Lamp driving circuit

Abstract

The utility model provides a lamp driving circuit, comprising a switching circuit which is directly or indirectly electrically connected with a commercial power input end and can switch an input AC electric signal into a high-frequency and discontinuous DC electric signal; the switching circuit comprises a first inductor, and the first inductor periodically stores and releases electric energy based on the electric signal; and the power regulation circuit is directly or indirectly connected in series between the switching circuit and the lamp, and is connected with electric energy and drives the lamp.

Description

Technical Field

[0001] The utility model relates to the technical field of lighting lamps, and in particular to a driving circuit of a lamp. Background Art

[0002] As people's living standards improve, the requirements for lighting fixtures are getting higher and higher, and the power of lighting fixtures is also getting higher and higher. In the existing related technologies, the energy conversion rate of the lighting fixture driving power supply is generally low, resulting in large power loss and serious heating of the lighting fixture. Utility Model Content

[0003] The purpose of the utility model is to provide a lamp driving circuit, wherein a switching circuit can switch an electrical signal input from a mains supply into a high-frequency, intermittent electrical signal. Based on the high-frequency, intermittent electrical signal, the lamp driving circuit can efficiently transmit the energy input from the mains supply to a rear-end load, thereby greatly improving the energy conversion rate of the driving power supply.

[0004] Another object of the utility model is to provide a lamp driving circuit, wherein the first inductor can periodically store and release electrical energy, continuously obtain energy from the mains, thereby making the current at the mains input end relatively smooth, avoiding input current spikes, and reducing the impact on electronic components in the circuit.

[0005] Another object of the utility model is to provide a lamp driving circuit, in which the switch tube can be turned off after the voltage at both ends of the switch tube drops to a lower level, thereby greatly reducing the power loss of the switch device, reducing circuit heating, and improving the power supply energy conversion rate.

[0006] Another object of the utility model is to provide a lamp driving circuit, in which the switch tube is controlled to be turned on based on its body diode, thereby limiting the unidirectional flow of current, while reducing power loss during power transmission and reducing circuit heating.

[0007] Another object of the utility model is to provide a lamp driving circuit, which can cut off the circuit when the current of the load lamp is too large, and reserve circuit recovery time after cutting off the circuit, so as to avoid frequent switching of the circuit at the current critical point and the problems of lamp flickering / circuit failure caused thereby.

[0008] Another object of the utility model is to provide a lamp driving circuit, which can supply power to the first control circuit of the switching circuit via the back end, thereby ensuring the power supply stability of the first control circuit, so that the switching circuit and even the entire circuit can be more stable when initially powered on.

[0009] Another object of the utility model is to provide a lamp driving circuit, which can control the frequency / time ratio of the high and low levels of the electrical signal output by the switching circuit, or control the cycle / time ratio of the charging and discharging of the first inductor based on the voltage at the input end of the power adjustment circuit / the output end of the switching circuit, so as to stabilize the voltage at the input end of the power adjustment circuit / the output end of the switching circuit.

[0010] Another object of the utility model is to provide a lamp driving circuit, which has a higher energy conversion efficiency as a whole and reduces circuit heating. Especially for larger output power (such as above 100W), it can effectively reduce power loss during energy transmission and reduce the manufacturing volume of the driving circuit.

[0011] To solve at least one of the above purposes, in one embodiment of the utility model, a lamp driving circuit is provided, including: a switching circuit, directly or indirectly electrically connected to the mains input terminal, capable of switching the input AC power signal into a high-frequency, intermittent DC power signal; the switching circuit includes a first inductor, and the first inductor periodically stores and releases electrical energy based on the electrical signal; a power adjustment circuit, directly or indirectly connected in series between the switching circuit and the lamp, receives electrical energy and drives the lamp.

[0012] In some embodiments of the present invention, the switching circuit includes a first control circuit, and the power adjustment circuit includes a second control circuit; wherein, when power is turned on, the second control circuit is started first, and then the second control circuit supplies power to the first control circuit.

[0013] In some embodiments of the utility model, the power adjustment circuit includes: a first sampling circuit, which is connected in series in the circuit where the lamp is located, and is used to continuously monitor the current in the circuit; wherein, when the current in the circuit exceeds a set threshold, power supply to the lamp is stopped; when the current in the circuit is less than the set threshold, power supply to the lamp is started.

[0014] In some embodiments of the present invention, the power adjustment circuit includes: a first auxiliary circuit, electrically connected to the first sampling circuit, and used to delay for a period of time after stopping the power supply to the lamp and then restarting the power supply to the lamp.

[0015] In some embodiments of the utility model, the power adjustment circuit includes: a driving sub-circuit, which is connected in series in the circuit where the lamp is located, and can adjust the voltage across the lamp to drive the lamp to dim; the driving sub-circuit is electrically connected to a first sampling circuit, and when the current in the circuit exceeds a set threshold, the driving sub-circuit is turned off to cut off the circuit where the lamp is located; when the current in the circuit is less than the set threshold, the driving sub-circuit is turned on to form a power supply circuit for the lamp.

[0016] In some embodiments of the utility model, a first auxiliary circuit is electrically connected to the first sampling circuit and the driving sub-circuit; the first auxiliary circuit includes a first switching tube, and the driving sub-circuit is turned off or turned on by the first switching tube according to the current in the loop collected by the first sampling circuit; wherein the gate of the first switching tube is not connected to a resistor, and a capacitor and a resistor are connected in parallel at both ends of the gate-source, so as to delay turning on the driving sub-circuit after turning off the driving sub-circuit.

[0017] In some embodiments of the present invention, the first auxiliary circuit includes: an operational amplifier, a reverse end electrically connected to at least one voltage-dividing resistor as a reference voltage, and a non-inverting end electrically connected to the first sampling circuit; the gate of the first switch tube is electrically connected to the operational amplifier, and the drain and source are electrically connected to the drive sub-circuit.

