CN109788603B - Power supply circuit and lighting equipment thereof - Google Patents
Power supply circuit and lighting equipment thereof Download PDFInfo
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- CN109788603B CN109788603B CN201711131319.8A CN201711131319A CN109788603B CN 109788603 B CN109788603 B CN 109788603B CN 201711131319 A CN201711131319 A CN 201711131319A CN 109788603 B CN109788603 B CN 109788603B
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Abstract
The invention discloses a power supply circuit, comprising: a transformer T1, a switching tube Q1, a diode D2 and a feedback circuit; the switching tube Q1 is electrically connected with the primary coil of the transformer T1 to control the current of the primary coil, and the base electrode of the switching tube Q1 is electrically connected with the power input end; the feedback circuit is connected in series between the base electrode of the switch tube Q1 and the output end of the secondary coil of the transformer T1; the diode D2 is connected in series between the secondary winding of the transformer T1 and the load terminal OUT-, wherein the anode of the diode D2 is connected to the load terminal OUT-. The circuit is skillfully designed by utilizing the performance characteristics of electronic components, has simple structure and low cost, does not need auxiliary power supply for a self-oscillation action control circuit, has the advantages of low cost, small volume and weight due to the simplified circuit and the optimized design, and is easy to control the output voltage; in addition, a lighting device adopting the power supply circuit is also disclosed.
Description
Technical Field
The present invention relates to the field of power supply circuits.
Background
The non-constant frequency power supply RCC (Ringing Choke converter) is a self-oscillating pulse converter formed by an intermittent oscillator, and is commonly found in low-cost low-power switching power supplies. At present, overvoltage protection in an RCC circuit is performed in a mode of voltage feedback of a later-stage circuit, the later-stage circuit feeds back a voltage signal to an input circuit through an optocoupler, and a switching tube is arranged between the input circuit and the optocoupler. The on-off of the switching tube is required to correspond to a corresponding voltage value, and when the voltage value fed back is low voltage, the switching tube is in an off state, and the overvoltage protection circuit is not conducted; when the fed back voltage value is high voltage, the switching tube is in a closed state, and the overvoltage protection circuit is conducted; the on-off of overvoltage protection of the circuit is controlled by the on-off of the switching tube.
RCC circuits are gradually applied to the field of LED lighting and used as driving circuits for LED lighting, however, most of RCC switching power supply circuits in the prior art use ICs to perform PWM control on switching transistors, or the existing circuits are too complex, so that the formed RCC switching power supply has a high manufacturing cost.
Disclosure of Invention
The present invention is directed to overcoming at least one of the shortcomings of the prior art described above.
In order to solve the technical problems, the technical scheme of the invention is as follows: a power supply circuit, comprising: a transformer T1, a switching tube Q1, a diode D2 and a feedback circuit;
the switching tube Q1 is electrically connected with the primary coil of the transformer T1 to control the current of the primary coil, and the base electrode of the switching tube Q1 is electrically connected with the power input end;
the feedback circuit is connected in series between the base electrode of the switch tube Q1 and the output end of the secondary coil of the transformer T1;
the diode D2 is connected in series between the secondary winding of the transformer T1 and the load terminal OUT-, wherein the anode of the diode D2 is connected to the load terminal OUT-.
In some embodiments, the feedback circuit includes a capacitor C2 and a resistor R2 in series with the capacitor C2.
When external direct current is input through an input end AC IN, the current flows to the base electrode of the switching tube Q1, at the moment, the triode Q1 is slightly conducted, so that an upper positive and lower negative induction voltage is generated on a winding of the transformer T1 (primary coil), and an upper positive and lower negative voltage is generated on a winding of the transformer T1 (secondary coil); further, the voltage is positively fed back to the switching tube Q1 via a feedback circuit (a feedback circuit composed of a capacitor C2 and a resistor R2), so that the base current of the switching tube Q1 is increased, and the switching tube Q1 is fully turned on until saturation; after the switch tube Q1 is saturated, the current flowing through the winding of the T1 transformer (primary coil) is not changed any more, namely, the current of the inductor (primary coil of the transformer T1) stops changing, and according to the property of the inductor, the primary coil of the transformer T1 generates back electromotive force, at the moment, the winding of the transformer T1 (primary coil) is subjected to positive voltage from top to bottom, so that the transformer T1 (secondary coil) is subjected to positive voltage from top to bottom, the voltage supplies power to a load connected with an OUT-end through a reverse bias diode D2, meanwhile, the power is supplied to an external load along with the back electromotive force, the voltage drops, when the back electromotive force voltage is lower than the conducting voltage of the diode DZ1, the diode DZ1 is closed, so that the power supply to the load is stopped, the switch tube Q1 is restored to the original micro-conducting state from the original saturated state, and the work is circularly performed, and the power is supplied to the external load; the operating state of transistor Q1 changes to: micro-conduction-saturation-cut-off.
