Dimming circuit and lighting control device for non-isolated LED constant current drive power supply

Abstract

The present invention discloses a dimming circuit and a lighting control device for a non-isolated LED constant current driving power supply, wherein the dimming circuit is electrically connected to an LED load, and the dimming circuit comprises: a power module and a driving module; the power module is used to convert an input voltage into a load voltage to drive the LED load; the power module comprises a switch tube, a freewheeling diode and a transformer, and a common node of the switch tube and the freewheeling diode is connected to the transformer; the driving module is electrically connected to the switch tube in the power module, and the driving module is used to control the conduction or cutoff of the switch tube to perform constant current driving and dimming on the LED load; the dimming circuit also comprises a detuning diode, and the detuning diode is coupled to at least one of the freewheeling diode, the switch tube and the primary winding of the transformer, and is used to eliminate the resonant energy generated between the transformer and the switch tube and the freewheeling diode, thereby reducing the influence of resonance on dimming.

Description

Technical Field

[0001] The present invention relates to the field of lighting technology, and in particular to a dimming circuit and a lighting control device for a non-isolated LED constant current driving power supply. Background Art

[0002] Common non-isolated LED constant current driver dimming circuits that support PWM (Pulse Width Modulation) signals, such as Figure 1 As shown. In this dimming circuit, the driver chip controls the peak current of the power inductor T1 and the corresponding start-up delay according to a preset algorithm, and finally makes the output current of the LED light string and the duty cycle of the pulse width modulation signal input to the driver chip have a linear relationship. In order to achieve a deeper dimming depth, when the duty cycle of the pulse width modulation signal is large, the dimming circuit works in the inductor current critical mode, such as Figure 2 As shown, the peak current of the power inductor T1 is adjusted according to the pulse width modulation signal to achieve the purpose of dimming. When the duty cycle of the pulse width modulation signal is small, the dimming circuit works in the inductor current discontinuous mode, such as Figure 3 As shown, the dimming purpose is achieved by controlling the length of the dead time period (ie, the pulse width modulation signal response time period, which is a protection time period).

[0003] like Figure 4 As shown in FIG. 1 , when the dimming circuit operates in the inductor current discontinuous mode, controlling the size of the dead time period can change the output current of the LED light string. Ideally, the switch tube Q1 is Figure 4 The output current corresponding to the on-state at point a shown in the figure is larger than the output current corresponding to the on-state at point b. However, in reality, the switch tube Q1 and the freewheeling diode D2 are both turned off in the dead time period, and the power inductor T1, the distributed capacitance Cds of the switch tube Q1, and the junction capacitance of the freewheeling diode D2 resonate; and because the resonant current at point a is negative, the output current will be reduced, and the resonant current at point b is positive, which will increase the output current. Therefore, it is possible that the on-state current at point b is larger than the on-state current at point a, which will affect the linearity of dimming, especially when the dimming circuit is working at low brightness, the above-mentioned influence is particularly obvious. When the dimming gradually turns on or off, nonlinear changes in brightness will occur. This nonlinear change is visually manifested as dimming jitter, which gives the user a poor experience.

[0004] Therefore, it is necessary to propose solutions to the existing technical problems. Summary of the invention

[0005] The present invention provides a dimming circuit and a lighting control device for a non-isolated LED constant current driving power supply, which aims to consume the resonant energy by connecting a load in parallel with a power inductor or by connecting an auxiliary winding coupled to the power inductor in parallel with the load, thereby reducing the influence of resonance on dimming.

[0006] According to one aspect of the present invention, an embodiment of the present invention provides a dimming circuit for a non-isolated LED constant current driving power supply, wherein the dimming circuit is electrically connected to an LED load, and the dimming circuit comprises: a power module and a driving module connected to the power module; the power module is used to convert an input voltage into a load voltage to drive the LED load; the power module comprises a switch tube, a freewheeling diode and a transformer, and a common node of the switch tube and the freewheeling diode is connected to the transformer; the driving module is electrically connected to the switch tube in the power module, and the driving module is used to control the conduction or cutoff of the switch tube to perform constant current driving and dimming on the LED load; the dimming circuit also comprises a detuning diode, and the detuning diode is coupled to at least one of the freewheeling diode, the switch tube and the primary winding of the transformer, and is used to eliminate the resonant energy generated between the transformer and the switch tube and the freewheeling diode.

