CN104811046A - Switch power supply circuit - Google Patents
Switch power supply circuit Download PDFInfo
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- CN104811046A CN104811046A CN201510208020.2A CN201510208020A CN104811046A CN 104811046 A CN104811046 A CN 104811046A CN 201510208020 A CN201510208020 A CN 201510208020A CN 104811046 A CN104811046 A CN 104811046A
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Abstract
The invention relates to the technical field of drive power supplies and discloses a switch power supply circuit. The switch power supply circuit comprises a power supply, a clamping power supply, two power switch tubes, a feedback unit, a control unit, a current direction control unit and at least one output unit, wherein the power supply is respective coupled with all output units; the power supply is connected with the node between the two power switch tubes through the current direction control unit; the current direction control unit only allows the currents flowing towards the power switch tubes to pass; the clamping power supply is parallelly connected between two ends of the two power switch tubes; the feedback unit is coupled with the power supply and outputs feedback voltage to the control unit; the control unit controls the alternative on time of the two power switch tubes according to the feedback voltage so as to adjust the voltage of each output unit. By the switch power supply circuit, clamping power switch voltage stress cost is low, multiway isolated output can be achieved, and a switch power supply is high in integration level.
Description
Technical field
The present invention relates to the driving power technology of motor, particularly a kind of switching power circuit.
Background technology
Auxiliary electric power supply in motor driver is developed to current Switching Power Supply from initial Industrial Frequency Transformer, and while efficiency improves, size also significantly reduces.For the power supply of power model driver element in motor driver, often adopt inverse-excitation type switch power-supply, to reach the object of Multiple isolated outputs.Meanwhile, also there is the power supply adopting step down switching regulator, as 24V, 12V etc.
Although inverse-excitation type switch power-supply easily realizes Multiple isolated outputs, high to the voltage stress demand of device for power switching, need voltage clamping circuit, cost is higher.And although step down switching regulator integrated level is high, its device for power switching voltage stress is low, realizes Multiple isolated outputs difficulty.
Summary of the invention
The object of the present invention is to provide a kind of switching power circuit, not only the cost of lamp power switching voltage stress is low, but also can realize Multiple isolated outputs, makes Switching Power Supply have the high advantage of integrated level concurrently; Meanwhile, the recycling of energy can be realized, energy savings.
For solving the problems of the technologies described above, embodiments of the present invention provide a kind of switching power circuit, comprise: power supply, clamp power supply, 2 power switch pipes, feedback unit, control unit, sense of current control unit and at least one output unit;
Described power supply and all output units are of coupled connections respectively; Described power supply is connected through the node between described sense of current control unit with 2 power switch pipes; Wherein, 2 power switch pipe series connection; Described sense of current control unit only allows the electric current flowing to described power switch pipe to pass through;
Described clamp power sources in parallel, at the two ends of 2 power switch pipes, firmly bears the voltage stress of the power switch pipe of the voltage of described power supply for clamp;
Described feedback unit and described power supply are of coupled connections, and output feedack voltage is to described control unit; Described control unit controls according to described feedback voltage the time that 2 power switch pipes carry out alternate conduction, regulates with the voltage exported each output unit.
Embodiment of the present invention in terms of existing technologies, it is a clamp power supply in parallel at the two ends of 2 power switch pipes, clamp firmly bear the voltage of power supply the voltage stress of power switch pipe, the clamp circuit that use cost is high can be avoided, reduce the cost of Switching Power Supply; Meanwhile, power supply is of coupled connections with each output unit respectively, can also realize Multiple isolated outputs, improves the integrated level of Switching Power Supply; Sense of current control unit only allows the electric current flowing to power switch pipe to pass through, and the energy feedback that can make to be coupled in power supply less than output unit, to clamp power supply, realizes the recycling of energy, energy savings.
