A silicon-controlled light-adjusting constant-voltage constant-current control circuit and a control method thereof

Abstract

This invention discloses a thyristor-controlled dimming voltage-stabilized constant-current control circuit and its control method. The feedback loop includes a voltage detection circuit and a bidirectional selection circuit. A load capacitor C is connected in parallel across the two ends of the LED lamp group. out The voltage detection circuit is used to detect the output voltage of the rectifier circuit, and when the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the voltage detection circuit enables the bidirectional selection circuit to connect from the output terminal of the rectifier circuit to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charging; when the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the voltage detection circuit turns on the bidirectional selection circuit, and the load capacitor C out Current is supplied to the output terminal of the rectifier circuit through the load capacitor C. out Power is supplied to the thyristor dimmer to maintain the output voltage of the rectifier circuit.

Description

Technical Field

[0001] This invention relates to the field of dimming circuit technology, and in particular to a regulated constant current control circuit and control method for silicon controlled rectifier (SCR) dimming. Background Technology

[0002] Thyristor dimming technology is a commonly used LED dimming solution. Utilizing the inherent characteristics of the thyristor, it can be effectively applied to LED dimming. It operates in two phases: on and off. The working principle is that the variable resistor (i.e., a knob or slider) inside the thyristor dimmer controls the load capacitance C of the LED circuit. out During charging, when the load capacitor C out When the voltage on the LED reaches the turn-on voltage of the internal SCR device, the SCR dimmer turns on. At this time, the voltage across the SCR dimmer is almost zero, and the entire AC voltage is applied to the input terminal of the LED lamp assembly. Therefore, by adjusting the resistance value of the variable resistor, the RC charging time of the SCR turn-on voltage can be adjusted, thereby changing the conduction time of the SCR dimmer and adjusting the brightness of the lamp.

[0003] like Figure 1 The circuit shown connects a thyristor dimmer before the rectifier bridge circuit, enabling dimming applications to adjust LED brightness. Here, VIN is the AC input voltage, V+ is the input voltage after rectification by the rectifier circuit, and the total input power of the circuit is... The output power is ,in, Because a silicon controlled rectifier (SCR) dimmer requires a certain holding current to remain on, it can only generate output current when its input power frequency voltage is greater than its output voltage. However, the initial and minimum conduction angles of various SCR dimmers on the market differ significantly. For SCR dimmers with a small initial conduction angle, the initial power at the maximum conduction angle will be much lower than when no SCR is connected; conversely, for dimmers with a large minimum conduction angle, the remaining power at the minimum conduction angle will be greater. Furthermore, when the SCR dimmer is adjusted to a point where the highest input power frequency voltage is close to the output voltage, even a small change in the conduction angle can cause a significant difference in output current, resulting in flickering lights.

[0004] To avoid flickering, the SCR dimmer needs to be kept on, and maintaining the SCR dimmer requires a current. For example... Figure 1 As shown, a common solution is to add a constant current source circuit to the LED circuit to maintain the current. Simultaneously, a diode D1 is inserted into the LED circuit to prevent the maintaining current from flowing from the load capacitor C. out The top part was removed. However, in this plan, such as... Figure 2As shown, the sustaining current exists continuously and is a constant value when the input voltage of the SCR dimmer is lower than the load voltage, resulting in low operating efficiency of the SCR dimmer. Furthermore, in the waveform chamfer section of the SCR dimmer, the constant current source circuit pulls the output voltage of the rectifier circuit to close to 0V, and the SCR dimmer will restart when its output voltage is very low. This leads to poor compatibility and low operating efficiency of the solution. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a thyristor-controlled dimming voltage-regulating constant current control circuit and its control method, which can solve the above-mentioned problems.