[0018] In some embodiments of the utility model, a protection circuit is included, which is electrically connected between the switching circuit and the power adjustment circuit; the protection circuit includes: a first diode, whose anode is electrically connected to the output end of the switching circuit and whose cathode is electrically connected to the input end of the power adjustment circuit to prevent backflow of back-end current; a first capacitor, which is electrically connected in parallel to the input end of the power adjustment circuit to stabilize the input voltage of the power adjustment circuit.

[0019] In some embodiments of the present invention, the first diode is a SiC diode.

[0020] In some embodiments of the present invention, the switching circuit includes: a first rectifier circuit, one end of which is directly or indirectly connected to the mains input terminal to switch the input AC signal into a DC signal, and the other end is electrically connected to one end of the first inductor; a second switch tube, one end of which is electrically connected to the other end of the first inductor to switch the input DC signal into a high-frequency, intermittent electrical signal.

[0021] It should be understood that the above general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the utility model or the prior art, the drawings required for use in the embodiments or the prior art description are briefly introduced below. The drawings herein are incorporated into the specification and constitute a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 It is a circuit diagram of a lamp driving circuit in one embodiment of the utility model;

[0024] Figure 2 It is a circuit timing diagram of a switching circuit in one embodiment of the utility model;

[0025] Figure 3 It is a circuit diagram of a power adjustment circuit in one embodiment of the utility model;

[0026] Figure 4 It is a circuit diagram of a power adjustment circuit in one embodiment of the utility model;

[0027] Figure 5 It is a circuit diagram of a switching circuit in one embodiment of the utility model;

[0028] Figure 6 It is a circuit timing diagram of a switching circuit in one embodiment of the utility model;

[0029] Figure 7 It is a circuit diagram of a lamp driving circuit in one embodiment of the utility model;

[0030] Figure 8 It is a circuit diagram of a lamp driving circuit in one embodiment of the utility model;

[0031] Fig. 9 It is a circuit diagram of a power adjustment circuit in one embodiment of the utility model;

[0032] Fig.10 It is a circuit diagram of a driving sub-circuit in one embodiment of the utility model;

[0033] Fig.11 It is a circuit diagram of a driving sub-circuit in one embodiment of the utility model;

[0034] Fig.12 It is a circuit diagram of a power adjustment circuit in one embodiment of the utility model;

[0035] Fig.13 It is a circuit diagram of a first auxiliary circuit in an embodiment of the utility model;

[0036] Fig.14 It is a circuit diagram of a protection circuit in one embodiment of the utility model. DETAILED DESCRIPTION

[0037] The embodiments of the utility model will be described in detail below. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0038] It should be understood that in the description of all embodiments of the present utility model, the terms "first" and "second" are only used for descriptive purposes and cannot 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. Terms such as "coupling" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral whole; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium to form a linkage relationship, and 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 utility model can be understood according to the specific circumstances.

[0039] At present, the power of lamps is getting bigger and bigger, usually reaching more than 100w, but the energy conversion rate of existing lamp driving power supplies is low (for example, usually only 80%-85%), which will cause a lot of power loss in the driving circuit. For example, for a 100w lamp, the power loss in the driving power supply is as high as 15w-20w, which will cause serious heating of the power supply.

[0040] In addition, the applicant found that the input current of the existing lamp driver power supply is intermittent, that is, it cannot continuously obtain energy from the power grid, so that a high peak current appears on the input side and impacts the circuit. Based on this, the applicant proposed a lamp driver circuit, in which the load can continuously obtain energy from the mains, solving the problem of large loss in the driver circuit and large peak current impact.

[0041] The lamp driving circuit can be applied to drive various types of lamps, such as but not limited to ceiling lamps, light strips, spotlights, downlights, etc. The lamp driving circuit can adjust the output voltage / current according to the power of the load lamp to adapt to the power supply requirements of various types of lamps.

[0042] Specific as Figure 1 , which is a schematic diagram of a lamp driving circuit according to an embodiment of the present utility model. The lamp driving circuit 1 at least comprises a switching circuit 10 and a power adjustment circuit 20 .

[0043] The switching circuit 10 is directly or indirectly electrically connected to the mains input terminal, and can switch the input AC signal into a high-frequency, intermittent DC signal. The input signal of the switching circuit 10 is a continuous AC signal, for example, a 220V / 50Hz sinusoidal AC.

[0044] It should be noted that the high-frequency, intermittent direct current signal can be short pulses of high level and low level alternating with each other, and the frequency is much greater than the input mains power, for example, it can be above 1kHz. In addition, in some embodiments, the high level amplitude can change periodically following the input mains power amplitude.

[0045] The switching circuit 10 includes a first inductor 11 that periodically stores and releases electrical energy based on the electrical signal.

[0046] The first inductor 11 is electrically connected between the input terminal and the output terminal of the switching circuit. Based on the high and low level electrical signals output by the switching circuit, the first inductor 11 is periodically charged and discharged.

[0047] Specifically, take the input signal as a 220V / 50Hz AC signal as an example. Figure 2 As shown, the figure uses a half cycle for exemplary explanation.

[0048] When the output end of the switching circuit 10 is at a low level, there is a voltage difference across the first inductor 11, and the charging stage is entered. A charging current flows through the first inductor 11 from the input end to the output end of the switching circuit, and the current value gradually increases. The energy of the AC power input is stored in the first inductor 11.

[0049] When the output end of the switching circuit 10 is switched to a high level, the voltage difference across the first inductor 11 suddenly decreases, and the first inductor 11 generates an induced current in the same direction as the charging current. The first inductor 11 enters a discharge phase, in which the stored energy is released to supply power to the back-end circuit, and the current flowing through the inductor gradually decreases. At the same time, the mains power also supplies power to the back-end circuit through the first inductor 11. When the output end of the switching circuit 10 is switched to a low level again, the first inductor 11 enters a charging phase again, storing the energy input from the mains power, and the cycle continues.

