CN211744812U

CN211744812U - Self-excited BUCK driving power supply for illumination

Info

Publication number: CN211744812U
Application number: CN202020133992.6U
Authority: CN
Inventors: 王小军
Original assignee: Shenzhen Letron Power Lighting Equipment Co ltd
Current assignee: Shenzhen Li chuangpu Power Supply Technology Co., Ltd
Priority date: 2020-01-20
Filing date: 2020-01-20
Publication date: 2020-10-23
Anticipated expiration: 2030-01-20

Abstract

The utility model discloses a self-excited BUCK drive power supply for illumination, including switch drive circuit, oscillating circuit, LC filter circuit and sampling control circuit, switch drive circuit's output is connected with oscillating circuit's input, oscillating circuit's output is connected with LC filter circuit's input, LC filter circuit's output is connected with sampling control circuit's input, sampling control circuit's output is connected with oscillating circuit's input. The utility model discloses regard VCC power as input voltage, through oscillation circuit's high-low level control switch drive circuit's break-make time, realize the charge-discharge time of inductance, change output voltage's average value, then filter through LC filter circuit, carry out voltage and current to output voltage through sampling control circuit and carry out feedback control, make its automatic adjustment output required voltage; the whole circuit has simple structure, low energy loss and high voltage conversion efficiency.

Description

Self-excited BUCK driving power supply for illumination

Technical Field

The utility model relates to a drive power supply field especially relates to a self-excited BUCK drive power supply for illumination.

Background

In the prior art, the pulse width modulation technology controls an analog circuit by controlling on and off of a switch of an inverter circuit. The output waveform of the pwm technique is a series of pulses of equal size to replace the desired waveform, for example, a sine wave, i.e., the equivalent voltage of the series of pulses is a sine wave, and the output pulses are as smooth as possible and have fewer low harmonics. According to different requirements, the width of each pulse can be correspondingly adjusted to change the equivalent value of the output voltage or the output frequency, so that the control of the analog circuit is achieved. The self-excited transformer driving power supply means that when a primary coil of a transformer is excited by a direct current pulse, a secondary coil of the transformer has power output. One of the biggest disadvantages of the self-excited driving power supply is that at the moment of switching off, due to electromagnetic induction, a large back electromotive force is generated in the primary and secondary coils, and the switching element is easily broken down, so that a coil needs to be added to absorb the energy of the back electromotive force during design, and the added coil circuit not only complicates the whole circuit, but also causes energy waste, thereby affecting the conversion efficiency of the driving power supply.

Accordingly, the prior art is deficient and needs improvement.

SUMMERY OF THE UTILITY MODEL

The utility model discloses the technical problem that will solve is: the self-excited BUCK driving power supply for lighting is simple in circuit structure, high in conversion efficiency and capable of achieving the current-limiting protection effect.

The technical scheme of the utility model as follows: a self-excited BUCK driving power supply for lighting comprises a switch driving circuit, an oscillating circuit, an LC filter circuit and a sampling control circuit, wherein the output end of the switch driving circuit is connected with the input end of the oscillating circuit, the output end of the oscillating circuit is connected with the input end of the LC filter circuit, the output end of the LC filter circuit is connected with the input end of the sampling control circuit, and the output end of the sampling control circuit is connected with the input end of the oscillating circuit;

the switch driving circuit comprises a VCC power supply, a first triode, a second triode and a first resistor, wherein the VCC power supply is connected with an emitting electrode of the first triode, a collecting electrode of the first triode is connected with an LC filter circuit, a base electrode of the first triode is connected with a collecting electrode of the second triode through the first resistor, an emitting electrode of the second triode is grounded, and a base electrode of the second triode is connected with an oscillating circuit;

the LC filter circuit comprises a diode, an inductor, a first capacitor, a second resistor and a third resistor, wherein a collector of the first triode is respectively connected with a first end of the inductor and a negative electrode of the diode, a second end of the inductor is respectively connected with first ends of the first capacitor, the second resistor and the third resistor, and a second end of the diode is respectively connected with second ends of the first capacitor, the second resistor and the third resistor;

the sampling control circuit comprises a first voltage comparator, a second voltage comparator, a third triode and a fourth triode, wherein the non-inverting input end of the first voltage comparator is connected with a third resistor, the non-inverting input end of the second voltage comparator is connected with the second end of an inductor, the inverting input ends of the first voltage comparator and the second voltage comparator are respectively connected with a VCC power supply, the output end of the first voltage comparator is connected with the base electrode of the third triode, the output end of the second voltage comparator is connected with the base electrode of the fourth triode, the emitter electrode of the third triode is connected with the emitter electrode of the fourth triode, and the collector electrode of the third triode is connected with the collector electrode of the fourth triode and then connected with the input end of the oscillating circuit;

the oscillating circuit comprises a timer, a fourth resistor, a fifth resistor and a second capacitor, a first pin of the timer is connected with a collector of a third triode, a second pin of the timer is connected with a VCC power supply through the fourth resistor, a third pin of the timer is connected with the fourth pin in parallel and then sequentially connected with the VCC power supply through the fifth resistor and the fourth resistor, the fifth pin of the timer is connected with an emitter of the third triode and a sixth pin of the timer and grounded through the second capacitor, and a seventh pin of the timer is connected with a base of a second diode.

