CN108574416B - Self-excited push-pull type conversion circuit - Google Patents

Self-excited push-pull type conversion circuit Download PDF

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Publication number
CN108574416B
CN108574416B CN201710145717.9A CN201710145717A CN108574416B CN 108574416 B CN108574416 B CN 108574416B CN 201710145717 A CN201710145717 A CN 201710145717A CN 108574416 B CN108574416 B CN 108574416B
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transistor
terminal
winding
resistor
pull type
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CN108574416A (en
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陈政鸿
李聪贤
黄昱豪
高志明
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Minmax Technology Co Ltd
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Minmax Technology Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/337—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only in push-pull configuration

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

A self-excited push-pull type conversion circuit comprises a push-pull type circuit unit, a first resistor and a second resistor, wherein the push-pull type circuit unit comprises a first transistor and a second transistor, input impedances are respectively arranged between the control ends and the grounding ends of the first transistor and the second transistor, the first resistor is connected in parallel with the input impedance of the first transistor, and the second resistor is connected in parallel with the input impedance of the second transistor; by the parallel circuit structure, the equivalent input total impedance of the first transistor and the second transistor can be reduced by ohm's law left-hand evidence, and further can be established at a definite action point, so that the first transistor and the second transistor can be rapidly switched between a saturation region and a cut-off region.