[0050] Thus, based on the high-frequency switching of the output signal of the switching circuit between high and low levels, the first inductor periodically stores and releases electrical energy. In the charging stage, the energy input by the mains is stored in the first inductor; in the discharging stage, the rear-end load obtains energy from the mains in addition to the energy stored by the first inductor in the charging stage. In other words, during the entire charge and discharge cycle of the first inductor, the mains transmits energy to the rear-end load. Therefore, based on the first inductor, the energy conversion efficiency of the power supply is greatly improved. In addition, since there is always a current from the mains input end to the load in the first inductor during the entire charge and discharge period, the overall current on the mains input side (that is, the current in the first inductor) has a relatively gentle trend, which avoids the occurrence of peak currents, thereby reducing the impact on the circuit.

[0051] The power adjustment circuit 20 is directly or indirectly connected in series between the switching circuit and the lamp, receives electric energy and drives the lamp. According to the power of the load lamp, the output power of the power adjustment circuit can be adjusted to provide stable power supply for the load lamp. In addition, by changing the output power of the power adjustment circuit, the dimming of the lamp can be achieved, for example, the dimming of the lamp can be achieved by adjusting the output voltage / current. The power adjustment circuit can be any circuit structure with power adjustment and energy supply, and the utility model does not limit this.

[0052] Thus, based on the lamp driving circuit provided by the above technical solution, the first inductor periodically stores and releases electric energy based on the high-frequency, intermittent DC signal output by the switching circuit, so that the current from the mains input end to the load lamp continues to exist in the first inductor, avoiding the occurrence of peak input current. At the same time, the energy stored in the first inductor is still used to release energy to the rear-end load, so the entire circuit can continuously and uninterruptedly obtain electric energy from the mains and transmit it to the load, thereby improving the conversion rate of input energy and the efficiency of the lamp driving power supply.

[0053] In addition, the applicant has also found that in the power adjustment circuit in the prior art, a large amount of power loss will occur during the conduction and shutdown of the switch tube. In order to further improve the energy transmission efficiency and reduce the loss, the applicant proposes a power adjustment circuit 20 in one embodiment.

[0054] like Figure 3 As shown, the power adjustment circuit 20 may include a third switch tube 31 , a fourth switch tube 32 and a transformer 33 .

[0055] The third switch tube 31 and the fourth switch tube 32 are connected in series and then connected in parallel to the input end of the power adjustment circuit 20, wherein the source of the third switch tube 31 is electrically connected to the drain of the fourth switch tube 32. The primary side of the transformer 33 is connected in series with the second inductor 34 and the second capacitor 35, and then connected in parallel to both ends of the drain and source of the fourth switch tube 32. The secondary side of the transformer 33 is the output end of the power adjustment circuit 20, which is electrically connected to the lamp to provide energy for it.

[0056] like Figure 3 As shown, the two switch tubes (31, 32) are turned on alternately to obtain electrical energy from the switching circuit 10. Specifically:

[0057] When the third switch tube 31 is turned on, the second capacitor 35 enters the charging stage. When the third switch tube 31 is turned on and the fourth switch tube 32 is turned off, the input end of the power adjustment circuit forms a loop with the third switch tube 31, the second inductor 34, the transformer 33, and the second capacitor 35, the second capacitor 35 stores energy, and the capacitor C2 is charged to the input voltage of the power adjustment circuit.

[0058] When the third switch tube 31 and the fourth switch tube 32 are turned off at the same time, the current in the loop continues to flow through the capacitor C1, and the input end of the power adjustment circuit forms a loop with the capacitor C1, the second inductor 34, the transformer 33, and the second capacitor 35. At this time, the capacitor C1 is charged. At the same time, the current in the loop continues to flow through the capacitor C2, and the second inductor 34, the transformer 33, the second capacitor 35, and the capacitor C2 form a loop to release the energy stored in the capacitor C2 until the capacitor C2 is completely discharged. The current flowing through the second inductor 34, the transformer 33, and the second capacitor 35 continues to flow through the body diode of the fourth switch tube 32. At this time, the voltage across the capacitor C2 is very low (i.e., the body diode conduction voltage drop of the switch tube 32).

[0059] At this time, the fourth switch tube 32 can be turned on to enter the second half cycle.

[0060] The fourth switch tube 32 is turned on, and the second capacitor 35 enters the discharge stage. When the fourth switch tube 32 is turned on and the third switch tube 31 is turned off, the second inductor 34, the transformer 33, the second capacitor 35 and the fourth switch tube 32 form a discharge loop to release the energy stored in the second capacitor 35, and the capacitor C1 is charged to the input voltage of the power adjustment circuit.

[0061] When the fourth switch tube 32 and the third switch tube 31 are turned off at the same time, the current in the loop continues to flow through the capacitor C2, and the second inductor 34, the transformer 33, the second capacitor 35, and the capacitor C2 form a loop to charge the capacitor C2. At the same time, the energy stored in the capacitor C1 is discharged through the loop formed by the input end of the power adjustment circuit, the second capacitor 35, and the second inductor 34 until the capacitor C1 is completely discharged, and the current continues to flow through the body diode of the third switch tube 31. At this time, the voltage across the capacitor C1 is very low (i.e., the body diode conduction voltage drop of the switch tube 31).

[0062] At this time, the third switch tube 31 can be turned on again to enter the next cycle, and the cycle continues.

[0063] That is to say, after the third switch tube 31 is turned off, the voltage across the drain and source of the fourth switch tube 32 gradually decreases, and when the voltage across the drain and source of the fourth switch tube 32 drops below Va, the fourth switch tube can be turned on. After the fourth switch tube 32 is turned off, the voltage across the drain and source of the third switch tube 31 gradually decreases, and when the voltage across the drain and source of the third switch tube drops below Va, the third switch tube 31 can be turned on. Wherein, Va is the body diode voltage drop of the switch tube (31, 32), which is usually below 1V.

