RU168258U1 - LED light fixture with high reliability power supply - Google Patents

Abstract

An LED light device with a high-reliability power supply contains a diode rectifier connected to the network through a choke connected in series to one of the network wires, a capacitor connected directly to the mains supply, and a capacitor connected in parallel to the rectifier on the rectified voltage side, as well as LEDs. In order to increase noise immunity, the source further comprises a choke connected in series to the second network wire. Both chokes are made on a common magnetic circuit. In addition, a capacitor connected in parallel to a rectifier on the rectified voltage side consists of two separate or common capacitors connected in series, the connection point of which is grounded. In addition, parallel to each of the capacitors making up the capacitor connected parallel to the rectifier on the side of the rectified voltage, capacitors of a thousand or more times smaller capacitance are connected.

Description

An LED light fixture with an increased reliability power supply relates to electric lighting devices, more specifically, to the network power supplies of LED lamps.

The LEDs used in LED lighting devices powered by AC networks are very sensitive to surge voltage in networks caused by switching processes or lightning (hereinafter - interference). Therefore, in their power sources (hereinafter referred to as sources), technical solutions are used that protect the LEDs from the effects of interference from the supply network.

A LED light device with an AC power source containing a group of series-connected LEDs, including a bridge diode rectifier connected to the network through a current-limiting capacitor shunted by a resistor, and a high-capacity smoothing capacitor connected in parallel to the rectifier on the rectified voltage side. In this source, to suppress the overvoltage coming from the network, an additional capacitor is connected in parallel with the rectifier from the AC side (PM RF No. 95214). A disadvantage of the known source is the low efficiency of surge protection. The amplitude and duration of the interference pulses, being random variables, vary in the widest range. To absorb the energy of pulses of long duration, the capacitance of the additional capacitor must be sufficiently large. But with an increase in capacitance, the intrinsic inductance of the capacitor also increases, reducing its ability to shunt no less dangerous pulses of short duration. Moreover, the smoothing capacitor, whose inductance is especially large, is unable to shunt short pulses. Therefore, a well-known source protects LED groups from surge surges only with certain amplitude-time characteristics, mainly of switching origin. But LED lights are designed for continuous long-term service. Sooner or later, an impulse noise appears in the network (more often from a lightning strike) with characteristics that differ significantly from those for which the parameters of the protective elements are designed.

The closest to the proposed technical essence and the achieved result is a LED light device with a power source from an alternating current network, containing at least one group of series-connected LEDs, including a bridge diode rectifier connected to the network through a line choke, a shunt capacitor connected directly to the mains, and a smoothing capacitor, smoothing the ripples of the rectified voltage, connected in parallel to the rectifier on side of the rectified voltage (PM RF № 107642). In the case when the light device contains several parallel-connected groups of LEDs, in addition, the source may include alignment resistors connected in series with each of the groups. In order to avoid reduction in efficiency the source resistance of these resistors is set small, and they can not suppress the noise or limit the current to a degree sufficient to protect the LEDs.

As mentioned above, protection through a capacitor connected in parallel to the network is not effective enough. The main disadvantage of the known source is that the serial noise suppressing element, the inductor, is included only in one of the network wires, namely, in the linear one. Apparently, under the assumption that the interference comes from two mains supply wires.

In fact, if we take into account the design features of real, manufactured by the industry, LED lighting devices, a short-pulse interference can reach the LEDs in pairs: the second network wire is the grounding conductor. The case of modern LED lighting fixtures with power from the network must be earthed with a separate conductor connected to the ground loop of the building or structure. The devices themselves contain a metal radiator connected to the body to remove the heat generated by the LEDs, and the LEDs used in them have special heat sink leads (see, for example, PM RF No. 119995 or No. 150815). To improve heat dissipation, the electrical insulating layer between these terminals and the radiator is made as thin as possible. In addition, the capacitance between the flat conductors of the printed circuit board supplying power to the LEDs and its grounded metal base or radiator, to which it is attached with the possibility of thermal contact, is significant. For these reasons, the total capacitance between the LEDs and the ground is sufficient to pass a short-pulse interference current, which is dangerous for LEDs, through the circuit: “a wire connecting the rectifier directly to the network — an open pair of rectifier diodes — LEDs and PCB conductors — the capacitance distributed between them on a grounded radiator - grounding conductor. "

The purpose and technical result of the proposed utility model is to increase the reliability of protection of the LED device from impulse noise, both switching nature and caused by lightning discharges coming from the mains.

