A dimming control circuit and system

Abstract

The present application provides a dimming control circuit and system. The dimming control circuit includes a ripple filtering unit and at least one load unit. The ripple filtering unit is connected in series with each load unit respectively, and the ripple filtering unit is used to remove the current ripple of each load unit; at least one dimming control unit, each dimming control unit is correspondingly connected to a load unit, wherein the number of dimming control units is the same as that of the load units, and the dimming control unit is used to adjust the voltage obtained by the connected load unit according to the received PWM signal to perform brightness adjustment.

Description

Technical Field

[0001] This application relates to the technical field of dimming control, and in particular, to a dimming control circuit and system. Background Art

[0002] Currently, traditional dimming control circuits such as Figure 1 shown, combine strobeless PWM intelligent dimming through a charging loop and a main power constant current loop. In the traditional circuit, the charging loop charges the capacitor C. Since this current does not flow through the LED, additional losses will be generated. Therefore, the ineffective losses of the entire LED dimming control circuit are large, resulting in low efficiency. And the charging loop also requires two diodes to set up the current path, thus causing waste of cost. Summary of the Invention

[0003] The purpose of the embodiments of this application is to provide a dimming control circuit and system to solve the above problems.

[0004] In a first aspect, the present invention provides a dimming control circuit, including: a ripple filtering unit and at least one load unit. The ripple filtering unit is connected in series with each load unit respectively, and the ripple filtering unit is used to remove the current ripple of each load unit; at least one dimming control unit, each dimming control unit is correspondingly connected to a load unit, wherein the number of the dimming control units is the same as that of the load units, and the dimming control unit is used to adjust the voltage obtained by the connected load unit according to the received PWM signal for brightness adjustment.

[0005] The dimming control circuit designed above filters the current ripple of each load unit based on the ripple filtering unit, thereby eliminating the stroboscopic effect of each load unit; and each dimming control unit adjusts the brightness of the correspondingly connected load unit according to the received PWM signal, so that the dimming control circuit designed in this application can achieve strobeless dimming with only one loop of the dimming control unit, abandoning the charging loop in the traditional circuit, thereby eliminating the losses brought by the charging loop in the traditional circuit, and omitting many components in the charging loop, reducing the cost.

[0006] In an optional implementation manner of the first aspect, the number of both the load unit and the dimming control unit is one, and the dimming control unit is connected in series with the ripple filtering unit and then connected in series with the load unit.

[0007] In an alternative embodiment of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a capacitor C2. The control terminal of the controllable switch tube M1 is connected to the capacitor C1 and then connected to the second terminal of the controllable switch tube M1. The control terminal of the controllable switch tube M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected to the negative electrode of the load unit in series after being connected in series with the resistor R1. The first terminal of the controllable switch tube M1 is connected to the negative electrode of the load unit. The positive electrode of the load unit is connected to the second terminal of the controllable switch tube M1 through the capacitor C2. The dimming control unit is connected to the second terminal of the controllable switch tube M1.

[0008] In an alternative embodiment of the first aspect, the number of the load unit and the dimming control unit is both one, and the load unit is connected in series between the dimming control unit and the ripple filtering unit.

[0009] In an alternative embodiment of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a capacitor C2. The second terminal of the controllable switch tube M1 is connected to the positive electrode of the load unit. The first terminal of the controllable switch tube M1 is connected to the negative electrode of the load unit in series after being connected in series with the capacitor C2. The control terminal of the controllable switch tube M1 is connected to the second terminal of the controllable switch tube M1 in series after being connected in series with the capacitor C1. The control terminal of the controllable switch tube M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected to the first terminal of the controllable switch tube M1 in series after being connected in series with the resistor R1. The dimming control unit is connected to the negative electrode of the load unit.

[0010] In an alternative embodiment of the first aspect, the number of the load unit and the dimming control unit is both multiple. Each dimming control unit is connected in series with a load unit and then connected in series with the ripple filtering unit.

[0011] In an alternative embodiment of the first aspect, the ripple filtering unit includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and multiple capacitors C2. The second terminal of the controllable switch tube M1 is connected to the positive electrode of each load unit. The negative electrode of each load unit is connected to the first terminal of the controllable switch tube M1 in series after being connected in series with a capacitor C2. The control terminal of the controllable switch tube M1 is connected to the second terminal of the controllable switch tube M1 in series after being connected in series with the capacitor C1. The control terminal of the controllable switch tube M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected to the first terminal of the controllable switch tube M1 in series after being connected in series with the resistor R1. Each dimming control unit is correspondingly connected to the negative electrode of a load unit.