Description

Self-excited push-pull type conversion circuit
Technical Field
The present invention relates to a dc-dc converter circuit, and more particularly to an improved self-excited push-pull converter circuit.
Background
The conventional Self-excited Push-Pull Converter (Self-Oscillating Push-Pull Converter) includes, for example, a typical Royer circuit or a typical Jensen circuit, which mainly includes two transistors and a transformer. The two transistors can be Bipolar Junction Transistors (BJTs), bases of the two transistors are electrically connected to an input terminal through two auxiliary windings in the transformer, and collectors of the two transistors are connected to the primary winding of the transformer. It should be noted that even though the two transistors have the same model, the electrical characteristics of the two transistors are not completely the same; thus, the transistor often has a difference that causes the transistor to enter different operation regions.
In brief, in an initial stage, the input end provides an input power source, the input power source provides a starting power source to the two transistors by using a starting circuit structure, because the electrical characteristics of the two transistors are not completely the same, any transistor between the two transistors can easily enter a saturation region from the initial state first due to the relationship of the electrical characteristics, and the other transistor is forced to enter a cut-off region from the initial state. Then, according to the hysteresis curve characteristic in the magnetic component of the transformer, through the left evidence of Gauss law, the transistor in the original saturation region is inverted by the polarity of the iron core, so that the state is converted into a cut-off region, the transistor in the original cut-off region is converted into the saturation region, and so on, the two transistors enter a switch region, namely alternately enter the saturation region or the cut-off region respectively; its entry into the switching region causes the transistor to switch, thereby achieving a self-oscillating frequency.
For the conventional self-excited push-pull type converting circuit, whether any transistor can quickly establish an action point to enter a switch region or not by virtue of the transformer design can be used as one of references for evaluating the conventional self-excited push-pull type converting circuit, and if the state transition time is shorter and more definite, the electric action characteristic and the efficiency are better.
In order to shorten the transition time of the transistor, the conventional method can increase the starting power, and the transistor can establish a correct operating point by designing higher starting power so that the transistor can rapidly enter a switching region (i.e. a saturation region or a cut-off region) rather than an active region, but the difference of the electrical characteristics of the existing two transistors and passive components has the difference of the transistor operating region at the crossing position of the active region and the saturation region or the cut-off region, so that the difference of the electrical operating characteristics exists; however, improving this difference will enhance the transistor driving capability so that it does not fall in the dim zone region, but with the enhancement of the start-up power, it will also be accompanied by an increase in the line-normal power loss, relatively reducing the power conversion efficiency.
Disclosure of Invention
The main objective of the present invention is to provide a self-excited push-pull type switching circuit, which allows the transistor to fall on the correct operation region and quickly enter the saturation region, and can maintain a certain level of power conversion efficiency.
The self-excited push-pull type conversion circuit of the present invention comprises:
a push-pull type circuit unit, comprising:
an input terminal;
a first transistor having a power terminal, a ground terminal and a control terminal;
a second transistor having a power terminal, a ground terminal and a control terminal; and
a transformer, comprising:
a primary side comprising a first winding connected between the input terminal and a power supply terminal of the first transistor and a second winding connected between the input terminal and a power supply terminal of the second transistor; and
an auxiliary side including a first auxiliary winding and a second auxiliary winding corresponding to the first winding and the second winding, respectively, the first auxiliary winding being connected between the input terminal and the control terminal of the first transistor, the second auxiliary winding being connected between the input terminal and the control terminal of the second transistor;
a first resistor connected between the control terminal of the first transistor and the ground terminal; and
and the second resistor is connected between the control end of the second transistor and the grounding end.
The first auxiliary winding is connected with the second auxiliary winding, and a connection node of the first auxiliary winding and the second auxiliary winding is connected with the input end through a starting circuit.
The first winding is connected with the second winding, and the connection node of the first winding and the second winding is connected with the input end.
Wherein the resistance values of the first resistor and the second resistor are more than 1k ohm and less than 510k ohm.
The first transistor and the second transistor are bipolar junction transistors, the power source terminal is a collector terminal, the ground terminal is an emitter terminal, and the control terminal is a base terminal.
According to the self-excited push-pull conversion circuit of the present invention, input impedances are respectively provided between the control terminals and the ground terminals of the first transistor and the second transistor, and the first resistor is connected in parallel to the input impedance of the first transistor, and the second resistor is connected in parallel to the input impedance of the second transistor. Therefore, by the parallel circuit architecture, the total input impedance of the first transistor and the second transistor is reduced, and the state transition time of the first transistor and the second transistor entering a saturation region is further shortened; moreover, compared with the prior art, the invention changes the structure of the existing self-excited push-pull type conversion circuit by the design configuration of the first resistor and the second resistor, so the invention can correctly and quickly establish an action point without enhancing a starting power supply, can achieve the effects of shortening the state transition time and preventing the transistor from entering a fuzzy working area, can not cause the circuit action characteristic to generate difference and increase the circuit normal electric energy loss, and ensures the electrical characteristic and the power supply conversion efficiency of the self-excited push-pull type conversion circuit.
Drawings
Fig. 1 is a circuit diagram of an embodiment of a self-excited push-pull type conversion circuit of the present invention.
