CN1028274C

CN1028274C - Power supply

Info

Publication number: CN1028274C
Application number: CN93118095A
Authority: CN
Inventors: 上岡淳; 平松明则; 迫造行; 五岛和宏
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1992-09-25
Filing date: 1993-09-25
Publication date: 1995-04-19
Anticipated expiration: 2013-09-25
Also published as: CN1085022A

Abstract

A power supply with an inverter which is energized by a fixed DC voltage source and includes at least one switching element and an L-C resonant circuit. The inverter includes first and second clamping diodes connected in series across the DC voltage source in anti-parallel relation thereto with the first and second diodes defining therebetween a first connection point. Also included in the inverter is a pair of first and second impedance elements which are connected in series across the inverter output to provide a divided voltage indicative of an output voltage of the inverter with the first and second impedance elements defining therebetween a second connection point. The first and second connection points are connected to each other so as to limit the output voltage of the inverter below a predetermined level .

Description

Power supply

The object of the present invention is to provide a kind of power supply that comprises inverter, it provides the high-frequency ac voltage that is converted by direct voltage source, in order to drive a load, for example, a discharge lamp.

The power supply that has inverter has been well-known in the present technique field, and it is at for example United States Patent (USP) the 5130610th; 4461980; Disclose in 5138234 and No. 4719556.

United States Patent (USP) has disclosed a kind of typical supply unit No. 5130610, and it has comprised that a conversion dc voltage is to provide the inverter of high-frequency ac voltage.As shown in Figure 1, the power supply of this prior art has a diode bridge rectifier circuit DB, it provides direct voltage after the rectification from an alternating-current voltage source AC, thereby described direct voltage smoothly provides once level and smooth direct voltage to inverter through smmothing capacitor Co.Described inverter INV comprises a pair of transistor Q that connects with smmothing capacitor Co ₁And Q ₂Cross-over connection is in the first transistor Q ₁Be a series connection L-C resonant circuit, it comprises an inductor L ₁And one and coupling capacitor C ₂The capacitor C that is in series ₁Also be connected to a transformer T in the circuit, its elementary winding T ₁Cross-over connection is in capacitor C ₁And secondary winding T ₂LD is connected with load, described transistor Q ₁And Q ₂Under one drive circuit control, flow to conducting and, make the L-C resonant circuit at elementary winding T by operation with the high-frequency wheel ₁Two ends produce oscillating voltage, thereby provide a corresponding alternating voltage to load LD.Like this, the L-C resonant circuit provides a predefined high-frequency ac voltage to drive load when good when load is connected with inverter.Yet, when the load disengagement causes power work under not load-carrying condition, or as frequent at the end seen in discharge lamp, damage under the situation that causes the impedance rising when load, described L-C resonant circuit will form a too high voltages thereupon, consequently make and flow through high a unusual resonance current on the transistor of inverter, finally destroyed transistor or transistor is met with because of loss sharply increases badly damaged.

In order to eliminate the problems referred to above, United States Patent (USP) has proposed to add one for No. 4461980 can make the inoperative protective circuit of inverter when load is thrown off.As shown in Figure 2, described inverter INV comprise one with capacitor C ₂And C ₃Be connected into the transistor Q of half-bridge form ₁And Q ₂, and the L-C resonant circuit of a series connection, described resonant circuit comprises an inductor L ₁With the capacitor C of cross-over connection in the output of half-bridge ₁Transistor Q ₁And Q ₂With transformer T ₃Be coupled, thus under it drives with self-energizing mode conducting with end.A load, it is a discharge lamp, cross-over connection is in capacitor C ₁Described protective circuit comprises the diode D of pair of series ₃And D ₄, described diode with the capacitor C of tandem compound thing ₁And C ₃Link to each other with parallel mode, and one has and is connected transistor Q ₂Base-the penetrate bimetal release B of the heater strip H on the path.Described heater strip H is connected on inductor L ₁Centre tap TP and diode D ₃And D ₄Tie point between.When lamp was thrown off, the voltage that the corresponding generation of L-C resonant circuit increases was thereupon at capacitor L ₁Two ends produce the voltage that increases, and provide enough electric currents to pass through heater strip H, thereby have made bimetal release B with transistor Q ₂Base-penetrate passage short circuit.Adopt this method, inverter quits work when lamp is thrown off, thereby has prevented the continuous oscillation of L-C resonant circuit and protected transistor to avoid producing too high voltage thus well as in other cases.

