the LED on detection unit may include a zeroth comparator, a first input terminal of the zeroth comparator is coupled to a reference voltage, and a second input terminal of the zeroth comparator is coupled to the constant current control circuit.

[ Detector ]

Referring to fig. 9, the bleeder current control circuit further includes a voltage dividing resistor, where the voltage dividing resistor includes a third resistor R3 and a fourth resistor R4; the first end of the third resistor is connected with the direct current bus, the second end of the third resistor is respectively connected with the first ends of the detector 2, the timer 1 and the fourth resistor R4, and the second end of the fourth resistor R4 is grounded.

Referring to fig. 10 and 11, the detector 2 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first comparator 21, a second comparator 22, a third comparator 23, an and gate 24, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5.

The first end of the first switch S1, the first end of the second switch S2, the first end of the third switch S3, and the first end of the fourth switch S4 are respectively connected to the second end of the third resistor R3. The second end of the first switch S1 is connected to the first end of the second capacitor C2, the inverting input end of the first comparator 21, the inverting input end of the second comparator 22, and the inverting input end of the third comparator 23, respectively, and the second end of the second capacitor C2 is grounded. The second end of the second switch S2 is connected to the first end of the third capacitor C3 and the non-inverting input end of the first comparator 21, and the second end of the third capacitor C3 is grounded. The second end of the third switch S3 is connected to the first end of the fourth capacitor C4 and the non-inverting input end of the second comparator 22, and the second end of the fourth capacitor C4 is grounded. The second end of the fourth switch S4 is connected to the first end of the fifth capacitor C5 and the non-inverting input end of the third comparator 23, and the second end of the fifth capacitor C5 is grounded. The output end of the first comparator 21, the output end of the second comparator 22 and the output end of the third comparator 23 are respectively connected with the input end of the and gate 24.

When the dimmer is turned on, the first switch S1 is turned on, the voltage at this time is sampled, and then the first switch S1 is turned off. And (2) starting the S2 sampling voltage after delaying M% by T (T is the time of the whole period). And similarly, sampling is performed for N times (the sampling time point of each time cannot exceed 50% T), and if the voltage sampled later is higher than that of the first time, EN outputs a high potential to indicate that the silicon controlled rectifier dimmer is normally started. M is a constant greater than 0 and less than 10.

[ timer ]

Referring to fig. 12, the timer 1 is used for detecting the on position of the dimmer and counting the number of cycles of VBUS. The on count of the dimmer is the time that the VBUS voltage is lower than VF 1.

[ controller ]

Please refer to fig. 13 to 15. Fig. 13 shows a functional block diagram of a controller according to an embodiment of the invention. The controller receives the outputs of the timer, detector and comparator, determines the condition by the logic control circuit, and further provides and adjusts the VPWM signal by the pulse modulation circuit.

Fig. 14 shows a block flow diagram of a controller adjusting a pulse current according to an embodiment of the invention. Firstly, judging whether to adjust the pulse signal according to a signal that whether the LED is turned on when the silicon controlled rectifier dimmer is turned on and a signal that whether the time position of the turned-on time position of the silicon controlled rectifier dimmer exceeds 50% T. If the LED is not turned on when the silicon controlled rectifier dimmer is turned on and the time position of the turn-on is less than 50% T, pulse current is required to be provided, and the pulse current is regulated according to the condition of N periods; if the LED is not turned on when the triac dimmer is turned on and the on time position exceeds 50% T, or the LED is turned on when the triac dimmer is turned on, then no pulse current is required and the EN judgment period is not counted.

And then judging whether the silicon controlled rectifier dimmer is normally started in N periods according to a judging signal EN output by the detector, increasing or decreasing the bleeder current corresponding to the pulse current, and correspondingly adjusting the current pulse by adjusting the parameters of a pulse width modulation circuit in the controller.