[0006] One aspect of the present invention provides a thyristor-controlled dimming voltage-regulating constant-current control circuit, comprising: SCR dimmer, rectifier circuit, feedback loop, LED lamp assembly, output capacitor C out Constant current source circuit; The thyristor dimmer, the rectifier circuit, and the corresponding AC power supply form an input circuit. The rectifier circuit is used to rectify the AC power supply, and the thyristor dimmer is used to adjust the output voltage of the rectifier circuit. The output terminal of the rectifier circuit, the feedback loop, the LED group, and the constant current source circuit are sequentially connected to form a loop. The feedback loop includes a voltage detection circuit and a bidirectional selection circuit. The LED group includes several LEDs connected in series. A load capacitor C is connected in parallel across the two ends of the LED group. out ; The voltage detection circuit is used to detect the output voltage of the rectifier circuit, and when the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the voltage detection circuit enables the bidirectional selection circuit to switch from the output terminal of the rectifier circuit to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charging; when the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the voltage detection circuit turns on the bidirectional selection circuit, and the load capacitor C out Current is supplied to the output terminal of the rectifier circuit through the load capacitor C. out Power is supplied to the thyristor dimmer to maintain the output voltage of the rectifier circuit.

[0007] Furthermore, it includes: a dimmer detection circuit; The input terminal of the dimmer detection circuit is connected to the output terminal of the rectifier circuit to detect whether a thyristor dimmer is connected before the rectifier circuit; the output terminal of the dimmer detection circuit is connected to the input terminal of the voltage detection circuit to provide an enable signal to the voltage detection circuit.

[0008] Furthermore, the feedback loop includes: a current sustaining control circuit; The input terminal of the sustaining current control circuit is connected to the output terminal of the voltage detection circuit to receive the control signal from the voltage detection circuit; the output terminal of the sustaining current control circuit is connected to the input terminal of the bidirectional selection circuit to control the magnitude of the sustaining current.

[0009] Furthermore, the sustaining current control circuit includes: amplifier I4, amplifier I5, resistor R6, resistor R7, resistor R8, resistor R9, and MOSFET Q4; The output terminal of amplifier I5 is connected to the gate of MOS transistor Q4 to form a follower, so that the voltage drop across resistor R9 is equal to its reference voltage Vref, thereby obtaining a constant sustaining current. The negative terminal of amplifier I4 is connected to resistors R6 and R7 to form a voltage divider structure for detecting the output voltage of the rectifier circuit. The positive terminal of amplifier I4 is connected to the reference voltage Vref. When the reference voltage Vref at the positive terminal of amplifier I4 is lower than the voltage at its negative terminal, a current is generated at the output terminal of amplifier I4. This current generates a voltage drop across resistor R8, thereby adjusting the voltage across resistor R9 and changing the magnitude of the sustaining current.

[0010] Furthermore, the bidirectional selection circuit includes: a driving module, a diode D1, a resistor R5, and a MOSFET Q1; The input terminal of the driving module is connected to the voltage detection circuit, and the output terminal of the driving module is connected to the gate of the MOS transistor Q1. The drain of the MOS transistor Q1 is connected in series with the resistor R5 and then in parallel across the diode D1. The anode of the diode D1 is connected to the output terminal of the rectifier circuit and the source of the MOS transistor Q1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0011] Furthermore, the bidirectional selection circuit includes: a driving module, diode D1, resistor R5, MOSFET Q1, and MOSFET Q2; The output terminal of the drive module is connected to the gate of the MOSFET Q1 and the gate of the MOSFET Q2 respectively. The resistor R5 is connected in parallel with the diode D1 to bear the excessive voltage. The drain of the MOSFET Q1 is connected to the positive terminal of the diode D1, and the drain of the MOSFET Q2 is connected to the negative terminal of the diode D1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0012] Another aspect of the present invention provides a regulated constant current control method for silicon controlled rectifier (SCR) dimming, comprising: The output voltage of the rectifier circuit is adjusted by the thyristor dimmer. The dimmer detection circuit detects whether the thyristor dimmer is connected before the rectifier circuit. If so, it outputs a high level to control the voltage detection circuit to detect the output voltage of the rectifier circuit. The voltage detection circuit controls the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer based on the detected output voltage of the rectifier circuit, and drives the holding current control circuit to maintain the input loop current.