United States Patent (USP) 5138234 has disclosed the supply unit of another kind of prior art, and it comprises when the load flow restricter that can avoid too high voltages the inverter when inverter is thrown off.As schematically reprinting in the accompanying drawing 3, described inverter is powered by a constant DC potential source E, and it comprises and a pair of capacitor C ₂And C ₃The pair of transistor Q that forms half-bridge ₁And Q ₂One series connection L-C resonant circuit is by inductor L ₁With by capacitor C ₁Form, the output that described resonant circuit is connected bridge circuit is with along with transistorized conducting with by producing high-frequency ac voltage.Also have an output transformer T, its elementary winding T in the circuit ₁Cross-over connection is in capacitor C ₁Two ends and secondary winding T ₂Link to each other with lamp.Described flow restricter comprises the clamping diode D of pair of series ₃And D ₄, described diode series connection cross-over connection in capacitor C ₂And C ₃The direct voltage source E that tandem compound is in parallel.Elementary winding T ₁Centre cap TP and diode D ₃And D ₄Between tie point be connected so that described diode D ₃And D ₄Between tie point be clamped at a fixed voltage value, described magnitude of voltage is with corresponding to the input voltage that inverter provided by direct voltage source E.Therefore, when lamp when inverter is thrown off, also increase if produce a too high voltage and the voltage on the described tie point in the L-C resonant circuit thereupon, then the voltage of Zeng Daing can pass through elementary winding T ₁, diode D ₃And D ₄Return capacitor C ₃And C ₄, avoided producing in the resonant circuit too high voltage thus.

United States Patent (USP) 4719556 has disclosed the another kind of power supply that has flow restricter with the prior art that reaches identical purpose.As shown in Figure 4, described power supply comprises one by transistor Q ₁And Q ₂And capacitor C ₁And C ₂The half-bridge circuit of forming and by inductor L ₁With a capacitor C ₁The series connection L-C resonant circuit of forming.One output transformer is arranged, its elementary winding T in the circuit ₁With capacitor C ₁Be in parallel and secondary winding T ₂Be connected with load.Described flow restricter comprises the diode D of pair of series ₃And D ₄, described diode with series capacitors to C ₂And C ₃The mode that parallels is connected across on the direct voltage source E.Above-mentioned diode D ₃And D ₄Be connected inductor L ₁With capacitor C ₁Thereby between contact on the voltage of tie point is clamped on the value corresponding to direct voltage source E.Similarly, described flow restricter has been arranged after, when load is thrown off or its impedance can be avoided producing too high voltages in the L-C resonant circuit during in variation once quite on a large scale in.

Yet, in the supply unit of these prior aries, still having problems, this is because inductor or transformer tapping make that manufacturing process is quite complicated and can bring the additional production cost, shown in the circuit of Fig. 2 and Fig. 3; And because clamp current will flow through inductor or output transformer raises its temperature, shown in the circuit of Fig. 2 and Fig. 3.Have again, in the circuit of Fig. 4, clamping diode D ₃And D ₄Be connected to and constitute L-C circuit inductance device L ₁With capacitor C ₁The centre a bit, so when guaranteeing in the L-C circuit, to produce required oscillating voltage, can not limit the output of inverter by the adjusting clamping voltage.That is, the output of inverter just is limited on the clamping voltage of fixing, and makes circuit design be subjected to strict restriction.

The invention solves the problems referred to above, it provides a kind of power supply that has inverter, and described inverter can avoid producing too high voltage when load disengagement or load impedance increase considerably.Supply unit constructed in accordance comprises a constant dc potential source to inverter power supply.Described inverter comprises at least one switch element and a L-C resonant circuit.Described switch element is driven to carry out the switching operation and produces a high-frequency ac voltage to drive a load that is connected with the output of inverter with the cooperation of L-C resonant circuit at the output of inverter.Described inverter comprises first and second clamping diodes of series connection, and described diode is with antiparallel manner, and cross-over connection is in the two ends of direct voltage source, and has determined one first tie point between described first and second diodes.First and second impedance components that also comprise pair of series in the described inverter so that the dividing potential drop of an expression inverter output voltage to be provided, have been determined one second tie point in the described impedance component access circuit between described first and second impedance components.Described first and second tie points are connected, so that the output voltage of inverter is limited in below the preset value.That is, the voltage of described tie point often is maintained at and the approaching numerical value that equates of the fixed voltage value of direct voltage source.Therefore, when load disengagement or load impedance increase, even make the L-C resonant circuit trend that produces a too high voltages be arranged thereupon at the output of inverter, described first and second impedance components will coact to make via them and via direct voltage source and flow through a clamp current avoiding producing too high voltage at the output of described inverter with first and second diodes, and described clamp current does not flow through the L-C resonant circuit.Simultaneously because clamp current is one of by first and second impedance components, can be only by selecting the first and second impedor dividing potential drops recently to limit the output of clamping voltage inverter at an easy rate by adjusting, and do not change the normal output voltage of inverter.

