CN100563088C - The high-voltage starting circuit of power converter - Google Patents

Abstract

The invention relates to a kind of high-voltage starting circuit of power converter, it includes a Junction fet, an impedance means, one first electric crystal, one second electric crystal and a diode.Junction fet couples a voltage source.First electric crystal is series at Junction fet, with the control circuit of foundation voltage source output one supply voltage to power converter.Diode is coupled between the Transformer Winding and control circuit of power converter, to supply another supply voltage to control circuit.Second electric crystal is controlled first electric crystal and Junction fet according to a controlling signal.Impedance means couples the Junction fet and first electric crystal.When second electric crystal ended, impedance means provided a bias voltage, so that the Junction fet and the first electric crystal conducting; When the second electric crystal conducting, first electric crystal ends, and Junction fet is the back bias voltage state.

Description

The high-voltage starting circuit of power converter

Technical field:

The invention relates to a kind of start-up circuit, be meant a kind of high-voltage starting circuit that is applied to power converter especially.

Background technology:

See also Fig. 1, it is a circuit diagram of commonly using the high-voltage starting circuit of power converter.As shown in the figure, commonly using start-up circuit is to be used to control a voltage source V _INConducting with end, and then provide a voltage V _DSupply voltage as a control circuit 10 of power converter.When power converter starts, voltage source V _INPromptly supply voltage V via an electric crystal 11 _DElectric crystal 11, one drain and one source pole couple voltage source V respectively _INWith control circuit 10.When control circuit 10 came into operation, a Transformer Winding 16 of power converter can provide supply voltage to control circuit 10 via a diode 17 and an electric capacity 18.Afterwards, electric crystal 11 will be driven by an electric crystal 12 and end, to save electrical source consumption.Transformer Winding 16, it is coupled to an end of an earth terminal and diode 17, and 18 of electric capacity are coupled between the other end and earth terminal of diode 17.Electric capacity 18 more is coupled to control circuit 10.One resistance 15, it is coupled between the gate of the drain of electric crystal 11 and electric crystal 11.Resistance 15 is used to provide a bias voltage with conducting electric crystal 11.

Electric crystal 12, one drain and one source pole couple the gate and the earth terminal of electric crystal 11 respectively.A gate of electric crystal 12 is outputs that couple an inverter 14 in addition, and an input of inverter 14 then receives a controlling signal S _N, allow controlling signal S _NCan see through inverter 14 control electric crystals 12.Electric crystal 12 can be at controlling signal S _NConducting when disabled state, and then electric crystal 11 is ended.Yet when electric crystal 12 conductings, resistance 15 will consume a power P _R, it can be expressed as:

$P_R=\frac{{V_{\mathrm{IN}}}^2}{R_{15}}---\left(1\right)$

Wherein, R ₁₅Resistance value for resistance 15.

Generally speaking, voltage source V _INNormally by the AC power supply, when being coupled to voltage source V by a very high line voltage (High Line Voltage) _IN, behind over commutation, voltage source V _INVoltage can so can learn that resistance 15 will produce a significant power loss up to 350 volts of direct voltages by equation (1).Can learn according to aforesaid equation (1), can reduce power loss if the resistance value of resistance 15 is high more, so adopt the resistance 15 of high resistance, for example millions of ohms can effectively reduce power loss.Yet the resistance 15 of high resistance is not suitable for being integrated in the integrated circuit (integratedcircuit).

Therefore, the present invention promptly provides a kind of high efficiency high-voltage starting circuit at the problems referred to above, its cpable of lowering power loss, and reach effective control high voltage source, and can be integrated in integrated circuit, effectively to address the above problem.

Summary of the invention:

Main purpose of the present invention is to provide a kind of high-voltage starting circuit of power converter, and it is to utilize Junction fet and impedance means, and reaches effective control high voltage source and the purpose that reduces power loss.

The high-voltage starting circuit of power converter of the present invention, it includes a Junction fet, an impedance means, one first electric crystal, one second electric crystal and a diode, and Junction fet couples a voltage source.First electric crystal is series at Junction fet, and according to the control circuit of voltage source output one supply voltage to power converter.Diode is coupled between the Transformer Winding and control circuit of power converter, provides another supply voltage to control circuit.Second electric crystal is controlled first electric crystal and Junction fet according to a controlling signal.Impedance means couples the Junction fet and first electric crystal, and when second electric crystal ends, provides one to be biased into the Junction fet and first electric crystal, so that the Junction fet and the first electric crystal conducting.In case during the second electric crystal conducting, first electric crystal will end, Junction fet is the back bias voltage state.