[0013] Furthermore, the dimmer detection circuit detects whether the thyristor dimmer is connected before the rectifier circuit, including: When the dimmer detection circuit detects that the output voltage of the rectifier circuit is a forward-angled waveform, it generates a positive pulse signal. When the dimmer detection circuit detects that the output voltage of the rectifier circuit is a back-cut waveform, it generates a negative pulse signal. If the dimmer detection circuit continuously detects the pulse signal within 3-10 cycles, it will continuously output a high-level signal; otherwise, it will output a low-level signal.

[0014] Furthermore, controlling the on / off switching of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0015] Furthermore, controlling the on / off switching of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0016] The beneficial effects of this invention are: Firstly, by setting up a dimmer detection circuit, it is possible to directly detect whether a thyristor dimmer is connected in the circuit, thereby determining the enabling of subsequent circuits and improving the overall circuit efficiency.

[0017] Secondly, the voltage detection circuit, the sustaining current control circuit, and the bidirectional selection circuit are combined into a feedback loop. When the output waveform of the dimmer has a chamfer, the output voltage of the chamfered part will not be pulled down to 0V by adjusting the sustaining current and selecting the conduction direction and conduction resistance of the bidirectional selection circuit.

[0018] Third, by reversing the power supply of the bidirectional selection circuit, the current of the sustaining current module is reduced, preventing the dimmer's input voltage from dropping further. This reduces the system's useless power consumption and improves system efficiency; moreover, it keeps the dimmer's input voltage at a relatively high value, avoiding dimmer restart issues and improving the overall circuit's compatibility with the dimmer. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a diagram of a thyristor dimming circuit in the background art of this invention.

[0021] Figure 2 This is a waveform diagram of the working state of the thyristor dimmer in the background art of this invention during restart.

[0022] Figure 3 This is a circuit diagram of the thyristor dimming voltage-stabilized constant current control circuit in this invention.

[0023] Figure 4 This is a waveform diagram of the voltage-stabilized constant-current control circuit in this invention.

[0024] Figure 5 This is a circuit diagram of the dimmer detection circuit in this invention.

[0025] Figure 6 This is a waveform diagram of the dimmer output waveform before cutting off the waveform in this invention.

[0026] Figure 7 This is a waveform diagram of the dimmer output waveform and the working waveform in this invention.

[0027] Figure 8 This is a circuit diagram of Embodiment 1 of the bidirectional gating circuit in this invention.

[0028] Figure 9 This is a circuit diagram of Embodiment 2 of the bidirectional selection circuit in this invention.

[0029] Figure 10 This is the circuit diagram for maintaining the current in this invention.

[0030] Figure 11 This is a rectifier circuit diagram in this invention.

[0031] Figure 12 This is the circuit diagram of the constant current source in this invention. Detailed Implementation

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] like Figure 3 As shown, this embodiment of the invention provides a regulated constant current control circuit for SCR dimming, including: a SCR dimmer, a rectifier circuit, a feedback loop, an LED lamp group, and an output capacitor C. out Constant current source circuit; The thyristor dimmer, the rectifier circuit, and the corresponding AC power supply form an input circuit. The rectifier circuit is used to rectify the AC power supply, and the thyristor dimmer is used to adjust the output voltage of the rectifier circuit. The output terminal of the rectifier circuit, the feedback loop, the LED group, and the constant current source circuit are sequentially connected to form a loop. The feedback loop includes a voltage detection circuit and a bidirectional selection circuit. The LED group includes several LEDs connected in series. A load capacitor C is connected in parallel across the two ends of the LED group. out ; In this embodiment, the rectifier circuit is a commonly used bridge rectifier circuit, such as... Figure 11 As shown; load capacitor C out It is a single-ended capacitor to prevent the holding current from flowing from the load capacitor C. out It was removed from the top.

[0034] The voltage detection circuit is used to detect the output voltage of the rectifier circuit, and when the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the voltage detection circuit enables the bidirectional selection circuit to flow from the output terminal of the rectifier circuit to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charging; when the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the voltage detection circuit turns on the bidirectional selection circuit, and the load capacitor C out Current is supplied to the output terminal of the rectifier circuit through the load capacitor C. out Power is supplied to the thyristor dimmer to maintain the output voltage of the rectifier circuit.

