CN219421104U - Deep dimming circuit for lamp and lamp system - Google Patents

Abstract

The utility model provides a deep dimming circuit for a lamp, which comprises: the device comprises a diode, an MOS switch tube, a controller, an inductor and a damping resistor, wherein the drain electrode of the MOS switch tube of the output capacitor is connected with the anode of the diode and the first end of the inductor, the source electrode of the MOS switch tube is connected with the first end of a sampling resistor, and the second end of the sampling resistor is grounded; the first end of the inductor is connected with the drain electrode of the MOS switch tube, the second end of the inductor is connected with the second end of the output capacitor, and the damping resistor is connected between the first end and the second end of the inductor in parallel; the negative electrode of the diode is connected with the first end of the output capacitor and is connected with the power input, and the lamp is connected between the first end and the second end of the output capacitor; and the controller is connected between the grid electrode of the MOS switch tube and the first end of the sampling resistor and used for controlling the current output to the lamp. The scheme of the utility model can effectively solve the problem that the lamp is easy to flicker when the lamp is subjected to low-brightness and deep dimming.

Description

Deep dimming circuit for lamp and lamp system

Technical Field

The present utility model relates to the field of circuitry, and more particularly to a deep dimming circuit for a luminaire and a luminaire system.

Background

In the application circuit of the traditional step-down DC-DC constant current converter, an intermittent mode (particularly when the load is smaller) is often used, and at the moment, the oscillation formed at two ends of the main inductor can cause inaccurate current detection of the controller, and particularly when the load is low, the lamp easily causes visible flicker. In the application of high-voltage non-isolated lamps, the most common mode is to use a high-voltage lamp bar and a high-voltage Buck circuit, so that the maximum efficiency and the lowest device temperature rise can be achieved. The Buck inductor has larger design inductance and more winding layers, which can lead to larger parasitic capacitance and larger waveform oscillation amplitude.

Therefore, there is a need in the art for a solution that can effectively address the effect of parasitic capacitance on brightness in a luminaire circuitry.

The above information disclosed in the background section is only for a further understanding of the background of the utility model and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

Disclosure of Invention

The utility model provides a deep dimming circuit for a lamp. By the scheme, the problem that the lamp is easy to flicker when the lamp is subjected to low-brightness and deep dimming can be effectively solved.

A first aspect of the utility model provides a deep dimming circuit for a luminaire, characterized in that the circuit comprises: the device comprises a diode, an MOS switch tube, a controller, an inductor, a damping resistor and an output capacitor, wherein the drain electrode of the MOS switch tube is connected with the anode of the diode and the first end of the inductor, the source electrode of the MOS switch tube is connected with the first end of a sampling resistor, and the second end of the sampling resistor is grounded; the first end of the inductor is connected with the drain electrode of the MOS switch tube, the second end of the inductor is connected with the second end of the output capacitor, and the damping resistor is connected between the first end and the second end of the inductor in parallel; the negative electrode of the diode is connected with the first end of the output capacitor and is connected with the power input, and the lamp is connected between the first end and the second end of the output capacitor; and the controller is connected between the grid electrode of the MOS switch tube and the first end of the sampling resistor and used for controlling the current output to the lamp.

According to one embodiment of the utility model, when the circuit is in a charging stage, the MOS switch tube is turned on, current input by a power supply passes through the lamp, the inductor and the MOS switch tube respectively and finally returns to the ground, and when the circuit is in the charging stage, the inductor is magnetized.

According to one embodiment of the utility model, when the circuit is in a follow current stage, the MOS switch tube is disconnected, the power supply input is not charged, and the output capacitor and the lamp are charged in follow current by means of the demagnetizing of the inductor through the diode so as to keep the voltage between the output capacitor and the two ends of the lamp constant.

According to one embodiment of the utility model, the controller controls the current output to the luminaire by detecting an inductor current, wherein the inductor current is detected by detecting a voltage drop of a sampling resistor.

According to one embodiment of the utility model, the MOS switch tube is an NMOS switch tube.