For making the juror further understanding and understanding more be arranged to architectural feature of the present invention and the effect reached, sincerely help with preferred embodiment figure and cooperate detailed explanation, illustrate as the back:

Description of drawings:

Fig. 1 is a circuit diagram of commonly using the high-voltage starting circuit of power converter;

Fig. 2 is the circuit diagram of a preferred embodiment of high-voltage starting circuit of the present invention;

Fig. 3 is the curve chart of the voltage of Junction fet of the present invention to electric current;

The circuit diagram of Fig. 4 current direction during for high-voltage starting circuit conducting of the present invention;

Fig. 5 be high-voltage starting circuit of the present invention by the time current direction circuit diagram.

The figure number explanation:

10 control circuits, 11 electric crystals

12 electric crystals, 14 inverters

15 resistance, 16 Transformer Winding

17 diodes, 18 electric capacity

20 Junction fets, 25 first electric crystals

30 impedance means, 40 inverters

50 second electric crystals, 60 resistance

70 electric capacity, 90 diodes

100 Transformer Winding I _JElectric current

V _DVoltage V _INVoltage source

V _JVoltage S _NControlling signal

Embodiment:

See also Fig. 2, it is the circuit diagram of a preferred embodiment of high-voltage starting circuit of the present invention.As shown in the figure, high-voltage starting circuit of the present invention includes a Junction fet (Junction Field Effect Transistor, JFET) 20,1 first electric crystal 25, an impedance means 30, one second electric crystal 50 and a diode 90.Junction fet 20 has one first end, one second end and one the 3rd end, and first end of Junction fet 20 is coupled to a voltage source V _INFirst electric crystal 25, it is series at Junction fet 20, and according to voltage source V _INExport a voltage V _D, so that the control circuit 10 of a supply voltage to power converter to be provided.One drain of first electric crystal 25 is connected in second end of Junction fet 20.The one source pole of first electric crystal 25 is coupled to control circuit 10.

The present invention is that impedance means 30 is coupled between second end and the 3rd end of Junction fet 20 for the conducting Junction fet 20 and first electric crystal 25.In addition, impedance means 30 more is coupled between the gate of the drain of first electric crystal 25 and first electric crystal 25.So impedance means 30 can provide one to be biased into the Junction fet 20 and first electric crystal 25.Wherein, impedance means 30 can be a resistance or an electric crystal.One electric capacity 70, the one end is coupled to control circuit 10, and the other end then is coupled to earth terminal.Diode 90, one end are coupled to electric capacity 70 and control circuit 10, and the other end then is coupled to a Transformer Winding 100 of power converter.When control circuit 10 comes into operation, Transformer Winding 100 will provide supply voltage to control circuit 10 via diode 90 and electric capacity 70.Afterwards, by Junction fet 20 and first electric crystal, 25 cut-ff voltage source V _IN, to save electrical source consumption.

Multiple with reference to figure 2, one controlling signal S _NTransfer to an input of high-voltage starting circuit, with conducting second electric crystal 50, and then cut-ff voltage source V _INSecond electric crystal 50, the one gate receives controlling signal S via an inverter 40 _NWherein, an input of inverter 40 receives controlling signal S _N, an output of inverter 40 then is coupled to the gate of second electric crystal 50.The one source pole of second electric crystal 50 is coupled to earth terminal.One drain of second electric crystal 50 is coupled to the gate of first electric crystal 25 and the 3rd end of Junction fet 20.So, when second electric crystal 50 according to controlling signal S _NEnabled status and by the time, impedance means 30 can provide and be biased into first electric crystal 25 and Junction fet 20, this bias voltage can conducting first electric crystal 25 and Junction fet 20.

In case second electric crystal 50 is according to controlling signal S _NDisabled state and during conducting, first electric crystal 25 will end, with cut-ff voltage source V _IN, and then stop output supply voltage to control circuit 10.Transformer Winding 100 will provide supply voltage to control circuit 10 via diode 90 this moment.Simultaneously, impedance means 30 will provide a back bias voltage to Junction fet 20.During second electric crystal, 50 conductings just, can provide back bias voltage to Junction fet 20 via impedance means 30, so be that may command Junction fet 20 ends.Wherein, Junction fet 20 has a negative critical voltage-V _TH, as shown in Figure 3.

See also Fig. 3, it is the curve chart of the voltage of Junction fet of the present invention to electric current.Electric current I in the diagram _JBe first end by Junction fet 20 and the electric current of second end.Voltage V _JBe the 3rd end of Junction fet 20 and the voltage between second end.In the present invention, Junction fet 20 is to be a voltage control impedance means.As shown in Figure 3, voltage V _JDuring reduction, electric current I _JAlso can be along with reduction, and as voltage V _JBe lower than the negative critical voltage-V of Junction fet 20 _THThe time, Junction fet 20 will end.

