AC drive circuit for LED lamp

Abstract

The present invention provides an AC driving circuit for an LED lamp tube, wherein two switch tubes Q1 and Q2 are connected in series, and two capacitors C1 and C2 are connected in series between the drain of the switch tube Q1 and the source of the switch tube Q2. A series choke coil L1 and a lamp tube Lamp1 are connected in parallel between a node a where the switch tubes Q1 and Q2 are connected and a connection node b where the series capacitors C1 and C2 are connected, and a series choke coil L3 and a lamp tube Lamp2 are connected in parallel, and the gates of the switch tubes Q1 and Q2 are controlled by a control signal, and are turned on and off in turn, so that the capacitors C1 and C2 discharge the lamp tubes Lamp1 and Lamp2 in turn, and the LED lamps of the lamp tubes Lamp1 and Lamp2 are lit. The present invention has the advantage that, due to the existence of the choke coil L2, the present invention can always maintain a complete output AC circuit during operation, and will not cause abnormal operation of the product due to damage to the LED load or an open circuit state when the contact is poor. This design avoids interference from the external environment as much as possible, and ensures the normal operation of the LED lighting system.

Description

Technical Field

[0001] The invention relates to a driving power supply for an LED lamp, and in particular to an AC driving power supply circuit for an LED lamp. Background Art

[0002] LED has the characteristics of energy saving, green environmental protection, long life, small size, rich colors, flexible combination, strong vibration resistance, no noise, etc. LED lamps are currently one of the recognized green light sources and have fully penetrated the market. With the popularization of LED technology, LED lamps have greatly enriched the lighting market and made the functions of lamps more diversified. LED lamps driven by electronic ballasts are common in the market.

[0003] The stable operation of LED lighting systems is becoming more and more important. If we install LED lamps (drivers and LED loads) due to human error, the LED load and the driver are not in firm contact, or because they are installed in a specific use environment and place (garages and other places prone to vibration), in this abnormal working environment, a driver circuit that can ensure the normal and stable operation of the LED lighting system will be very important.

[0004] When existing LED lighting driver products encounter special circumstances where the LED load tube is damaged or has poor contact, the product will enter an abnormal working state or even cause the product to fail. Summary of the invention

[0005] In order to solve the problem that the existing LED lamp has unstable load and cannot work normally, the present invention provides an AC driving circuit for an LED lamp tube. The technical solution of the present invention is that two switch tubes Q1 and Q2 are connected in series, and two capacitors C1 and C2 are connected in series between the drain of the switch tube Q1 and the source of the switch tube Q2. The connection point between the drain of the switch tube Q1 and the capacitor C1 is connected to the positive electrode of the DC voltage. The LED lamp tube and the choke are connected in parallel between the node a where the switch tubes Q1 and Q2 are connected in series and the node b where the capacitors C1 and C2 are connected in series. The parallel LED lamp tubes are connected in series with the choke. The gates of the switch tubes Q1 and Q2 are controlled by a control signal to be turned on and off in turn, so that the capacitors C1 and C2 discharge the LED lamp tube in turn, and the LED lamp is driven by AC.

[0006] There are at least two LED lamp tubes with choke coils connected in series.

[0007] The advantage of the present invention is that due to the presence of the parallel choke coil, the present invention can always maintain a complete output AC circuit during operation, and will not cause abnormal operation of the product due to damage to the LED load or an open circuit state due to poor contact. This design avoids interference from the external environment as much as possible and ensures the normal operation of the LED lighting system. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Attached Figure 1 The block diagram of the present invention having two LED lamp tubes

[0009] Attached Figure 2 The block diagram of the present invention having four LED lamp tubes

[0010] Attached Figure 3 This is an example of a chip IC controlling a switch tube.

[0011] Description of the numbers in the figure:

[0012] Input signal (i.e. AC / DC conversion circuit); 2-half-bridge drive circuit; DETAILED DESCRIPTION

[0013] Please see attached Figure 3 , two switch tubes Q1 and Q2 are connected in series, two capacitors C1 and C2 are connected in series between the drain of the switch tube Q1 and the source of the switch tube Q2, the connection point between the drain of the switch tube Q1 and the capacitor C1 is connected to the positive electrode Vin+ of the DC voltage, and the LED lamp tube Lamp1 and the choke coil L2 are connected in parallel between the node a where the switch tubes Q1 and Q2 are connected in series and the node b where the capacitors C1 and C2 are connected in series. The parallel LED lamp tube Lamp1 is connected in series with the choke coil L1, and the gates of the switch tubes Q1 and Q2 are controlled by the control signal IC to be turned on and off in turn, so that the capacitors C1 and C2 discharge the LED lamp tube in turn, and the LED lamp is driven by AC.