[0064] Thus, the lamp driving circuit provided by the above technical solution, which turns off the switch tube when the voltage across the switch tube drops below the set value, greatly reduces the loss caused by the switch tube conduction and shutdown components in the power adjustment circuit, and improves the efficiency of the power supply. At the same time, it also greatly reduces the heating of the entire circuit, reduces the use of heat sinks in the circuit, and can greatly reduce the overall volume of the power driver.

[0065] Furthermore, the power adjustment circuit 20 may also include at least one fifth switch tube 34, which is connected in series between the secondary side of the transformer 33 and the output end of the power adjustment circuit 20, and is used to limit the unidirectional conduction of current, and can reduce energy loss in the process of transmitting energy to the load, thereby improving efficiency.

[0066] like Figure 4 In the present embodiment, the secondary side of the transformer 33 includes two windings and two fifth switch tubes (341, 342). The two fifth switch tubes (341, 342) are alternately turned on to output a stable voltage (such as 24V) to power the lamp. Specifically:

[0067] When current flows through the primary side of the transformer 33, where the same-name terminal is the negative pole, the upper winding of the secondary side of the transformer 33 is turned on, and the upper winding, the lamp, and the switch tube 341 form a loop. Initially, the current flows through the body diode of the switch tube 341 to form a loop. When the body diode of the switch tube 341 is detected to be turned on, the switch tube 341 is driven to be turned on. When current flows through the primary side of the transformer 33, where the same-name terminal is the positive pole, the lower winding is turned on, and the lower winding, the lamp, and the switch tube 342 form a loop. Initially, the current flows through the body diode of the switch tube 342 to form a loop. When the body diode of the switch tube 342 is detected to be turned on, the switch tube 342 is driven to be turned on.

[0068] In some embodiments, the drain potential of the fifth switch tube 34 may be monitored to determine whether the body diode is turned on. For example, when the drain potential is lower than the ground, the fifth switch tube 34 is driven to be turned on.

[0069] In some other embodiments, whether the body diode is turned on can be determined by monitoring the drain-source voltage of the fifth switch tube 34 . For example, when the drain-source voltage reaches a set threshold, the fifth switch tube 34 is driven to turn on.

[0070] Therefore, the switch tube is controlled to be turned on based on the body diode, and the rectification function is realized by using the switch tube, which avoids excessive power loss in traditional rectifier devices, further reduces the loss of electronic components in the power supply, can reduce the heat of the overall circuit, and improve transmission efficiency.

[0071] In some of the embodiments, Figure 5 As shown, the switching circuit 10 includes a first rectifier circuit 12 and a second switch tube 13 .

[0072] Among them, one end of the first rectifier circuit 12 is directly or indirectly connected to the mains input end to switch the input AC signal to a DC signal, and the other end is electrically connected to one end of the first inductor 11. The first rectifier circuit 12 can rectify the input mains signal and prevent the back-end current from being input in reverse. That is to say, when there is no mains input, or when the output of the switching circuit is greater than the input, the back-end current can be prevented from entering the mains.

[0073] The second switch tube 13 is connected in parallel to the output end of the switching circuit, and one end of the second switch tube 13 is electrically connected to the other end of the first inductor 11, and switches the input DC signal into a high-frequency, intermittent electrical signal. The second switch tube 13 has an on state and an off state. It should be noted that the switching frequency of the second switch tube 13 is high frequency, which can be above 1kHz. In this way, based on the high-frequency on and off of the second switch tube 13, the continuous sine wave of the mains input is switched into a high-frequency, short pulse with alternating high and low levels.

[0074] The first inductor 11 is electrically connected between the first rectifier circuit 12 and the second switch tube 13 , and a controlled periodic and repeated charging and discharging process is formed based on the high-frequency on and off of the second switch tube 13 .

[0075] like Figure 6 As shown, Figure 6 Taking a half-cycle as an example, one end of the second switch tube 13 is connected to the first inductor 11, and the other end is connected to the output end of the switching circuit, such as the negative electrode / ground. When the second switch tube 13 is turned on, the end of the first inductor 11 connected to the second switch tube 13 is connected to the negative electrode / ground, and the switching circuit 10 outputs a low level. At this time, the mains input end forms a loop with the first rectifier circuit 12, the first inductor 11, and the second switch tube 13. The first inductor 11 enters the charging stage, obtains electric energy from the mains and stores it, and the current in the first inductor 13 gradually increases.

[0076] When the second switch tube 13 is turned off, the AC input end forms a loop with the first rectifier circuit 12, the first inductor 11, and the rear-end load. The potential at one end of the first inductor 11 connected to the second switch tube 13 changes suddenly, causing the first inductor 11 to generate an induced current from the AC to the load to resist the instantaneous reduction in current. At this time, the instantaneous output voltage of the switching circuit is the sum of the AC input voltage and the induced electromotive force generated by the first inductor 11. The switching circuit outputs a high level, and the first inductor 11 enters the discharge stage to release the energy stored in the charging stage to the load. In this discharge stage, the first inductor 11 and the AC power supply the load together. The load obtains energy from the AC power stored in the first inductor 11 during the charging stage, and also obtains energy from the AC power at the same time. The current in the first inductor 11 gradually decreases during the discharge stage. Figure 6 As shown, in this embodiment, the amplitude of the high level output by the switching circuit follows the input AC power amplitude, and the switching circuit output voltage envelope is consistent in phase with the AC power input voltage, and the envelope of the first inductor current is also consistent in phase with the AC power input voltage (switching circuit output voltage envelope).

[0077] Based on the above technical solution, it can be known that in the embodiment of the utility model, based on the high-frequency conduction and shutdown of the second switch tube, the first inductor performs periodic charging and discharging. When the switch tube is turned on, the energy obtained from the mains is stored, and when the switch tube is turned off, the stored electric energy is released to supply energy to the load together with the mains, that is, during the entire charge and discharge cycle of the first inductor, there is a continuous current in the first inductor from the mains input to the load, and the mains continuously and steadily inputs energy to the load, thereby avoiding the input peak current and improving the conversion efficiency of the power supply.