See also Fig. 4 and Fig. 5, when it shows high-voltage starting circuit conducting of the present invention respectively and ends, electric current I _JThe circuit diagram of flow direction.Resistance 60 in the diagram is the impedance means 30 for Fig. 2.In Fig. 4, controlling signal S _NBe enabled status, 50 of second electric crystals are according to controlling signal S _NEnabled status and end, so do not have electric current to pass through resistance 60, so resistance 60 provides the voltage V of a zero-bias to Junction fet 20 _JThis external resistance 60 also provides an identical bias between the gate and drain of first electric crystal 25, therefore, the Junction fet 20 and first electric crystal 25 both all can conducting.

In Fig. 5, controlling signal S _NBe disabled state, 50 of second electric crystals are according to controlling signal S _NDisabled state and conducting, first electric crystal 25 is that end the accurate position of low-voltage because of its gate.The same time, electric current I _JBe to flow through second electric crystal 50 and resistance 60.This moment, resistance 60 provided the voltage V of back bias voltage to Junction fet 20 _JIn this moment, electric current I _JIncrease the voltage V of back bias voltage to Junction fet 20 can further be provided _J, make back bias voltage bigger.When back bias voltage reaches negative critical voltage-V _THThe time, Junction fet 20 will be by to avoid electric current I _JIncrease.

High-voltage starting circuit of the present invention is to operate in the negative feedback mode.Though when first electric crystal 25 ends, an electric current is still arranged, because the current value of this electric current is very little, so can ignore by Junction fet 20.Because Junction fet 20 is to be integrated into integrated circuit with impedance means 30, so high-voltage starting circuit shown in Figure 2 of the present invention is can be integrated in integrated circuit and reach purpose of the present invention.

The above, it only is a preferred embodiment of the present invention, be not to be used for limiting scope of the invention process, all equalizations of doing according to the described shape of claim scope of the present invention, structure, feature and spirit change and modify, and all should be included in the claim scope of the present invention.

Claims (13)

1, a kind of high-voltage starting circuit of power converter is characterized in that, it includes:

One Junction fet, it has one first end, one second end and one the 3rd end, and this first end couples a voltage source;

One first electric crystal, it has a drain, one source pole and a gate, this drain of this first electric crystal connects this second end of this Junction fet, and this source electrode of this first electric crystal is coupled to a control circuit of this power converter, so that a supply voltage to be provided;

One diode, it is coupled between the Transformer Winding and this control circuit of this power converter, to provide another supply voltage to this control circuit;

One second electric crystal, it has a drain, one source pole and a gate, this drain of this second electric crystal couples this gate of this first electric crystal and the 3rd end of this Junction fet, this source electrode of this second electric crystal is coupled to an earth terminal, this gate of this second electric crystal receives a controlling signal, this controlling signal is used for this second electric crystal of conducting, to end this first electric crystal;

One impedance means, it is coupled between the 3rd end and this second end of this Junction fet;

Wherein, when this second electric crystal ended, this impedance means provided a bias voltage, with this first electric crystal of conducting and this Junction fet.

2, start-up circuit as claimed in claim 1 is characterized in that, during this second electric crystal conducting, this impedance means provides a back bias voltage to this Junction fet.

3, start-up circuit as claimed in claim 1 is characterized in that, after this control circuit comes into operation, and this second electric crystal conducting.

4, start-up circuit as claimed in claim 1 is characterized in that, this Junction fet has a negative critical voltage.

5, start-up circuit as claimed in claim 1 is characterized in that, this Junction fet is a voltage control impedance means.

6, start-up circuit as claimed in claim 1 is characterized in that, when this first electric crystal ends, an electric current is still arranged by this Junction fet.

7, start-up circuit as claimed in claim 1 is characterized in that, this impedance means can be a resistance or an electric crystal.

8, a kind of high-voltage starting circuit of power converter is characterized in that, it includes:

One Junction fet, it couples a voltage source;

One first electric crystal, it is series at this Junction fet, so that the control circuit of a supply voltage to this power converter to be provided according to this voltage source;

One impedance means, it couples this Junction fet and this first electric crystal, in order to a bias voltage to be provided, in order to this Junction fet of conducting and this first electric crystal; And

One second electric crystal, it couples this first electric crystal and this Junction fet, in order to end this first electric crystal;

One diode, it is coupled between the Transformer Winding and this control circuit of this power converter, to provide another supply voltage to this control circuit;

Wherein, this second electric crystal is to be controlled by a controlling signal.

9, start-up circuit as claimed in claim 8 is characterized in that, this second electric crystal provides a back bias voltage to this Junction fet via this impedance means.

10, start-up circuit as claimed in claim 8 is characterized in that, this Junction fet has a negative critical voltage.

11, start-up circuit as claimed in claim 8 is characterized in that, this Junction fet is a voltage control impedance means.

12, start-up circuit as claimed in claim 8 is characterized in that, when this first electric crystal ends, an electric current is still arranged by this Junction fet.

13, start-up circuit as claimed in claim 8 is characterized in that, this impedance means can be a resistance or an electric crystal.

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