In addition, 2 filter capacitors are also comprised; A filter capacitor is connected between the lowest electric potential point of described power supply and described switching power circuit; Another filter capacitor is connected between the lowest electric potential point of described clamp power supply and described Switching Power Supply.Utilize filter capacitor can isolate the impact of interference on Switching Power Supply, clamp power supply, strengthen the stability of switch power source output voltage.
Accompanying drawing explanation
Fig. 1 is the structural representation of the switching power circuit according to the present invention one better embodiment;
The circuit diagram of switching power circuit when Fig. 2 is the energising in the present invention one better embodiment.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, the embodiments of the present invention are explained in detail.But, persons of ordinary skill in the art may appreciate that in each execution mode of the present invention, proposing many ins and outs to make reader understand the application better.But, even without these ins and outs with based on the many variations of following execution mode and amendment, each claim of the application technical scheme required for protection also can be realized.
A better embodiment of the present invention relates to a kind of switching power circuit, concrete structure, as shown in Fig. 1 ~ 2, comprises: power supply, clamp power supply, 2 power switch pipes (Q1, Q2), feedback unit 105, control unit, sense of current control unit 106, two filter capacitors (C1, C4) and 4 output units 101,102,103,104.
Power supply and 4 output units are of coupled connections respectively, are separate between 4 output units, like this, just achieve the Multiple isolated outputs of Switching Power Supply, and then, the integrated level of Switching Power Supply can be made to be improved.
2 power switch pipe (Q1, Q2) series connection, power supply is connected through the node between sense of current control unit 106 with 2 power switch pipes (Q1, Q2).In the present embodiment, 2 power switch pipes (Q1, Q2) are MOSFET pipe (metal-oxide semiconductor fieldeffect transistor).Wherein, the drain electrode of Q1 is connected with clamp power supply, and the grid of Q1 is connected with control unit, and the source electrode of Q1 is connected with the drain electrode of Q2 by node, the source ground of Q2, and the grid of Q2 is connected with control unit.Wherein, the voltage that Q2 bears is at least the voltage of power supply, and the voltage stress namely Q2 born is higher, and the lowest electric potential point of switching power circuit is ground.Sense of current control unit 106 only allows the electric current flowing to power switch pipe to pass through.Like this, the energy feedback that can make to be coupled in power supply less than output unit, to clamp power supply, realizes the recycling of energy, energy savings.
In the present embodiment, sense of current control unit 106 is the diode (D3) of the restriction sense of current; The positive pole of diode (D3) is connected with power supply, and the node between negative pole with 2 power switch pipes is connected.Specifically, when Q2 opens, D3 conducting, now Q1 turns off, and D1 ends, and D4, D5, D6, D7, D8 all end.When Q2 turns off, D3 conducting, now because T1 flux change, T1B, T1C, T1D, T1E, T1F polarity changes.Now Q1 conducting, D2 ends.Because the existence of D3 diode, the sense of current of T1A winding is limited, and the energy of transformer (T1) will be provided by power supply, and the leakage inductance energy of transformer T1 can feed back to clamp power supply by D1, realizes the recycling of energy.
Feedback unit 105 and power supply are of coupled connections, and output feedack voltage is to control unit; Control unit controls according to feedback voltage the time that 2 power switch pipes (Q1, Q2) carry out alternate conduction, carries out feedback regulation, make output voltage stabilization with the voltage (Vo1, Vo2, Vo3, Vo4) exported 4 output units.
Clamp power sources in parallel, at the two ends of 2 power switch pipes (Q1, Q2), make the voltage at Q2 two ends lower than the voltage of clamp power supply, and then clamp lives the voltage stress of power switch pipe (Q2).Wherein, clamp power supply one end is connected with the drain electrode of Q1, and one end is connected with the source electrode of Q2.Like this, can avoid using clamp circuit, the cost of Switching Power Supply can be reduced.
Filter capacitor (C1) is connected between the lowest electric potential point of power supply and switching power circuit, and filter capacitor (C4) is connected between the lowest electric potential point of clamp power supply and switching power circuit.C1, C4 can isolate the impact of interference on Switching Power Supply, clamp power supply respectively, strengthen the stability of switch power source output voltage.