[0035] Furthermore, it includes: a dimmer detection circuit; The input terminal of the dimmer detection circuit is connected to the output terminal of the rectifier circuit to detect whether a thyristor dimmer is connected before the rectifier circuit; the output terminal of the dimmer detection circuit is connected to the input terminal of the voltage detection circuit to provide an enable signal to the voltage detection circuit.

[0036] Furthermore, the dimmer detection circuit includes: resistor R1, resistor R2, capacitor C1, comparator I1, comparator I2, AND gate I3, counter, and timer; the positive terminal of comparator I1 is connected to the output terminal of the rectifier circuit to receive the input signal rectified by the SCR dimmer; resistor R1 and capacitor C1 are connected in series between the positive terminal of comparator I1 and the rectifier circuit to generate a pulse signal; the output terminal of comparator I1 is connected to the counter to output the counting of the pulse signal; the positive terminal of comparator I2 is connected to the output terminal of the rectifier circuit to receive the input signal rectified by the SCR dimmer; resistor R2 is connected in series between the positive terminal of comparator I1 and the rectifier circuit to generate a pulse signal; the output terminal of comparator I2 is connected to the timer to output the timing of the pulse signal; the output terminals of the counter and the timer are respectively connected to the AND gate I3 for filtering and outputting the detection result.

[0037] In this embodiment, as Figure 5 As shown, the RC network consisting of resistors R1 and R2, and capacitor C1 is used to generate pulse signals. When a thyristor dimmer is connected in the circuit, the RC network will generate a pulse output. Comparators I1 and I2, AND gate I3, counter, and timer together implement pulse detection and filtering functions. The positive terminal of comparator I1 is grounded through resistor R3, and the negative terminal of comparator I1 is grounded to detect whether there is a sudden change in the input voltage, thereby identifying whether a dimmer is connected. The positive terminal of comparator I2 is grounded through resistor R4, and the negative terminal of comparator I2 receives a reference voltage Vref to detect the cycle of the input mains power. The dimmer detection circuit is used to detect whether a dimmer is connected before the rectifier circuit, thereby determining the enabling of subsequent circuits.

[0038] Furthermore, the feedback loop includes: a current sustaining control circuit; The input terminal of the sustaining current control circuit is connected to the output terminal of the voltage detection circuit to receive the control signal from the voltage detection circuit; the output terminal of the sustaining current control circuit is connected to the input terminal of the bidirectional selection circuit to control the magnitude of the sustaining current.

[0039] like Figure 10 As shown, the sustaining current control circuit includes: amplifier I4, amplifier I5, resistor R6, resistor R7, resistor R8, resistor R9, and MOSFET Q4; The output terminal of amplifier I5 is connected to the gate of MOS transistor Q4 to form a follower, so that the voltage drop across resistor R9 is equal to its reference voltage Vref, thereby obtaining a constant sustaining current. The negative terminal of amplifier I4 is connected to resistors R6 and R7 to form a voltage divider structure for detecting the output voltage of the rectifier circuit. The positive terminal of amplifier I4 is connected to the reference voltage Vref. When the reference voltage Vref at the positive terminal of amplifier I4 is lower than the voltage at its negative terminal, a current is generated at the output terminal of amplifier I4. This current generates a voltage drop across resistor R8, thereby adjusting the voltage across resistor R9 and changing the magnitude of the sustaining current.

[0040] In this embodiment, MOSFET Q3 is the enable transistor. If no dimmer is detected, Q3 will be turned on, thereby turning off the sustaining current. The output of the voltage detection circuit is connected to the sustaining current control circuit and the bidirectional selection circuit. When the voltage detection circuit detects that the input voltage is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, it outputs a high level to control the drive module in the bidirectional selection circuit, allowing the bidirectional selection circuit to supply power in reverse. At the same time, it also reduces the current of the sustaining current control module, preventing the input voltage of the SCR dimmer from dropping further. The operating waveform is as follows: Figure 4 As shown. This reduces the overall circuit's useless power consumption, improves system efficiency, and keeps the input voltage of the SCR dimmer at a high value, avoiding SCR dimmer restart issues and improving the overall circuit's compatibility with SCR dimmers.