[0012] In the embodiment of the above design, multiple load units share a ripple filtering unit, thereby achieving the purpose of saving costs and simplifying the circuit while realizing flicker-free dimming of multiple loads.

[0013] In an alternative embodiment of the first aspect, each of the dimming control units includes a PWM sub-unit, a reference modulation sub-unit, an integrating circuit, a power control sub-unit, a controllable switching transistor M2, and a resistor R2. The PWM sub-unit, the reference modulation sub-unit, the integrating circuit, and the power control sub-unit are connected in series in sequence. The power control sub-unit is connected to the control terminal of the controllable switching transistor M2. The second terminal of the controllable switching transistor M2 is connected to the integrating circuit and grounded through the resistor R2. The first terminal of the controllable switching transistor M2 is connected to the corresponding load unit. The PWM sub-unit is configured to receive a PWM signal and output a level signal corresponding to the PWM signal to the reference modulation sub-unit according to the PWM signal. The reference modulation sub-unit is configured to determine a voltage value transmitted to the integrating circuit according to the received level signal. The integrating circuit is configured to output an integration signal to the power control sub-unit according to the voltage value received at the non-inverting input terminal and the feedback voltage received at the inverting input terminal. The power control sub-unit is configured to adjust the voltage divided by the resistor R2 according to the integration signal.

[0014] In an alternative embodiment of the first aspect, the PWM sub-unit includes an operational amplifier L1, the reference modulation sub-unit includes an inverter A1, an inverter A2, a controllable switch K1, and a controllable switch K2. The integrating circuit includes an integrator G1 and a capacitor C3. The power control sub-unit includes an operational amplifier L2. The non-inverting input terminal of the operational amplifier L1 is configured to receive the PWM signal. The inverting input terminal of the operational amplifier L1 is configured to receive a first reference voltage. The output terminal of the operational amplifier L1 is connected to the input terminal of the inverter A1. The output terminal of the inverter A1 is connected to the input terminal of the inverter A2. The output terminal of the inverter A2 is connected to the control terminal of the controllable switch K1. The input terminal of the controllable switch K1 is connected to a second reference voltage. The output terminal of the controllable switch K1 is connected to the non-inverting input terminal of the integrator G1. The output terminal of the inverter A1 is also connected to the control terminal of the controllable switch K2. The input terminal of the controllable switch K2 is grounded. The output terminal of the controllable switch K2 is connected to the output terminal of the controllable switch K1. The inverting input terminal of the integrator G1 is connected to the second terminal of the controllable switching transistor M2. The output terminal of the integrator G1 is connected to the non-inverting input terminal of the operational amplifier L2. The output terminal of the integrator G1 is also grounded through the capacitor C3. The inverting input terminal of the operational amplifier L2 is connected to the second terminal of the controllable switching transistor M2. The output terminal of the operational amplifier L2 is connected to the control terminal of the controllable switching transistor M2.

[0015] In the embodiment of the above design, based on the combination of the ripple filtering unit and the dimming control unit, the voltage at the first terminal of the controllable switching transistor M2 changes with the change of the bus voltage, rather than being continuously maintained at a relatively high value as in the traditional method, thereby reducing the loss of the dimming control unit and improving the efficiency of the entire dimming control circuit.

[0016] In an alternative embodiment of the first aspect, each of the dimming control units further includes a bus sampling subunit and a current compensation subunit. The bus sampling subunit is connected to the current compensation subunit, and the current compensation subunit is connected to the power control subunit. The bus sampling subunit is configured to sample the bus voltage signal and transmit the bus voltage signal to the current compensation subunit. The current compensation subunit is configured to generate a corresponding compensation signal according to the bus voltage signal and transmit the compensation signal to the power control subunit. The power control subunit is further configured to compensate the current of resistor R2 according to the compensation signal, so that the current of resistor R2 is inversely proportional to the bus current, thereby reducing the power consumption of resistor R2.

[0017] In an alternative embodiment of the first aspect, the bus sampling subunit includes resistor R3 and resistor R4, and the current compensation subunit includes operational amplifier L3, MOS transistor M3, MOS transistor M4, MOS transistor M5, resistor R5, and resistor R6. Resistor R3 and resistor R4 are connected in series and then connected to the second terminal of controllable switch transistor M1 and the ground terminal respectively. The non-inverting input terminal of operational amplifier L3 is connected between resistor R3 and resistor R4. The inverting input terminal of operational amplifier L3 is grounded through resistor R5. The output terminal of operational amplifier L3 is connected to the gate of MOS transistor M3. The source terminal of MOS transistor M3 is connected to the inverting input terminal of operational amplifier L3. The drain terminal of MOS transistor M3 is connected to the drain terminal of MOS transistor M4. The drain terminal of MOS transistor M4 is also connected to the gate of MOS transistor M4. The source terminal of MOS transistor M4 is connected to the source terminal of MOS transistor M5. The gate of MOS transistor M4 is connected to the gate of MOS transistor M5. The drain terminal of MOS transistor M5 is connected to the power control subunit and is connected to resistor R2 through resistor R6.

