Current regulating circuit, LED lighting system and control method thereof

Abstract

The application discloses a current regulating circuit, an LED lighting system and a control method thereof. The current regulating circuit is used for multiple dimming modes, comprising: a first current control module, configured to generate a first concave wave driving signal according to a proportional signal of a direct current input voltage or an end voltage of a load; and a first transistor, connected with the first current control module, configured to generate a second concave wave load current according to the driving signal. The first current control module controls a reference signal of the load current in the multiple dimming modes, and adjusts a shape of the second concave wave of the load current according to the reference signal. The current regulating circuit realizes dimming control by changing the shape of the concave wave, can realize multiple dimming mode functions, and can improve the working efficiency of the circuit.

Description

Technical Field

[0001] This invention relates to the field of power electronics, and in particular to current regulation circuits for LED light sources with multiple dimming modes, LED lighting systems, and control methods thereof. Background Technology

[0002] As LED manufacturing processes become increasingly sophisticated, LED light sources have become the primary light source for home lighting applications. The dimming capabilities of LED light sources allow for adjustments to brightness and color tone, thus providing a more comfortable lighting environment.

[0003] Depending on the dimming principle of the LED light source, dimming control methods include: PWM dimming control, analog dimming control, and SCR dimming control. Using SCR control requires a separate SCR dimmer. Due to environmental limitations, it may be impossible to install a SCR dimmer. Therefore, the dimming control method for LED light sources needs to be compatible with existing switch panels to achieve multiple dimming modes for application in different practical environments.

[0004] However, existing LED lighting systems with multiple dimming modes struggle to provide stable operation across the entire dimming range. In particular, at low brightness levels, the LED lamp's load current is relatively small. Due to current dip compensation, this leads to significant fluctuations in the input current, causing instability in the LED lamp's load current under the SCR dimmer. This results in flickering or jittering of the LED light, and may even cause damage. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a current regulation circuit for multiple dimming modes, an LED lighting system and a control method thereof, wherein dimming control for multiple dimming modes and improvement of circuit stability are achieved by changing the shape of the concave waveform.

[0006] According to a first aspect of the present invention, a current regulation circuit for multiple dimming modes is provided, comprising:

[0007] A first current control module is used to generate a drive signal for a first concave waveform based on a proportional signal of the DC input voltage or the terminal voltage of the load; and

[0008] The first transistor, connected to the first current control module, is used to generate a second concave waveform load current according to the drive signal.

[0009] The first current control module generates a reference signal for controlling the load current under the various dimming modes, and adjusts the second concave waveform shape of the load current according to the reference signal.

[0010] Preferably, the multiple dimming modes include a SCR dimming mode using a SCR dimmer, a switch dimming mode using a switch as a dimmer, and a hybrid dimming mode using both a SCR dimmer and a switch as dimmers.

[0011] Preferably, in the thyristor dimming mode and the hybrid dimming mode, the first current control module adjusts the amplitude and / or the degree of concavity of the second concave waveform according to the conduction angle of the thyristor.

[0012] Preferably, in the switch dimming mode and the hybrid dimming mode, the first current control module adjusts the amplitude and / or the degree of concavity of the second concave waveform according to the switch switching count value.

[0013] Preferably, the first current control module includes:

[0014] A switch detection module is used to detect the switching action of a switch.

[0015] A counter, connected to the switch detection module, receives the detection signal of the switch action and is used to generate a count value according to the number of switches according to the control logic;

[0016] A reference generation module, connected to the counter to receive the count value, is used to convert the count value into the reference signal; and

[0017] A concave control module, connected to the reference generation module to receive the reference signal, is used to generate a control signal for a third concave waveform, and to adjust the amplitude and / or degree of concaveness of the control signal according to the reference signal.

[0018] Preferably, the third concave waveform changes proportionally to the second concave waveform.

[0019] Preferably, the current regulating circuit further includes:

[0020] A reference detection module is connected to the reference generation module to receive the reference signal and determine the dimming range of the LED lamp based on the reference signal.

[0021] The concave coefficient generation module is connected to the reference detection module and provides a corresponding concave coefficient based on the dimming range of the LED light.

[0022] The concave control module receives the concave coefficient and controls the degree of concaveness of the concave waveform according to the concave coefficient.

[0023] Preferably, when the dimming range of the LED lamp is greater than or equal to a predetermined value, the concave coefficient generating module provides a fixed concave coefficient.