[0078] The applicant has found that in the prior art, the power supply of the control circuit in the switching circuit is usually provided by the inductive winding of the first inductor 11 in the switching circuit. However, when the voltage signal on the inductive winding of the first inductor is unstable or even fluctuates greatly, for example, when the power is first turned on or other conditions occur, the working state of the control circuit in the switching circuit will be greatly affected, which will in turn affect the power supply stability of the power adjustment circuit, thereby causing abnormal operation of the entire circuit.

[0079] Based on this, the utility model proposes that the switching circuit 10 includes a first control circuit 14, and the power adjustment circuit 20 includes a second control circuit 21. When powered on, the second control circuit 21 is started first, and then the second control circuit 21 supplies power to the first control circuit 14, so as to reduce the influence of voltage fluctuations on the power supply of the first control circuit 14 when powered on, and improve the working stability of the entire circuit.

[0080] The first control circuit 14 is directly or indirectly electrically connected to the output end of the first inductor 11 / the output end of the switching circuit, and is used to control the switching circuit to output high-frequency, intermittent direct current.

[0081] The second control circuit 21 is used to control the output power of the power adjustment circuit 20 .

[0082] like Figure 7 As shown, one end of the second control circuit 21 is electrically connected before the first inductor 11, and obtains energy before the first inductor 11. Specifically, the second control circuit 21 is directly or indirectly electrically connected to the input end of the first inductor 11 or the mains input end, and the mains directly supplies power to the second control circuit 21 without passing through the first inductor 11, thereby ensuring the stability of the working state of the second control circuit 21.

[0083] In some embodiments, the second control circuit includes a second rectifier circuit for rectifying the current from the mains input to the second control circuit, while preventing the current of the second control circuit from flowing back into the mains input. Specifically, the second rectifier circuit can be implemented as a diode, with the anode electrically connected to the mains input, and the cathode electrically connected to the second control circuit. The second rectifier circuit can also be implemented as a rectifier bridge, with the rectifier bridge input electrically connected to the mains input, and the rectifier bridge output electrically connected to the second control circuit. In other embodiments, the second control circuit 21 and the switching circuit 10 can share the first rectifier circuit 12, that is, the second control circuit is electrically connected to the output of the first rectifier circuit 12, and the current flowing into the mains input is rectified by the first rectifier circuit 12, and a part enters the first inductor 11, and the other part enters the second control circuit.

[0084] After power-on, the second control circuit 21 is directly powered by the AC power supply, and can first start and enter a stable working state, so that the entire power adjustment circuit 20 enters the working state. At this time, the second control circuit 21 supplies power to the first control circuit 14, so that the power supply signal of the first control circuit is more stable, so that it can output the drive signal (such as a stable PWM signal or PFM signal) more stably, and then control the switching circuit 10 to stably output high-frequency, intermittent electrical signals, while further promoting the stability of the power supply at the input end of the power adjustment circuit, so that the overall circuit structure can enter a stable working state faster.

[0085] Therefore, based on this technical solution, it is possible to avoid the unstable working state of the switching circuit caused by an unstable power supply signal, the instability of the power adjustment circuit caused by the unstable power supply signal, and even the instability and failure of the entire circuit.

[0086] In some embodiments, the first control circuit 14 can be used to control the on and off of the second switch tube 13. Specifically, the first control circuit 14 can be implemented as a logic circuit or an integrated control chip, which can output a high-frequency, high-low level alternating drive signal. The drive signal can be a PWM signal or a PFM signal with a frequency of more than 1K. When the first control circuit 14 outputs a high level to drive the second switch tube 13 to turn on, the output end of the first inductor / switching circuit outputs a low level; when the first control circuit 14 outputs a low level to drive the second switch tube 13 to turn off, the output end of the first inductor / switching circuit outputs a high level. In this way, the switching circuit is controlled to output a high-frequency, intermittent electrical signal based on the first control circuit 14.

[0087] In some embodiments, the second control circuit 21 can be used to control the on and off of the third switch tube 31 and the fourth switch tube 32. Specifically, the second control circuit 21 can be implemented as a logic circuit or an integrated control chip, which can drive the on and off of the third switch tube 31 and the fourth switch tube 32.

[0088] like Figure 8 As shown, in some embodiments, in order to further stabilize the input voltage of the power adjustment circuit 20, a second sampling circuit 28 may be provided, which is connected in parallel to the input end of the power adjustment circuit 20 to monitor the voltage at the input end of the power adjustment circuit 20, and the second sampling circuit 28 is electrically connected to the first control circuit 14. The first control circuit 14 obtains the input status of the power adjustment circuit 20 through the second sampling circuit 28, and then controls the time ratio of the frequency / high and low levels of the output electrical signal of the switching circuit, or controls the cycle / time ratio of the charge and discharge of the first inductor, thereby gradually stabilizing the input voltage of the power adjustment circuit.

[0089] When the second sampling circuit 28 detects that the voltage at the input end of the power adjustment circuit 20 exceeds the set voltage, the first control circuit 14 controls the switching circuit 10 to output a high level, so that the first inductor 11 stops charging and enters the discharge stage. For example, in some embodiments, the first control circuit 14 outputs a driving signal to control the second switch tube 13 to turn off, so that the switching circuit 10 outputs a high level, and the first inductor 11 stops charging and enters the discharge stage.

[0090] When the second sampling circuit 28 detects that the voltage at the input end of the power adjustment circuit 20 has not reached the set voltage, the first control circuit 14 controls the switching circuit to output a low level, so that the first inductor 11 enters the charging stage. For example, in some embodiments, the first control circuit 14 outputs a driving signal to control the second switch tube 13 to turn on, so that the switching circuit 10 outputs a low level, and the first inductor 11 enters the charging stage.