[0041] In this invention, two embodiments of the bidirectional gating circuit are provided.

[0042] like Figure 8 As shown, the bidirectional selection circuit includes: a driving module, a diode D1, a resistor R5, and a MOSFET Q1; The input terminal of the driving module is connected to the voltage detection circuit, and the output terminal of the driving module is connected to the gate of the MOS transistor Q1. The drain of the MOS transistor Q1 is connected in series with the resistor R5 and then in parallel across the diode D1. The anode of the diode D1 is connected to the output terminal of the rectifier circuit and the source of the MOS transistor Q1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0043] In this embodiment, resistor R5 is connected in series with MOSFET Q1, and then in parallel with diode D1. When the input voltage is ≥20-60V, diode D1 conducts, MOSFET Q1 is turned off, and the input current supplies power to the LED group and the load capacitor C through diode D1. out Charging; when the input voltage is lower than the output voltage, diode D1 is cut off. The drive module is controlled by a signal from the voltage detection circuit. At the dimmer corner, when the input voltage is pulled down to a lower level by the holding current, the drive circuit outputs a high level, causing MOSFET Q1 to conduct, thereby energizing the load capacitor C. out It will pass through resistor R set Power is supplied to the input terminal to maintain the input voltage from dropping to 0.

[0044] like Figure 9 As shown, the bidirectional selection circuit includes: a driving module, diode D1, resistor R5, MOSFET Q1, and MOSFET Q2; The output terminal of the drive module is connected to the gate of the MOSFET Q1 and the gate of the MOSFET Q2 respectively. The resistor R5 is connected in parallel with the diode D1 to bear the excessive voltage. The drain of the MOSFET Q1 is connected to the positive terminal of the diode D1, and the drain of the MOSFET Q2 is connected to the negative terminal of the diode D1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0045] In this embodiment, the output terminal of the drive module is connected to the gate of MOSFET Q1 and the gate of MOSFET Q2, respectively. A polysilicon resistor R5 is connected between the drains of MOSFET Q1 and MOSFET Q2, and resistor R5 is connected in parallel with diode D1. When the input voltage is higher than the load capacitor voltage, MOSFET Q2, which is connected to the negative terminal of the diode, turns on, and the other MOSFET Q1 turns off, flowing through the load capacitor C. out Reverse power supply: When a thyristor dimmer is connected, and the input voltage is lower than the output voltage during the chamfered portion of the dimmer's operating waveform, diode D1 conducts, MOSFET Q1 connected to the positive terminal of diode D1 turns on, and the other MOSFET Q2 turns off, providing forward power and simultaneously supplying power to the load capacitor C. out Charge.

[0046] It should be noted that MOSFET Q1, MOSFET Q2 and resistor R5 can be integrated into a single high-voltage device. Resistor R5 can be integrated using polysilicon, achieving a high degree of integration of the overall circuit and reducing the discreteness of components.

[0047] like Figure 12 As shown, the constant current source circuit includes: amplifier I6, resistor R10, and MOSFET Q5; amplifier I6 and MOSFET Q5 form a source follower structure, such that the source voltage of the MOSFET is equal to the reference voltage Vref, then the voltage drop across resistor R10 is equal to Vref, and the current flowing through resistor R10... This is the constant current.

[0048] Another embodiment of the present invention provides a thyristor-controlled dimming voltage-regulating constant current control method, comprising: S1 adjusts the output voltage of the rectifier circuit through the silicon controlled rectifier dimmer; S2 detects whether the thyristor dimmer is connected before the rectifier circuit through the dimmer detection circuit. If so, it outputs a high level to control the voltage detection circuit to detect the output voltage of the rectifier circuit. Furthermore, the dimmer detection circuit detects whether the thyristor dimmer is connected before the rectifier circuit, including: When the dimmer detection circuit described in S201 detects that the output voltage of the rectifier circuit is a forward-angled waveform, it generates a positive pulse signal. When the dimmer detection circuit described in S202 detects that the output voltage of the rectifier circuit is a back-cut waveform, it generates a negative pulse signal. S203 If the dimmer detection circuit continuously detects the pulse signal within 3-10 cycles, it continuously outputs a high-level signal; otherwise, it outputs a low-level signal.