[0024] When the dimming range of the LED lamp is less than the predetermined value, the concave coefficient generating module provides a dynamically adjustable concave coefficient.

[0025] Preferably, the concavity coefficient decreases as the reference voltage decreases.

[0026] Preferably, the current regulating circuit further includes:

[0027] A conduction angle detection module is used to detect whether the conduction angle of the thyristor is less than a predetermined value.

[0028] Specifically, when the conduction angle of the thyristor is greater than or equal to the predetermined value, the counter uses a fixed counting step size for counting.

[0029] When the conduction angle of the thyristor is less than the predetermined value, the counter uses a dynamically adjusted counting step size for counting.

[0030] Preferably, the counting step size increases as the conduction angle of the thyristor decreases.

[0031] Preferably, the concave control module includes:

[0032] The concave compensation module is used to obtain a corresponding proportional signal based on the voltage sampling signal of the DC input voltage or the load terminal voltage;

[0033] A feedback compensation module is used to generate a compensation voltage based on the error of the sampled signal of the load current relative to the reference signal; and

[0034] The calculation module is connected to the concave compensation module to receive the proportional signal and to the feedback compensation module to receive the compensation voltage. The calculation module obtains the control signal by calculating the difference between the compensation voltage and the proportional signal.

[0035] According to a second aspect of the present invention, an LED lighting system is provided, comprising:

[0036] LED lights, wherein the LED lights serve as a light source;

[0037] A dimmer is used to generate a waveform change in the AC input voltage based on the dimming action;

[0038] A rectifier bridge, connected to the dimmer, is used to rectify the AC input voltage to generate a DC input voltage;

[0039] A discharge circuit, connected between the first and second output terminals of the rectifier bridge, is used to provide a discharge current when the load current is less than a predetermined value; and

[0040] In any of the above current regulation circuits, the LED and the current regulation circuit are connected in series between the first output terminal and the second output terminal of the rectifier bridge.

[0041] Preferably, the LED lighting system further includes a diode connected between the discharge circuit and the LED lamp.

[0042] According to a third aspect of the present invention, a control method for multiple dimming modes is provided, comprising:

[0043] A drive signal that generates a first concave waveform is generated based on a proportional signal of the DC input voltage or the terminal voltage of the load; and

[0044] The load current with a second concave waveform is generated according to the drive signal.

[0045] In this process, a reference signal for controlling the load current is generated under the various dimming modes, and the shape of the second concave waveform of the load current is adjusted according to the reference signal.

[0046] Preferably, the multiple dimming modes include a SCR dimming mode using a SCR dimmer, a switch dimming mode using a switch as a dimmer, and a hybrid dimming mode using both a SCR dimmer and a switch as dimmers.

[0047] Preferably, in the thyristor dimming mode and the hybrid dimming mode, the amplitude and / or degree of the second concave waveform are adjusted according to the conduction angle of the thyristor.

[0048] Preferably, in the switch dimming mode and the hybrid dimming mode, the amplitude and / or degree of the second concave waveform are adjusted according to the switch switching count value.

[0049] According to the current regulation circuit of the present invention, the current control module performs dimming control on the LED load current based on the DC input voltage or the terminal voltage of the load, and the load current of the LED lamp is always a concave waveform or close to a concave waveform. In the SCR dimming mode, the load current of the LED lamp is a phase-cut concave waveform, and the operating range of the load current is adjusted by changing the conduction angle of the SCR; in the switch dimming mode, the amplitude and / or degree of concave waveform of the load current is adjusted by counting the number of switch cycles. Therefore, this LED lighting system can support multiple dimming modes. Regardless of whether a SCR dimmer, a switch, or both are used, the current regulation circuit changes the shape of the concave waveform in different ways to adjust and improve the system's operating efficiency. Therefore, this LED lighting system can realize multiple dimming mode functions.

[0050] In a preferred embodiment, when the LED lamp's load current is relatively small within the low-brightness dimming range, the shape change of the concave waveform of the LED lamp's load current helps to improve the stability of the load current. Therefore, this LED lighting system can improve circuit stability. Attached Figure Description

[0051] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0052] Figure 1 A schematic circuit diagram of an LED lighting system according to the prior art is shown.

[0053] Figure 2 A schematic circuit diagram of an LED lighting system according to an embodiment of the present invention is shown.

[0054] Figure 3 Show Figure 2 The diagram shows a schematic block diagram of the current control module in the current regulation circuit of the LED lighting system.