[0091] In some embodiments, the second sampling circuit 28 may be implemented to include a plurality of voltage-dividing resistors connected in series.

[0092] In addition, in order to prevent the entire circuit from being damaged by excessive current flowing through the load, in some embodiments, a first sampling circuit 22 is provided in the power adjustment circuit 20, which is connected in series in the loop where the lamp is located, and is used to continuously monitor the current in the loop; wherein, when the current in the loop exceeds a set threshold, the power supply to the lamp is stopped; and when the current in the loop is less than the set threshold, the power supply to the lamp is turned on. One end of the first sampling circuit 22 is electrically connected to the lamp, and the other end is electrically connected to the output end of the power adjustment circuit 20, such as the negative pole / ground, and the current flowing through the load lamp can be detected through the first sampling circuit 22. In some embodiments, the first sampling circuit 22 is implemented as a sampling resistor, for example, it can be 5mΩ or 10mΩ.

[0093] like Fig. 9 As shown, in some embodiments, the power adjustment circuit 20 includes a driving subcircuit 23, through which the power supply to the lamp is turned on / off. The driving subcircuit 23 is connected in series in the circuit where the lamp is located, and can adjust the voltage across the lamp to drive the lamp to dim; the driving subcircuit 23 is electrically connected to the first sampling circuit 22, and when the current in the circuit exceeds the set threshold, the driving subcircuit 23 is turned off to cut off the circuit where the lamp is located; when the current in the circuit is less than the set threshold, the driving subcircuit 23 is turned on to form a power supply circuit for the lamp.

[0094] The driving subcircuit 23 can control the voltage applied to the two ends of the lamp, for example, it can adjust the average voltage applied to the two ends of the lamp to achieve dimming (brightness and / or color temperature). Fig. 9As shown, the power adjustment circuit 20 can be electrically connected to the communication circuit 3, and can receive dimming control signals from other control devices such as gateways, terminals, and the cloud through the communication circuit 3 based on any one or more of wireless communications such as Bluetooth, radio frequency, wifi, and wired communications, and then adjust the average voltage applied to both ends of the lamp.

[0095] In some embodiments, the driving subcircuit 23 adjusts the average voltage across the lamp through the lamp control chip. When the first sampling circuit 22 detects that the current in the lamp circuit exceeds the set threshold, the driving subcircuit 23 can be turned off by cutting off the power supply of the lamp control chip, thereby cutting off the lamp circuit; when the first sampling circuit 22 detects that the current in the lamp circuit is less than the set threshold, the driving subcircuit 23 can be turned on by turning on the power supply of the lamp control chip again, thereby connecting the lamp circuit.

[0096] like Fig.10 As shown, in some embodiments, the lamp control chip U10 drives the switch tube Q4 to drive the lamp, one end of the switch tube Q4 is electrically connected to the lamp, and the other end is electrically connected to the first sampling circuit 22. The driving sub-circuit 23 includes a switch tube QA, which is electrically connected to the power supply terminal VCC of the lamp control chip U10 to control the power supply and power off of the lamp control chip U10, thereby controlling the on and off of the driving sub-circuit 23. Specifically:

[0097] Under normal working conditions, the Zener diode D14 is reversely broken down, causing V D The voltage is stable (such as 12V), the switch tube QA remains on, V A is high level (such as about 12V), the lamp control chip U10 is powered normally, that is, the driving sub-circuit 23 is in the on state, and current flows through the circuit where the lamp is located. When the first sampling circuit 22 detects that the current in the circuit where the lamp is located exceeds the set threshold, it forces V D (If it can be pulled down to about 0V), the switch tube QA is turned off, V A When the voltage is low (eg, about 0V), the lamp control chip U10 is powered off, that is, the driving sub-circuit 23 is cut off, and the lamp circuit is disconnected.

[0098] In this embodiment, the lamp control chip U10 can receive a dimming control signal (such as a PWM signal) wirelessly or wiredly, thereby adjusting the driving pulse signal of the switch tube Q4 (such as adjusting the duty cycle of the Q4 driving pulse), thereby adjusting the average voltage applied across the lamp to achieve dimming of the lamp. Fig.11As shown, a schematic diagram of adjusting and controlling the R channel of a lamp is given as an example. In some embodiments, the G, B, Y, and W channels that affect the brightness and color temperature of the lamp can be controlled separately in the same control manner as the R channel to achieve accurate adjustment of the color temperature and / or brightness of the light. In this embodiment, the current in the circuit where the lamp is located collected by the first sampling circuit 22 is the sum of the currents of the R, G, B, Y, and W channels.

[0099] However, the applicant has found that when the current in the circuit where the lamp is located fluctuates around the set threshold, it may cause the lamp to flicker / circuit damage. For example, when the current in the circuit where the lamp is located exceeds the set threshold, the lamp is powered off, and the current in the circuit decreases rapidly. Once it is less than the set threshold, the lamp will be powered on again, and the current in the circuit will increase. When it exceeds the set threshold again, the lamp will be powered off again. In this way, the circuit where the lamp is located will be repeatedly turned on and off, which may cause the lamp to flicker / circuit failure. Therefore, if Fig.12 As shown, the applicant proposes that a first auxiliary circuit 24 can be further provided in the power adjustment circuit, electrically connected to the first sampling circuit 22, for delaying a period of time after stopping the power supply to the lamp and then restarting the power supply to the lamp.

[0100] In some embodiments, when the current in the circuit where the lamp is located exceeds the set threshold and the driver sub-circuit 23 is to be turned off, the first auxiliary circuit 24 does not extend the turn-off time of the driver sub-circuit 23, but turns it off quickly. In some embodiments, the first auxiliary circuit 24 achieves a fast turn-off of the driver sub-circuit 23 by accelerating the power off of the lamp control chip.

