CN202679728U - A non-isolated critical self-excited LED drive power supply - Google Patents

Abstract

The utility model discloses a non-isolated critical self-excited LED driving power supply, comprising an input end, a starting and oscillation module, a protection module, a positive feedback and current balancing module and an output end. The input end is connected to the starting and oscillation module, the starting and oscillation module is connected to the output end through the positive feedback and current balancing module, and the protection module is connected between the starting and oscillation module and the positive feedback and current balancing module. Since discrete component design is adopted, the utility model has a simple structure and low cost. The positive feedback and current balancing module can enable the utility model to be used to drive different LED loads, and the utility model has good adaptability. In addition, the utility model has the advantages of low heat generation, easy debugging and detection, etc., and therefore has good application prospects.

Description

A non-isolated critical self-excited LED drive power supply

technical field

The utility model relates to the technical field of LED lighting, in particular to a non-isolated critical self-excited LED drive power supply.

Background technique

In today's advocacy of green energy saving, LED light-emitting products, which are the future development trend of the lighting field, are entering our lives, but many factors hinder its rapid popularization. One of the important reasons is the lack of low-cost, high-performance drive power.

The status of the existing LED power supply is as follows: low-cost "power supply" generally adopts resistance-capacitance step-down and current-limiting, which completely obliterates the energy-saving advantages of LEDs, and the light intensity will change with the input voltage; Low-power power supplies such as light bulbs generally adopt its exciting and flyback structure. Although the application of primary-side feedback technology reduces the manufacturing cost of the power supply to a certain extent, the low efficiency still makes the power supply itself generate heat; T8 and other strips A large number of other exciting non-isolated power supplies are used in lamps, which have good efficiency but high cost; high-power lamps generally use forward power supplies, and the manufacturing cost is high; in addition, the above-mentioned several power supplies cannot simultaneously achieve the following in the development and production process Points: low development cost, single-mode stylized design; the same circuit structure is used for output power from small to large; device parameters are unchanged or only slightly changed in different applications.

In view of the above-mentioned problems and defects, it is necessary to propose new improvements to the existing LED driving power supply.

Utility model content

In view of the above problems, the utility model provides a novel non-isolated critical self-excited LED drive power supply with low cost, simple structure and strong versatility.

The technical scheme that the utility model adopts for solving its technical problem is:

A non-isolated critical self-excited LED drive power supply, characterized by comprising:

input terminal for initial direct current input;

The start-up and oscillation module receives the current at the input terminal for the start-up of its own circuit, and provides the oscillation current to the subsequent modules;

The protection module is used to protect the starting and oscillation modules;

The positive feedback and current sharing module receives the oscillating current to generate oscillation, and provides positive feedback voltage to the starting and oscillating module and ensures the balance of the output current;

and an output terminal for obtaining the required direct current;

The input terminal is connected to the starting and oscillation module, the starting and oscillation module is connected to the output terminal through the positive feedback and current sharing module, and the protection module is connected between the starting and oscillation module and the positive feedback and current sharing module.

As a further improvement to the above scheme, the starting and oscillating module includes resistors R1, R2, R3 and R4, a switch tube Q1, a transistor Q2, and a capacitor C1. One end of the resistor R1 is connected to the input terminal (1) DC positive pole and the switch tube The drain of Q1, the other end of which is connected to the gate of the switching tube Q1 and the resistor R2, the other end of the resistor R2 is connected to the collector of the triode Q2, the emitter of the triode Q2 is connected to the protection module, and the bases are respectively The resistor R3 and the capacitor C1 are connected, and the source of the switching tube Q1 is connected to the other end of the resistor R3 and then connected to the other end of the capacitor C1 through the resistor R4.

Further, the positive feedback and current sharing module includes a diode D3, resistors R5 and R6, a capacitor C2, a voltage regulator tube D4 and a transformer T1, the cathode of the diode D3 is connected to the protection module after being connected to one end of the capacitor C2, and the diode D3 The positive pole is connected to the other end of the capacitor C2 and then connected to the resistor R5. The other end of the resistor R5 is respectively connected to the secondary end of the transformer T1 and the negative pole of the voltage regulator tube D4. The positive pole of the voltage regulator tube D4 is connected to the base of the transistor Q2 through the resistor R6. The other end of the secondary of the transformer T1 is connected to the starting and oscillation module, and the primary of the transformer T1 is connected to the output end.

In addition, the protection module is a voltage regulator tube D2, the anode of the voltage regulator tube D2 is connected to the emitter of the triode Q2 and then grounded together, and its cathode is connected to the cathode of the diode D3.