[0018] In the embodiment of the above design, the current of resistor R2 is inversely proportional to the change of the bus voltage through the bus sampling subunit and the current compensation subunit, thereby improving the efficiency of the entire dimming control circuit.

[0019] In a second aspect, the present invention provides a dimming control system, including: a dimming control circuit, a rectification unit, and a power supply in any alternative embodiment of the first aspect. The power supply is connected to the dimming control circuit through the rectification unit.

[0020] In the dimming control system of the above design, since the dimming control system is designed based on the dimming control circuit in the first embodiment, only one loop of the dimming control unit can be used to achieve flicker-free dimming, and the charging loop in the traditional circuit is discarded, thereby eliminating the loss brought by the charging loop in the traditional circuit, and omitting many components in the charging loop, reducing the cost. Description of the Drawings

[0021] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required for the embodiments of the present application will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related accompanying drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 Structural schematic diagram of the traditional circuit provided by the embodiment of the present application;

[0023] Figure 2 First structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0024] Figure 3 Second structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0025] Figure 4 Third structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0026] Figure 5 Fourth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0027] Figure 6 Fifth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0028] Figure 7 Sixth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0029] Figure 8 Seventh structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0030] Figure 9 Eighth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0031] Figure 10 Ninth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0032] Figure 11 Tenth structural schematic diagram of the dimming control circuit provided by the embodiment of the present application;

[0033] Figure 12 Structural schematic diagram of the dimming control system provided by the embodiment of the present application.

[0034] Icon: 1 - Dimming control circuit; 2 - Rectification unit; 3 - Power supply; 10 - Ripple filtering unit; 20 - Load unit; 30 - Dimming control unit; 301 - PWM sub - unit; 302 - Reference modulation sub - unit; 303 - Integrating circuit; 304 - Power control sub - unit; 305 - Bus sampling sub - unit; 306 - Current compensation sub - unit. Detailed implementation mode

[0035] Next, the technical solutions in the embodiments of the present application will be described in conjunction with the accompanying drawings in the embodiments of the present application.

[0036] The first embodiment

[0037] The embodiment of the present application provides a dimming control circuit, which includes a ripple filtering unit 10, at least one load unit 20, and at least one dimming control unit 30. The ripple filtering unit 10 is respectively connected in series with each load unit 20. Each dimming control unit 30 is correspondingly connected to a load unit 20. Based on the designed dimming control circuit, the ripple filtering unit is used to filter the current ripple generated by each series - connected load unit 20, thereby eliminating the stroboscopic phenomenon of each load unit; each dimming control unit 30 can adjust the brightness of the correspondingly connected load unit according to the received PWM signal, so that the dimming control circuit designed in the present application has only one loop of the dimming control unit 30 on the basis of realizing stroboscopic - free dimming. Thus, the charging loop in the traditional circuit is discarded, the loss brought by the charging loop in the traditional circuit is eliminated, and many components in the charging loop are omitted, reducing the cost.

[0038] In an alternative implementation manner of this embodiment, for the foregoing dimming control unit 30 correspondingly connected to the load unit 20, it may specifically include the following different connection manners: As a possible implementation manner, the dimming control unit 30 is connected in series with the ripple filtering unit 10 and then connected in series with the corresponding load unit 20. As another possible implementation manner, the dimming control unit 30 can be directly connected in series with the corresponding load unit 20 and then connected in series with the ripple filtering unit 10.

[0039] In the first above - mentioned implementation manner, the dimming control unit 30 is connected in series with the ripple filtering unit 10 and then connected in series with the corresponding load unit 20. As Figure 2 shown, the number of the dimming control unit 30 and the load unit 20 designed in the solution of the present application can both be one. Among them, the load unit 20 can specifically be an LED display unit including a plurality of light - emitting diodes connected in series in sequence or other forms of display units. Figure 2 This is an illustration taking the LED display unit as an example.

[0040] Based on the above - mentioned connection structure, the present application designs as Figure 3The circuit structure shown is a specific implementation of the above structure. In the design of this embodiment, the ripple filtering unit 10 may include a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1, and a capacitor C2. Among them, the controllable switch tube M1 may specifically be a MOS tube, a triode, or other controllable switch tubes. Figure 3 It is an example diagram with the controllable switch tube M1 being a MOS tube.