Above the switching power circuit in present embodiment is introduced generally, below in conjunction with design parameter, the switching power circuit in present embodiment is described in detail:
Specifically, in the present embodiment, power supply is coupled with 4 output units, 101,102,103,104, feedback unit 105 respectively by transformer T1.Wherein, transformer T1 comprises a former limit winding T1A and 5 limit winding (T1B, T1C, T1D, T1E, T1F), and the number of winding turns of winding T1A, T1B, T1C, T1D, T1E, T1F is respectively nA, nB, nC, nD, nE and nF.Feedback unit 105 is coupled by time limit winding T1C and T1A, and 4 output units 101,102,103,104 are respectively by T1B, T1D, T1E, T1F and T1A coupling.
Feedback unit 105 comprises input, output, rectifier diode (D5), filter capacitor (C3), load resistance (R2) and 2 divider resistances (R3, R4).Wherein, input is the Same Name of Ends (drawing one end of pore) of secondary limit winding T1C, the T1C of transformer is positive port, and the other end is negative terminal mouth; Filter capacitor (C3), load resistance (R2) are connected in parallel between the positive port of the input of feedback unit 105 and negative terminal mouth successively; Diode (D5) positive pole is connected with positive port, and negative pole is connected with filter capacitor (C3); 2 divider resistances (R3, R4) are connected between the lowest electric potential point of negative terminal mouth and switching power circuit; Node between 2 divider resistances is the output of feedback unit 105, for output feedack voltage to control unit.
Each output unit all comprises input, output, rectifier diode, filter capacitor and load resistance.Now be described for output unit 101.In output unit 101, comprise input (T1B), output (Vo1), rectifier diode (D4), filter capacitor (C2) and load resistance (R1).Wherein, between filter capacitor (C2), load resistance (R1) the positive port that is connected in parallel on input (T1B) successively and negative terminal mouth; The positive pole of diode (D4) is connected with the positive port of (T1B), and negative pole is connected with filter capacitor (C2); The node that load resistance (R1) is connected with the negative terminal mouth of (T1B) is connected with the lowest electric potential point of switching power circuit, and the other end of load resistance (R1) is the output (Vo1) of output unit.The input (T1D, T1E, T1F) of other output units 102,103,104, output (Vo2, Vo3, Vo4), rectifier diode (D6, D7, D8), filter capacitor (C5, C6, C7) are similar to output unit 101 to the annexation of load resistance (R5, R6, R7), do not repeat them here.
Above the concrete structure of the mains switch in present embodiment is described in detail, below the operation principle of mains switch is introduced.
As shown in Figure 2, wherein, D1, D2 are the parasitic diode of Q1, Q2 to switching power circuit in Fig. 1 circuit structure in the energized state.
First, introduce how to realize the voltage stress that clamp power supply clamp lives in Q2.
Suppose that Q1, Q2, D1, D2, D4, D5, D6, D7, D8 are ideal component, open impedance, pressure drop is 0), the voltage of power supply is Vim, the voltage of clamp power supply is Via, and the operation principle of switching power circuit is as follows:
When Q2 opens, T1A bears voltage for-Vim (Same Name of Ends is just), and now Q1 turns off, and D1 ends, and D4, D5, D6, D7, D8 all end, output unit no-output.
When Q2 turns off, now because T1 flux change, T1B, T1C, T1D, T1E, T1F polarity changes, D4, D5, D6, D7, D8 conducting.It is that to bear voltage be (Vo1*nC)/nB for (Vo1*nA)/nB, T1C that T1A bears voltage, now Q1 conducting, and because Q2 turns off, D2 ends.
Arrange the magnitude of voltage (Vim) of clamp power supply, make (Vo1*nA)/nB+Vim<Via, so the voltage stress maximum of Q2 is lower than Via, thus, realize the voltage stress that clamp power supply clamp lives in Q2.