Fig. 2 is a schematic circuit diagram of a push-pull type circuit unit of the self-excited push-pull type conversion circuit of the present invention.
Fig. 3 is a schematic diagram of the connection of the input impedance of the first transistor and the first resistor in parallel in the self-excited push-pull type conversion circuit of the present invention.
Fig. 4 is a schematic diagram of the connection between the equivalent input impedance of the small signal model of the first transistor and the first resistor of the self-excited push-pull conversion circuit of the present invention.
Wherein, the reference numbers:
100 input terminal 101 output terminal
11 primary side 111 first winding
112 secondary side of the second winding 12
13 auxiliary side 131 first auxiliary winding
132 second auxiliary winding 20 output circuit
30 starting circuit
Q1A first transistor Q2Second transistor
R1First resistor R2Second resistor
T transformer VinInput voltage
VoutOutput voltage
Detailed Description
Referring to fig. 1 and fig. 2, the self-excited push-pull conversion circuit of the present invention includes a push-pull circuit unit, a first resistor R1And a second resistor R2. The push-pull type circuit unit may be a typical self-excited push-pull type circuit, such as a typical Royer circuit or a typical Jensen circuit. In the embodiment of the invention, the push-pull circuit unit includes an input terminal 100, a first transistor Q1A second transistor Q2And a transformer T.
The first transistor Q1And the second transistor Q2Can be three-terminal control components, each of which comprises a power terminal, a ground terminal and a control terminal1And the second transistor Q1May be, but not limited to, a Bipolar Junction Transistor (BJT), the power source terminal is a Collector terminal (C), the ground terminal is an Emitter terminal (Emitter, E), and the control terminal is a Base terminal (Base, B). Note that even the first transistor Q1And the second transistor Q2The same type, the first transistor Q1And the second transistor Q2Are not exactly the same in quality and characteristics.
The transformer T includes a primary side 11, a secondary side 12 and an auxiliary side 13.
The primary side 11 comprises a first winding 111 and a second winding 112, the first winding 111 being connected to the input terminal 100 and the first transistor Q1Between the power supply terminals (collector terminals), the second winding 112 is connected between the input terminal 100 and the second transistor Q2As shown in fig. 2, the first winding 111 is connected to the second winding 112, and the connection node of the first winding 111 and the second winding 112 is connected to the input terminal 100.
The winding of the secondary side 12 is provided for connection to an output circuit 20, which outputs powerWay 20 to one output power supply VoutAfter rectification and filtering, the output voltage V is provided to the outside through an output terminal 101outTo a load.
The auxiliary side 13 includes a first auxiliary winding 131 and a second auxiliary winding 132, the first auxiliary winding 131 corresponds to the first winding 111 and generates a first induced voltage according to the first winding 111, the second auxiliary winding 132 corresponds to the second winding 112 and generates a second induced voltage according to the second winding 112, wherein the polarity of the first induced voltage is opposite to the polarity of the second induced voltage. The first auxiliary winding 131 is connected between the input terminal 100 and the first transistor Q1Between the control terminal (base terminal) of the second transistor Q, the second auxiliary winding 132 is connected between the input terminal 100 and the second transistor Q2Between the control terminals (base terminals). As shown in fig. 2, the first auxiliary winding 131 is connected to the second auxiliary winding 132, and a connection node of the first auxiliary winding 131 and the second auxiliary winding 132 is connected to the input terminal 100 through a start line 30.
The first resistor R1Is connected to the first transistor Q1Between the control terminal (base terminal) and the ground terminal (emitter terminal); the second resistor R2Is connected to the second transistor Q2Between the control terminal (base terminal) and the ground terminal (emitter terminal). Wherein the first resistor R1And the second resistor R2The resistance value of (b) may be 1k ohm (Ω) or more and 510k ohm (Ω) or less.
The push-pull circuit unit of the present invention operates in a self-excited operation mechanism, the principle of which is common knowledge in the art of the present invention, and briefly, in an initial stage, the input terminal 100 provides an input voltage VinThe input voltage VinIs supplied to the first transistor Q via the start-up line 301And the second transistor Q2Because of the first transistor Q1And the second transistor Q2The electrical characteristics are not exactly the same, so that one transistor is easier to enter the saturation region from the initial state, and the other transistor is forced to enter the cut-off region from the initial state. For example, from the first crystalTransistor Q1Into the saturation region, the second transistor Q2The cut-off region is entered. Then, the first transistor Q is enabled according to the hysteresis curve characteristic of the transformer T itself1Switching from saturation region to cut-off region and allowing the second transistor Q to be turned off2Switching from the cut-off region into the saturation region and so on, the first transistor Q1And the second transistor Q2Alternately entering a saturation region or a cutoff region respectively to achieve the self-excited oscillation frequency action mechanism.
The first transistor Q1And the first resistor R1For example. Referring to fig. 3 and 4, fig. 4 shows the first transistor Q1The small signal model of the first transistor Q1Having an input impedance r between the base terminal B and the emitter terminal EBThe invention uses the first resistor R1The first resistor R1Is connected with the first transistor Q1Between the base terminal B and the emitter terminal E, so that the first resistor R1And the input impedance rBForming a parallel connection.
Thus, the first resistor R1And the first transistor Q1Input impedance r ofBEquivalent input total impedance Z after parallel connectioninIs smaller than the first transistor Q1Input impedance r ofBTherefore, the first transistor Q can be reduced1Equivalent input total impedance ZinThe second transistor Q2And so on, i.e., the second transistor Q2Through the second resistor R2The equivalent input total impedance is reduced. The first transistor Q is not limited to normal temperature or extreme working environment (such as negative 40 degree)1And the second transistor Q2The equivalent input total impedance is reduced and the operating point can be correctly established, so that the first transistor Q can be shortened even if the starting power is not increased1And the second transistor Q2And the conversion time of entering a saturation region can ensure the electrical characteristics and the power conversion efficiency of the self-excited push-pull conversion circuit.
The present invention is capable of other embodiments, and various changes and modifications may be made by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (3)