[0041] The gate of the controllable switch tube M1 is connected to the capacitor C1 and then to the source of the controllable switch tube M1. The gate of the controllable switch tube M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected to the negative pole of the load unit 20 in series with the resistor R1. The drain of the controllable switch tube M1 is connected to the negative pole of the load unit 20. The positive pole of the load unit is connected to the source of the controllable switch tube M1 through the capacitor C2. The source of the controllable switch tube M1 is connected to the dimming control unit 30.

[0042] When the above-designed circuit is applied, the principle of stroboscopic elimination is as follows: The positive pole of the load unit 20 and the dimming control unit 30 are respectively connected to the power supply, so that the circuit forms a loop. During the application process, the voltage across the capacitor C2 contains an AC component. The ripple filtering unit 10 samples the voltage across the capacitor C2 and filters the sampled signal through the capacitor C1, the zener diode Q1, and the resistor R1, so that the gate voltage of the MOS tube M1 is a DC voltage. The zener diode Q1 is used to adjust the drain voltage of the MOS tube M1 to make it work in the saturation region, so that the current flowing through the MOS tube M1 is constant. Since the MOS tube M1 and the load unit 20 are in series, the current flowing through the LED load unit is also constant, that is, the current flowing through the LED display unit 20 does not contain an AC component, thereby eliminating the stroboscopic phenomenon of the load unit 20.

[0043] It should be noted here that when the ripple is small, the zener diode Q1 can be omitted; when the ripple is large, a certain number of zener diodes Q1 can be connected in series to effectively remove the large ripple. The above ripple filtering unit 10 is only a circuit for realizing ripple filtering. In addition to the ripple filtering circuit with the above structure, the present application can also be other circuit structures with ripple elimination functions.

[0044] In the above second embodiment, that is, the dimming control unit 30 and the corresponding load unit 20 are directly connected in series and then connected in series with the ripple filtering unit 10. The number of the dimming control unit 30 and the load unit 20 designed in the solution of the present application can be one or more. The components of the ripple filtering unit 10 are the same as those of the foregoing components. When the number of the dimming control unit 30 and the load unit 20 is one, its circuit structure is as Figure 4 and Figure 5 shown:

[0045] The source of the controllable switch tube M1 is connected to the positive pole of the load unit 20. The drain of the controllable switch tube M1 is connected to the negative pole of the load unit 20 after being serially connected with a capacitor C2. The gate of the controllable switch tube M1 is connected to the source of the controllable switch tube M1 after being serially connected with a capacitor C1. The gate of the controllable switch tube M1 is connected to the anode of the voltage stabilizing diode Q1. The cathode of the voltage stabilizing diode Q1 is connected to the drain of the controllable switch tube M1 after being serially connected with a resistor R1. The dimming control unit 30 is connected to the negative pole of the load unit 20.

[0046] When the numbers of both the dimming control unit 30 and the load unit 20 are multiple, the number of the capacitor C2 among the components of the ripple filtering unit 10 can be the same as that of the dimming control unit 30, and the other components are the same as those described above. Its circuit structure is as Figure 6 and Figure 7 shown:

[0047] The source of the controllable switch tube M1 is connected to the positive pole of each load unit 20. The negative pole of each load unit 20 is serially connected with a capacitor C2 and then connected to the source of the controllable switch tube M1. The gate of the controllable switch tube M1 is serially connected with a capacitor C1 and then connected to the source of the controllable switch tube M1. The gate of the controllable switch tube M1 is connected to the anode of the voltage stabilizing diode Q1. The cathode of the voltage stabilizing diode Q1 is connected to the drain of the controllable switch tube M1 after being serially connected with a resistor R1. Each dimming control unit 30 is correspondingly connected to the negative pole of a load unit 20.

[0048] The above Figure 7 designed structure, since the ripple filtering unit 10 filters the current ripple of the bus current and then transmits it to each load unit 20, therefore, in such a case, multiple load units 20 can share one ripple filtering unit 10, thereby achieving the purpose of saving cost and simplifying the circuit while realizing the flicker-free dimming of multiple load units 20. It should be noted here that for the Figure 5 and Figure 7 connection methods, the principle of the ripple filtering unit 10 to eliminate flicker is the same as that of the foregoing Figure 3 and will not be elaborated here.

[0049] In an alternative implementation manner of this embodiment, the dimming control unit 30 may include a PWM sub-unit 301, a reference modulation sub-unit 302, an integration circuit 303, a power control sub-unit 304, a controllable switch tube M2, and a resistor R2. Among them, the controllable switch tube M2 may also be a controllable switch tube such as a MOS tube or a triode. The following connection methods are all exemplified by MOS tubes.