Secondly, for output unit 101, introduce how to realize FEEDBACK CONTROL, make Switching Power Supply stable output voltage.
If Q2 ON time is T2on, the turn-off time is T2off;
According to T1A volt-seconds area law of conservation, can obtain
-T2on*Vim+T2off*(Vo1*nA)/nB＝0
Obtain after arrangement
Vo1＝Vim*nB*T2on/(nA*T2off)
In the prior art, buck control chip is taked by FEEDBACK CONTROL Q1 pipe service time, and the mode of Q2 and Q1 complementation works: feedback voltage raises, and Q1 service time reduces, and feedback voltage reduces, and Q1 service time improves.If directly from Vo1 voltage as feedback, then positive feedback oscillatory occurences can occur: Vo1 raises, and Q1 service time reduces, and Q2 service time improves, Vo1 voltage continues rising, namely, the spread of voltage of output unit output.
In order to overcome defect of the prior art, the present invention increases winding T1C, from the dividing point of R3, R4 as feedback, thus has
Vfb＝(Vim-Vo1*nC/nB)*R4/(R3+R4)
Wherein, Vfb is the voltage on R4, namely feedback voltage.
Therefore, when having Vo1 voltage to raise, Vfb voltage reduces, and Q1 service time raises, and Q2 service time reduces, and Vo1 voltage reduces; Otherwise when Vo1 voltage reduces, Vfb voltage raises, and Q1 service time reduces, and Q2 service time raises, and Vo1 voltage raises, namely realize close loop negative feedback and control.
In a word, will be dragged down when the output voltage of Switching Power Supply raises exactly, when output voltage reduces, will be elevated, in other words, be exactly stop output voltage variation tendency, maintain output voltage stabilization.
In the present embodiment, the parameters of Switching Power Supply can get following numerical value: nA, nB, nD, nE and nF are equal to 10, nC and equal 1, Via=24V, and Vim=5V, Vo1, Vo2, Vo3, Vo4 are 15V.According to
Vo1＝Vim*nB*T2on/(nA*T2off)
Can obtain
T2on/(T2on+T2off)＝0.75
During Q2 cut-off, voltage to earth is
Vim+Vo1*nA/nB＝20V，
This voltage is lower than Via, so Q2 tube voltage stress will be lived by clamp, feedback voltage is (5-1.5) * R4/ (R3+R4).
It should be noted that, in actual applications, the number of output unit is not limited to 4, and the parameters of switching power circuit is also not limited to the parameters enumerated in present embodiment.
Persons of ordinary skill in the art may appreciate that the respective embodiments described above realize specific embodiments of the invention, and in actual applications, various change can be done to it in the form and details, and without departing from the spirit and scope of the present invention.
Claims (7)
1. a switching power circuit, is characterized in that, comprises: power supply, clamp power supply, 2 power switch pipes, feedback unit, control unit, sense of current control unit and at least one output unit;
Described power supply and all output units are of coupled connections respectively; Described power supply is connected through the node between described sense of current control unit with 2 power switch pipes; Wherein, 2 power switch pipe series connection; Described sense of current control unit only allows the electric current flowing to described power switch pipe to pass through;
Described clamp power sources in parallel, at the two ends of 2 power switch pipes, firmly bears the voltage stress of the power switch pipe of the voltage of described power supply for clamp;
Described feedback unit and described power supply are of coupled connections, and output feedack voltage is to described control unit; Described control unit controls according to described feedback voltage the time that 2 power switch pipes carry out alternate conduction, regulates with the voltage exported each output unit.
2. switching power circuit according to claim 1, is characterized in that, described sense of current control unit is diode;
The positive pole of described diode is connected with described power supply, and the node between negative pole with 2 power switch pipes is connected.
3. switching power circuit according to claim 1, is characterized in that, also comprises transformer;
Described transformer comprises former limit winding and time limit winding;
Each described output unit and described feedback unit are respectively by described limit winding and described former limit winding coupled;
Described power supply is connected with the node between 2 power switch pipes through described former limit winding.