[0101] When the lamp is disconnected from the circuit due to excessive current in the circuit and needs to be restored, the first auxiliary circuit will extend the on-time of the driving subcircuit 23, that is, the driving subcircuit is turned on after a delay. In some embodiments, the first auxiliary circuit 24 delays the restoration of power supply of the lamp control chip to achieve delayed connection of the driving subcircuit 24. The delay of the first auxiliary circuit 24 for a period of time can be in the order of seconds (such as 5s), and the specific value can be freely set by those skilled in the art and is not limited here.

[0102] Specifically, in some embodiments, the first auxiliary circuit 24 is electrically connected to the first sampling circuit 22 and the driving sub-circuit 23. The first auxiliary circuit 24 includes a first switch tube 25, and the first switch tube 25 turns off or turns on the driving sub-circuit 23 according to the current in the loop collected by the first sampling circuit 22. The gate of the first switch tube 25 is not connected to a resistor, and a capacitor and a resistor are connected in parallel at both ends of the gate-source, which is used to delay turning on the driving sub-circuit 23 after turning off the driving sub-circuit 23.

[0103] Among them, the drain of the first switch tube 25 is electrically connected to the driving sub-circuit, the source is electrically connected to the output end of the power adjustment circuit, such as the negative pole / ground, and the gate is directly or indirectly electrically connected to the first sampling circuit 22. The current in the circuit where the lamp is located collected by the first sampling circuit 22 drives the first switch tube 25 to be turned on and off.

[0104] When the current in the loop exceeds the set threshold, the collected current drives the first switch tube 25 to turn on, thereby turning off the drive sub-circuit 23 and cutting off the loop where the lamp is located. During the conduction process of the first switch tube 25, since there is no resistor set at the gate, the capacitor connected in parallel between the gate and the source can be quickly charged by the collected current, so that the first switch tube 25 is quickly turned on, thereby quickly turning off the drive sub-circuit 23 and cutting off the loop where the lamp is located.

[0105] When the current in the loop is less than the set threshold, the collected current drives the first switch tube 25 to turn off, thereby turning on the drive sub-circuit 23 and turning on the loop where the lamp is located. During the period when the first switch tube 25 is turned off, since the capacitor at both ends of the gate-source electrode needs to be discharged through the parallel resistor, the first switch tube is turned off with a delay, thereby delaying the turning on of the drive sub-circuit 23 and the turning on of the lamp with a delay. The resistor in parallel with the capacitor at both ends of the gate-source electrode has a relatively large resistance value, for example, it can be 5.1MΩ.

[0106] In some embodiments, the first switch tube 25 turns off and on the driving sub-circuit by cutting off and turning on the power supply of the lamp control chip. Specifically, when the first switch tube 25 is turned on, the power supply of the lamp control chip is cut off, and when the first switch tube 25 is turned off, the power supply of the lamp control chip is turned on.

[0107] like Fig.13 As shown, in some embodiments, the first auxiliary circuit 24 may further include an operational amplifier 26. The reverse end of the operational amplifier 26 is electrically connected to at least one voltage-dividing resistor as a reference voltage, and the in-phase end is electrically connected to the first sampling circuit. The gate of the first switch tube 25 is electrically connected to the operational amplifier 26, and the drain and source are electrically connected to the driving sub-circuit 23.

[0108] The operational amplifier 26 drives the first switch tube 25 based on the comparison result between the current Is in the loop collected by the first sampling circuit 22 and the set threshold value. Specifically, when the current Is in the loop exceeds the set threshold value, the first switch tube 25 is driven to turn on, thereby turning off the drive subcircuit 23 and cutting off the loop where the lamp is located. When the current Is in the loop is less than the set threshold value, the first switch tube 25 is driven to turn off, thereby turning on the drive subcircuit 23 and turning on the loop where the lamp is located.

[0109] like Fig.13As shown, when the current in the loop exceeds the set threshold, the current Is in the loop where the lamp is located collected by the first sampling circuit 22 is converted into a sampling voltage V1 through a resistor. The sampling voltage V1 is compared with the reference voltage Vref of the operational amplifier 26. When V1>Vref, the operational amplifier 26 outputs a high level to drive the first switch tube 25 to turn on. Since the gate of the first switch tube 25 has no resistance, the capacitor C48 is quickly charged, the first switch tube 25 is quickly turned on, and its drain is quickly grounded, forcibly pulled down, V D Close to 0V. Combined Fig.10 , Fig.11 At this time, the switch tube QA is turned off, and the power supply to the lamp control chip stops, thereby quickly turning off the drive sub-circuit 23.

[0110] When the current in the loop is less than the set threshold, such as when V1 < Vref, the operational amplifier 26 outputs a low level, driving the first switch tube 25 to turn off. Due to the existence of the resistor R91 and the large resistance of R91, the capacitor C48 slowly discharges through the resistor R91 (such as 5s). When the capacitor C48 gradually discharges until the voltage at both ends is lower than the opening voltage of the first switch tube 25, the first switch tube 25 is turned off. Fig.10 , Fig.11 After the first switch tube 25 is turned off, under the action of the voltage stabilizing diode D14, V D The potential is pulled high, and the lamp control chip is powered again, thereby reconnecting the drive subcircuit 23. In this way, when the current in the loop is detected to exceed the set threshold and the drive subcircuit 23 is turned off, the drive subcircuit 23 can be turned on again after a delay of a period of time (such as 5s).

[0111] In addition, in this embodiment, a diode D16 is provided between the first switch tube 25 and the operational amplifier 26, with its anode electrically connected to the operational amplifier 26 and its cathode electrically connected to the first switch tube 25, which ensures that the current can flow from the operational amplifier to the first switch tube on the one hand; on the other hand, it prevents the capacitor C48 from discharging in the direction of the operational amplifier during the process of turning off the first switch tube 25, thereby preventing the capacitor C48 from discharging too quickly and shortening the delay time. In other words, the provision of the diode D16 ensures that the capacitor C48 discharges through the parallel resistor R91, thereby ensuring the delay time before the first switch tube 25 is turned off.