[0007] Optionally, the driving module includes a driving power chip, wherein the driving power chip is used to receive a pulse width modulation signal and an operating mode control signal, and when the operating mode control signal is a linear dimming mode control signal, it operates in a linear dimming mode, and converts the pulse width modulation signal into a linear voltage signal, and adjusts the output current of the LED load through the linear voltage signal; when the operating mode control signal is an intermittent mode control signal, it operates in an intermittent mode, and generates a frequency signal based on the received pulse width modulation signal to provide it to the transformer, and adjusts the output current of the LED load through the pulse width modulation signal.

[0008] Optionally, the drop-tuning diode is connected in series with the primary winding of the transformer, the anode of the drop-tuning diode is connected to one end of the primary winding of the transformer, and the cathode of the drop-tuning diode is connected to a common node of the switch tube and the freewheeling diode.

[0009] Optionally, the tuning reduction diode is connected in series with the switch tube, the cathode of the dimming diode is connected to the first end of the switch tube, and the anode of the tuning reduction diode is connected to the anode of the freewheeling diode.

[0010] Optionally, the tuning reduction diode is connected in series with the freewheeling diode, the cathode of the tuning reduction diode is connected to the anode of the freewheeling diode, and the anode of the tuning reduction diode is connected to the first end of the switch tube.

[0011] Optionally, the driving power chip of the driving module includes a pulse width modulation pin and a communication pin, the PWM pin is used to receive a pulse width modulation signal, and the communication pin is used to receive an operating mode control signal.

[0012] Optionally, the driving power chip of the driving module includes a driving pin, which is connected to the control end of the switching tube, the first end of the switching tube is electrically connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the cathode of the LED load; the driving power chip is used to provide the generated frequency signal to the transformer through the switching tube when working in the intermittent mode.

[0013] Optionally, the driving power chip of the driving module includes an RC integration circuit, which is used to convert the pulse width modulation signal received by the driving power chip when it operates in a linear dimming mode into a linear voltage signal. If the duty cycle of the pulse width modulation signal increases, the converted linear voltage signal value increases, and the output current of the LED load increases.

[0014] Optionally, the driving power chip of the driving module includes a sampling pin, one end of the sampling pin is respectively connected to one end of the sampling resistor and the other end of the switching tube, and the other end of the sampling resistor is grounded; the driving power chip is used to use the sampling pin to check the peak current on the sampling resistor when working in the linear dimming mode, so as to detect the average current of the LED load.

[0015] Optionally, the driving power chip of the driving module includes a sampling pin, one end of the sampling pin is respectively connected to one end of the sampling resistor and the other end of the switching tube, and the other end of the sampling resistor is grounded; the driving power chip is used to use the sampling pin to detect the peak voltage on the sampling resistor when working in the intermittent mode, amplify the peak voltage on the sampling resistor, and calculate the average current of the LED load after processing by the RC integration circuit.

[0016] Optionally, the driving power chip of the driving module includes a zero current detection pin, and one end of the zero current detection pin is connected to one end of the secondary winding of the transformer through a zero current detection resistor.

[0017] Optionally, the power module also includes: a first capacitor and a second capacitor, one end of the first capacitor is connected to the input end of the power module, and the other end of the first capacitor is grounded; one end of the second capacitor is respectively connected to the cathode of the freewheeling diode and the anode of the LED load, and the other end of the second capacitor is respectively connected to the other end of the primary winding of the transformer and the cathode of the LED load.

[0018] Optionally, the switching tube is a power field effect tube, the gate of the power field effect tube is connected to the driving pin of the driving power chip of the driving module, the drain of the power field effect tube is electrically connected to the anode of the freewheeling diode, and the source of the power field effect tube is respectively connected to the sampling pin of the driving power chip and one end of the sampling resistor.

[0019] According to another aspect of the present invention, an embodiment of the present invention provides a lighting control device, which includes the dimming circuit, LED load and control end described in any embodiment of the present invention; the dimming circuit is used to receive the dimming control signal sent by the control end, and adjust the output current of the LED load through the dimming control signal.

[0020] The dimming circuit and lighting control device for a non-isolated LED constant current driving power supply described in the embodiment of the present invention are intended to consume resonant energy by coupling a reduction diode with at least one of the freewheeling diode, the switching tube, and the primary winding of the transformer, thereby reducing the influence of resonance on dimming. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The technical solutions and other beneficial effects of the present invention will be made apparent by describing in detail the specific embodiments of the present invention in conjunction with the accompanying drawings.