4. switching power circuit according to claim 1, is characterized in that, 2 power switch pipes are metal-oxide semiconductor fieldeffect transistor MOSFET;
The drain electrode of bearing the high MOSFET of voltage stress is connected with described clamp power supply, and the grid of this MOSFET is connected with described control unit, and the source electrode of this MOSFET is connected with the drain electrode of another MOSFET by described node;
The source electrode of another MOSFET described is connected with the lowest electric potential point of described switching power circuit, and grid is connected with described control unit.
5. switching power circuit according to claim 1, is characterized in that, described feedback unit comprises input, output, diode, filter capacitor, load resistance and 2 divider resistances;
Described filter capacitor, described load resistance are connected in parallel between the positive port of described input and negative terminal mouth successively; Described diode cathode is connected with described positive port, and negative pole is connected with described filter capacitor;
Described 2 divider resistances are connected between the lowest electric potential point of described negative terminal mouth and described switching power circuit; Node between described 2 divider resistances is the output of described feedback unit, for exporting described feedback voltage.
6. switching power circuit according to claim 1, is characterized in that, described output unit comprises input, output, diode, filter capacitor and load resistance;
Described filter capacitor, described load resistance are connected in parallel between the positive port of described input and negative terminal mouth successively;
Described diode cathode is connected with described positive port, and negative pole is connected with described filter capacitor;
The node that described load resistance is connected with described negative terminal mouth is connected with the lowest electric potential point of described switching power circuit, and the other end of described load resistance is the output of described output unit.
7. switching power circuit according to claim 1, is characterized in that, also comprises 2 filter capacitors;
A filter capacitor is connected between the lowest electric potential point of described power supply and described switching power circuit;
Another filter capacitor is connected between the lowest electric potential point of described clamp power supply and described switching power circuit.
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| CN201510208020.2A CN104811046A (en) | 2015-04-27 | 2015-04-27 | Switch power supply circuit |
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| CN201510208020.2A CN104811046A (en) | 2015-04-27 | 2015-04-27 | Switch power supply circuit |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5303138A (en) * | 1993-04-29 | 1994-04-12 | At&T Bell Laboratories | Low loss synchronous rectifier for application to clamped-mode power converters |
| US20120069607A1 (en) * | 2010-09-17 | 2012-03-22 | Sampat Shekhawat | Inverter and driving method thereof |
| CN102437741A (en) * | 2011-12-28 | 2012-05-02 | 南京航空航天大学 | Double-input direct-current converter using non-isolation type pulse voltage source unit |
| CN102761276A (en) * | 2012-07-31 | 2012-10-31 | 广州金升阳科技有限公司 | Step-down type power factor correction (PFC) circuit |
| CN104485831A (en) * | 2014-12-29 | 2015-04-01 | 杭州禾迈电力电子技术有限公司 | Leakage inductance energy absorption and feedback circuit of flyback transformer and control method thereof |
-
2015
- 2015-04-27 CN CN201510208020.2A patent/CN104811046A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5303138A (en) * | 1993-04-29 | 1994-04-12 | At&T Bell Laboratories | Low loss synchronous rectifier for application to clamped-mode power converters |
| US20120069607A1 (en) * | 2010-09-17 | 2012-03-22 | Sampat Shekhawat | Inverter and driving method thereof |
| CN102437741A (en) * | 2011-12-28 | 2012-05-02 | 南京航空航天大学 | Double-input direct-current converter using non-isolation type pulse voltage source unit |
| CN102761276A (en) * | 2012-07-31 | 2012-10-31 | 广州金升阳科技有限公司 | Step-down type power factor correction (PFC) circuit |
| CN104485831A (en) * | 2014-12-29 | 2015-04-01 | 杭州禾迈电力电子技术有限公司 | Leakage inductance energy absorption and feedback circuit of flyback transformer and control method thereof |
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Application publication date: 20150729 |