[0055] Figure 4 Show Figure 3 The diagram shows a schematic block diagram of the recessed control module in the current control module.

[0056] Figure 5 Show Figure 2 The waveform diagram of the LED lighting system in switch dimming mode is shown.

[0057] Figure 6 Show Figure 2 The waveform diagram of the LED lighting system shown is in a hybrid mode of SCR dimming and switch dimming. Detailed Implementation

[0058] The invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.

[0059] Many specific details of the invention, such as the structure, materials, dimensions, processing methods, and techniques of the devices, are described below to provide a clearer understanding of the invention. However, as those skilled in the art will understand, the invention may be implemented without following these specific details.

[0060] Figure 1 A schematic circuit diagram of an LED lighting system according to the prior art is shown.

[0061] The LED lighting system 100 includes a silicon controlled rectifier dimmer 102, a rectifier bridge 103, a discharge circuit 110, a current regulation circuit 120, and an LED lamp 105.

[0062] AC power supply 101 is connected to the two AC input terminals of rectifier bridge 103 via a silicon controlled rectifier dimmer 102. AC power supply 101 is, for example, a mains AC power supply or a UPS power supply. AC power supply 101 provides an AC supply voltage of 220V Vac, for example, an AC supply voltage Vac is a sinusoidal AC voltage with a rated frequency (also known as "power frequency") of 50Hz.

[0063] By adjusting the dimming action of the SCR dimmer 102, the conduction angle of the SCR can be changed, chopping the AC supply voltage Vac to obtain a phase-cut AC input voltage Vcut. The effective voltage of the AC input voltage Vcut is related to the conduction angle of the SCR compared to the AC supply voltage Vac; therefore, the dimming action of the SCR dimmer 102 can change the brightness of the LED lamp 105, which serves as the load. Further, the rectifier bridge 103 rectifies the AC input voltage Vcut to obtain a DC input voltage Vrec.

[0064] The bleeder circuit 110 and the current regulation circuit 120 are connected in sequence to the rectifier bridge 103. The bleeder circuit 110 provides bleeder current when the load current is less than the current threshold to maintain the conduction state of the thyristor. The current regulation circuit 120 regulates the load current Iout flowing through the LED lamp 105 to the desired current waveform to improve circuit efficiency.

[0065] The bleeder circuit 110 includes resistors R11 and R12 connected in series between the two DC output terminals of the rectifier bridge 103, transistor M1 connected in series between the two DC output terminals of the rectifier bridge 103, and resistors R3 and R4. Resistors R11 and R12 are used to obtain the voltage sampling signal Vrs of the DC input voltage Vrec. Transistor M1, resistors R3 and R4 are used to provide a bleeder current path, and resistors R3 and R4 are also used to obtain the current sampling signal Vcs1 of the bleeder current.

[0066] The discharge circuit 110 also includes a discharge control module 111. The first input terminal of the discharge control module 111 is connected to the intermediate node of resistors R11 and R12 to receive the voltage sampling signal Vrs of the DC input voltage Vrec, the second input terminal is connected to the intermediate node of transistor M1 and resistor R3 to receive the current sampling signal Vcs1 of the discharge current, the third input terminal is connected to the intermediate node of resistors R3 and R4 to receive the current sampling signal Vcs2 of the load current Iout, and the output terminal is connected to the control terminal of transistor M1 to provide a drive signal Vg1.

[0067] At the start of a half-wave power frequency cycle, when the DC input voltage Vrec is less than the voltage threshold, the discharge control module 111 turns on transistor M1, thereby conducting the discharge path. While transistor M1 is on, the discharge control module 111 dynamically adjusts the amplitude of the drive signal Vg1 according to the current sampling signal Vcs1, thus maintaining the discharge current at a predetermined value. When the load current Iout is greater than the current threshold, the discharge control module 111 turns off transistor M1, thereby cutting off the discharge path. Therefore, the discharge circuit 110 can maintain the load current of the thyristor at a level greater than the thyristor's holding current, solving the problems of LED flickering and limited dimming range caused by premature thyristor turn-off due to insufficient load current.

[0068] The current regulation circuit 120 includes transistor M2 and resistor R5. LED 105, transistor M2, resistors R5 and R4 are connected in series between the two DC output terminals of rectifier bridge 103. Resistors R5 and R4 are used to obtain the current sampling signal Vcs3 for obtaining the load current Iout.