According to one embodiment of the present utility model, the power consumption of the damping resistor is a fixed value in milliwatt level, and the damping resistor is used for: and when the MOS switch tube is conducted, a parasitic circuit in the MOS switch tube is released, so that the instantaneous current fluctuation of the inductor is stable and the turn-off period of the MOS switch tube is stable.

According to one embodiment of the utility model, the damping resistor has a power consumption of a fixed value in the order of milliwatts.

According to one embodiment of the utility model, the circuit is used in a circuit system which works in an intermittent mode when the lamp is lightly loaded.

According to one embodiment of the utility model, the lamp is a high-voltage non-isolated intelligent lamp of a deep dimming type or a lamp of a household appliance.

A second aspect of the utility model provides a luminaire system, characterized in that the system comprises a luminaire and a deep dimming circuit as described above for the luminaire.

Aiming at the lamp circuit system working in the intermittent mode under light load, the scheme of the utility model is characterized in that damping resistors are connected in parallel at two ends of the inductor to accelerate the discharge speed of damping oscillation, so that the level of each period of the MOS switch tube at the conduction moment tends to be consistent and stable, and the output current is more stable.

Drawings

In order to more clearly illustrate the technical solutions of the present utility model, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present utility model, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 shows a circuit block diagram of a deep dimming circuit for a luminaire according to an exemplary embodiment of the present utility model.

Fig. 2 illustrates a schematic diagram of deep dimming circuit operation in a charging phase according to an exemplary embodiment of the present utility model.

Fig. 3 shows a schematic diagram of deep dimming circuit operation in a freewheel phase according to an exemplary embodiment of the present utility model.

Fig. 4 shows a waveform diagram of a circuit sample without damping resistor according to an exemplary embodiment of the present utility model.

Fig. 5 shows a sampling waveform of a circuit after setting a damping resistor according to an exemplary embodiment of the present utility model.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

As used herein, the terms "first," "second," and the like may be used to describe elements in exemplary embodiments of the present utility model. These terms are only used to distinguish one element from another element, and the inherent feature or sequence of the corresponding element, etc. is not limited by the terms. Unless defined otherwise, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this utility model belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

Those skilled in the art will understand that the devices and methods of the present utility model described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present utility model is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present utility model.

Hereinafter, exemplary embodiments of the present utility model will be described in detail with reference to the accompanying drawings. In the drawings, detailed descriptions of related known functions or configurations are omitted so as not to unnecessarily obscure the technical gist of the present utility model. In addition, throughout the description, the same reference numerals denote the same circuits, modules or units, and repetitive descriptions of the same circuits, modules or units are omitted for brevity.

Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.

In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, and indicates that three relationships may exist, for example, a and/or b may indicate: the first and second cases exist separately, and the first and second cases exist separately. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.

In the description of the embodiments of the present application, the term "plurality" refers to two or more (including two), and similarly, "plural sets" refers to two or more (including two), and "plural sheets" refers to two or more (including two).

In the description of the embodiments of the present application, the orientation or positional relationship indicated by the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. are based on the orientation or positional relationship shown in the drawings, and are merely for convenience of describing the embodiments of the present application and for simplifying the description, rather than indicating or implying that the apparatus or element referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the embodiments of the present application.

In the description of the embodiments of the present application, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured" and the like are to be construed broadly and may be, for example, fixedly connected, detachably connected, or integrally formed; or may be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the embodiments of the present application will be understood by those of ordinary skill in the art according to the specific circumstances.

Embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical solutions of the present application, and thus are only examples, and are not intended to limit the scope of protection of the present application.

In the traditional lamp circuit system, the Buck inductor has larger design inductance and more winding layers, which can lead to larger parasitic capacitance and larger waveform oscillation amplitude. The utility model provides a solution of a deep dimming optimization circuit of a buck converter, which comprises a buck DCDC constant current converter, wherein damping resistors are connected in parallel at two ends of an inductor to accelerate the discharge speed of damping oscillation, so that the level at the moment of conducting each period tends to be consistent and stable, and the output current is more stable. The problem that the lamp is easy to flicker when the lamp is dimmed in low brightness and depth is solved. The deep dimming circuit adopts an optimization circuit of the DC-DC buck converter, and the solution can be widely applied to high-voltage non-isolated intelligent lamps or household appliances of deep dimming.