The specified goal and technical result is achieved by the fact that in the LED light device powered by an alternating current main, containing a bridge diode rectifier connected to the network through a barrier choke connected in series to one of the network wires, a shunt capacitor connected directly to the mains, and a smoothing capacitor connected in parallel to the rectifier on the side of the rectified voltage, as well as LEDs, a surge choke is additionally introduced, which is switched on after to the second network cable.

In addition, both chokes of the LED light fixture are made on a common magnetic circuit (ferromagnetic core).

In addition, the smoothing capacitor of the LED light fixture is connected in parallel to the rectifier on the rectified voltage side and is made of two capacitors connected in series, the connection point of which is grounded.

In addition, the capacitors of the LED light fixture constituting the smoothing capacitor, connected in parallel to the rectifier on the rectified voltage side, have a common housing.

In addition, in parallel to each of the capacitors of the LED light fixture that make up the smoothing capacitor, connected in parallel to the rectifier on the rectified voltage side, capacitors of a thousand or more times smaller capacitance are connected.

Due to the introduction of an additional inductor at the input of the power source included in the second network wire, the impulse noise cannot penetrate into it and through it to the LEDs through any of the supply network wires. This achieves the claimed technical result.

Due to the implementation on the common ferromagnetic core of the windings of chokes in both network wires, the cost of the proposed power source exceeds the cost of a source with one choke by a very small amount, which facilitates and accelerates the practical implementation of the proposed noise-resistant source.

Due to the implementation of a capacitor connected in parallel to the rectifier on the rectified voltage side, from two capacitors connected in series, the connection point of which is grounded, the reverse voltage on the LEDs decreases due to the flow of high-frequency pulse interference current through the capacitance between the LEDs and the grounded radiator. This increases the reliability of protection of LEDs from impulse noise.

Due to the fact that the capacitors that make up the smoothing capacitor have a common housing (the so-called two-section capacitor), the inductance of the capacitor is reduced and its ability to absorb short-pulse interference energy is increased.

Due to the fact that in parallel to each of the capacitors that make up the smoothing capacitor, capacitors are connected that are a thousand or more times smaller in capacitance, efficient energy absorption of the high-frequency component of the short-pulse interference is achieved.

The essence of the utility model is illustrated by drawings.

In FIG. 1 shows a circuit diagram of the proposed LED light fixture with a power source with separate protective chokes.

In FIG. 2 shows a circuit diagram of the proposed LED light device with a power source with protective chokes having a common ferromagnetic core, and with additional elements that improve noise immunity and increase the reliability of the source.

Where:

1 - half-wave single-phase rectifier,

2, 3 - conductors,

4, 5 - throttles,

6 - LEDs of the light device,

7 - protective capacitor,

8 - resistor, with a resistance of the order of units of Ohms,

9 - distributed containers,

10 - the base of the printed circuit board,

11 - smoothing capacitor

12, 13 - capacitors having a common housing,

14 - connection point of capacitors 12, 13,

15 - ground loop

16 - a resistor with a resistance of the order of units of Ohms,

17, 18 - capacitors, the capacity of which is at least 1000 times less than the capacity of the capacitors 12, 13.

The proposed LED light device with a power source of increased reliability (Fig. 1) contains a half-wave single-phase rectifier 1, the input of which is connected by conductors 2 and 3 to the AC network through protective reactors 4 and 5, and the output (side of the rectified voltage) is connected to the LEDs 6 of the light instrument. The LEDs 6, as shown in the drawings, can be assembled in series and the light fixture can contain several such circuits connected in parallel. Directly at the input of the source, a protective capacitor 7 of relatively small capacitance not exceeding a few microfarads is connected in parallel with it. To limit the current in the circuit of this capacitor, a resistor 8 with a resistance of the order of units of Ohms can be connected in series with it (Fig. 2). Due to the installation of protective chokes in the gap of both network wires 2 and 3, the operability and noise immunity of the light device does not depend on which of the wires is linear and which is neutral. This is an important advantage of the proposed source, since when installing lighting devices it is far from always possible or willing to establish which of the network wires is linear and which is neutral.

To reduce the cost and simplify the design of the power supply, the inductor windings can be placed on a common ferromagnetic core, as shown in FIG. 2.