[0049] In this step, such as Figure 6 and Figure 7 As shown, Figure 6 and Figure 7 The waveform diagrams of the module's operation when connected to pre-cut and post-cut dimming are shown. In pre-cut dimming, a positive pulse signal is generated; in post-cut dimming, a negative pulse is generated. The pulse detection module outputs a high level if it detects a pulse signal, and a low level otherwise. When a dimmer is connected, the pulse detection module will continuously output a signal of 1 at a certain period; if there is no dimmer and only interference, the pulse detection module will output 0, or only occasionally output 1; interference information can be filtered out through digital filtering.

[0050] S3 uses the voltage detection circuit to control the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer based on the detected output voltage of the rectifier circuit, and drives the holding current control circuit to maintain the input loop current.

[0051] Furthermore, controlling the on / off switching of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0052] This step is... Figure 8 The control method of the bidirectional gating circuit shown.

[0053] Furthermore, controlling the on / off switching of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

[0054] This step is... Figure 9 The control method of the bidirectional gating circuit shown.

[0055] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0056] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0057] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0058] It should be noted that any reference signs placed between parentheses in the claims should not be construed as limiting the claims. The word "comprising" does not exclude the presence of components or steps not listed in the claims. The word "a" or "an" preceding a component does not exclude the presence of a plurality of such components. The invention can be implemented by means of hardware comprising several different components and by means of a suitably programmed computer. In a unit claim enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0059] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0060] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0061] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

Claims

1. A thyristor-controlled dimming voltage-regulating constant-current control circuit, characterized in that, include: SCR dimmer, rectifier circuit, feedback loop, LED lamp assembly, output capacitor C out Constant current source circuit, dimmer detection circuit, and sustaining current control circuit; The thyristor dimmer, the rectifier circuit, and the corresponding AC power supply form an input circuit. The rectifier circuit is used to rectify the AC power supply, and the thyristor dimmer is used to adjust the output voltage of the rectifier circuit. The output terminal of the rectifier circuit, the feedback loop, the LED group, and the constant current source circuit are sequentially connected to form a loop. The feedback loop includes a voltage detection circuit and a bidirectional selection circuit. The LED group includes several LEDs connected in series. A load capacitor C is connected in parallel across the two ends of the LED group. out ; The voltage detection circuit is used to detect the output voltage of the rectifier circuit, and when the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the voltage detection circuit enables the bidirectional selection circuit to flow from the output terminal of the rectifier circuit to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charging; when the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the voltage detection circuit enables the bidirectional selection circuit to conduct in one direction, and the load capacitor C out Current is supplied to the output terminal of the rectifier circuit through the load capacitor C. out Power is supplied to the thyristor dimmer to maintain the output voltage of the rectifier circuit; The input terminal of the dimmer detection circuit is connected to the output terminal of the rectifier circuit to detect whether a thyristor dimmer is connected before the rectifier circuit; the output terminal of the dimmer detection circuit is connected to the input terminal of the voltage detection circuit to provide an enable signal to the voltage detection circuit. The input terminal of the sustaining current control circuit is connected to the output terminal of the voltage detection circuit to receive the control signal from the voltage detection circuit; the output terminal of the sustaining current control circuit is connected to the input terminal of the bidirectional selection circuit to control the magnitude of the sustaining current.