[0022] Figure 1 The present invention is a circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply in the prior art.

[0023] Figure 2 for Figure 1 The dimming circuit shown operates in the inductor current critical mode.

[0024] Figure 3 for Figure 1 The dimming circuit shown operates in the inductor current discontinuous mode.

[0025] Figure 4 for Figure 3 The figure shows the dead time period of the switch tube and the freewheeling diode when working in the discontinuous current mode of the inductor.

[0026] Figure 5 A circuit diagram of a dimming circuit for a non-isolated LED constant current drive power supply provided by an embodiment of the present invention.

[0027] Figure 6 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0028] Figure 7A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by yet another embodiment of the present invention.

[0029] Figure 8 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0030] Fig. 9 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0031] Fig.10 for Figures 5 to 9 Schematic diagram of the resonant waveform generated by the dimming circuit.

[0032] Fig.11 A schematic diagram of the structure of a lighting control device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0034] The terms "first" and "second" in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] The disclosure below provides many different embodiments or examples to implement different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed.

[0037] Figure 5 A circuit diagram of a dimming circuit for a non-isolated LED constant current drive power supply provided by an embodiment of the present invention.

[0038] See also Figure 5 As shown, an embodiment of the present invention provides a dimming circuit 1000 for a non-isolated LED constant current driving power supply, wherein the dimming circuit 1000 is electrically connected to an LED load, and the dimming circuit 1000 includes: a power module 110 and a driving module 120 connected to the power module 110. The power module 110 is used to convert the input voltage into a load voltage to drive the LED load; the power module 110 includes a switch tube Q1, a freewheeling diode D2 and a transformer T1, and the common node of the switch tube Q1 and the freewheeling diode D2 is connected to the transformer T1; the driving module 120 is electrically connected to the switch tube Q1 in the power module 110, and the driving module 120 is used to control the conduction or cutoff of the switch tube Q1 to perform constant current driving and dimming on the LED load; the dimming circuit 1000 also includes a detuning diode D1, and the detuning diode D1 is coupled to at least one of the freewheeling diode D2, the switch tube Q1, and the primary winding of the transformer T1, and is used to eliminate the resonant energy generated between the transformer T1 and the switch tube Q1 and the freewheeling diode D2. In addition, the LED load can be formed by combining multiple LEDs, such as a combination of LEDs connected in series or in parallel, and the embodiments of the present invention do not specifically limit this.

[0039] The dimming circuit 1000 for a non-isolated LED constant current driving power supply described in the embodiment of the present invention is coupled through a detuning diode D1 and at least one of a freewheeling diode D2, a switch tube Q1, and a primary winding of a transformer T1, so as to eliminate the resonant energy generated between the transformer T1, the switch tube Q1, and the freewheeling diode D2, thereby reducing the influence of resonance on dimming.

[0040] It should be noted that the tuning reduction diode D1 is actually a diode, which is used in the dimming circuit to reduce the resonance energy.

[0041] The dimming circuit 1000 will be further described below in conjunction with the accompanying drawings. Figure 5 As shown, Figure 5 A circuit diagram of a dimming circuit for a non-isolated LED constant current drive power supply provided by an embodiment of the present invention.

[0042] In some embodiments of the present invention, the driving module 120 includes a driving power chip U1. The driving power chip U1 is used to receive a pulse width modulation signal and an operating mode control signal. When the operating mode control signal is a linear dimming mode control signal, it works in a linear dimming mode, and converts the pulse width modulation signal into a linear voltage signal, and adjusts the output current of the LED load through the linear voltage signal. When the operating mode control signal is a discontinuous mode control signal, it works in a discontinuous mode, and generates a frequency signal based on the received pulse width modulation signal to provide it to the transformer T1, and adjusts the output current of the LED load through the pulse width modulation signal. Further, the pulse width modulation signal and the operating mode control signal received by the driving power chip U1 are generated by a micro control unit (not shown) after receiving the user's dimming control signal. The micro control unit generates a linear dimming mode control signal when analyzing that the dimming power corresponding to the dimming control signal is greater than the preset power (that is, the driving power chip U1 works in the linear dimming mode). When the microcontroller unit analyzes that the dimming power corresponding to the dimming control signal is less than the preset power, it generates a discontinuous mode control signal (i.e., drives the power chip U1 to work in the discontinuous mode) and controls the operating frequency of the transformer T1 to be within the preset frequency range. In this way, the noise generated by the transformer T1 is effectively eliminated by combining the linear dimming mode and the discontinuous mode. Moreover, the discontinuous mode can also effectively increase the dimming depth and enhance the user's lighting experience. In addition, by adjusting the operating frequency of the transformer T1 to the preset frequency range, the good EMI (Electronic Magnetic Interference) performance and good efficiency characteristics of the power circuit can be maintained.