[0069] Furthermore, the current regulation circuit 120 also includes a current control module 121. The first input terminal of the current control module 121 is connected to the intermediate node of resistors R11 and R12 to receive the voltage sampling signal Vrs of the DC input voltage Vrec, the second input terminal is connected to the intermediate node of transistor M2 and resistor R5 to receive the current sampling signal Vcs3 of the load current Iout, and the output terminal is connected to the control terminal of transistor M2 to provide the drive signal Vg2.

[0070] The current regulating circuit 120 is used to regulate the current waveform of the load current Iout flowing through the LED lamp 105. In one example, the current regulating circuit 120 is a linear regulating circuit that dynamically adjusts the signal amplitude of the drive signal Vg2 according to the current sampling signal Vcs3, thereby maintaining the load current Iout at a predetermined value during the conduction phase of the thyristor.

[0071] Preferably, the LED lighting system 100 also includes a capacitor Cout connected in parallel with the LED lamp 105. Since the DC input voltage Vrec of the LED lamp is a phase-cut DC input voltage, the charging and discharging characteristics of the capacitor Cout can be used to obtain a ramp edge, which is beneficial to extending the life of the LED lamp 105. When the current regulating circuit 120 is a linear regulating circuit, the charging and discharging characteristics of the capacitor Cout can be used to obtain a roughly trapezoidal current waveform.

[0072] Figure 2 A schematic circuit diagram of an LED lighting system according to an embodiment of the present invention is shown.

[0073] The LED lighting system 200 includes a dimmer 10, a rectifier bridge 103, a discharge circuit 210, a current regulation circuit 220, and an LED lamp 105.

[0074] AC power supply 101 is connected to the two AC input terminals of rectifier bridge 103 via dimmer 10. AC power supply 101 is, for example, AC mains power or UPS power supply. AC power supply 101 provides 220V AC supply voltage Vac, for example, AC supply voltage Vac is a sinusoidal AC voltage with a rated frequency (also known as "power frequency") of 50Hz.

[0075] The dimmer 10 includes at least one of a switch S1 and a silicon controlled rectifier (SCR) dimmer 11. Further, the rectifier bridge 103 rectifies the AC input voltage Vcut to obtain a DC input voltage Vrec for half a power frequency cycle.

[0076] The bleeder circuit 210 and the current regulation circuit 220 are connected in sequence to the rectifier bridge 103. The bleeder circuit 210 provides bleeder current when the load current is less than the current threshold to maintain the conduction state of the thyristor. The current regulation circuit 220 regulates the load current Iout flowing through the LED lamp 105 to the desired current waveform to improve circuit efficiency.

[0077] According to the circuit structure and working principle of the discharge circuit 210 in the LED lighting system of this embodiment, and Figure 1 The discharge circuit 110 used in the prior art shown is essentially the same, and its detailed description is omitted here.

[0078] The current regulation circuit 220 includes transistor M2 and resistor R5. LED 105, transistor M2, resistors R5 and R4 are connected in series between the two DC output terminals of rectifier bridge 103. Resistors R5 and R4 are used to obtain the current sampling signal Vcs3 for obtaining the load current Iout.

[0079] Furthermore, the current regulation circuit 220 also includes a current control module 20. The first input terminal of the current control module 20 is connected to the intermediate node of resistors R11 and R12 to receive the voltage sampling signal Vrs of the DC input voltage Vrec, the second input terminal is connected to the intermediate node of transistor M2 and resistor R5 to receive the current sampling signal Vcs3 of the load current Iout, and the output terminal is connected to the control terminal of transistor M2 to provide the drive signal Vg2.

[0080] The current regulation circuit 220 is used to regulate the current waveform of the load current Iout flowing through the LED lamp 105. In this embodiment, the current regulation circuit 220 supports multiple dimming modes. Whether using a SCR dimmer, a switch, or both simultaneously, the current regulation circuit 220 can provide the desired current waveform for the LED lamp 105 and meet the operating current requirements of the circuit devices. The current regulation circuit 220 not only realizes the dimming function of the LED lighting system but also improves the circuit efficiency under both heavy and light load conditions.

[0081] When the dimmer 10 only includes switch S1, the current regulation circuit 220 adjusts the effective value of the load current of the LED lamp 105 based on the count of the number of switching operations when the user operates the switch multiple times. Therefore, the brightness of the LED lamp 105, which is the load, can be changed by switching S1.