[0014] Please see attached Figure 1 As shown, the present invention has two switch tubes Q1 and Q2 connected in series, two capacitors C1 and C2 are connected in series between the drain of the switch tube Q1 and the source of the switch tube Q2, the connection point between the drain of the switch tube Q1 and the capacitor C1 is connected to the positive electrode Vin+ of the DC voltage, LED lamp tubes Lamp1 and Lamp2 and a choke coil L2 are connected in parallel between a node a where the switch tubes Q1 and Q2 are connected in series and a node b where the capacitors C1 and C2 are connected in series, the parallel LED lamp tubes Lamp1 and Lamp2 are connected in series with choke coils L1 and L3, the gates of the switch tubes Q1 and Q2 are controlled by a chip IC control signal, and are turned on and off in turn, so that the capacitors C1 and C2 discharge the LED lamp tube in turn, and the AC-driven LED lamp is implemented.

[0015] When Q1 is turned on and Q2 is turned off, the current flows through: Vin+➡Q1➡a➡ L1, Lamp1, L3, Lamp2, L2➡C2-(ground).

[0016] When Q2 is on and Q1 is off, the current flows through: C2➡Lamp1, L1, Lamp2, L3, L2➡a➡Q2 source➡(ground).

[0017] In the above working process, the current flows in opposite directions. Q1 and Q2 are turned on for half a cycle respectively. When Q1 is turned on, the energy on capacitor C1 is released to loads Lamp1 and Lamp2, and when Q2 is turned on, the energy on capacitor C2 is released to loads Lamp1 and Lamp2. In this way, when Q1 and Q2 are turned on in turn, AC power is obtained at both ends of the load. By changing the switching frequency of the switch tube, the desired output AC frequency can be obtained. During the entire operation of this product, the choke coil L2 is always involved in the work, that is, even if Lamp1 or Lamp2 is replaced due to application requirements, there is no possibility of open circuit, so a complete AC circuit can always be maintained to ensure that the LED lighting system works normally. Please refer to the attached Figure 2 As shown in the figure, there are four LED lamps Lamp1, Lamp2, Lamp3, Lamp4 and a choke coil L5 in parallel. When the lamps Lamp1 and Lamp2 are damaged and S3 is disconnected, the lamps Lamp3 and Lamp4 work normally. Or the lamps Lamp1, Lamp2, Lamp3, Lamp4 are all damaged and S3 and S6 are disconnected, the circuit 2 still works normally.

[0018] Attached Figure 3 This is an embodiment diagram of IC using chip L6574D to control the operation of switch tubes Q1 and Q2. In the figure, the input signal circuit outputs a DC high voltage power supply Vin to the chip IC through resistor R1, and the chip IC outputs a 26KHz--90KHz AC signal for Q1 and Q2 to work.

Claims

1. An AC driving circuit for an LED lamp, characterized in that: Two switch tubes Q1 and Q2 are connected in series. Two capacitors C1 and C2 are connected in series between the drain of the switch tube Q1 and the source of the switch tube Q2. The connection point between the drain of the switch tube Q1 and the capacitor C1 is connected to the positive electrode Vin+ of the DC voltage. The LED lamp tube Lamp1 and the choke coil L2 are connected in parallel between the node a where the switch tubes Q1 and Q2 are connected in series and the node b where the capacitors C1 and C2 are connected in series. The parallel LED lamp tube Lamp1 is connected in series with the choke coil L1. The gates of the switch tubes Q1 and Q2 are controlled by the control signal IC to be turned on and off in turn, so that the capacitors C1 and C2 discharge the LED lamp tube in turn, thereby implementing AC driving of the LED lamp.

2. An AC driving circuit for an LED lamp tube according to claim 1, characterized in that: There are at least two LED lamp tubes with choke coils connected in series.

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