[0043] In some embodiments of the present invention, the driving power chip U1 of the driving module 120 includes a pulse width modulation PWM pin and a communication pin (not shown in the figure), the PWM pin is used to receive a pulse width modulation signal, and the communication pin is used to receive an operating mode control signal.

[0044] In some embodiments of the present invention, the driving power chip U1 includes a driving pin GD, and the driving pin GD is connected to the control end of the switch tube Q1. The first end of the switch tube Q1 can be directly electrically connected to one end of the primary winding of the transformer T1 (the same-name end A of the primary winding), or the first end of the switch tube Q1 can be indirectly electrically connected to one end of the primary winding of the transformer T1 (the same-name end A of the primary winding) through a detuning diode D1. The other end of the primary winding of the transformer T1 (the opposite-name end of the primary winding) is connected to the cathode of the LED load. The driving power chip U1 is used to provide the generated frequency signal to the transformer T1 through the switch tube Q1 when working in the discontinuous mode. Further, when the driving power chip U1 works in the discontinuous mode, the frequency signal generated in the preset range can be sent to the switch tube Q1, and the frequency loaded on the switch tube Q1 is the operating frequency of the transformer T1, so the switch tube Q1 can provide the frequency signal to the transformer T1. In addition, in some embodiments, a driving resistor (not shown) can be set between the driving pin GD and the control end of the switch tube Q1.

[0045] In some embodiments of the present invention, the driver power chip U1 includes an RC integration circuit (not shown in the figure), which is used to convert the pulse width modulation signal received by the driver power chip U1 when it works in the linear dimming mode into a linear voltage signal. If the duty cycle of the pulse width modulation signal increases, the converted linear voltage signal value increases, thereby increasing the preset reference voltage, thereby controlling the output current of the LED load to increase. Among them, the preset reference voltage is a voltage value pre-set inside the driver power chip U1, and the embodiment of the present invention does not limit its specific value. The signal output by the RC integration circuit can be proportional to the time integral value of the signal input therein.

[0046] In some embodiments of the present invention, the driving power chip U1 includes a sampling pin CS, one end of the sampling pin CS is respectively connected to one end of the sampling resistor Rcs and the other end of the switch tube Q1, and the other end of the sampling resistor Rcs is grounded. The driving power chip U1 is used to detect the peak current on the sampling resistor Rcs using the sampling pin CS when working in the linear dimming mode to detect the average current of the LED load.

[0047] In some other embodiments of the present invention, the driving power chip U1 includes a sampling pin CS, one end of the sampling pin CS is respectively connected to one end of the sampling resistor Rcs and the other end of the switch tube Q1, and the other end of the sampling resistor Rcs is grounded. The driving power chip U1 is used to check the peak voltage on the sampling resistor Rcs using the sampling pin CS when working in the discontinuous mode, amplify the peak voltage on the sampling resistor Rcs, and calculate the average current of the LED load after being processed by the RC integration circuit.

[0048] In some embodiments of the present invention, the driving power chip U1 includes a zero current detection pin ZCD, and one end of the zero current detection pin ZCD is connected to one end of the secondary winding of the transformer T1 (the same-name end B of the secondary winding) through a zero current detection resistor Rzcd. When the zero-crossing detection module (not shown in the figure) in the driving power chip U1 detects that the secondary winding of the transformer T1 connected to the zero current detection pin ZCD (i.e., the inductance of the secondary winding) has been discharged to zero, a zero-crossing detection signal is generated and sent to the control logic module (not shown in the figure) in the driving power chip U1, so that the control logic module is reset. Then the control logic module sends a conduction signal to the switch tube Q1 to turn on the switch tube Q1 again.