Fig. 1 shows a circuit block diagram of a deep dimming circuit for a luminaire according to an exemplary embodiment of the present utility model.

As shown in fig. 1, the circuit of the deep dimming circuit for a lamp includes a diode D0, a MOS switch Q0, a controller U1, an inductor L1, a damping resistor R0, and an output capacitor C0, where Vout represents a power supply input, rs represents a sampling resistor, an LED represents the lamp, and Iout represents an output current of the lamp in the circuit block diagram of fig. 1.

As shown in fig. 1, a drain electrode of a MOS switch tube Q0 is connected to an anode of a diode D0 and a first end of an inductor L1, a source electrode of the MOS switch tube Q0 is connected to a first end of a sampling resistor Rs, and a second end of the sampling resistor Rs is grounded; the first end of the inductor L1 is connected with the drain electrode of the MOS switch tube Q0, the second end of the inductor L1 is connected with the second end of the output capacitor C0, and the damping resistor R0 is connected between the first end and the second end of the inductor L1 in parallel; the cathode of the diode D0 is connected with the first end of the output capacitor C0 and is connected with the power input Vout (or Vin), and the lamp LED is connected between the first end and the second end of the output capacitor C0; and the controller U1 is connected between the grid electrode of the MOS switch tube Q0 and the first end of the sampling resistor Rs, and is used for controlling the current output to the LED of the lamp to carry out deep dimming and solving the problem that the lamp is easy to flicker. Wherein the diode may be a schottky diode or a fast recovery diode or the like.

According to one or more embodiments of the present utility model, the damping resistor R0 is connected in parallel to two ends of the inductor L0, so as to accelerate the discharging speed of the damping oscillation, and make the level of each period conduction moment of Q0 tend to be consistent and stable, and further the output current is also more stable.

Fig. 2 illustrates a schematic diagram of deep dimming circuit operation in a charging phase according to an exemplary embodiment of the present utility model.

As shown in fig. 2, the charging phase. At this time, Q0 is turned on, and the power input Vi n passes through LED, L0, Q0, and finally returns to GND, respectively. At this time, the L0 inductor is magnetized.

Fig. 3 shows a schematic diagram of deep dimming circuit operation in a freewheel phase according to an exemplary embodiment of the present utility model.

As shown in fig. 3, during the freewheeling phase, when Q0 is off, the power input Vin does not charge any circuit, but only the C0 and LED freewheels are charged through D0 by means of inductance demagnetization after L0 is reversed, thereby keeping the voltage across C0 and LED constant.

According to one or more embodiments of the present utility model, wherein L0 charging and discharging is a process of magnetizing and demagnetizing the inductor, conforming to the law of u=l (d i/dt). If each turn-on instant of Q0, C _oss If the nodes (i.e., parasitic capacitance of Q0) are all at different potentials, then the current will be different for each cycle. The controller U1 controls the current output to the LED by detecting the inductor current, so that the current output to the LED is different in each period, and the lamp is easy to flicker. The inductor current is detected by detecting the voltage drop across the sampling resistor.

According to one or more embodiments of the present utility model, for a circuit in an intermittent operation mode under light load, parasitic oscillation exists before Q0 is turned on again, and this energy has no fast path for discharging, at this time, the controller U1 cannot determine the phase of the oscillation (the waveform of the oscillation is similar to an ac sine wave), so that the level/phase of Q0 is different every time it is turned on. Then the controller U1 controls the period or frequency of the next turn-off of Q0 to change, thereby causing a larger current fluctuation range of the LED lamp bead.