Fig. 15 shows a circuit schematic of a pwm circuit in a controller according to an embodiment of the present invention, where the pwm circuit of the controller 3 includes a switch, a charging current source, a discharging current source, a fourth comparator 31, a fifth comparator 32, a sixth comparator 33, an SR flip-flop, a sixth capacitor C6, a first power transistor Q1, and a fifth resistor R5. The controller is connected with the first power amplifier EA1, wherein the output end of the power amplifier EA1 is coupled with the control end of the power tube Q1.

The first end of the change-over switch can be switched between the charging current source and the discharging current source, and the output end of the SR trigger sends a signal to the change-over switch; the second end of the change-over switch is connected to the first end of the sixth capacitor, the non-inverting input end of the fourth comparator 31, the inverting input end of the fifth comparator 32 and the inverting input end of the sixth comparator 33, respectively.

The inverting input end of the fourth comparator 31 is connected with the second reference voltage VREF2, and the output end of the fourth comparator 31 is connected with the SR trigger; the second end of the sixth capacitor C6 is grounded; the non-inverting input end of the fifth comparator 32 is connected with the third reference voltage VREF3, and the output end of the fifth comparator 32 is connected with the SR trigger.

The non-inverting input end of the sixth comparator 33 is connected with a reference voltage VF2, the output end of the sixth comparator 33 is connected with an EN port of the first power amplifier EA1, the non-inverting input end of the first power amplifier EA1 is connected with a fourth reference voltage VREF4, the fourth reference voltage VREF4 determines the amplitude of the bleed current Ibld, and the inverting input end of the first power amplifier EA1 is connected with the first end of the first resistor R1 and the source electrode of the first power tube Q1; the output end of the operational amplifier is connected with the grid electrode of the first power tube Q1, the source electrode of the first power tube Q1 is connected with the busbar voltage VBUS, and the second end of the first resistor R1 is grounded.

Wherein VREF2 and VREF3 are reference voltages that generate a lower limit and an upper limit of the triangular wave signal, respectively; VF2 is the reference voltage that controls the pulse width; VREF4 in fig. 15 corresponds to Ref2 in fig. 7 (and fig. 9).

Pulse current modulation principle: with sufficient power to the capacitor, a triangular wave signal Vtrig is generated, which is then compared with a reference voltage VF2 to generate a pulse signal VPWM that controls the generation of current. The pulse width can be adjusted by adjusting the size of VF 2; the frequency can be adjusted by adjusting the charge and discharge current of the Vtrig, the capacitance, VREF2 and VREF 3; adjusting VREF4 may adjust the amplitude.

The control principle of the controller is as follows:

First case:

as shown in the timing chart of fig. 8, when the dimmer is turned on at a larger angle and the LED lamp is not turned on at time T2, a speed of the current (i.e., the Bleed current Ibld) from T2 to T3 is required. An initial state (referring to the time of power-on) provides an initial current, and the initial current has set amplitude, frequency and pulse width; the fixed amplitude, the fixed frequency and the pulse width are adjustable in the adjusting process, or the fixed frequency, the fixed pulse width and the amplitude are adjustable, or the fixed amplitude, the fixed pulse width and the frequency are adjustable.

1. If the EN output is high for N consecutive periods, the amplitude is reduced or the pulse width is reduced or the frequency is reduced according to a given proportion; then continuing to detect whether EN is high or not in N periods; if the pulse width is always high, continuing to reduce the amplitude or the pulse width or the frequency according to a given proportion; similarly, the amplitude or pulse width or frequency is increased back to the last value until EN goes low and then remains unchanged.

2. If EN is not all high for N consecutive periods, increasing the amplitude or increasing the pulse width or increasing the frequency by a given ratio; then continuing to detect whether EN is high or not in N periods; if not, continuing to increase the amplitude or the pulse width or the frequency according to the given proportion; and so on, the amplitude, pulse width and frequency remain unchanged until the EN output is high.

Second case:

referring to fig. 19, at time T2 when the dimmer is turned on, VBUS voltage is already higher than the LED lamp turn-on voltage, ILED can act as a bleedcurrent, and the dimmer can remain normally turned on without the bleedcurrent of the T2-T3 segments.