[0049] like Figure 5 As shown, in this embodiment, the power module 110 further includes: a first capacitor C1 and a second capacitor C2. One end of the first capacitor C1 is connected to the input end of the power module 110, and the other end of the first capacitor C1 is grounded. One end of the second capacitor C2 is respectively connected to the cathode of the freewheeling diode D2 and the anode of the LED load, and the other end of the second capacitor C2 is respectively connected to the other end of the primary winding of the transformer T1 (the opposite end of the primary winding) and the cathode of the LED load.

[0050] It should be noted that the switch tube Q1 is a power field effect tube, and the gate of the power field effect tube is connected to the drive pin GD of the drive power chip U1 of the drive module 120. The drain of the power field effect tube is directly electrically connected to the anode of the freewheeling diode D2, or the drain of the power field effect tube is indirectly electrically connected to the anode of the freewheeling diode D2 through the detuning diode D1. The source of the power field effect tube is respectively connected to the sampling pin CS of the drive power chip U1 and one end of the sampling resistor Rcs.

[0051] As described in the background technology of this article, when the switch tube Q1 and the freewheeling diode D2 are both turned off in the dead time period, the primary winding of the transformer T1 (i.e., the power inductor) and the distributed capacitance Cds of the switch tube Q1 and the junction capacitance of the freewheeling diode D2 resonate. Therefore, in this embodiment, a detuning diode D1 coupled to at least one of the freewheeling diode D2, the switch tube Q1, and the primary winding of the transformer T1 is designed.

[0052] Continue reading Figure 5 As shown, in this embodiment, the anode of the detuning diode D1 is connected to one end of the primary winding (i.e., the power inductor) of the transformer T1 (i.e., the same-name end of the primary winding), and the cathode of the detuning diode D1 is connected to the common node of the switch tube Q1 and the freewheeling diode D2. In this way, the resonant energy can be consumed by the detuning diode D1, so that the amplitude is greatly reduced, and the problem of dimming jitter is eliminated, that is, the following is achieved. Fig.10 The effect shown, where Fig.10 The I(L1) in the figure represents the current flowing through the primary winding (power inductor L1) of the transformer T1, and V(Vds) represents the voltage across the source and drain of the switch tube Q1.

[0053] In this embodiment, the cathode of the drop-tuning diode D1 is connected to the anode of the freewheeling diode D2 and the first end of the switch tube Q1 respectively, that is, the drop-tuning diode D1 is simultaneously connected in series with the junction capacitance of the freewheeling diode D2 and the switch tube Q1, so that the total capacitance is minimized. In this way, the resonant energy between the transformer T1 and the freewheeling diode D2 and the switch tube Q1 can be consumed to the maximum extent.

[0054] like Figure 6 As shown, Figure 6 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0055] In this embodiment, the detuning diode D1 is connected in series with the switch tube Q1, the cathode of the dimming diode is connected to the first end of the switch tube Q1, and the anode of the detuning diode D1 is connected to the anode of the freewheeling diode D2. In this way, the resonant energy can be consumed by the detuning diode D1, so that the amplitude is greatly reduced, and the problem of dimming jitter is eliminated, that is, the following is achieved: Fig.10 The effect shown.

[0056] like Figure 7 As shown, Figure 7 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by yet another embodiment of the present invention.

[0057] In this embodiment, the detuning diode D1 is connected in series with the freewheeling diode D2, the cathode of the detuning diode D1 is connected to the anode of the freewheeling diode D2, and the anode of the detuning diode D1 is connected to the first end of the switch tube Q1. In this way, the resonant energy can be consumed by the detuning diode D1, so that the amplitude is greatly reduced, and the problem of dimming jitter is eliminated, that is, the following is achieved: Fig.10 The effect shown.

[0058] like Figure 8 As shown, Figure 8 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0059] In this embodiment, there are two detuning diodes. One detuning diode D1 is connected in series with the freewheeling diode D2, and the other detuning diode D3 is connected in series with the switch tube Q1. That is, the cathode of the detuning diode D1 is connected to the anode of the freewheeling diode D2, the anode of the detuning diode D1 is connected to the anode of the other detuning diode D3, and the cathode of the other detuning diode D3 is connected to the first end of the switch tube Q1. In this way, the resonant energy can be consumed by the detuning diode, so that the amplitude is greatly reduced, and the problem of dimming jitter is eliminated, that is, the following is achieved. Fig.10 The effect shown.

