CN204721240U - A kind of switching power circuit - Google Patents

A kind of switching power circuit Download PDF

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Publication number
CN204721240U
CN204721240U CN201520449968.2U CN201520449968U CN204721240U CN 204721240 U CN204721240 U CN 204721240U CN 201520449968 U CN201520449968 U CN 201520449968U CN 204721240 U CN204721240 U CN 204721240U
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resistance
output
circuit
filter
transformer
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CN201520449968.2U
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李轻
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Guangzhou Shiyuan Electronics Thecnology Co Ltd
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Guangzhou Shiyuan Electronics Thecnology Co Ltd
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Abstract

The utility model discloses a kind of switching power circuit, comprise input rectifying filter circuit, transformer, output rectifier and filter and voltage stabilizing circuit; The output of input rectifying filter circuit is connected to the first end of the armature winding of transformer; Output rectifier and filter is connected across the two ends of the secondary winding of transformer; Voltage stabilizing circuit comprises voltage stabilizing didoe, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, triode and PWM chip; The negative pole of voltage stabilizing didoe connects output rectifier and filter, and positive pole is by the first grounding through resistance and via the second resistance, the 3rd grounding through resistance; The base stage of triode is connected to the junction of the second resistance and the 3rd resistance, grounded emitter by the 4th resistance, collector electrode is connected to the feedback signal input terminal of PWM chip; The control signal output of PWM chip is connected to the second end of the armature winding of transformer.The utility model, under the constant prerequisite of switching power circuit performance, simplifies circuit, reduces costs.