By adopting the technical scheme, in the self-excited BUCK driving power supply for lighting, the oscillating circuit further comprises a sixth resistor, and the non-inverting input end of the second voltage comparator is connected with the second end of the inductor through the sixth resistor.

By adopting the technical scheme, in the self-excited BUCK driving power supply for illumination, the VCC power supply is a 12V power supply.

By adopting the technical scheme, in the self-excited BUCK driving power supply for lighting, the reference voltage output by the seventh pin of the timer is 5V.

With the above technical solutions, in the self-excited BUCK driving power supply for lighting, the duty ratio K of the oscillation circuit is 80%, and the oscillation frequency f of the oscillation circuit is 28 KHZ.

By adopting the technical scheme, in the self-excited BUCK driving power supply for lighting, the type of the timer is LM555 CM.

By adopting the technical proposal, the utility model discloses regard VCC power as input voltage, through oscillation circuit's high-low level control switch drive circuit's break-make time, realize the charge-discharge time of inductance, change output voltage's average value, then filter through LC filter circuit, carry out voltage and current feedback control to output voltage through sampling control circuit again, make its automatic adjustment output required voltage; the whole circuit has simple structure, low energy loss and high voltage conversion efficiency, and can be popularized and used.

Drawings

Fig. 1 is a circuit diagram of the present invention.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

As shown in FIG. 1, the self-excited BUCK driving power supply for lighting comprises a switch driving circuit 1, an oscillating circuit 2, an LC filter circuit 3 and a sampling control circuit 4, wherein an output end of the switch driving circuit 1 is connected with an input end of the oscillating circuit 2, an output end of the oscillating circuit 2 is connected with an input end of the LC filter circuit 3, an output end of the LC filter circuit 3 is connected with an input end of the sampling control circuit 4, and an output end of the sampling control circuit 4 is connected with an input end of the oscillating circuit 2. In this embodiment, the switch driving circuit 1 can be used as an input voltage, the on-off time of the switch driving circuit 1 is controlled by the high and low levels of the oscillating circuit 2, the charging and discharging time of the inductor is realized, the average value of the output voltage is changed, filtering is performed by the LC filter circuit 3, and the output voltage is subjected to voltage and current feedback control by the sampling control circuit 4, so that the output voltage can be automatically adjusted and output a required voltage.

Switch drive circuit 1 includes VCC power, first triode Q1, second triode Q2 and first resistance R1, the VCC power is connected with first triode Q1's projecting pole, first triode Q1's collecting electrode is connected with LC filter circuit 3, first triode Q1's base is connected with second triode Q2's collecting electrode through first resistance R1, second triode Q2's projecting pole ground connection, second triode Q2's base is connected with oscillating circuit 2. In this embodiment, the VCC power supply is used as an input power supply, the first transistor Q1 is a high power transistor, the second transistor Q2 is a medium power transistor, the first transistor Q1 and the second transistor Q2 can achieve amplification and switching, the high power transistor is usually driven by a large current, and the first transistor Q1 is driven by the second transistor Q2 in an amplification manner.

The LC filter circuit 3 includes a diode D, an inductor L, a first capacitor C1, a second resistor R2 and a third resistor R3, a collector of the first triode Q1 is connected to a first end of the inductor L and a cathode of the diode D, a second end of the inductor L and a second end of the diode D are connected to first ends of the first capacitor C1, the second resistor R2 and the third resistor R3, and a second end of the diode D is connected to second ends of the first capacitor C1, the second resistor R2 and the third resistor R3. In this embodiment, when the switch driving circuit 1 is turned off, the inductor L is discharged, and the diode D and the second resistor R2 form a current storage loop. Because inductance L is the energy storage component, the electric current can not break suddenly, realizes step-down constant voltage power supply through the charge-discharge of inductance L, has the filtering effect simultaneously. The first capacitor C1 and the inductor L form an LC filter circuit, which has a ripple suppression effect. The third resistor R3 acts as a load resistor.

The sampling control circuit 4 comprises a first voltage comparator U1, a second voltage comparator U2, a third triode Q3 and a fourth triode Q4, wherein a non-inverting input end of the first voltage comparator U1 is connected with a third resistor R3, a non-inverting input end of the second voltage comparator U2 is connected with a second end of an inductor L, inverting input ends of the first voltage comparator U1 and the second voltage comparator U2 are respectively connected with a VCC power supply, an output end of the first voltage comparator U1 is connected with a base of the third triode Q3, an output end of the second voltage comparator U2 is connected with a base of the fourth triode Q4, an emitter of the third triode Q3 is connected with an emitter of the fourth triode Q4, and a collector of the third triode Q3 is connected with a collector of the fourth triode Q4 and then connected with an input end of the oscillating circuit 2.