[0060] like Fig. 9 As shown, Fig. 9 A circuit diagram of a dimming circuit for a non-isolated LED constant current driving power supply provided by another embodiment of the present invention.

[0061] In this embodiment, the number of the detuning diodes is three. One of the detuning diodes D1 is connected in series with the freewheeling diode D2, another detuning diode D3 is connected in series with the switch tube Q1, and the remaining detuning diode D4 is connected in series with the primary winding (i.e., the power inductor) of the transformer T1. That is, the cathode of the detuning diode D1 is connected to the anode of the freewheeling diode D2, the anode of the detuning diode D1 is respectively connected to the anode of another detuning diode D3 and the cathode of the remaining detuning diode D4, the cathode of another detuning diode D3 is connected to the first end of the switch tube Q1, and the anode of the remaining detuning diode D4 is connected to one end of the primary winding (i.e., the power inductor) of the transformer T1 (i.e., the same-name end of the primary winding). In this way, the step-down diode is connected in series with the freewheeling diode D2, the switch tube Q1 and the transformer T1 respectively, that is, the junction capacitance of the step-down diode is in series with the distributed capacitance Cds of the switch tube Q1, the junction capacitance of the freewheeling diode D2 and the capacitance of the transformer T1, so that the resonant capacitance can be greatly reduced, thereby reducing the resonant energy and reducing the influence of the resonant energy on dimming.

[0062] Based on the same inventive concept, an embodiment of the present invention further provides a lighting control device 5000. Fig.11 As shown, the lighting control device 5000 includes the dimming circuit 1000, the LED load 1100 and the control terminal 1200 described in any embodiment of the present invention. The dimming circuit 1000 is used to receive the dimming control signal sent by the control terminal 1200, and adjust the output current of the LED load 1100 through the dimming control signal. The control terminal 1200 is used to send the dimming control signal to the micro control unit described above, and generate a corresponding pulse width modulation signal and a working mode control signal to the driving power chip U1, or to receive the output power of the LED load 1100 calculated by the driving power chip U1. The control terminal 1200 can transmit signals with the micro control unit or the driving power chip U1 through wired transmission or wireless transmission. For example, if wireless transmission is used to transmit signals, wireless communication modules can be respectively set at the control terminal 1200 and the micro control unit to enable the micro control unit to receive the dimming control signal from the control terminal 1200, or the micro control unit to send the output power of the LED load 1100 to the control terminal 1200. The wireless communication module may be a wifi module, a bluetooth module, etc., which is not specifically limited here. In addition, the driving power chip U1 may also send the status of each device connected to the driving power chip U1 to the control end 1200, and the control end 1200 may display the status of the driving power through a corresponding display module.

[0063] It should be noted that the dimming circuit 1000 described in the embodiment of the present invention is suitable for the application of LED constant current power supply, including an independent power supply and a built-in power supply matching the LED load, and is particularly suitable for application in the dimming circuit of a non-isolated LED constant current drive power supply.

[0064] The dimming circuit and lighting control device for a non-isolated LED constant current driving power supply described in the embodiment of the present invention are intended to couple the diode, the switch tube Q1, and at least one of the primary windings of the transformer T1 through a detuning diode to consume resonant energy, thereby reducing the impact of resonance on dimming.

[0065] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0066] The above is a detailed introduction to a dimming circuit and a lighting control device for a non-isolated LED constant current drive power supply provided in an embodiment of the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the present invention. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dimming circuit for a non-isolated LED constant current drive power supply, electrically connected to an LED load, characterized in that: The dimming circuit includes: a power module and a driving module connected to the power module; the power module is used to convert the input voltage into a load voltage to drive the LED load; the power module includes a switch tube, a freewheeling diode and a transformer, and the common node of the switch tube and the freewheeling diode is connected to the transformer; the driving module is electrically connected to the switch tube in the power module, and the driving module is used to control the conduction or cutoff of the switch tube to perform constant current driving and dimming on the LED load; the driving power chip of the driving module includes a driving pin, the driving pin is connected to the control end of the switch tube, the first end of the switch tube is electrically connected to one end of the primary winding of the transformer, and the other end of the primary winding of the transformer is connected to the cathode of the LED load; the dimming circuit also includes at least one of a first detuning diode, a second detuning diode, and a third detuning diode, and the first detuning diode, the second detuning diode, and the third detuning diode are respectively connected in series with the primary winding of the transformer, the switch tube, and the freewheeling diode, so as to eliminate the resonant energy generated between the transformer and the switch tube and the freewheeling diode.