[0050] The PWM subunit 301, the reference modulation subunit 302, the integrating circuit 303, and the power control subunit 304 are connected in series in sequence. The power control subunit 304 is connected to the gate of the controllable switch tube M2. The source of the controllable switch tube M2 is connected to the integrating circuit 303 and grounded through the resistor R2. When the connection mode between the ripple filtering unit 10 and the load unit 20 is as Figure 3 shown, as Figure 8 shown, the drain of the controllable switch tube M2 is connected to the source of the controllable switch tube M1; when the connection mode between the ripple filtering unit 10 and the load unit 20 is Figure 5 shown, as Figure 9 shown, the drain of the controllable switch tube M2 is connected to the negative pole of the load unit 20; when the connection mode between the ripple filtering unit 10 and the load unit 20 is Figure 7 shown, as Figure 10 shown, the drain of each controllable switch tube M2 is connected to the negative pole of each load unit 20.

[0051] When the above-designed circuit is applied, the dimming control principle is as follows: The PWM subunit 301 receives an externally input PWM signal and outputs a level signal corresponding to the PWM signal to the reference modulation subunit according to the PWM signal. The reference modulation subunit 302 determines the voltage value transmitted to the integrating circuit 303 according to the received level signal. The integrating circuit 303 outputs an integration signal to the power control word subunit 304 according to the voltage value received at the non-inverting input terminal and the feedback voltage received at the inverting input terminal. The power control subunit 304 adjusts the voltage divided by the resistor R2 according to the received integration signal, thereby realizing the brightness adjustment of the load unit 20.

[0052] The circuit designed in this application has the following advantages over the traditional circuit when realizing flicker-free and dimming: As Figure 1When the traditional circuit shown realizes stroboscopic-free, the charging loop accounts for the main power consumption. The POWERMOS transistor in the main power loop must operate in the saturation region, that is, the drain voltage (VDRN2) of the POWERMOS transistor must be greater than the difference between its gate voltage (VG) and the threshold value (VTH), that is, VG - VTH ≤ VDRN2. This makes the minimum voltage at the DRN2 end of the main power loop must be maintained at a relatively large value, that is, greater than VG - VTH, resulting in more losses in the main power loop. When the circuit designed in the present application realizes stroboscopic-free, the charging loop in the traditional circuit is deleted, greatly reducing the reactive power of the designed dimming control circuit and improving the efficiency of the dimming control circuit. In addition, the capacitor C1 and the resistor R1 make the voltage at the drain end, that is, the DRN end, of the controllable switch transistor M2 change with the change of the bus voltage. It increases and decreases with the bus voltage instead of always maintaining at a relatively large value, reducing the loss of the dimming control unit and further improving the efficiency of the dimming control circuit. At the same time, the two diodes above the charging loop are deleted, thus saving the circuit cost.

[0053] Further, the specific implementation circuit of the above dimming control unit 30 can be as Figure 8 、 Figure 9 or Figure 10 shown. The PWM sub-unit 301 includes an operational amplifier L1. The reference modulation sub-unit 302 includes an inverter A1, an inverter A2, a controllable switch K1, and a controllable switch K2. The integration circuit 303 includes an integrator G1 and a capacitor C3. The power control sub-unit includes an operational amplifier L2.

[0054] The non-inverting input terminal of the operational amplifier L1 is used to receive the externally input PWM signal. A first reference voltage VREF1 is set at the inverting input terminal of the operational amplifier L1. The output terminal of the operational amplifier L1 is connected to the input terminal of the inverter A1.

[0055] The output terminal of the inverter A1 is connected to the input terminal of the inverter A2. The output terminal of the inverter A2 is connected to the control terminal of the controllable switch K1. The input terminal of the controllable switch K1 is connected to the second reference voltage VREF. The output terminal of the controllable switch K1 is connected to the non-inverting input terminal of the integrator G1. The output terminal of the inverter A1 is also connected to the control terminal of the controllable switch K2. The input terminal of the controllable switch K2 is grounded. The output terminal of the controllable switch K2 is connected to the output terminal of the controllable switch K1. The inverting input terminal of the integrator G1 is connected to the source of the controllable switch transistor M2. The output terminal of the integrator G1 is connected to the non-inverting input terminal of the operational amplifier L2. The output terminal of the integrator G1 is also grounded through the capacitor C3. The inverting input terminal of the operational amplifier L2 is connected to the source of the controllable switch transistor M2. The output terminal of the operational amplifier L2 is connected to the gate of the controllable switch transistor M2.