The circuit is skillfully designed by utilizing the performance characteristics of electronic components (the inductance characteristic of a voltage device, the conduction voltage limit of a diode, the switching characteristic of a switching tube and the saturation characteristic of the switching tube), has the advantages of simple structure, low manufacturing cost, no auxiliary power supply (only a feedback circuit is needed, PWM control is not needed) of a self-oscillation action control circuit, low cost, small volume and weight effect due to the simplified and optimized design of the circuit, and easy control of output voltage.
In some embodiments, the power supply circuit further includes a resistor R3, the resistor R3 being connected to the emitter of the switching tube Q1. The resistor R3 can protect the switch tube Q1 from large current impact when being opened, and prevent the switch tube Q1 from impact damage caused by the large current.
In some embodiments, the power circuit further includes a current limiting resistor R1, and the current limiting resistor R1 is connected to the base of the switching tube Q1. The current limiting resistor R1 can play a role in stabilizing current and preventing large current from striking the switching tube Q1.
In some embodiments, the power supply circuit further comprises a current reverse bias circuit, and the current reverse bias circuit is connected to the base electrode of the switch tube Q1.
In some embodiments, the current reverse bias circuit includes a zener diode DZ1, an anode of the zener diode DZ1 is connected to an anode of the diode D2, and a cathode of the zener diode DZ1 is connected to a base of the switching tube Q1.
When the transformer T1 generates back electromotive force to supply power to an external load, the current of the base electrode of the switching tube Q1 is shunted by the current reverse bias circuit, so that the base current of the switching tube Q1 is reduced, the switching tube Q1 is rapidly cut off, and the cut-off mobility and reliability of the switching tube Q1 are improved. The voltage-stabilizing diode DZ1 is adopted as a reverse bias circuit device, on one hand, the reverse conduction voltage of the voltage-stabilizing diode DZ1 is smaller, the sensitivity of the current reverse bias circuit is ensured, on the other hand, the voltage-stabilizing diode DZ1 plays a role in stabilizing the output voltage, and the voltage of the voltage-stabilizing diode DZ1 is in direct proportion to the load output voltage in a steady state, so that the voltage-stabilizing of the voltage-stabilizing diode DZ1 determines the magnitude of the output voltage, and in addition, the output voltage can be adjusted by changing the voltage-stabilizing value of the voltage-stabilizing diode D2.
In some embodiments, the power circuit further comprises a capacitor C3, the capacitor C3 being connected to the anode of the diode D2.
The voltage of the winding of the transformer T1 (secondary coil) is determined by the winding turn ratio, and during the saturation period of the switching tube Q1, the winding of the transformer T1 (secondary coil) supplies power to a load through the conducting diode D2, meanwhile, the capacitor C3 is charged, the voltage of the capacitor C3 is positive and negative voltages, the voltage of the capacitor C3 can provide reverse bias voltage for the diode D2, namely, forward voltage is provided for the anode of the diode D2, so that the conducting of the diode D2 is facilitated, and the circuit is facilitated to supply power to the load.
On the other hand, the capacitor C3 can provide voltage for the voltage-stabilizing tube DZ1, when the capacitor C3 is charged to enable the voltage of the capacitor C3 to reach the conducting voltage of the voltage-stabilizing tube DZ1, the base current of the switching tube Q1 loses forward bias current due to the conducting of the voltage-stabilizing tube DZ1, so that the switching tube Q1 enters a cut-off state, and the control purpose is achieved; in addition, the capacitor C3 may also form a rectifying filter circuit together with the diode D2.