[0082] When the dimmer 10 only includes the SCR dimmer 11, the user adjusts the conduction angle of the SCR in the SCR dimmer 11, and the effective voltage of the DC input voltage Vrec is related to the conduction angle of the SCR. Therefore, the brightness of the LED lamp 105, which is the load, can be changed by adjusting the SCR dimmer 11.

[0083] In the case where the dimmer 10 includes both a switch S1 and a SCR dimmer 11, the switch S1 and the SCR dimmer 11 are connected in series. Therefore, the brightness of the LED lamp 105, which is the load, can be changed by switching the switch S1 and by adjusting the SCR dimmer 11.

[0084] Preferably, the LED lighting system 200 may further include a diode D1 connected between the high-potential terminal of the two DC output terminals of the rectifier bridge 103 and the LED lamp 105. The current regulation circuit 220 exhibits a certain degree of capacitance. When the absolute value of the DC input voltage Vrec decreases, the voltage decreases more slowly due to the capacitance of the current regulation circuit 220. By using diode D1 to isolate the discharge circuit 210 and the LED lamp 105, it can be ensured that the voltage sampling signal Vrs obtained by the resistor network composed of resistors R11 and R12 follows the absolute value of the DC input voltage Vrec, thereby ensuring the accuracy of sampling the DC input voltage Vrec.

[0085] Preferably, the LED lighting system 200 also includes a capacitor Cout connected in parallel with the LED lamp 105. Since the DC input voltage Vrec of the LED lamp is a phase-cut DC input voltage, the charging and discharging characteristics of the capacitor Cout can be used to obtain a ramp edge, which is beneficial to extending the life of the LED lamp 105.

[0086] In this embodiment, the current control module 20 generates a concave waveform drive signal Vg2 based on the proportional signal of the DC input voltage Vrec. The current control module 20 provides the drive signal Vg2 to the transistor M2, and the transistor M2 adjusts the load current Iout flowing through the LED lamp 105 according to the drive signal Vg2, thereby obtaining the concave waveform load current.

[0087] In an alternative embodiment, the current control module 20 provides a drive signal Vg2 based on a sampled signal of the load terminal voltage. The current control module 20 provides the drive signal Vg2 to the transistor M2, and the transistor M2 adjusts the load current Iout flowing through the LED lamp 105 according to the drive signal Vg2, thereby obtaining a concave waveform load current.

[0088] According to the LED lighting system of this embodiment, the LED load current is dimmed based on the DC input voltage Vrec, and the load current of the LED lamp is always a concave waveform or close to a concave waveform. In the SCR dimming mode, the load current of the LED lamp is a phase-cut concave waveform, and the operating range of the load current is adjusted by changing the conduction angle of the SCR. In the switch dimming mode, the amplitude and / or degree of concave waveform of the load current is adjusted by counting the number of times the switch is turned on and off. Therefore, this LED lighting system can support multiple dimming modes. Regardless of whether a SCR dimmer, a switch, or both are used, the current regulation circuit 220 can control the reference signal of the load current, change the shape of the concave waveform of the load current, and control the effective current of the load current according to the reference signal. Therefore, this LED lighting system can realize multiple dimming mode functions.

[0089] In a preferred embodiment, within the low-brightness dimming range, the dimming range can be set to 0-100% brightness, and the low-brightness dimming range can be below 10% brightness. When the load current of the LED lamp is relatively small, the shape change of the concave waveform of the LED lamp's load current is beneficial to improving the system's working efficiency. For example, under a light load, by adjusting the degree of concavity of the load current waveform to make it close to a flat concave shape, the holding current requirement of the thyristor can be met, and the loss caused by the discharge current of the thyristor can be greatly reduced in terms of system efficiency. Moreover, this LED lighting system can improve circuit stability. Under a light load, by adjusting the degree of concavity of the load current waveform to make it close to a flat concave shape, the current of the thyristor at the initial moment can meet the holding current requirement, and the thyristor operates stably.

[0090] Figure 3 Show Figure 2 The diagram shows a schematic block diagram of the current control module in the current regulation circuit of the LED lighting system.

[0091] The current control module 20 includes a switch detection module 21, a counter 22, a reference generation module 23, a descent control module 30, and a drive module 24.