[0056] When the dimming control unit 30 of the above design is applied, the operational amplifier L1 outputs a high-level signal or a low-level signal according to the received PWM signal and the first reference voltage VREF1. Assuming it is a high-level signal, this high-level signal is transmitted to the inverter A1 for inversion to obtain a low-level signal. On the one hand, this low-level signal is transmitted to the controllable switch K2 to control the opening and closing of the controllable switch K2. Assuming that both the controllable switches K1 and K2 are closed at high level, then at this time the controllable switch K2 is disconnected. On the other hand, the low-level signal output by the inverter A1 is inverted again by the inverter A2 to obtain a high-level signal, which controls the controllable switch K1 to close, so that the second reference voltage VREF is connected to the non-inverting input terminal of the integrator G1. The non-inverting input terminal of the integrator G1 inputs the average value (which is also a voltage value) after integrating the second reference voltage VREF and the duty cycle of the controllable switch K1. The inverting input terminal of the integrator G1 receives the average value after integrating the voltage fed back on R2. The second reference voltage VREF, the average value after integrating the duty cycle of the controllable switch K1, and the average value after integrating the fed-back voltage are integrated by the integrator G1 to output an integration signal, and this integration signal is the average value after integrating the second reference voltage VREF, the average value after integrating the duty cycle of the controllable switch K1, and the average value after integrating the fed-back voltage.

[0057] This integration signal is transmitted into the operational amplifier L2 through the non-inverting input terminal of the operational amplifier L2. Since the operational amplifier L2 needs to maintain the same voltage at its non-inverting input terminal and inverting input terminal, therefore, the inverting input terminal of the operational amplifier L2 will adjust the voltage value of the resistor R2 to the voltage value of the integration signal input at its non-inverting input terminal, so that the average value of the voltage value of this resistor R2 is equal to the average value after integrating the second reference voltage VREF input at the non-inverting input terminal of the integrator G1 and the duty cycle of the controllable switch K1, thereby changing the voltage across the resistor R2. Since the average value of the current flowing through the resistor R2 is the same as the average value of the current of the load unit 20, therefore, the opening and closing of the controllable switches K1 and K2 and the duty cycle can be adjusted by the PWM signal to adjust the voltage across the resistor R2, and then adjusting the voltage across the load unit 20 can achieve the brightness adjustment of the load unit 20.

[0058] In an alternative embodiment of this embodiment, as Figure 11 shown, the dimming control unit 30 further includes a bus sampling sub-unit 305 and a current compensation sub-unit 306. The bus sampling sub-unit 305 is connected to the current compensation sub-unit 306, and the current compensation sub-unit 306 is connected to the power control sub-unit 304.

[0059] When the above-designed circuit structure is applied, the bus sampling sub-unit 305 samples the bus voltage signal and then transmits the bus voltage signal to the current compensation sub-unit 306. The current compensation sub-unit 306 generates a corresponding compensation signal according to the bus voltage signal and transmits it to the power control sub-unit 304. The power control sub-unit 304 compensates the current of the resistor R2 according to the compensation signal, so that the current of the resistor R2 is inversely proportional to the bus current, thereby reducing the power consumption of the resistor R2.

[0060] It should be noted here that the integrating circuit 303 can be other circuits with digital integration in addition to the integrator G1.

[0061] As a possible implementation, as Figure 11 shown, the bus sampling sub-unit 305 includes a resistor R3 and a resistor R4, and the current compensation sub-unit 306 includes an operational amplifier L3, a MOS transistor M3, a MOS transistor M4, a MOS transistor M5, a resistor R5, and a resistor R6. The resistors R3 and R4 are connected in series and then connected to the source of the controllable switch transistor M1 and the ground terminal respectively. The non-inverting input terminal of the operational amplifier L3 is connected between the resistors R3 and R4. The inverting input terminal of the operational amplifier L3 is grounded through the resistor R5. The output terminal of the operational amplifier L3 is connected to the gate of the MOS transistor M3. The source of the MOS transistor M3 is connected to the inverting input terminal of the operational amplifier L3. The drain of the MOS transistor M3 is connected to the drain of the MOS transistor M4. The drain of the MOS transistor M4 is also connected to its own gate. The source of the MOS transistor M4 is connected to the source of the MOS transistor M5. The gate of the MOS transistor M4 is connected to the gate of the MOS transistor M5. The drain of the MOS transistor M5 is connected to the power control sub-unit 304 and is connected to the resistor R2 through the resistor R6.