In some embodiments, the power supply circuit further includes a rectifying circuit, an output terminal of the rectifying circuit is connected to an input terminal of the transformer T1, and an output terminal of the rectifying circuit is connected to a base electrode of the switching tube Q1. The utility power (alternating current) can be directly input, when the alternating current voltage is input from the external utility power input end AC IN and rectified by the diode D1, the direct current voltage is obtained through the filtering of the capacitor C1, and the direct current voltage enters the power supply circuit to supply power to the load.
In some embodiments, the switching transistor Q1 is an NPN junction transistor or a PNP junction transistor.
The invention also provides a lighting device comprising one or more loads and the power supply circuit, wherein the one or more loads are electrically connected with the load ends OUT-and OUT+ of the power supply circuit, and the power supply circuit is used for the lighting device, so that the cost can be reduced, and the reliability of the circuit can be improved.
Drawings
Fig. 1 is a schematic diagram of a power circuit according to an embodiment of the invention.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the present patent; for the purpose of better illustrating the embodiments, certain elements of the drawings may be omitted, enlarged or reduced and do not represent the actual product dimensions; it will be appreciated by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.
As shown in fig. 1, the power supply circuit of the present embodiment includes: a rectifying circuit 10, a transformer T1, a switching tube Q1, a diode D2, a feedback circuit 20, and a current reverse bias circuit 40;
the rectifying circuit 10 is connected to the transformer T1 and the base of the switching tube Q1 for supplying power, and the switching tube Q1 is electrically connected to the primary winding of the transformer T1 for controlling the current of the primary winding.
The feedback circuit 20 is connected in series between the base of the switching tube Q1 and the output end of the secondary coil of the transformer T1; the diode D2 is connected in series between the secondary coil of the transformer T1 and the load end OUT-, wherein the anode of the diode D2 is connected to the load end OUT-; the current reverse bias circuit 40 is connected to the base of the switching tube Q1, specifically, the current reverse bias circuit 40 includes a zener diode DZ1, the anode of the zener diode DZ1 is connected to the anode of the diode D2, and the cathode of the zener diode DZ1 is connected to the base of the switching tube Q1.
When the AC power supply is used, the commercial power is input into an AC IN end, the alternating voltage is rectified by a diode D1 of the rectifying circuit 10, and the alternating voltage is filtered by a capacitor C1; then obtaining direct current; the current flows to the base electrode of the switching tube Q1 through the resistor R1, the switching tube Q1 is slightly conducted, an upper positive and lower negative induced voltage is generated on the winding of the transformer T1 (primary coil), and an upper positive and lower negative voltage is generated on the winding of the transformer T1 (secondary coil), and the voltage positively feeds back to the switching tube Q1 through the capacitor C2 and the resistor R2 to enable the Q1 to be fully conducted until saturation; after the switch tube Q1 is saturated, the current flowing through the winding of the T1 transformer (primary coil) is not changed any more, namely, the current of the inductor (primary coil of the transformer T1) stops changing, and according to the property of the inductor, the primary coil of the transformer T1 generates back electromotive force, at the moment, the winding of the transformer T1 (primary coil) is subjected to positive voltage from top to bottom, so that the transformer T1 (secondary coil) is subjected to positive voltage from top to bottom, the voltage supplies power to a load connected with an OUT-end through a reverse bias diode D2, and meanwhile, the voltage drops along with the back electromotive force to supply power to an external load, when the back electromotive force voltage is lower than the on voltage of the diode DZ1, the diode DZ1 is closed, so that the power supply to the load is stopped, the switch tube Q1 is recovered from an original saturated state to an original micro-on state, and is enabled to be conducted again, and the power is supplied to the external load in a circulating way; the operating state of transistor Q1 changes to: micro-conduction-saturation-cut-off.