[0112] In some embodiments, Fig.14 As shown, the power adjustment circuit 20 also includes a protection circuit 27, which includes: a first capacitor 271, electrically connected in parallel to the input end of the power adjustment circuit 20 to stabilize the input voltage of the power adjustment circuit 20; a first diode 272, the anode of which is electrically connected to the output end of the switching circuit 10, and the cathode of which is electrically connected to the input end of the power adjustment circuit 20 to prevent backflow of rear-end current.

[0113] The first capacitor 271 can store energy obtained from the mains, including energy stored by the first inductor 11 in the charging stage and then released in the discharging stage, as well as energy directly obtained from the mains, and transmit the stored energy to the power adjustment circuit 20. The first capacitor 271 can stabilize the input voltage of the power adjustment circuit 20 when the first inductor 11 is continuously charged and discharged periodically, thereby ensuring stable power supply of the power adjustment circuit and improving the stability of the overall circuit.

[0114] The first diode 272 is arranged between the output end of the switching circuit and the input end of the power adjustment circuit. Its anode is electrically connected to the output end of the switching circuit, and its cathode is electrically connected to the input end of the power adjustment circuit / the first capacitor 271. On the one hand, it ensures that the current can flow from the switching circuit to the power adjustment circuit. On the other hand, it prevents the current of the rear-end power adjustment circuit 20 / the first capacitor 271 from flowing back into the switching circuit when the output end of the switching circuit is at a low level, thereby ensuring the stability of the input voltage of the power adjustment circuit 20.

[0115] In some embodiments, the first diode 272 is implemented as a SiC diode to further reduce power loss on electronic components.

[0116] Thus, the lamp driving circuit proposed based on the utility model has a higher energy conversion efficiency and reduces circuit heating, especially for a larger output power (such as above 100W), which can effectively reduce the power loss in the energy transmission process, thereby reducing the manufacturing volume of the driving circuit.

[0117] In the description of this specification, the description with reference to the terms "some embodiments", "a specific implementation", "a specific implementation process", "an example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the utility model. In this specification, the schematic expressions of the above terms corresponding to the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0118] It should also be noted that the above-mentioned embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments, that is, the technical solutions disclosed in the later (order of sequence recorded in the text) embodiments should include the technical solutions recorded in the embodiment and the technical solutions recorded in all embodiments before the embodiment.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it. Although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A lamp driving circuit, characterized in that: include: A switching circuit is directly or indirectly electrically connected to the mains input terminal and is capable of switching the input AC power signal into a high-frequency, intermittent DC power signal; the switching circuit comprises a first inductor, and the first inductor periodically stores and releases electric energy based on the electric signal; The power adjustment circuit is directly or indirectly connected in series between the switching circuit and the lamp, receives electric energy and drives the lamp.

2. The lamp driving circuit according to claim 1, characterized in that: The switching circuit includes a first control circuit, and the power adjustment circuit includes a second control circuit; When power is turned on, the second control circuit is started first, and then the second control circuit supplies power to the first control circuit.

3. The lamp driving circuit according to claim 1, characterized in that: The power adjustment circuit comprises: The first sampling circuit is connected in series in the circuit where the lamp is located, and is used to continuously monitor the current in the circuit; wherein, When the current in the loop exceeds a set threshold, power supply to the lamp is stopped; When the current in the loop is less than a set threshold, power is supplied to the lamp.

4. The lamp driving circuit according to claim 3, characterized in that: The power adjustment circuit comprises: The first auxiliary circuit is electrically connected to the first sampling circuit and is used for delaying a period of time after stopping the power supply to the lamp and then restarting the power supply to the lamp.

5. The lamp driving circuit according to claim 4, characterized in that: The power adjustment circuit includes: a driving subcircuit, which is connected in series in the loop where the lamp is located and can adjust the voltage across the lamp to drive the lamp to dim; The driving subcircuit is electrically connected to the first sampling circuit. When the current in the loop exceeds a set threshold, the driving subcircuit is turned off to cut off the loop where the lamp is located; when the current in the loop is less than the set threshold, the driving subcircuit is turned on to form a power supply loop for the lamp.

6. The lamp driving circuit according to claim 5, characterized in that: The first auxiliary circuit is electrically connected to the first sampling circuit and the driving sub-circuit; the first auxiliary circuit includes a first switch tube, and the driving sub-circuit is turned off or turned on by the first switch tube according to the current in the loop collected by the first sampling circuit; The gate of the first switch tube is not connected to a resistor, and a capacitor and a resistor are connected in parallel at both ends of the gate-source, so as to delay turning on the drive sub-circuit after turning off the drive sub-circuit.

7. The lamp driving circuit according to claim 6, characterized in that: The first auxiliary circuit comprises: An operational amplifier, wherein the reverse end is electrically connected to at least one voltage-dividing resistor, and the non-inverting end is electrically connected to the first sampling circuit; The gate of the first switch tube is electrically connected to the operational amplifier, and the drain and source are electrically connected to the driving sub-circuit.

8. The lamp driving circuit according to claim 1, characterized in that: The power regulation circuit includes a protection circuit, and the protection circuit includes: a first capacitor electrically connected in parallel to an input end of the power regulating circuit to stabilize an input voltage of the power regulating circuit; The first diode has an anode electrically connected to the output end of the switching circuit and a cathode electrically connected to the input end of the power adjustment circuit to prevent backflow of rear-end current.

9. The lamp driving circuit according to claim 8, characterized in that: The first diode is a SiC diode.

10. The lamp driving circuit according to any one of claims 1 to 9, characterized in that: The switching circuit comprises: A first rectifier circuit, one end of which is directly or indirectly connected to the mains input terminal to convert the input AC signal into a DC signal, and the other end of which is electrically connected to one end of the first inductor; The second switch tube is connected in parallel to the output end of the switching circuit, one end of which is electrically connected to the other end of the first inductor, and switches the input direct current signal into a high-frequency, intermittent electrical signal.

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