[0062] When the above-designed circuit is applied, the resistors R3 and R4 sample the voltage information of the DRN terminal. Since the voltage information of the DRN changes with the change of the bus voltage, the voltage information of the DRN can represent the information of the bus voltage. It should be noted here that the above Figure 11 the bus sampling sub-unit 305 is connected to the voltage information of the DRN terminal. In practice, it is not limited to this. Any signal that can express the bus information is acceptable. For example, directly connecting to the bus to sample the bus voltage or bus current, or connecting to the load unit to sample the voltage of the load unit, etc.

[0063] The collected voltage signal is transmitted to the operational amplifier L3, and the current corresponding to the voltage signal is output to the resistor R6 through the operational amplifier L3, the MOS transistors M3, M4, and M5. Therefore, the current flowing through the resistor R6 changes synchronously with the bus signal. Therefore, when the current in the resistor R6 increases, the current in the resistor R2 decreases; when the current in the resistor R6 decreases, the current in the resistor R2 increases, thereby making the current in the resistor R2 inversely proportional to the bus signal, that is, when the bus signal voltage is at its maximum, the current in the resistor R2 is at its minimum, thus further reducing the loss of the entire circuit system and improving the efficiency of the dimming control circuit.

[0064] Second Embodiment

[0065] This application provides a dimming control system, as Figure 12 shown. The system includes the dimming control circuit 1, the rectification unit 2, and the power supply 3 described in any optional implementation manner of the first embodiment. The power supply 3 is connected to the dimming control circuit 1 through the rectification unit 2.

[0066] The power supply 3 is specifically an AC power supply, and the rectification unit 2 is specifically a rectifier bridge. The power supply 3 is connected to the dimming control circuit 1 through the rectifier bridge.

[0067] In the dimming control system designed above, since the dimming control system is designed based on the dimming control circuit 1 in the first embodiment, only one loop of the dimming control unit 30 can be used to achieve flicker-free dimming, eliminating the charging loop in the traditional circuit, thereby eliminating the loss brought by the charging loop in the traditional circuit, and omitting many components in the charging loop, reducing the cost.

[0068] In the embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For another example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point, the couplings or direct couplings or communication connections shown or discussed with each other can be through some communication interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0069] In addition, the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they can be located in one place, or they can be distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0070] Furthermore, in each embodiment of the present application, each functional module may be integrated together to form an independent part, or each module may exist alone, or two or more modules may be integrated to form an independent part.

[0071] In this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0072] The above description is only for the embodiments of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dimming control circuit, characterized in that, Comprising: A ripple filtering unit (10) and at least one load unit (20), the ripple filtering unit (10) is connected in series with each load unit (20) respectively, and the ripple filtering unit (10) is used to remove the current ripple of each load unit (20); At least one dimming control unit (30), each dimming control unit (30) is correspondingly connected to a load unit (20), wherein the number of the dimming control units (30) is the same as that of the load units (20), and the dimming control unit (30) is used to adjust the voltage obtained by the connected load unit (20) according to the received PWM signal for brightness adjustment; Each of the dimming control units (30) includes a PWM subunit (301), a reference modulation subunit (302), an integrating circuit (303), a power control subunit (304), a controllable switch tube M2 and a resistor R2. The PWM subunit (301), the reference modulation subunit (302), the integrating circuit (303) and the power control subunit (304) are connected in series in sequence. The power control subunit (304) is connected to the control end of the controllable switch tube M2. The second end of the controllable switch tube M2 is connected to the integrating circuit (303) and grounded through the resistor R2. The first end of the controllable switch tube M2 is connected to the corresponding load unit (20), wherein the controllable switch tube M2 is any one of a MOS tube or a triode; The PWM subunit (301) is used to receive the PWM signal and output a level signal corresponding to the PWM signal to the reference modulation subunit (302) according to the PWM signal; The reference modulation subunit (302) is used to determine the voltage value transmitted to the integrating circuit (303) according to the received level signal; The integrating circuit (303) is used to output an integration signal to the power control subunit (304) according to the voltage value received by the non-inverting input terminal and the feedback voltage received by the inverting input terminal; The power control subunit (304) is used to adjust the voltage obtained by the resistor R2 according to the integration signal.

2. The dimming control circuit according to claim 1, wherein The number of the load units (20) and the dimming control units (30) is both one. The dimming control unit (30) is connected in series with the ripple filtering unit (10) and then connected in series with the load unit (20).