While the transformer T1 generates back electromotive force to supply power to an external load, the current of the base electrode of the switching tube Q1 is shunted by the current reverse bias circuit 30, so that the base current of the switching tube Q1 is reduced, the switching tube Q1 is rapidly cut off, and the cut-off mobility and reliability of the switching tube Q1 are improved. The voltage-stabilizing diode DZ1 is adopted as a reverse bias circuit device, on one hand, the reverse conduction voltage of the voltage-stabilizing diode DZ1 is smaller, the sensitivity of the current reverse bias circuit is ensured, on the other hand, the voltage-stabilizing diode DZ1 plays a role in stabilizing the output voltage, and the voltage of the voltage-stabilizing diode DZ1 is in direct proportion to the load output voltage in a steady state, so that the voltage-stabilizing of the voltage-stabilizing diode DZ1 determines the magnitude of the output voltage, and in addition, the output voltage can be adjusted by changing the voltage-stabilizing value of the voltage-stabilizing diode D2.
Among these, the following schemes are included for feedback circuit 20: the capacitor C2 and the resistor R2 connected in series with the capacitor C2 can be a simple resistor R2, and when the capacitor C2 is adopted, the saturation and the cut-off time of the switching tube Q1 can be changed according to the selection of the parameters of the capacitor C2.
The switching tube Q1 can be an NPN junction triode or a PNP junction triode; as a peripheral circuit of the switching tube Q1, the power supply circuit of the present invention further includes a resistor R3 and a current limiting resistor R1, where the resistor R3 is connected to an emitter of the switching tube Q1, and the current limiting resistor R1 is connected to a base of the switching tube Q1. Wherein, the resistor R3 and the current limiting resistor R1 both play a role of limiting current, and prevent excessive current from striking the switching tube Q1 to damage the switching tube Q1.
In one embodiment, the power supply circuit of the present invention may further include a capacitor C3, where the capacitor C3 is connected to the anode of the diode D2. The voltage of the winding of the transformer T1 (secondary coil) is determined by the winding turn ratio, and during the saturation period of the switching tube Q1, the winding of the transformer T1 (secondary coil) supplies power to a load through the conducting diode D2, meanwhile, the capacitor C3 is charged, the voltage of the capacitor C3 is positive and negative voltages, the voltage of the capacitor C3 can provide reverse bias voltage for the diode D2, namely, forward voltage is provided for the anode of the diode D2, so that the conducting of the diode D2 is facilitated, and the circuit is facilitated to supply power to the load.
On the other hand, the capacitor C3 can provide voltage for the voltage-stabilizing tube DZ1, when the capacitor C3 is charged to enable the voltage of the capacitor C3 to reach the conducting voltage of the voltage-stabilizing tube DZ1, the base current of the switching tube Q1 loses forward bias current due to the conducting of the voltage-stabilizing tube DZ1, so that the switching tube Q1 enters a cut-off state, and the control purpose is achieved; in addition, the capacitor C3 may also form a rectifying filter circuit together with the diode D2.
The circuit of the invention is a skillfully designed circuit by utilizing the performance characteristics of electronic components (the inductance characteristic of a voltage device, the conduction voltage limit of a diode, the switching characteristic of a switching tube and the saturation characteristic thereof), has simple structure and low manufacturing cost, and the self-oscillation action control circuit does not need auxiliary power supply (only needs a feedback circuit and does not need PWM control), so that the circuit is simplified, the optimal design brings the effects of low cost and small volume and weight, and the output voltage is easy to control.
Based on the advantages, the circuit of the technology can be used for the lighting equipment, the lighting equipment further comprises one or more loads, the one or more loads are electrically connected with the load ends OUT-and OUT+ of the power supply circuit, and the power supply circuit is used for the lighting equipment, so that the cost can be reduced, and the reliability of the circuit is improved.
In the drawings, the positional relationship is described for illustrative purposes only and is not to be construed as limiting the present patent; it is to be understood that the above examples of the present invention are provided by way of illustration only and not by way of limitation of the embodiments of the present invention. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. Any modification, equivalent replacement, improvement, etc. which come within the spirit and principles of the invention are desired to be protected by the following claims.