1. A self-excited push-pull type switching circuit, comprising:
a push-pull type circuit unit, comprising:
an input terminal;
a first transistor having a power terminal, a ground terminal and a control terminal;
a second transistor having a power terminal, a ground terminal and a control terminal; and
a transformer, comprising:
a primary side including a first winding and a second winding, the first winding being connected between the input terminal and a power supply terminal of the first transistor, the second winding being connected between the input terminal and a power supply terminal of the second transistor, the first winding being connected to the second winding, a connection node of the first winding and the second winding being connected to the input terminal; and
an auxiliary side including a first auxiliary winding and a second auxiliary winding corresponding to the first winding and the second winding, respectively, the first auxiliary winding being connected between the input terminal and the control terminal of the first transistor, the second auxiliary winding being connected between the input terminal and the control terminal of the second transistor, the first auxiliary winding being connected to the second auxiliary winding, and a connection node of the first auxiliary winding and the second auxiliary winding being connected to the input terminal through a start-up line;
the first auxiliary winding generates a first induced voltage according to the first winding, the second auxiliary winding generates a second induced voltage according to the second winding, and the polarity of the first induced voltage is opposite to that of the second induced voltage;
a first resistor connected between the control terminal of the first transistor and the ground terminal; and
and the second resistor is connected between the control end of the second transistor and the grounding end.
2. A self-excited push-pull type conversion circuit according to claim 1, wherein the first resistor and the second resistor have resistance values of 1k ohm or more and 510k ohm or less.
3. A self-excited push-pull type conversion circuit as claimed in claim 1 or 2, wherein the first transistor and the second transistor are bipolar junction transistors, the power source terminal is a collector terminal, the ground terminal is an emitter terminal, and the control terminal is a base terminal.
CN201710145717.9A 2017-03-13 2017-03-13 Self-excited push-pull type conversion circuit Active CN108574416B (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004147369A (en) * 2002-10-22 2004-05-20 Nichicon Corp Switching power supply
CN101599698A (en) * 2009-05-19 2009-12-09 广州金升阳科技有限公司 A kind of micro-power DC-DC power supply and manufacture method thereof
WO2014058966A1 (en) * 2012-10-09 2014-04-17 Murata Manufacturing Co., Ltd. Lossless over-current detection circuit for royer oscillators and push-pull converters
CN204392092U (en) * 2015-03-06 2015-06-10 广州市爱浦电子科技有限公司 A kind of transformer is without the self-excitation push-pull circuit of feedback winding
WO2016065223A1 (en) * 2014-10-24 2016-04-28 Murata Manufacturing Co., Ltd. Method of driving fets in saturating self-oscillating push-pull isolated dc-dc converter
CN206533284U (en) * 2017-03-13 2017-09-29 捷拓科技股份有限公司 Auto-excitation type push-pull type change-over circuit

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102299658B (en) * 2011-07-18 2014-11-05 广州金升阳科技有限公司 Self-excited push-pull converter and method to realize push-pull oscillating by using self-excited push-pull converter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2004147369A (en) * 2002-10-22 2004-05-20 Nichicon Corp Switching power supply
CN101599698A (en) * 2009-05-19 2009-12-09 广州金升阳科技有限公司 A kind of micro-power DC-DC power supply and manufacture method thereof
WO2014058966A1 (en) * 2012-10-09 2014-04-17 Murata Manufacturing Co., Ltd. Lossless over-current detection circuit for royer oscillators and push-pull converters
WO2016065223A1 (en) * 2014-10-24 2016-04-28 Murata Manufacturing Co., Ltd. Method of driving fets in saturating self-oscillating push-pull isolated dc-dc converter
CN204392092U (en) * 2015-03-06 2015-06-10 广州市爱浦电子科技有限公司 A kind of transformer is without the self-excitation push-pull circuit of feedback winding
CN206533284U (en) * 2017-03-13 2017-09-29 捷拓科技股份有限公司 Auto-excitation type push-pull type change-over circuit

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