[0092] The switch detection module 21 receives the voltage sampling signal Vrs of the DC input voltage Vrec and determines whether switch S1 has switched. If the voltage amplitude of the voltage sampling signal Vrs is continuously lower than a predetermined value during at least one continuous power frequency cycle, switch S1 is determined to be in the open state. If the voltage amplitude of the voltage sampling signal Vrs is greater than or equal to a predetermined value for a period of time during at least one continuous power frequency cycle, switch S1 is determined to be in the closed state. For each transition of switch S1 from the closed state to the open state, the switch detection module 21 detects one switching action.

[0093] In one alternative embodiment, the switch detection module 21 can determine whether switch S1 has switched based on the AC input voltage Vcut. In another alternative embodiment, the switch detection module 21 can determine whether switch S1 has switched based on the load current Iout.

[0094] The counting module 22 is connected to the switch detection module 21. The counting module 22 counts the number of times switch S1 is switched according to control logic to obtain a count value N. This control logic includes a counting direction and a counting step size. The counting direction includes incrementing and decrementing counts, and the counting step size includes incrementing and decrementing values. When the initial counting direction of the counting module 22 is incrementing, it increments the count and reverses to decrementing when the count value exceeds a predetermined value. Conversely, when the initial counting direction of the counting module 22 is decrementing, it decrements the count and reverses to incrementing when the count value reaches zero. The counting module 22 can dynamically adjust the counting step size to optimize circuit efficiency.

[0095] The reference generation module 23 is connected to the counting module 22. The reference generation module 23 is, for example, an analog-to-digital converter circuit. The reference generation module 23 generates a corresponding reference signal Vref based on the count value N. The reference signal Vref is used to characterize the dimming signal in the switch control mode. Using the above control logic, the switching action of switch S1 can be converted into two-way dimming actions. If continuous switching actions cause the count value N to increase, the reference signal Vref increases accordingly, and the dimming action is to brighten the LED. If continuous switching actions cause the count value N to decrease, the reference signal Vref decreases accordingly, and the dimming action is to dim the LED.

[0096] The concave control module 30 receives a voltage sampling signal Vrs from the DC input voltage Vrec and generates a concave waveform control signal Vc based on a proportional signal of the DC input voltage Vrec. The concave control module 30 is connected to the reference generation module 23 to receive a reference signal Vref generated by the reference, and controls the shape (current amplitude and / or degree of concaveness) of the concave waveform of the control signal Vc based on the reference signal Vref. The shape of the concave waveform of the control signal changes proportionally to the shape of the concave waveform of the load current.

[0097] The drive module 24 is connected to the concave control module 30. The drive module 24 is, for example, an operational amplifier configured as a follower. The non-inverting input of the operational amplifier receives the control signal Vc, the inverting input is connected to the source of transistor M2, and the output is connected to the gate of transistor M2. The drive module 24 generates a gate drive signal Vg2 for transistor M2 based on the control signal Vc. Transistor M2 adjusts the load current Iout flowing through LED 105 according to the drive signal Vg2, thereby obtaining the concave waveform load current.

[0098] In this embodiment, see Figure 4 The concave control module 30 includes a concave compensation module 31, a feedback compensation module 32, and a calculation module 33.

[0099] The concave compensation module 31 is used to obtain the proportional signal K*Vrs of the voltage sampling signal Vrs of the DC input voltage Vrec, where K represents the concave coefficient of the current waveform of the load current Iout, and the concave coefficient characterizes the degree of concaveness of the current waveform of the load current Iout. The feedback compensation module 32 compensates for the error between the reference signal Vref and the current sampling signal Vcs3 of the load current Iout to obtain the compensation voltage Vcomp, and the current sampling signal Vcs3 is the feedback signal characterizing the load current Iout. The calculation module 33 calculates the difference between the compensation voltage Vcomp and the proportional signal K*Vrs to obtain the control signal Vc of the concave waveform.

[0100] In a preferred embodiment, the current control module 20 further includes a reference detection module 25 and a concave coefficient generation module 26.

[0101] The reference detection module 25 is connected to the reference generation module 23. Further, the reference detection module 25 compares the reference signal Vref with a predetermined value. When the reference signal Vref is less than the predetermined value, the reference detection module 25 determines that the LED lamp is in a low-brightness dimming range.