Third case:

referring to fig. 20, the time T2 when the dimmer is turned on exceeds 50% T, and the VBUS voltage is already lower than the LED lamp turn-on voltage, and the LED is turned off without the need of the Bleed current of the T2-T3 segments.

Example two

Referring to fig. 7, the present invention discloses a bleeder module for a scr dimmer, comprising: a bleeder circuit 5, a bleeder current control circuit 9. The bleeder circuit 5 is coupled to the dc bus, the bleeder circuit 5 provides a current bleeder path for the operation of the scr dimmer, and the bleeder circuit 5 includes a power tube. The bleeder current control circuit 9 has an input end and an output end, wherein the input end of the bleeder current control circuit 9 is coupled with a direct current bus for obtaining a bus voltage, the output end of the bleeder current control circuit 9 is coupled with a control end of a power tube, and the bleeder current control circuit 9 selectively controls the power tube according to the state of the bus voltage so that the bleeder current outputs a pulse current as a bleeder current, wherein the pulse current comprises a plurality of continuous current pulses.

Referring to fig. 9, in the present embodiment, the bleeder current control circuit includes: the timer 1, the detector 2 and the controller 3, wherein the controller 3 is respectively connected with the detector 2 and the timer 1.

The detector 2 is configured to detect whether the scr dimmer is normally turned on, and feed back the detected result to the controller 3. The timer 1 is configured to detect an on position after the triac dimmer is turned on, and feed back acquired information to the detector 2 and the controller 3; the counter 1 is also used to count the number of cycles of VBUS.

The controller 3 is configured to adaptively control the bleed current according to the information about whether the triac dimmer is normally turned on and the triac dimmer on position time information. The controller 3 drives the triac dimmer by a predetermined pulse current (having a set amplitude, frequency and pulse width); and the pulse current modulation circuit is also used for adjusting the amplitude or the pulse width or the frequency of the pulse current according to the detection result after knowing that the thyristor dimmer is not normally started (the pulse current modulation circuit of the controller realizes the function) so that the pulse current reaches the minimum current of the corresponding thyristor dimmer which is normally started.

In addition, the bleeder current control circuit further comprises a zeroth comparator 4 for detecting whether the LED lamp is turned on or not; the non-inverting input end of the zeroth comparator 4 is connected with a third main reference voltage Ref3, and the inverting input end of the zeroth comparator is connected with a constant current control circuit; the third main reference voltage Ref3 is used for detecting whether the LED lamp is normally turned on or not.

The LED on detection unit may take other forms besides the zeroth comparator, such as a current detection mode, a current sensor, other types of current detection circuits, and the like.

The controller 3 controls the bleed current differently according to the different feedback results of the zeroth comparator 4, the timer 1 and the detector 2. Of course, the zeroth comparator 4 may also be part of the controller.

The controller 3 makes different control processes according to different feedback results of the zeroth comparator 4, the timer 1 and the detector 2;

(1) Referring to fig. 19, according to the feedback result of the zeroth comparator 4, if the LED lamp is already turned on at the moment of turning on the dimmer, then there is no need to adjust the bleed current Ibld;

(2) Referring to fig. 20, according to the feedback result of the zeroth comparator 4, if the LED lamp is not turned on at the time of turning on the dimmer, and the counter knows that the time of turning on the dimmer has exceeded 50% T, it indicates that the voltage at the time of turning on the dimmer is insufficient to turn on the LED lamp, so that the bleed current Ibld does not need to be adjusted;

(3) Referring to fig. 8, according to the feedback result of the zeroth comparator 4, if the triac dimmer is turned on at time T2, the LED lamp is not turned on yet, and the counter knows that the time of the dimmer is less than 50% T, then the bleeder current Ibld in the triac dimmer turn-on interval T2-T3 is needed; an initial state (referring to the time of power-on) provides an initial current, and the initial current has set amplitude, frequency and pulse width; the fixed amplitude, the fixed frequency and the pulse width are adjustable in the adjusting process, or the fixed frequency, the fixed pulse width and the amplitude are adjustable, or the fixed amplitude, the fixed pulse width and the frequency are adjustable.