In order to solve the problem, the damping resistors R0 and R0 with the discharging function are connected in parallel at the two ends of the inductor L0, and the proper value is selected to ensure that the oscillation is basically finished or near tail sound when the inductor is turned on next time, parasitic current is discharged timely, so that the instantaneous current fluctuation of the inductor L0 is smaller, the turn-off period of the inductor Q0 is controlled to be basically stable, and the current of the LED lamp bead is kept stable.

In accordance with one or more embodiments of the present utility model, the power consumption of the damping resistor R0 with bleed-off function is fixed, e.g., may be of the milliwatt level, which has negligible effect when the lamp circuitry is fully loaded, without any impact on the circuit.

Fig. 4 shows a waveform diagram of a circuit sample without damping resistor according to an exemplary embodiment of the present utility model. Fig. 5 shows a sampling waveform of a circuit after setting a damping resistor according to an exemplary embodiment of the present utility model.

As shown in FIGS. 4 and 5, the upper waveform is parasitic capacitance C _oss The lower waveform is a sampled waveform of the lamp current. As is apparent from a comparison of fig. 4 and 5, the deep dimming circuit provided with the damping resistor R0 is significantly superior to the circuit not provided with the damping resistor R0. And as is apparent from fig. 5, parasitic capacitance C _oss The influence of the lamp current output is reduced and the lamp current output is also more stable.

The utility model also provides a lamp system which is characterized by comprising a lamp and the deep dimming circuit for the lamp.

The figures and detailed description of the utility model referred to above as examples of the utility model are intended to illustrate the utility model, but not to limit the meaning or scope of the utility model described in the claims. Accordingly, modifications may be readily made by one skilled in the art from the foregoing description. In addition, one skilled in the art may delete some of the constituent elements described herein without deteriorating the performance, or may add other constituent elements to improve the performance. Furthermore, one skilled in the art may vary the order of the steps of the methods described herein depending on the environment of the process or equipment. Thus, the scope of the utility model should be determined not by the embodiments described above, but by the claims and their equivalents.

While the utility model has been described in connection with what is presently considered to be practical, it is to be understood that the utility model is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims (8)

1. A deep dimming circuit for a luminaire, the circuit comprising: diode, MOS switch tube, controller, inductance, damping resistance, output capacitance, wherein,

the drain electrode of the MOS switch tube is connected with the anode of the diode and the first end of the inductor, the source electrode of the MOS switch tube is connected with the first end of the sampling resistor, and the second end of the sampling resistor is grounded;

the first end of the inductor is connected with the drain electrode of the MOS switch tube, the second end of the inductor is connected with the second end of the output capacitor, and the damping resistor is connected between the first end and the second end of the inductor in parallel;

the negative electrode of the diode is connected with the first end of the output capacitor and is connected with the power input, and the lamp is connected between the first end and the second end of the output capacitor; and

the controller is connected between the grid electrode of the MOS switch tube and the first end of the sampling resistor and is used for controlling the current output to the lamp.

2. The circuit of claim 1, wherein the controller controls the current output to the lamp by detecting an inductor current, wherein the inductor current is detected by detecting a voltage drop across a sampling resistor.

3. The circuit of claim 1, wherein the MOS switch tube is an NMOS switch tube.

4. The circuit of claim 1, wherein the damping resistor consumes a fixed value in the order of milliwatts, the damping resistor being configured to: and when the MOS switch tube is conducted, a parasitic circuit in the MOS switch tube is released, so that the instantaneous current fluctuation of the inductor is stable and the turn-off period of the MOS switch tube is stable.

5. The circuit of claim 1, wherein the damping resistor consumes a fixed value in the order of milliwatts.

6. The circuit of claim 1, wherein the circuit is used in circuitry that operates in an intermittent mode when the light load of the light fixture is present.

7. The circuit of claim 1, wherein the light fixture is a deep dimming type high voltage non-isolated intelligent light fixture or a light fixture of a household appliance.

8. A luminaire system, characterized in that the system comprises a luminaire and a deep dimming circuit for a luminaire according to any one of claims 1-7.