Description

A kind of switching power circuit
Technical field
The utility model relates to electronic circuit technology field, is specifically related to a kind of switching power circuit.
Background technology
At present, Switching Power Supply is widely used.The voltage stabilizing loop of isolation reverse exciting switching voltage regulator directly controls the stable of output voltage, is related to Switching Power Supply safety, has the voltage stabilizing loop of high stability, can effectively prevent output voltage too high or too low, thus ensure the personal safety of people.
Existing Switching Power Supply typical circuit generally selects three terminal regulator TL431 to carry out regulated output voltage.This typical circuit comprises: output rectifier and filter, output voltage sample circuit, inner three terminal regulator a reference source, three terminal regulator external feedback network, optocoupler.As shown in Figure 1, R3, C2 form three terminal regulator external feedback network; R4, R5 form output voltage sample circuit; D2, C3 form output rectifier and filter.When output voltage rises, R4, R5 mid-point voltage rises, now IC3 internal adjustment 3 pin voltage drop makes the electric current flowing through IC2 (1,2) pin increase, the FB pin voltage drop of PWM IC is made through IC2 internal adjustment, thus the output of PWM IC drives duty ratio to reduce, output voltage declines, and reaches the stable object exported.When output voltage declines, R4, R5 mid-point voltage declines, now IC3 internal adjustment 3 pin voltage rise makes the electric current flowing through IC2 (1,2) pin reduce, the FB pin voltage rise of PWMIC is made through IC2 internal adjustment, thus the output of PWM IC drives duty ratio to increase, output voltage rises, and reaches the stable object exported.The weak point of above-mentioned switching power circuit is adopted to be: components and parts used are more, circuit more complicated, and fault in production rate is high, and components and parts cost is high.
Utility model content
The purpose of this utility model, be there is to overcome switching power circuit of the prior art the shortcoming that components and parts are more, circuit more complicated, failure rate are high, cost is high, a kind of switching power circuit is provided, ensureing under the prerequisite that switching power circuit performance is constant, simplify circuit, reduce costs.
For solving above technical problem, the utility model embodiment provides a kind of switching power circuit, comprises input rectifying filter circuit, transformer, output rectifier and filter and voltage stabilizing circuit; The output of described input rectifying filter circuit is connected to the first end of the armature winding of described transformer; Described output rectifier and filter is connected across the two ends of the secondary winding of described transformer; Described voltage stabilizing circuit comprises voltage stabilizing didoe, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, triode and PWM chip; The negative pole of described voltage stabilizing didoe connects the positive voltage output end of described output rectifier and filter, and positive pole is by described first grounding through resistance; The positive pole of described voltage stabilizing didoe is via described second resistance, described 3rd grounding through resistance; The base stage of described triode is connected to the junction of described second resistance and the 3rd resistance by described 4th resistance; The grounded emitter of described triode; The collector electrode of described triode is connected to the feedback signal input terminal of described PWM chip; The control signal output of described PWM chip is connected to the second end of the armature winding of described transformer.
Preferably, described output rectifier and filter comprises the first diode and the first electric capacity; The two ends of the secondary winding of described transformer are connected across after described first diode and the first capacitances in series; The junction of described first diode and described first electric capacity forms the positive voltage output end of described output rectifier and filter; The minus earth of described first electric capacity also forms the negative voltage output of described output rectifier and filter.
Preferably, described voltage stabilizing circuit also comprises the second electric capacity; The first end of described second electric capacity connects the collector electrode of described triode; Second end of described second electric capacity is connected to the junction of described second resistance and the 3rd resistance.
Preferably, the control signal output of described PWM chip is connected to the second end of the armature winding of described transformer by field effect transistor and the second diode; Wherein, the grid of described field effect transistor is connected to the control signal output of described PWM chip, the source ground of described field effect transistor; The drain electrode of described field effect transistor is connected to the second end of the armature winding of described transformer; The positive pole of described second diode is connected to the source electrode of described field effect transistor, and the negative pole of described second diode is connected to the drain electrode of described field effect transistor.
Compared to prior art, the beneficial effect of a kind of switching power circuit of the present utility model is: prior art needs three-terminal voltage-stabilizing source and photoelectrical coupler, circuit is more complicated, and cost is higher, the utility model embodiment then just can realize the function of feedback regulation by a voltage stabilizing didoe, triode, several resistance and a PWM chip, circuit structure is simple, and cost is low, failure rate is low, therefore has the beneficial effect simplifying circuit structure and reduce costs.The utility model is mainly used in isolation inverse-excitation type switch power-supply circuit, as household appliances Switching Power Supply product.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of switching power circuit of prior art;
Fig. 2 is the structural representation of the switching power circuit of the utility model embodiment.
Embodiment
Below in conjunction with the accompanying drawing in the utility model embodiment, be clearly and completely described the technical scheme in the utility model embodiment, obviously, described embodiment is only the utility model part embodiment, instead of whole embodiments.Based on the embodiment in the utility model, those of ordinary skill in the art are not making the every other embodiment obtained under creative work prerequisite, all belong to the scope of the utility model protection.
Refer to Fig. 2, it is the structural representation of the switching power circuit of the utility model embodiment.The switching power circuit of the utility model embodiment comprises input rectifying filter circuit 11, transformer TR, output rectifier and filter 12 and voltage stabilizing circuit 13; The output of described input rectifying filter circuit 11 is connected to the first end of the armature winding of described transformer TR; Described output rectifier and filter 12 is connected across the two ends of the secondary winding of described transformer TR;
Described voltage stabilizing circuit 13 comprises voltage stabilizing didoe ZD, the first resistance R1, the second resistance R2, the 3rd resistance R3, the 4th resistance R4, triode Q and PWM chip IC; The negative pole of described voltage stabilizing didoe ZD connects the positive voltage output end Vout+ of described output rectifier and filter 12, and positive pole is by described first resistance R1 ground connection; The positive pole of described voltage stabilizing didoe ZD is via described second resistance R2, described 3rd resistance R3 ground connection; The base stage of described triode Q is connected to the junction of described second resistance R2 and the 3rd resistance R3 by described 4th resistance R4; The grounded emitter of described triode Q; The collector electrode of described triode Q is connected to the feedback signal input terminal of described PWM chip IC; The control signal output of described PWM chip IC is connected to the second end of the armature winding of described transformer TR.Wherein, described voltage stabilizing didoe ZD is used for clamping action, and described first resistance R1 is used for current limliting; Described second resistance R2 and the 3rd resistance R3 forms bleeder circuit, and the voltage got is input to the base stage of described triode Q by described 4th resistance R4; Described 4th resistance R4 is used for biased.
Preferably, described output rectifier and filter 12 comprises the first diode D1 and the first electric capacity C1; Described first diode D1 and the first electric capacity C1 is connected across the two ends of the secondary winding of described transformer TR after connecting; The junction of described first diode D1 and described first electric capacity C1 forms the positive voltage output end Vout+ of described output rectifier and filter 12; The minus earth of described first electric capacity C1 also forms the negative voltage output of described output rectifier and filter 12.
Preferably, described voltage stabilizing circuit 13 also comprises the second electric capacity C2; The first end of described second electric capacity C2 connects the collector electrode of described triode Q; Second end of described second electric capacity C2 is connected to the junction of described second resistance R2 and the 3rd resistance R3.Described second electric capacity C2 is for the formation of AC regeneration.
Preferably, the control signal output of described PWM chip IC is connected to the second end of the armature winding of described transformer TR by field effect transistor FET and the second diode D2; Wherein, the grid of described field effect transistor FET is connected to the control signal output of described PWM chip IC, the source ground of described field effect transistor FET; The drain electrode of described field effect transistor FET is connected to the second end of the armature winding of described transformer TR; The positive pole of described second diode D2 is connected to the source electrode of described field effect transistor FET, and the negative pole of described second diode D2 is connected to the drain electrode of described field effect transistor FET.
The operation principle of the utility model embodiment is as follows: alternating current obtains level and smooth DC power supply after input rectifying filter circuit 11, transformer TR and output rectifier and filter 12.When output voltage rises, the terminal voltage of described first resistance R1 rises, the voltage obtained through described second resistance R2 and described 3rd resistance R3 dividing potential drop also rises, namely the electric current being input to the base stage of described triode Q also increases, voltage between the collector and emitter of described triode Q increases, and the feedback voltage being input to described PWM chip IC increases, and described PWM chip IC output duty cycle is reduced, reduce output voltage, thus reach the object of regulated output voltage.When output voltage declines, the terminal voltage of described first resistance R1 declines, the voltage obtained through described second resistance R2 and described 3rd resistance R3 dividing potential drop also declines, namely the electric current being input to the base stage of described triode Q also reduces, voltage between the collector and emitter of described triode Q reduces, and the feedback voltage being input to described PWM chip IC reduces, and described PWM chip IC output duty cycle is increased, increase output voltage, thus reach the object of regulated output voltage.
Compared to prior art, the beneficial effect of a kind of switching power circuit of the utility model embodiment is: prior art needs three-terminal voltage-stabilizing source and photoelectrical coupler, circuit is more complicated, and cost is higher, the utility model embodiment then just can realize the function of feedback regulation by a voltage stabilizing didoe ZD, triode Q, several resistance and a PWM chip IC, circuit structure is simple, cost is low, failure rate is low, therefore has the beneficial effect simplifying circuit structure and reduce costs.The utility model is mainly used in isolation inverse-excitation type switch power-supply circuit, as household appliances Switching Power Supply product.
The above is preferred implementation of the present utility model; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the utility model principle; can also make some improvements and modifications, these improvements and modifications are also considered as protection range of the present utility model.