3. The dimming control circuit according to claim 2, wherein, The ripple filtering unit (10) includes a capacitor C1, a controllable switch tube M1, a zener diode Q1, a resistor R1 and a capacitor C2. The control end of the controllable switch tube M1 is connected to the capacitor C1 and then connected to the second end of the controllable switch tube M1. The control end of the controllable switch tube M1 is connected to the anode of the zener diode Q1. The cathode of the zener diode Q1 is connected in series with the resistor R1 and then connected to the negative electrode of the load unit (20). The first end of the controllable switch tube M1 is connected to the negative electrode of the load unit (20). The positive electrode of the load unit (20) is connected to the second end of the controllable switch tube M1 through the capacitor C2. The dimming control unit (30) is connected to the second end of the controllable switch tube M1.

4. The dimming control circuit according to claim 1, wherein The number of the load unit (20) and the dimming control unit (30) is one each, and the load unit (20) is connected in series between the dimming control unit (30) and the ripple filtering unit (10).

5. The dimming control circuit according to claim 1, wherein, The number of the load unit (20) and the dimming control unit (30) is multiple. After each dimming control unit (30) is connected in series with a load unit (20), they are connected in series with the ripple filtering unit (10).

6. The dimming control circuit according to claim 1, wherein The PWM sub-unit (301) includes an operational amplifier L1, the reference modulation sub-unit (302) includes an inverter A1, an inverter A2, a controllable switch K1, and a controllable switch K2, the integrating circuit (303) includes an integrator G1 and a capacitor C3, and the power control sub-unit (304) includes an operational amplifier L2; The non-inverting input terminal of the operational amplifier L1 is used to receive the PWM signal, the inverting input terminal of the operational amplifier L1 is used to receive a first reference voltage, and the output terminal of the operational amplifier L1 is connected to the input terminal of the inverter A1; The output terminal of the inverter A1 is connected to the input terminal of the inverter A2, the output terminal of the inverter A2 is connected to the control terminal of the controllable switch K1, the input terminal of the controllable switch K1 is connected to a second reference voltage, the output terminal of the controllable switch K1 is connected to the non-inverting input terminal of the integrator G1, the output terminal of the inverter A1 is also connected to the control terminal of the controllable switch K2, the input terminal of the controllable switch K2 is grounded, and the output terminal of the controllable switch K2 is connected to the output terminal of the controllable switch K1; The inverting input terminal of the integrator G1 is connected to the second terminal of the controllable switch tube M2, the output terminal of the integrator G1 is connected to the non-inverting input terminal of the operational amplifier L2, and the output terminal of the integrator G1 is also grounded through the capacitor C3; The inverting input terminal of the operational amplifier L2 is connected to the second terminal of the controllable switch tube M2, and the output terminal of the operational amplifier L2 is connected to the control terminal of the controllable switch tube M2.

7. The dimming control circuit according to claim 1, wherein Each dimming control unit (30) further includes a bus sampling sub-unit (305) and a current compensation sub-unit (306). The bus sampling sub-unit (305) is connected to the current compensation sub-unit (306), and the current compensation sub-unit (306) is connected to the power control sub-unit (304); The bus sampling sub-unit (305) is used to sample the bus voltage signal and transmit the bus voltage signal to the current compensation sub-unit (306); The current compensation sub-unit (306) is used to generate a corresponding compensation signal according to the bus voltage signal and transmit the compensation signal to the power control sub-unit (304); The power control sub-unit (304) is further used to compensate the current of the resistor R2 according to the compensation signal.

8. The dimming control circuit according to claim 7, wherein The bus sampling sub-unit (305) includes a resistor R3 and a resistor R4, and the current compensation sub-unit (306) includes an operational amplifier L3, a MOS tube M3, a MOS tube M4, a MOS tube M5, a resistor R5, and a resistor R6; The resistor R3 and the resistor R4 are connected in series and then respectively connected to the second terminal of the controllable switch tube M1 and the ground terminal. The non-inverting input terminal of the operational amplifier L3 is connected between the resistor R3 and the resistor R4. The inverting input terminal of the operational amplifier L3 is grounded through the resistor R5. The output terminal of the operational amplifier L3 is connected to the gate of the MOS tube M3. The source of the MOS tube M3 is connected to the inverting input terminal of the operational amplifier L3. The drain of the MOS tube M3 is connected to the drain of the MOS tube M4. The drain of the MOS tube M4 is also connected to the gate of the MOS tube M4. The source of the MOS tube M4 is connected to the source of the MOS tube M5. The gate of the MOS tube M4 is connected to the gate of the MOS tube M5. The drain of the MOS tube M5 is connected to the power control sub-unit (304) and is connected to the resistor R2 through the resistor R6.

9. A dimming control system, characterized in that, Comprising: The dimming control circuit (1), the rectification unit (2) and the power supply (3) according to any one of claims 1-8, and the power supply (3) is connected to the dimming control circuit (1) through the rectification unit (2).

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