The beneficial effects of the utility model are: the utility model is used as a non-isolated critical self-excited LED drive power supply, including an input terminal, a start-up and oscillation module, a protection module, a positive feedback and a current equalization module, an output terminal, an input terminal and a start-up and the oscillation module, the start and oscillation module is connected to the output terminal through the positive feedback and current sharing module, and the protection module is connected between the start and oscillation module and the positive feedback and current sharing module. The structure is simple and the cost is low, the positive feedback and current sharing module can make the utility model can be used to drive different LED loads, and its adaptability is good. In addition, the utility model also has the advantages of small heat generation, easy debugging and detection, etc., so it has good performance Application prospect.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described:

Fig. 1 is a schematic structural diagram of the utility model circuit principle;

Fig. 2 is a structural schematic diagram of another improved embodiment of the utility model.

Detailed ways

Referring to Figure 1, a non-isolated critical self-excited LED drive power supply includes an input terminal 1 for initial DC input; a start-up and oscillation module 2 that receives the current from input terminal 1 for the start-up of its own circuit and provides an oscillating current For subsequent modules; protection module 3, used to protect the starting and oscillating module 2; positive feedback and current sharing module 4, receiving the oscillating current to generate oscillations, and providing positive feedback voltage and ensuring output current to the starting and oscillating module 2 and the output terminal 5 is used to obtain the required direct current; the input terminal 1 is connected to the starting and oscillating module 2, and the starting and oscillating module 2 is connected to the output terminal 5 through the positive feedback and current equalizing module 4, so that The protection module 3 is connected between the starting and oscillating module 2 and the positive feedback and current sharing module 4. The starting and oscillating module 2 includes resistors R1, R2, R3 and R4, a switch tube Q1, a transistor Q2, a capacitor C1, and the resistor R1 One end is connected to the DC positive pole of the input terminal 1 and the drain of the switch tube Q1, and the other end is connected to the gate of the switch tube Q1 and the resistor R2, and the other end of the resistor R2 is connected to the collector of the transistor Q2, and the transistor Q2 The emitter is connected to the protection module 3, and its base is respectively connected to the resistor R3 and the capacitor C1. The source of the switching tube Q1 is connected to the other end of the resistor R3 and then connected to the other end of the capacitor C1 through the resistor R4. Positive feedback and equalization The flow module 4 includes a diode D3, resistors R5 and R6, a capacitor C2, a voltage regulator tube D4 and a transformer T1. The cathode of the diode D3 is connected to one end of the capacitor C2 and then connected to the protection module 3, and the anode of the diode D3 is connected to the other end of the capacitor C2. After being connected, connect resistor R5, the other end of resistor R5 is respectively connected with one end of the secondary side of transformer T1 and the negative pole of voltage regulator tube D4, the positive pole of the voltage regulator tube D4 is connected with the base of the transistor Q2 through resistor R6, the transformer The other end of the secondary side of T1 is connected to the start-up and oscillation module 2, the primary side of the transformer T1 is connected to the output terminal 5, and the protection module 3 is a voltage regulator tube D2, and the anode of the voltage regulator tube D2 is connected to the emitter of the triode Q2. It is grounded, and its cathode is connected to the cathode of diode D3.