Claims (7)
1. A power supply circuit, comprising: a transformer T1, a switching tube Q1, a diode D2 and a feedback circuit (20);
the switching tube Q1 is electrically connected with the primary coil of the transformer T1 to control the current of the primary coil, and the base electrode of the switching tube Q1 is electrically connected with the power input end;
the feedback circuit (20) is connected in series between the base electrode of the switch tube Q1 and the output end of the secondary coil of the transformer T1;
the diode D2 is connected in series between the secondary coil of the transformer T1 and a load end OUT-, wherein the anode of the diode D2 is connected to the load end OUT-;
the power supply circuit further comprises a resistor R3, and the resistor R3 is connected to the emitter of the switching tube Q1;
the power supply circuit further comprises a current limiting resistor R1, and the current limiting resistor R1 is connected to the base electrode of the switching tube Q1;
the power supply circuit further comprises a current reverse bias circuit (40), and the current reverse bias circuit (40) is connected to the base electrode of the switching tube Q1.
2. The power supply circuit according to claim 1, characterized in that the feedback circuit (20) comprises a capacitor C2 and a resistor R2 connected in series with the capacitor C2.
3. The power supply circuit according to claim 1, wherein the current reverse bias circuit (40) includes a zener diode DZ1, an anode of the zener diode DZ1 is connected to an anode of the diode D2, and a cathode of the zener diode DZ1 is connected to a base of the switching tube Q1.
4. The power supply circuit according to claim 1, further comprising a capacitor C3, the capacitor C3 being connected to the anode of the diode D2.
5. The power supply circuit according to any one of claims 1 to 4, further comprising a rectifying circuit (10), wherein an output end of the rectifying circuit (10) is connected to an input end of the transformer T1, and an output end of the rectifying circuit (10) is connected to a base electrode of the switching tube Q1.
6. The power supply circuit according to any one of claims 1 to 4, wherein the switching transistor Q1 is an NPN junction transistor or a PNP junction transistor.
7. A lighting device comprising one or more loads and a power supply circuit as claimed in any one of claims 1 to 6, said one or more loads being electrically connected to load terminals OUT-and out+ of said power supply circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711131319.8A CN109788603B (en) | 2017-11-15 | 2017-11-15 | Power supply circuit and lighting equipment thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711131319.8A CN109788603B (en) | 2017-11-15 | 2017-11-15 | Power supply circuit and lighting equipment thereof |
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| Publication Number | Publication Date |
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| CN109788603A CN109788603A (en) | 2019-05-21 |
| CN109788603B true CN109788603B (en) | 2024-03-15 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201711131319.8A Active CN109788603B (en) | 2017-11-15 | 2017-11-15 | Power supply circuit and lighting equipment thereof |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202652073U (en) * | 2012-03-31 | 2013-01-02 | 深圳市高斯宝电气技术有限公司 | Switch power supply circuit capable of realizing output constant current control |
| CN103326325A (en) * | 2013-06-05 | 2013-09-25 | 广州凯盛电子科技有限公司 | Short-circuit and low-voltage protective circuit of output of switching power source |
| WO2017020189A1 (en) * | 2015-07-31 | 2017-02-09 | 常州明石晶电科技有限公司 | Switching mode power supply |
| CN106686826A (en) * | 2017-02-09 | 2017-05-17 | 中山自信照明科技有限公司 | Led lighting power supply circuit |
| CN207692089U (en) * | 2017-11-15 | 2018-08-03 | 广东金莱特电器股份有限公司 | Power circuit and its lighting apparatus |
-
2017
- 2017-11-15 CN CN201711131319.8A patent/CN109788603B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN202652073U (en) * | 2012-03-31 | 2013-01-02 | 深圳市高斯宝电气技术有限公司 | Switch power supply circuit capable of realizing output constant current control |
| CN103326325A (en) * | 2013-06-05 | 2013-09-25 | 广州凯盛电子科技有限公司 | Short-circuit and low-voltage protective circuit of output of switching power source |
| WO2017020189A1 (en) * | 2015-07-31 | 2017-02-09 | 常州明石晶电科技有限公司 | Switching mode power supply |
| CN106686826A (en) * | 2017-02-09 | 2017-05-17 | 中山自信照明科技有限公司 | Led lighting power supply circuit |
| CN207692089U (en) * | 2017-11-15 | 2018-08-03 | 广东金莱特电器股份有限公司 | Power circuit and its lighting apparatus |
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| CN109788603A (en) | 2019-05-21 |
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