2. The dimming circuit according to claim 1, characterized in that: The driving module includes a driving power chip, wherein the driving power chip is used to receive a pulse width modulation signal and an operating mode control signal. When the operating mode control signal is a linear dimming mode control signal, the driving power chip operates in a linear dimming mode, and converts the pulse width modulation signal into a linear voltage signal, and adjusts the output current of the LED load through the linear voltage signal; when the operating mode control signal is a discontinuous mode control signal, the driving module operates in a discontinuous mode, and generates a frequency signal based on the received pulse width modulation signal to provide to the transformer, and adjusts the output current of the LED load through the pulse width modulation signal.

3. The dimming circuit according to claim 1 or 2, characterized in that: The first drop-tuning diode is connected in series with the primary winding of the transformer, and an anode of the first drop-tuning diode is connected to one end of the primary winding of the transformer.

4. The dimming circuit according to claim 1 or 2, characterized in that: The second tuning reduction diode is connected in series with the switch tube, and the cathode of the second tuning reduction diode is connected to the first end of the switch tube.

5. The dimming circuit according to claim 1 or 2, characterized in that: The third down-tuning diode is connected in series with the freewheeling diode, and the cathode of the third down-tuning diode is connected to the anode of the freewheeling diode.

6. The dimming circuit according to claim 1, characterized in that: The driving power chip of the driving module includes a pulse width modulation pin and a communication pin. The pulse width modulation pin is used to receive a pulse width modulation signal, and the communication pin is used to receive an operation mode control signal.

7. The dimming circuit according to claim 1, characterized in that: The driving power chip is used to provide the generated frequency signal to the transformer through the switch tube when working in the discontinuous mode.

8. The dimming circuit according to claim 1, wherein: The driving power chip of the driving module includes an RC integration circuit, which is used to convert the pulse width modulation signal received by the driving power chip when it operates in the linear dimming mode into a linear voltage signal. If the duty cycle of the pulse width modulation signal increases, the converted linear voltage signal value increases, and the output current of the LED load increases.

9. The dimming circuit according to claim 1, characterized in that: The driving power chip of the driving module includes a sampling pin, one end of the sampling pin is respectively connected to one end of the sampling resistor and the other end of the switch tube, and the other end of the sampling resistor is grounded; the driving power chip is used to use the sampling pin to check the peak current on the sampling resistor when working in the linear dimming mode, so as to detect the average current of the LED load.

10. The dimming circuit according to claim 1, characterized in that: The driving power chip of the driving module includes a sampling pin, one end of which is respectively connected to one end of a sampling resistor and the other end of the switch tube, and the other end of the sampling resistor is grounded; the driving power chip is used to detect the peak voltage on the sampling resistor using the sampling pin when working in the discontinuous mode, amplify the peak voltage on the sampling resistor, and calculate the average current of the LED load after being processed by the RC integration circuit.

11. The dimming circuit according to claim 1, characterized in that: The driving power chip of the driving module comprises a zero current detection pin, one end of which is connected to one end of the secondary winding of the transformer via a zero current detection resistor.

12. The dimming circuit according to claim 1, characterized in that: The power module also includes: a first capacitor and a second capacitor, one end of the first capacitor is connected to the input end of the power module, and the other end of the first capacitor is grounded; one end of the second capacitor is respectively connected to the cathode of the freewheeling diode and the anode of the LED load, and the other end of the second capacitor is respectively connected to the other end of the primary winding of the transformer and the cathode of the LED load.

13. The dimming circuit according to claim 1, characterized in that: The switch tube is a power field effect tube, the gate of the power field effect tube is connected to the driving pin of the driving power chip of the driving module, the drain of the power field effect tube is electrically connected to the anode of the freewheeling diode, and the source of the power field effect tube is respectively connected to the sampling pin of the driving power chip and one end of the sampling resistor.

14. A lighting control device, characterized in that: The lighting control device comprises a dimming circuit, an LED load and a control end as described in any one of claims 1 to 13; the dimming circuit is used to receive a dimming control signal sent by the control end, and adjust the output current of the LED load through the dimming control signal.

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