The controller judges whether the dimmer can be normally started in N continuous periods according to the state of the dimmer detected by the detector; if yes, go to (1), otherwise go to (2);

(1) if the detector detects that the dimmer is normally on in N continuous periods, the amplitude of the bleeding current Ibld is reduced or the pulse width is reduced or the frequency is reduced according to a given proportion (the given proportion can be a set proportion or value, or can be an uncertain value, a proportion or even a random value within a certain range) so as to reduce the average value of the bleeding current Ibld; then continuously detecting whether the dimmer can be normally started or not in N continuous periods; if the dimmer can be normally started in N continuous periods, continuously reducing the amplitude of the release current Ibld or reducing the pulse width or reducing the frequency according to a given proportion; and the like, until the detector detects that the dimmer cannot be normally started in N continuous periods, increasing the amplitude or pulse width or frequency of the release current Ibld to a value which can normally start the dimmer last time, and then keeping unchanged; n is more than or equal to 2, and N is a natural number;

(2) If the detector detects that the dimmer cannot be normally turned on in N continuous periods, the amplitude of the bleeding current Ibld is increased or the pulse width is increased or the frequency is increased according to a given proportion (the given proportion or the preset value, the preset proportion or even a random value within a certain range) to increase the average value of the bleeding current Ibld; then continuously detecting whether the dimmer can be normally started or not in N continuous periods; if the dimmer cannot be normally started in N continuous periods, continuously increasing the amplitude of the release current Ibld or increasing the pulse width or increasing the frequency according to a given proportion; and the like, the amplitude, pulse width and frequency of the release current Ibld are kept unchanged until the detector detects that the dimmer can be normally started in N continuous periods.

Specifically, the control mode of the controller includes:

(1) Referring to fig. 19, if the bus voltage VBUS is higher than the LED lamp turn-on voltage at time T2 when the scr dimmer is turned on, the current ILED flowing through the LED lamp can be used as the bleed current Ibld, and the dimmer can be kept normally turned on, so that the bleed current Ibld in the interval of T2 to T3 is not required;

(2) Referring to fig. 20, if the time T2 when the scr dimmer is turned on exceeds 50% T, and the bus voltage VBUS is already lower than the LED lamp turn-on voltage, the LED is turned off, and no bleed current Ibld in the interval of T2 to T3 is needed;

(3) Referring to fig. 8, if the opening angle of the scr dimmer is larger, the LED lamp is not turned on at the time T2, and then a Bleed current Ibld (Bleed current) of T2 to T3 is required; an initial state (referring to the time of power-on) provides an initial current, and the initial current has set amplitude, frequency and pulse width; the fixed amplitude, the fixed frequency and the pulse width are adjustable in the adjusting process, or the fixed frequency, the fixed pulse width and the amplitude are adjustable, or the fixed amplitude, the fixed pulse width and the frequency are adjustable;

(1) if the detector detects that the dimmer is normally on (EN outputs are all high) for N consecutive periods, then the amplitude is reduced or the pulse width is reduced or the frequency is reduced by a given ratio; then continue to check for N cycles, whether the dimmer is normally on (whether the EN output is all high); if the dimmer is normally on (EN outputs are all high), continuing to decrease the amplitude or decrease the pulse width or decrease the frequency by a given ratio; and so on, until the detector detects that the dimmer cannot be normally turned on (the EN outputs are not all high), the amplitude or pulse width or frequency is increased back to the last value, and then remains unchanged; n is more than or equal to 2, and N is a natural number;

(2) if the detector detects that the dimmer cannot be normally turned on (EN is not all high) for N consecutive periods, increasing the amplitude or increasing the pulse width or increasing the frequency by a given ratio; then continue to check for N cycles, whether the dimmer is normally on (whether the EN output is all high); if the dimmer is not normally on (EN is not all high), then continuing to increase the amplitude or increase the pulse width or increase the frequency by a given ratio; and so on, until the detector detects that the dimmer is normally on (EN output is high), the amplitude, pulse width and frequency are kept unchanged;