The oscillating circuit 2 comprises a timer U0, a fourth resistor R4, a fifth resistor R5 and a second capacitor C2, a first pin of the timer U0 is connected with a collector of a third triode Q3, a second pin of the timer U0 is connected with a VCC power supply through the fourth resistor R4, a third pin of the timer U0 is connected with the fourth pin in parallel and then sequentially connected with the VCC power supply through a fifth resistor R5 and a fourth resistor R4, a fifth pin of the timer U0 is connected with an emitter of the third triode Q3 and a sixth pin of the timer U0 and grounded through the second capacitor C2, and a seventh pin of the timer U0 is connected with a base of a second diode Q2.

Preferably, the oscillating circuit 2 further includes a sixth resistor R6, and the non-inverting input terminal of the second voltage comparator U2 is connected to the second terminal of the inductor L through the sixth resistor R6.

The sampling control circuit 4 has the functions of automatic voltage adjustment and current-limiting control. The voltage automatic adjustment function refers to that: the first voltage comparator U1 can set a certain reference voltage, the sampling voltage at the output end of the LC filter circuit 3 is compared with the reference voltage, when the sampling voltage is greater than the reference voltage, the output end of the first voltage comparator U1 outputs a high level, the base of the third triode Q3 receives the high level and is turned on, and the collector of the third triode Q3 outputs a low level to the oscillation circuit 2, thereby realizing feedback control; similarly, when the sampling voltage is smaller than the reference voltage, the output end of the first voltage comparator U1 outputs a low level, the base of the third transistor Q3 receives the low level and is cut off, the collector of the third transistor Q3 outputs a high level to the oscillating circuit 2, and the output voltage of the oscillating circuit 2 rises to realize feedback control. The current limiting control function means: the sixth resistor R6 may convert the current output by the sampling control circuit 4 into a voltage, and compare the voltage with the feedback voltage set by the second voltage comparator U2, and when the voltage converted by the sixth resistor R6 is greater than the feedback voltage, the fourth transistor Q4 is turned on, thereby implementing current-limiting protection. The feedback mechanism of the current limit control is the same as the mechanism of the voltage automatic adjustment.

In this embodiment, when the VCC power supply is turned on, the third pin of the timer U0 outputs a high level, and the VCC power supply charges the first capacitor C1, and when the voltage on the first capacitor C1 reaches the reference voltage of the seventh pin of the timer U0, the voltage on the first capacitor C1 is discharged, and the third pin of the timer U0 changes from a high level to a low level. When the voltage of the first capacitor C1 drops to the value of the sampled voltage, the third pin of the timer U0 goes high again, while the VCC power supply charges the first capacitor C1 again. This is repeated to form an oscillation.

Preferably, the VCC power supply is a 12V power supply.

Preferably, the reference voltage output from the seventh pin of the timer U0 is 5V. That is, in this embodiment, the driving power supply can convert the 12V voltage into the 5V voltage.

Preferably, the duty ratio K of the oscillation circuit 2 is 80%, and the oscillation frequency f of the oscillation circuit 2 is 28 KHZ. Since the present driving power supply can convert the 12V voltage into the 5V voltage, the duty ratio of the on time of the timer U0 in one period cannot be smaller than 5/12, and in order to make the circuit have a certain margin, in the present embodiment, the duty ratio of the oscillation circuit 2 is 80%, and the oscillation frequency f of the oscillation circuit 2 is 28 KHZ.

Preferably, the timer U0 is LM555 CM.

The above description is only exemplary of the present invention and should not be construed as limiting the present invention, and any modifications, equivalents and improvements made within the spirit and principles of the present invention are intended to be included within the scope of the present invention.

Claims

1. An auto-excited BUCK driving power supply for lighting, comprising: the sampling circuit comprises a switch driving circuit, an oscillating circuit, an LC filter circuit and a sampling control circuit, wherein the output end of the switch driving circuit is connected with the input end of the oscillating circuit, the output end of the oscillating circuit is connected with the input end of the LC filter circuit, the output end of the LC filter circuit is connected with the input end of the sampling control circuit, and the output end of the sampling control circuit is connected with the input end of the oscillating circuit;

2. The self-excited BUCK driving power supply for lighting according to claim 1, wherein: the oscillating circuit further comprises a sixth resistor, and the non-inverting input end of the second voltage comparator is connected with the second end of the inductor through the sixth resistor.

3. The self-excited BUCK driving power supply for lighting according to claim 1, wherein: the VCC power supply is a 12V power supply.

4. The self-excited BUCK driving power supply for lighting according to claim 3, wherein: and the reference voltage output by the seventh pin of the timer is 5V.

5. The self-excited BUCK driving power supply for lighting according to claim 4, wherein: the duty ratio K of the oscillating circuit is 80%, and the oscillating frequency f of the oscillating circuit is 28 KHZ.

6. The self-excited BUCK driving power supply for lighting according to any one of claims 1 to 5, wherein: the model of the timer is LM555 CM.