The dotted line in the drawing shows the distributed capacitance 9 between the LEDs 6 and the grounded conductive radiator (base of the printed circuit board) 10 connected to the housing of the light device.

In parallel to the output of the rectifier 1, a smoothing capacitor 11 is connected, consisting of two capacitors 12 and 13 connected in series. It serves to smooth the rectified voltage. The capacitor 11 can be made two-piece, when the capacitors 12 and 13 have a common housing (Fig. 2), or the capacitors 12 and 13 can be made in separate housings (Fig. 1). From the point of view of smoothing purposes, this is one capacitor with a capacity half that of each of its constituent capacitors 12 and 13. The connection point 14 of these capacitors is connected to the device body and, through it, to the ground loop 15 of the building or structure. A two-piece design of the capacitor 12 is preferable, since it has a lower inductance and, therefore, a greater ability to absorb short-pulse interference. The capacitance of the capacitor 11 is selected from the condition of obtaining a sufficient level of smoothing of the ripples of the rectified voltage, but not less than a thousand times the total distributed capacitance 9. To limit the surge of the charging current when the source is turned on, a resistor 16 with a resistance of the order of several ohms can be connected in series with the capacitor 11.

Capacitor 11 must satisfy two conflicting requirements. On the one hand, its capacitance must be large enough to effectively smooth the rectified voltage. On the other hand, its inductance should be small enough to effectively absorb the energy of the short-pulse interference. To eliminate this contradiction, capacitors 17 and 18 are connected in parallel to each of the components of the capacitor 11 of the capacitors 12 and 13, the capacitance of which is at least 1000 times less than the capacitance of the capacitors 12 and 13. Small capacitors, due to their design features, have low inductance bypass the high-frequency component of the interference pulse. A low-frequency suppress capacitors 12 and 13.

The implementation of a smoothing capacitor from two connected in series allows, by grounding the point of their connection, to reduce to almost zero the level of interference and overvoltage applied to the LEDs along the chain "one of the wires 2 or 3 - rectifier diodes 1 - distributed capacitance 9 - ground 15".

The proposed LED light device with a power source operates as follows.

The impulse voltage of interference from the mains can be applied between one of the wires 2 and 3 and ground, and can be applied between these wires. In the second case, part of the energy of the interference pulse, mainly its low-frequency component, is absorbed by the capacitor 7. The propagation of high-frequency interference components towards the rectifier 1 is prevented by the blocking inductors 4 and 5. Due to the fact that the inductors are installed in the gap (sequentially) of each of the wires 2 and 3, protection is provided regardless of how the interference came, on one wire or both.

In power supplies of powerful lighting devices, inductors 4 and 5, as well as rectifier diodes 1 designed for high currents, have noticeable intrinsic capacitances through which the most high-frequency component of interference pulses falls on the sides of the rectified voltage, that is, on the LEDs. In this case, part of the interference energy can be absorbed by the smoothing capacitor 11, and its most high-frequency component is absorbed by low-inductance capacitors 17 and 18.

Protection of the proposed power supply with increased reliability is enough to meet the requirements of GOST R 51317.4.5-99 "Electromagnetic compatibility of technical equipment. Resistance to microsecond pulsed noise of high energy requirements and test methods, "according to which luminaires must withstand test microsecond pulses of high energy, the amplitude of which, depending on the purpose of the lamp, can be in the range from 0.5 to 4 kV.

Claims (5)

1. An LED light device with an increased reliability power supply, comprising a diode rectifier connected to the network through a choke connected in series to one of the network wires, a capacitor connected directly to the mains supply, and a capacitor connected in parallel to the rectifier on the rectified voltage side, and also LEDs, characterized in that it further comprises a choke, connected in series in the second network wire. 2. LED light device with a power source of high reliability according to claim 1, characterized in that both chokes are made on a common magnetic circuit. 3. An LED light fixture with an increased reliability power supply according to claim 1, characterized in that the capacitor connected in parallel to the rectifier on the rectified voltage side consists of two capacitors connected in series, the connection point of which is grounded. 4. The LED light device with a high-reliability power supply according to claim 3, characterized in that the capacitors connected in parallel to the rectifier on the rectified voltage side have a common housing. 5. An LED light fixture with a high-reliability power supply according to claim 3, characterized in that in parallel with each of the capacitors connected in parallel with the rectifier on the side of the rectified voltage, capacitors are connected, a thousand times or more less capacity.

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