Wherein, the working period T is divided into sections of T0-T2, T2-T3, T3-T4, T4-T5 and T5-T0; maintaining the T5 state in the interval of T0-T2; in the interval of T2-T3, the silicon controlled rectifier dimmer is started; in the interval of T3-T4, the LED lamp is conducted; in the interval of T4-T5, the LED lamp is turned off; in the interval of T5-T0, VBUS < VF1; VF1 is a set detection voltage point;

in the interval of T4-T5, only the busbar voltage VBUS is required to be ensured to be capable of changing along with the mains supply, the silicon controlled rectifier dimmer is not required to be completely started, and pulse current with very low frequency and pulse width can be provided.

In the interval from T5 to T0, since the bus voltage VBUS is already low, the thyristor dimmer needs to be turned on completely, so that the unrectified bus voltage can reset the thyristor dimmer at the normal zero crossing point, and a large current is required to drive the dimmer to turn on.

Referring to fig. 15, the controller 3 includes a switch, a charging current source, a discharging current source, a fourth comparator 31, a fifth comparator 32, a sixth comparator 33, an SR flip-flop, a sixth capacitor C6, a first power transistor Q1, and a fifth resistor R5.

The inverting input end of the fourth comparator 31 is connected with VREF2, and the output end of the fourth comparator 31 is connected with an SR trigger; the second end of the sixth capacitor C6 is grounded; the non-inverting input end of the fifth comparator 32 is connected with VREF3, and the output end of the fifth comparator 32 is connected with an SR trigger.

The non-inverting input end of the sixth comparator 33 is connected with the reference voltage VF2, the output end of the sixth comparator 33 is connected with the EN port of the operational amplifier (i.e. the first power amplifier EA 1), the non-inverting input end of the operational amplifier is connected with VREF4, the inverting input end of the operational amplifier is connected with the first end of the first resistor R1 and the source electrode of the first power tube Q1; the output end of the operational amplifier is connected with the grid electrode of the first power tube Q1, the source electrode of the first power tube Q1 is connected with the busbar voltage VBUS, and the second end of the first resistor R1 is grounded.

Generating a triangular wave signal Vtrig by charging and discharging a capacitor, and then comparing the triangular wave signal Vtrig with a reference voltage VF2 to generate a pulse signal VPWM, wherein the pulse signal VPWM controls the generation of current; the pulse width is adjusted by adjusting the magnitude of the reference voltage VF 2; the frequency can be adjusted by adjusting the charge and discharge current of the triangular wave signal Vtrig, the capacitance, VREF2 and VREF 3; adjusting VREF4 can adjust the amplitude.

As shown in fig. 9, the bleeder current control circuit further includes a voltage dividing resistor, where the voltage dividing resistor includes a third resistor R3 and a fourth resistor R4; the first end of the third resistor is connected with the direct current bus, the second end of the third resistor is respectively connected with the first ends of the detector, the timer and the fourth resistor R4, and the second end of the fourth resistor R4 is grounded.

The detector 2 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first comparator, a second comparator, a third comparator, an and gate, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, and a fifth capacitor C5.

The first end of the first switch S1, the first end of the second switch S2, the first end of the third switch S3, and the first end of the fourth switch S4 are respectively connected to the second end of the third resistor R3. The second end of the first switch S1 is respectively connected with the first end of the second capacitor C2, the inverting input end of the first comparator, the inverting input end of the second comparator and the inverting input end of the third comparator, and the second end of the second capacitor C2 is grounded. The second end of the second switch S2 is connected to the first end of the third capacitor C3 and the non-inverting input end of the first comparator, and the second end of the third capacitor C3 is grounded. The second end of the third switch S3 is respectively connected with the first end of the fourth capacitor C4 and the non-inverting input end of the second comparator, and the second end of the fourth capacitor C4 is grounded. The second end of the fourth switch S4 is connected to the first end of the fifth capacitor C5 and the non-inverting input end of the third comparator, and the second end of the fifth capacitor C5 is grounded. The output end of the first comparator, the output end of the second comparator and the output end of the third comparator are respectively connected with the input end of the AND gate.