Specifically, according to Figure 1, the circuit is composed of discrete components, mainly including five major parts, and the functions of the components of each part are as follows, input: electrolytic capacitor CD1 is used for input filtering; start-up and oscillation: Q1 is a switch tube. Marked as a MOS tube, it can also be a triode or a composite transistor, etc. Q2 is a turn-off control transistor, R1 is a start-up resistor, R2 is a Q1 gate current-limiting resistor, R3 is a Q2 base current-limiting resistor, R4 is a load current-limiting resistor, C1 For anti-interference capacitance; protection: D2 is a voltage regulator tube used to prevent Q1 gate breakdown; positive feedback and current sharing: the secondary combination of C2, D3, R5 and T1 provides positive feedback voltage for the gate of Q1, D4 Combination with R6 is used to offset the output current change caused by the change of the switch off time caused by the change of input voltage and positive feedback voltage; output: T1 primary output current to the load, CD2 is used for filtering, D1 is the freewheeling diode when Q1 is turned off . The specific working process is as follows: Start-up stage: After the power is turned on, the current passes through R1 to charge the gate junction capacitance of Q1, making Q1 conduction, the conduction current supplies power to the load through R4, T1 primary, OUT+, and the current passes through OUT- Form a loop; at this time, the primary potential of T1 is positive at pin 1 and negative at pin 4, and the secondary induction is positive at pin 5 and negative at pin 8. Pin 5 forms positive feedback to the gate of Q1 through R5, C2, D3, and R2, so that Q1 is rapidly saturated; saturated conduction stage: after Q1 is saturated and conducted, the current flowing through the primary of T1 continues to rise, and the voltage across R4 also rises continuously. When the voltage across R4 rises to the conduction voltage of the base of Q2, Q2 is turned on , the gate voltage of Q1 decreases, Q1 exits saturation, and the current flowing through the source of Q1 begins to drop, which reverses the primary potential of T1, which in turn causes the secondary voltage of T1 to reverse (that is, pin 5 is negative and pin 8 is positive), and the gate of Q1 Under the action of positive feedback, the voltage is pulled down instantly, Q1 is cut off, and D1 is turned on; inductance discharge stage: after Q1 is cut off, the energy stored in the primary of T1 begins to release to the load, and the released current gradually decreases from the maximum value at the moment Q1 is cut off; When the current decreases to 0, because there is still a small amount of residual energy that cannot be fully released, T1 will generate magnetic shock, and then the voltage of T1 will reverse, so that the pin 5 of T1 will output a positive voltage, causing Q1 to turn on. Under the action of positive feedback, it is rapidly saturated, thus starting a new oscillation cycle.

Fig. 2 is a structural schematic diagram of another improved embodiment, and the circuit structure is basically the same.

The preferred implementation of the present utility model has been specifically described above. Of course, the present utility model can also adopt forms different from the above-mentioned embodiments, and similar fields, and these do not constitute any limitation to the present embodiment. Equivalent transformations or corresponding changes made by personnel without violating the spirit of the utility model should fall within the protection scope of the utility model.

Claims (4)

1. critical auto-excitation type LED driving power of non-isolation is characterized in that comprising:

Input (1) is used for initial direct current input;

Start and concussion module (2), the electric current that receives input (1) is used for the startup of self circuit, and provides the concussion electric current to subsequent module;

Protection module (3) is for the protection of starting and concussion module (2);

Positive feedback and current-sharing module (4) receive described concussion electric current and produce concussion, and the equilibrium of positive feedback voltage being provided and guaranteeing output current for described startup and concussion module (2);

And output (5), be used for obtaining required direct current;

Described input (1) links to each other with startup and concussion module (2); described startup and concussion module (2) link to each other with output (5) by positive feedback and current-sharing module (4), and described protection module (3) is connected between startup and concussion module (2) and positive feedback and the current-sharing module (4).

2. the critical auto-excitation type LED driving power of a kind of non-isolation according to claim 1; it is characterized in that: described startup and concussion module (2) comprise resistance R 1; R2; R3 and R4; switching tube Q1; triode Q2; capacitor C 1; described resistance R 1 one ends connect the drain electrode of input (1) DC positive pole and switching tube Q1; grid and the resistance R 2 of its other end connecting valve pipe Q1; the other end of described resistance R 2 links to each other with the collector electrode of triode Q2; the emitter of described triode Q2 links to each other with protection module (3); its base stage is contact resistance R3 and capacitor C 1 respectively, links to each other with the other end of capacitor C 1 by resistance R 4 after the source electrode of described switching tube Q1 links to each other with the other end of resistance R 3.

3. the critical auto-excitation type LED driving power of a kind of non-isolation according to claim 1; it is characterized in that: described positive feedback and current-sharing module (4) comprise diode D3; resistance R 5; R6; capacitor C 2; voltage-stabiliser tube D4 and transformer T1; the negative pole of described diode D3 be connected to protection module (3) after capacitor C 2 one ends link to each other; contact resistance R5 after the positive pole of diode D3 links to each other with capacitor C 2 other ends; the other end of resistance R 5 links to each other with voltage-stabiliser tube D4 negative pole with an end of T1 level of transformer respectively; described voltage-stabiliser tube D4 is anodal to link to each other with the base stage of described triode Q2 by resistance R 6; the other end of T1 level of described transformer is connected to and starts and concussion module (2), and the elementary and output (5) of transformer T1 links to each other.

4. the critical auto-excitation type LED driving power of a kind of non-isolation according to claim 1; it is characterized in that: described protection module (3) is voltage-stabiliser tube D2; common ground after the positive pole of described voltage-stabiliser tube D2 links to each other with the emitter of triode Q2, its negative pole links to each other with the negative pole of diode D3.

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