Claims (4)

1. a switching power circuit, is characterized in that, comprises input rectifying filter circuit, transformer, output rectifier and filter and voltage stabilizing circuit; The output of described input rectifying filter circuit is connected to the first end of the armature winding of described transformer; Described output rectifier and filter is connected across the two ends of the secondary winding of described transformer; Described voltage stabilizing circuit comprises voltage stabilizing didoe, the first resistance, the second resistance, the 3rd resistance, the 4th resistance, triode and PWM chip; The negative pole of described voltage stabilizing didoe connects the positive voltage output end of described output rectifier and filter, and positive pole is by described first grounding through resistance; The positive pole of described voltage stabilizing didoe is via described second resistance, described 3rd grounding through resistance; The base stage of described triode is connected to the junction of described second resistance and the 3rd resistance by described 4th resistance; The grounded emitter of described triode; The collector electrode of described triode is connected to the feedback signal input terminal of described PWM chip; The control signal output of described PWM chip is connected to the second end of the armature winding of described transformer.
2. switching power circuit as claimed in claim 1, it is characterized in that, described output rectifier and filter comprises the first diode and the first electric capacity; The two ends of the secondary winding of described transformer are connected across after described first diode and the first capacitances in series; The junction of described first diode and described first electric capacity forms the positive voltage output end of described output rectifier and filter; The minus earth of described first electric capacity also forms the negative voltage output of described output rectifier and filter.
3. switching power circuit as claimed in claim 1 or 2, it is characterized in that, described voltage stabilizing circuit also comprises the second electric capacity; The first end of described second electric capacity connects the collector electrode of described triode; Second end of described second electric capacity is connected to the junction of described second resistance and the 3rd resistance.
4. switching power circuit as claimed in claim 3, it is characterized in that, the control signal output of described PWM chip is connected to the second end of the armature winding of described transformer by field effect transistor and the second diode; Wherein, the grid of described field effect transistor is connected to the control signal output of described PWM chip, the source ground of described field effect transistor; The drain electrode of described field effect transistor is connected to the second end of the armature winding of described transformer; The positive pole of described second diode is connected to the source electrode of described field effect transistor, and the negative pole of described second diode is connected to the drain electrode of described field effect transistor.
CN201520449968.2U 2015-06-25 2015-06-25 A kind of switching power circuit Active CN204721240U (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105375435A (en) * 2015-11-30 2016-03-02 深圳市中电电力技术股份有限公司 Self-power protection device and self-power protection device on the basis of power and tripping induction of three-phase current

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105375435A (en) * 2015-11-30 2016-03-02 深圳市中电电力技术股份有限公司 Self-power protection device and self-power protection device on the basis of power and tripping induction of three-phase current
CN105375435B (en) * 2015-11-30 2018-06-26 深圳市中电电力技术股份有限公司 Electricity and the Self-power protective device and system of tripping are taken based on three-phase current sensing

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