Example III

Referring to fig. 9, the present invention discloses an LED driving circuit, comprising: the device comprises a silicon controlled rectifier dimmer 8, a rectifying circuit 7, a constant current control circuit 6 and a bleeder module.

The silicon controlled rectifier dimmer 8 is coupled with a mains supply; the rectifying circuit 7 is connected in series with the silicon controlled rectifier 8 to rectify the mains supply; the constant current control circuit 6 is coupled with the rectifying circuit 7, and the constant current control circuit 6 is connected with the LED lamp in series and is used for providing a constant current source for the LED lamp.

The bleeder module comprises a bleeder circuit 5, a bleeder current control circuit 9. The bleeder circuit 5 is coupled to the dc bus, the bleeder circuit 5 provides a current bleeder path for the operation of the scr dimmer, and the bleeder circuit 5 includes a power tube. The bleeder current control circuit 9 has an input end and an output end, wherein the input end of the bleeder current control circuit 9 is coupled with a direct current bus for acquiring a bus voltage, the output end of the bleeder current control circuit 9 is coupled with a control end of a power tube, and the bleeder current control circuit 9 selectively controls the power tube according to the state of the bus voltage so that the bleeder circuit 5 outputs a pulse current as a bleeder current, wherein the pulse current comprises a plurality of continuous current pulses.

In addition, the bleeder current control circuit 9 may further include a zeroth comparator 4 for detecting whether the LED lamp is turned on; the non-inverting input end of the zeroth comparator 4 is connected with a third main reference voltage Ref3, and the inverting input end of the zeroth comparator 4 is connected with a constant current control circuit 6; the third main reference voltage Ref3 is used for detecting whether the LED lamp is normally turned on or not.

The specific processing procedure of the bleeder module can be referred to the description of the first embodiment.

As shown in fig. 9, as an embodiment of the present invention, the output end of the first power amplifier EA1 is connected to the gate of the first power tube Q1, the drain of the first power tube Q1 is connected to the bus, and the source of the first power tube Q1 is respectively connected to the first end of the first resistor R1 and the inverting input end of the first power amplifier EA 1; the non-inverting input end of the first power amplifier EA1 is connected with a first main reference voltage Ref1, the first power amplifier EA1 is connected with the controller, and the second end of the first resistor R1 is connected with the constant current control circuit. The first main reference voltage Ref1 is a reference voltage that controls the bleed current.

As shown in fig. 9, as an embodiment of the present invention, the constant current control circuit 6 includes a second power amplifier EA2, a second power transistor Q2, and a second resistor R2. The output end of the second power amplifier EA2 is connected with the grid electrode of the second power tube Q2, the drain electrode of the second power tube Q2 is connected with the second main reference voltage Ref2, and the source electrode of the second power tube Q2 is respectively connected with the first end of the second resistor R2, the inverting input end of the second power amplifier EA2, the second end of the first resistor R1 and the inverting input end of the zeroth comparator; the non-inverting input end of the second power amplifier EA2 is connected with a second main reference voltage, and the second end of the second resistor R2 is grounded. The second main reference voltage Ref2 is a reference voltage controlling the LED lamp current.

The first end of the rectifying circuit 7 is connected with the silicon controlled rectifier dimmer 8, the second end of the rectifying circuit 7 is respectively connected with the first end of the third resistor R3, the drain electrode of the first power tube Q1 and the positive electrode of the first diode D1, and the third end of the rectifying circuit is grounded.

The timer 1 is respectively connected with the second end of the third resistor R3 and the first end of the fourth resistor R4, and is connected with the controller; the detector is respectively connected with the second end of the third resistor R3 and the first end of the fourth resistor R4, and is connected with the controller; the second end of the fourth resistor R4 is grounded.