[0102] The concavity coefficient generation module 26 is connected to the reference detection module 25 and is used to generate a concavity coefficient K based on the reference signal Vref. When the reference signal Vref is greater than or equal to a predetermined value, the concavity coefficient generation module 26 provides a fixed value for the concavity coefficient K. When the reference signal Vref is less than the predetermined value, the concavity coefficient generation module 26 dynamically adjusts the concavity coefficient K. For example, as the reference signal Vref decreases, the concavity coefficient K decreases accordingly, thereby reducing the degree of concavity in the load current Iout waveform.

[0103] According to the above preferred embodiment, when the LED lamp is in the low brightness dimming range, the shape change of the concave waveform of the LED lamp's load current Iout is beneficial to improving the system's working efficiency, reducing the losses caused by the thyristor discharge current, and also beneficial to the stability of the thyristor's operation and the stability of the load current.

[0104] In a preferred embodiment, the current control module 20 further includes a reference detection module and a conduction angle detection module 28.

[0105] The output of the conduction angle detection module 28 is connected to the counter 22. It receives the voltage sampling signal Vrs of the DC input voltage Vrec and is used to obtain the conduction angle of the thyristor based on the DC input voltage Vrec, and to generate a counting step size dN based on the conduction angle of the thyristor. The initial angle at which the thyristor becomes conductive is the conduction angle. For example, the conduction angle detection module 28 detects the edge position of the DC input voltage Vrec in the power frequency cycle to obtain the conduction angle of the thyristor. When the conduction angle of the thyristor is greater than or equal to a predetermined value, the conduction angle detection module 28 provides a fixed counting step size dN. When the conduction angle of the thyristor is less than the predetermined value, the conduction angle detection module 28 dynamically adjusts the counting step size dN. For example, as the conduction angle of the thyristor decreases, the counting step size dN increases accordingly.

[0106] According to the above preferred embodiment, when the LED lamp is in a hybrid mode of SCR dimming and switch dimming, precise switch dimming control can still be achieved on the basis of SCR dimming control. Alternatively, when dimming at low brightness, after the brightness is adjusted by the switch control mode, the SCR dimming mode can further dim the light, which can meet the needs of deep adjustment and fine adjustment in low brightness dimming and improve the dimming performance of the system.

[0107] In an alternative embodiment, the output of the conduction angle detection module 28 is connected to the reference generation module 23, and receives the voltage sampling signal Vrs of the DC input voltage Vrec, which is used to obtain the conduction angle of the thyristor based on the DC input voltage Vrec, and to directly generate the reference signal Vref based on the conduction angle of the thyristor.

[0108] In another alternative embodiment, the conduction angle detection module 28 is connected to the concave coefficient generation module 26, and receives the voltage sampling signal Vrs of the DC input voltage Vrec. It is used to obtain the conduction angle of the thyristor based on the DC input voltage Vrec, and to change the concave coefficient K based on the conduction angle of the thyristor, thereby changing the control signal Vc.

[0109] See Figure 5 In switch-mode dimming, the AC input voltage Vcut of the rectifier bridge is a copy of the AC supply voltage Vac. VF represents the turn-on threshold of LED 105, and Iout represents the load current of LED 105. In the dimming direction where the LED dims, as the number of switching cycles increases, the amplitude of the load current Iout decreases and the degree of dip decreases.

[0110] See Figure 6 In the hybrid mode of SCR dimming and switching dimming, the AC input voltage Vcut of the rectifier bridge is a phase-cut version of the AC supply voltage Vac. VF represents the conduction threshold of LED 105, and Iout represents the load current of LED 105. Based on SCR dimming, the conduction angle of the SCR remains constant. In the dimming direction where the LED dims, as the number of switching operations increases, the current amplitude of the load current Iout decreases, and the degree of dip also decreases. The number of switching operations is used for segmented dimming (e.g., three segments) corresponding to the conduction angle. Under certain conditions, such as when the LED load current is very small, the current amplitude of the load current Iout can remain at a certain value, but the degree of dip decreases, approaching a horizontal level. Thus, while satisfying the SCR's operating current requirement, the overall system efficiency is effectively improved, and compatibility between SCR dimming and switching dimming is ensured.