2. The thyristor-controlled dimming voltage-regulating constant-current control circuit as described in claim 1, characterized in that, The current sustaining control circuit includes: amplifier I4, amplifier I5, resistor R6, resistor R7, resistor R8, resistor R9, and MOSFET Q4; The output terminal of amplifier I5 is connected to the gate of MOS transistor Q4 to form a follower, so that the voltage drop across resistor R9 is equal to its reference voltage Vref, thereby obtaining a constant sustaining current. The negative terminal of amplifier I4 is connected to resistors R6 and R7 to form a voltage divider structure for detecting the output voltage of the rectifier circuit. The positive terminal of amplifier I4 is connected to the reference voltage Vref. When the reference voltage Vref at the positive terminal of amplifier I4 is lower than the voltage at its negative terminal, a current is generated at the output terminal of amplifier I4. This current generates a voltage drop across resistor R8, thereby adjusting the voltage across resistor R9 and changing the magnitude of the sustaining current.

3. The thyristor-controlled dimming voltage-regulating constant-current control circuit as described in claim 2, characterized in that, The bidirectional selection circuit includes: a driving module, diode D1, resistor R5, and MOSFET Q1; The input terminal of the driving module is connected to the voltage detection circuit, and the output terminal of the driving module is connected to the gate of the MOS transistor Q1. The drain of the MOS transistor Q1 is connected in series with the resistor R5 and then in parallel across the diode D1. The anode of the diode D1 is connected to the output terminal of the rectifier circuit and the source of the MOS transistor Q1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

4. The regulated constant current control circuit for thyristor dimming as described in claim 1, characterized in that, The bidirectional selection circuit includes: a driving module, diode D1, resistor R5, MOSFET Q1, and MOSFET Q2; The output terminal of the drive module is connected to the gate of the MOSFET Q1 and the gate of the MOSFET Q2 respectively. The resistor R5 is connected in parallel with the diode D1 to bear the excessive voltage. The drain of the MOSFET Q1 is connected to the positive terminal of the diode D1, and the drain of the MOSFET Q2 is connected to the negative terminal of the diode D1. When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

5. A thyristor-controlled dimming method with constant voltage and current regulation, characterized in that, A thyristor-controlled dimming voltage-regulating constant-current control circuit based on any one of claims 1-4 includes: The output voltage of the rectifier circuit is adjusted by the thyristor dimmer. The dimmer detection circuit detects whether the thyristor dimmer is connected before the rectifier circuit. If so, it outputs a high level to control the voltage detection circuit to detect the output voltage of the rectifier circuit. The voltage detection circuit controls the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer based on the detected output voltage of the rectifier circuit, and drives the holding current control circuit to maintain the input loop current.

6. The regulated constant current control method for thyristor dimming as described in claim 5, characterized in that, The dimmer detection circuit detects whether a thyristor dimmer is connected before the rectifier circuit, including: When the dimmer detection circuit detects that the output voltage of the rectifier circuit is a forward-angled waveform, it generates a positive pulse signal. When the dimmer detection circuit detects that the output voltage of the rectifier circuit is a back-cut waveform, it generates a negative pulse signal. If the dimmer detection circuit continuously detects the pulse signal within 3-10 cycles, it will continuously output a high-level signal; otherwise, it will output a low-level signal.

7. The regulated constant current control method for thyristor dimming as described in claim 5, characterized in that, The control of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, the MOSFET Q1 is turned off and the diode D1 is turned on, making the output terminal of the rectifier circuit connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on and the diode D1 is turned off, thus turning on the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

8. The regulated constant current control method for thyristor dimming as described in claim 5, characterized in that, The control of the bidirectional selection circuit to stabilize the input voltage of the thyristor dimmer includes: When the voltage detection circuit detects that the output voltage of the rectifier circuit is greater than the valley value of 20V or greater than the peak value of 60V, MOSFET Q1 is turned off, MOSFET Q2 is turned on, and diode D1 is turned on, so that the output terminal of the rectifier circuit is connected to the load capacitor C. out Unidirectional conduction, for the load capacitor C out Charge; When the voltage detection circuit detects that the output voltage of the rectifier circuit is less than or equal to the valley value of 20V or less than or equal to the peak value of 60V, the MOSFET Q1 is turned on, the MOSFET Q2 is turned off, and the diode D1 is turned off, thus turning off the load capacitor C. out Unidirectional conduction to the output terminal of the rectifier circuit, unidirectional conduction through the load capacitor C out Power is supplied to the silicon controlled rectifier dimmer.

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