In this embodiment, the LED driving circuit further includes a first diode D1 and a first capacitor C1; the negative electrode of the first diode D1 is connected with the first end of the first capacitor C1 and the positive electrode of the LED lamp, and the drain electrode of the second power tube Q2 is connected with the second end of the first capacitor C1 and the negative electrode of the LED lamp respectively. The first diode D1 is a diode for preventing reverse current flow, and the first capacitor C1 is for reducing current ripple of the LED lamp. Of course, the first diode D1 and the first capacitor C1 are not essential to the present invention, and may be replaced by other circuits.

The invention also discloses an LED driving method with the silicon controlled rectifier dimmer, which comprises the following steps: a pulsed current is selectively output as a bleed current according to a state of the bus voltage, wherein the pulsed current comprises a plurality of consecutive current pulses.

The method specifically comprises the following steps:

detecting the starting position of the silicon controlled rectifier dimmer;

detecting whether the silicon controlled rectifier dimmer is normally started;

The specific driving method of the present invention can be found in the description of the driving circuit above.

Example IV

The difference between the present embodiment and the third embodiment is that in the present embodiment, the first diode D1 and the first capacitor C1 may be replaced by a strobe removal circuit.

Example five

The difference between the present embodiment and the first, second and third embodiments is that in the present embodiment, the detector may adopt other manners. As shown in fig. 17 and 18, the number of rising edges or falling edges in i cycles is counted and then compared with the number of cycles obtained by the counter. If the two types of the light sources are equal, the light modulator is considered to be normally started; if the number of rising edges or falling edges is more, the dimmer is opened more, and the dimmer does not work normally.

Example six

The difference between the present embodiment and the first, second and third embodiments is that in the present embodiment, pulse current control may not be adopted, and the controller is configured to control with a dc current having an adjustable current value, that is, to use the dc current as the bleed current, and directly adjust the magnitude of the bleed current Ibld according to the result of detecting whether the dimmer is normally turned on, so that the dc current reaches the minimum current corresponding to the normally turned on scr dimmer.

The controller adopts the direct current control with adjustable current value, and directly adjusts the magnitude of the discharge current Ibld current according to the result of detecting whether the dimmer is normally started, and the two conditions are as follows:

(1) Under the given initial condition, if the dimmer can be normally started, the current value is reduced according to the proportion set each time until the dimmer cannot be normally started, the current value is adjusted to the last value, and then the current value is fixed;

(2) Under the given initial conditions, if the dimmer cannot be normally turned on, the current value is increased in proportion to each setting until the value is fixed after the dimmer is normally turned on.

Referring to fig. 21, the controller includes a first operational amplifier, a third power tube, a plurality of switches (switches S1 to Sn), and a plurality of resistors; the non-inverting input end of the first operational amplifier is connected with a fifth reference voltage VREF5, the inverting input end of the first operational amplifier is connected with the source electrode of the third power tube, and the output end of the first operational amplifier is connected with the grid electrode of the third power tube.

The fifth reference voltage VREF5 (which is a fixed reference voltage) generates a plurality of equally decreasing reference voltages through the first operational amplifier, and then gates the required reference voltages with the switches S1 to Sn as the fourth reference voltage VREF4.

The S1-Sn switches are controlled by signals generated by the controller, and the reference voltages required by gating are sequentially increased or decreased.

Example seven

The difference between the present embodiment and the first and second embodiments is that in the present embodiment, the number of switches and comparators may be selected according to the needs; the detector comprises a first switch S1, a second switches, a+1 capacitors, an AND gate and a comparators, wherein a is an integer greater than or equal to 1. And performing AND logic on the output signals of the a comparators. In the first embodiment, a is 3, and a may have other values, such as 1, 2, 4, 5, 10, etc.

The first ends of the first switch S1 and the second switches are respectively connected with the second end of the third resistor R3; the second ends of the first switches S1 are respectively connected with the inverting input ends of the comparators, the second ends of the second switches are respectively connected with the non-inverting input ends of the different comparators, the second ends of the second switches are respectively connected with the first ends of the different capacitors, and the second ends of the capacitors are grounded; the output end of each comparator is connected with the input end of the AND gate.