[0111] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0112] As described above, these embodiments of the present invention do not exhaustively cover all details, nor do they limit the invention to the specific embodiments described. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A current regulation circuit for multiple dimming modes, wherein, include: The first current control module is used to generate a drive signal for a first concave waveform based on a proportional signal of the DC input voltage or the terminal voltage of the load. as well as The first transistor, connected to the first current control module, is used to generate a second concave waveform load current according to the drive signal. The various dimming modes include a SCR dimming mode using a SCR dimmer, a switch dimming mode using a switch as a dimmer, and a hybrid dimming mode using both a SCR dimmer and a switch as dimmers. In the thyristor dimming mode and the hybrid dimming mode, the first current control module generates a reference signal based on the conduction angle of the thyristor; In the switch dimming mode and the hybrid dimming mode, the first current control module generates a reference signal based on the switch switching count value. The first current control module also adjusts the amplitude and / or degree of the second concave waveform of the load current according to the reference signal.

2. The current regulating circuit according to claim 1, wherein, The first current control module includes: A switch detection module is used to detect the switching action of a switch. A counter, connected to the switch detection module, receives the detection signal of the switch action and is used to generate a count value according to the number of switches according to the control logic; A reference generation module, connected to the counter to receive the count value, is used to convert the count value into the reference signal; and A concave control module, connected to the reference generation module to receive the reference signal, is used to generate a control signal for a third concave waveform, and to adjust the amplitude and / or degree of concaveness of the control signal according to the reference signal.

3. The current regulating circuit according to claim 2, wherein, The third concave waveform changes proportionally to the second concave waveform.

4. The current regulating circuit according to claim 2 further includes: A reference detection module is connected to the reference generation module to receive the reference signal and determine the dimming range of the LED lamp based on the reference signal. The concave coefficient generation module is connected to the reference detection module and provides a corresponding concave coefficient based on the dimming range of the LED light. The concave control module receives the concave coefficient and controls the degree of concaveness of the concave waveform according to the concave coefficient.

5. The current regulating circuit according to claim 4, wherein, When the dimming range of the LED lamp is greater than or equal to a predetermined value, the concave coefficient generating module provides a fixed concave coefficient. When the dimming range of the LED lamp is less than the predetermined value, the concave coefficient generating module provides a dynamically adjustable concave coefficient.

6. The current regulating circuit according to claim 5, wherein, The concavity coefficient decreases as the reference voltage decreases.

7. The current regulating circuit according to claim 2 further includes: A conduction angle detection module is used to detect whether the conduction angle of the thyristor is less than a predetermined value. Specifically, when the conduction angle of the thyristor is greater than or equal to the predetermined value, the counter uses a fixed counting step size for counting. When the conduction angle of the thyristor is less than the predetermined value, the counter uses a dynamically adjusted counting step size for counting.

8. The current regulating circuit according to claim 7, wherein, The counting step size increases as the conduction angle of the thyristor decreases.

9. The current regulating circuit according to claim 2, wherein, The concave control module includes: The concave compensation module is used to obtain a corresponding proportional signal based on the voltage sampling signal of the DC input voltage or the load terminal voltage; A feedback compensation module is used to generate a compensation voltage based on the error of the sampled signal of the load current relative to the reference signal; and The calculation module is connected to the concave compensation module to receive the proportional signal and to the feedback compensation module to receive the compensation voltage. The calculation module obtains the control signal by calculating the difference between the compensation voltage and the proportional signal.

10. An LED lighting system, comprising: LED lights, wherein the LED lights serve as a light source; A dimmer is used to generate a waveform change in the AC input voltage based on the dimming action; A rectifier bridge, connected to the dimmer, is used to rectify the AC input voltage to generate a DC input voltage; A discharge circuit is connected between the first and second output terminals of the rectifier bridge to provide discharge current when the load current is less than a predetermined value. as well as According to any one of claims 1 to 9, the LED lamp and the current regulating circuit are connected in series between the first output terminal and the second output terminal of the rectifier bridge.

11. The LED lighting system according to claim 10, further comprising: A diode is connected between the discharge circuit and the LED.

12. A control method for multiple dimming modes, comprising: The drive signal that generates the first concave waveform is based on the proportional signal of the DC input voltage or the terminal voltage of the load. as well as The load current with a second concave waveform is generated according to the drive signal. in, The various dimming modes include a SCR dimming mode using a SCR dimmer, a switch dimming mode using a switch as a dimmer, and a hybrid dimming mode using both a SCR dimmer and a switch as dimmers. The control method further includes: In the thyristor dimming mode and the hybrid dimming mode, a reference signal is generated based on the conduction angle of the thyristor; in the switch dimming mode and the hybrid dimming mode, a reference signal is generated based on the switching count value of the switch; and Adjust the amplitude and / or degree of concavity of the second concave waveform according to the reference signal.

Images