Example eight

The difference between the present embodiment and the first and second embodiments is that in the present embodiment, the comparator of the constant current control circuit in the bleeder module may be used as a part of the controller (in the second embodiment, the comparator is not a part of the controller but exists separately).

In summary, the bleeder module for the scr dimmer, the LED driving circuit and the driving method thereof provide the pulse current as the bleeder current, and intermittently provide the current with a certain frequency, pulse width and amplitude, so that the power consumption can be saved to the maximum extent and the efficiency can be improved under the condition of maintaining the normal operation of the scr dimmer. In addition, the bleeder module, the LED driving circuit and the driving method thereof provided by the invention can be compatible with all the silicon controlled dimmers, and can control the starting of the silicon controlled dimmers according to the pulse currents with different amplitudes or different pulse widths generated by different silicon controlled dimmers, so that the efficiency of different systems can be improved to the greatest extent and all the silicon controlled dimmers can be compatible.

The description and applications of the present invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. Variations and modifications of the embodiments disclosed herein are possible, and alternatives and equivalents of the various components of the embodiments are known to those of ordinary skill in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other assemblies, materials, and components, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.

Claims

1. A bleeder module for a thyristor dimmer, comprising:

the bleeder current control circuit is provided with an input end and an output end, wherein the input end of the bleeder current control circuit is coupled with a direct current bus for acquiring bus voltage, the output end of the bleeder current control circuit is coupled with the control end of the power tube, and the bleeder current control circuit selectively controls the power tube according to the state of the bus voltage so that the bleeder circuit outputs pulse current as bleeder current, and the pulse current comprises a plurality of continuous current pulses;

the bleed current control circuit includes:

the controller is coupled with the timer and the detector and is used for judging whether the silicon controlled rectifier dimmer is normally started according to feedback results of the detector and the timer, and then one or more of the frequency, the pulse width or the amplitude of the pulse current is adjusted, so that the pulse current reaches the minimum current for normally starting the corresponding silicon controlled rectifier dimmer;

The bleeder module is used for the LED drive circuit, bleeder current control circuit still includes the LED and opens the detecting element for detect the LED lamp and open whether, the controller is according to LED and open detecting element, time-recorder and the feedback result of detector and control:

2. The bleeder module of claim 1, wherein the bleeder circuit outputs a pulsed current as the bleeder current when it is detected that the bus voltage transitions from less than a predetermined threshold voltage to greater than the predetermined threshold voltage until the bus voltage rises to the load drive voltage.

3. The bleed module of claim 1, wherein the adjusting one or more of a frequency, a pulse width, or a magnitude of the pulsed current comprises:

4. The bleeder module of claim 1, wherein the LED on detection unit comprises a zeroth comparator, a first input terminal of the zeroth comparator is coupled to a reference voltage, and a second input terminal of the zeroth comparator is coupled to the constant current control circuit.

5. The bleeder module of claim 1, wherein the controller comprises a switch, a charge current source, a discharge current source, a fourth comparator, a fifth comparator, a sixth comparator, an SR flip-flop, a sixth capacitor, the controller coupled to a power amplifier, an output of the power amplifier coupled to the power tube, wherein:

6. The bleeder module as defined in claim 1, wherein:

the detector comprises a first switch, a second switches, a+1 capacitors, an AND gate and a comparators, wherein a is an integer greater than or equal to 1;

7. An LED driving circuit comprising:

A silicon controlled rectifier dimmer coupled to a mains supply;

a rectifying circuit connected in series with the thyristor dimmer for rectifying the mains supply;

the constant current control circuit is coupled with the rectifying circuit, is connected with the LED lamp in series and is used for providing a constant current source for the LED lamp; and

the bleeder module as defined in any one of claims 1-6.

8. A method of driving an LED with a thyristor dimmer, comprising: a pulsed current is selectively output as a bleed current according to a state of the bus voltage, wherein the pulsed current comprises a plurality of consecutive current pulses.

9. The driving method according to claim 8, characterized in that: further comprises:

detecting the starting position of the silicon controlled rectifier dimmer;

detecting whether the silicon controlled rectifier dimmer is normally started;