Therefore; a basic purpose of the present invention provides a kind of power supply; described power supply can limit output when the impedance of load disengagement or load increases greatly alternating voltage makes it not damaged by excessive electric current with the protection switch element; described power supply has simple circuit configuration; its clamp current does not flow through the inductor of L-C resonant circuit; otherwise will cause heat accumulation in inductor, design of the present invention also has bigger flexibility.

Described first and second impedance components can be capacitors, resistor, inductor or their combination.When capacitor was used as first and second impedance components, these capacitors can be used to constitute the L-C resonant circuit with inductor usually.In addition, described inverter can comprise an output transformer, the elementary winding of described transformer and capacitor parallel coupled are to form the L-C resonant circuit, its inferior utmost point winding is connected with load, in this case, a kind of more desirable method be make described first and second impedance components series connection back cross-over connection in the two ends of elementary winding the dividing potential drop with output voltage that an expression inverter is provided.On the other hand, the back cross-over connection of can connecting of described first and second impedance components constitutes the dividing potential drop of L-C resonant circuit with output voltage that an expression inverter is provided equally in the two ends of inductor.

In a preferred embodiment, described power supply also comprises a tracer in addition, having only when abnormal conditions occurring is that load is damaged or when throwing off, the L-C resonant circuit has produced too high voltage thereupon, at this moment flows through to be connected between first and second tie points clamp current on the lead and to make described detector can indicate impedance to increase.Thereby described tracer comprises at least one switch element of indicating superpotential warning circuit of appearance and to pass through control inverter and reduces the control circuit of the output voltage of inverter.Therefore, the overvoltage that results from the L-C resonant circuit is used for making tracer to move with the generation of indication fault admirably or is used to limit the work of inverter and need not additional other voltage source, so this is an another object of the present invention.

Above-mentioned control circuit has significant advantage, with often occur in discharge lamp at the end discharge lamp damaged that thereby the situation that impedance increases to occur be example, in this case, the effect of described control circuit is the output of inverter to be reduced and information notification user that the life-span of discharge lamp has been ended, need not lamp is extinguished but make it deepening, thereby this also is an another purpose of the present invention.

In a preferred embodiment, described power supply comprises that one is connected and is used in the circuit receiving boost chopper through the direct voltage of over commutation by the ac voltage rectifier device, and produces through level and smooth direct voltage at the two ends of a smmothing capacitor.Described chopper comprises a break-and-make switch element, this element is connected the back cross-over connection in the rectifier two ends with an inductor, it carries out make-break operation repeatedly so that a chopping voltage to be provided under the driving of chopper controller, described chopping voltage smoothly produces the smooth voltage that boosts through smmothing capacitor at the smmothing capacitor two ends, except that this this, also have from rectifier at the smoothed voltage in this place, thus with described smmothing capacitor as the above-mentioned direct voltage source that constant DC voltage is provided to inverter.In this power supply that has a chopper, comprised a tracer, it just causes action by clamp current when only the L-C resonant circuit produces overvoltage under abnormal conditions.Described tracer is connected to the chopper controller to stop the make-break operation of chopper switches element under abnormal conditions, reduced the direct voltage that offers inverter thus, thereby reduced the output of inverter, and make load for the power voltage supply of identical purpose noted earlier by reduction, thereby this is the present invention's a purpose again.

In yet another embodiment, load is a discharge lamp that has a target, has comprised also in the structure of inverter that one has the transformer of an elementary winding and a pair of secondary winding.Described elementary winding is access between first and second tie points so that have only when the L-C resonant circuit produces and just induces voltage when the overvoltage clamp current flows through described circuit and be added to respectively on the described secondary winding.Described secondary winding is connected respectively to come the negative electrode of heating lamp thereon by the voltage that induces.In this mode, begin that discharge lamp presents a high impedance and causes producing clamp current when luminous, at this moment described clamp current is used for heated cathode admirably so that the lighting of lamp, and this is again an another object of the present invention.

In an embodiment more of the present invention, a discharge lamp is used as load and is connected in the circuit, and described power supply comprises that a timer and is connected to the switch between described first and second tie points.One section preset time that described timer only was used for after the starting time of the negative electrode of preheat lamp is opened switch at interval, only in the described time interval, stop inverter output voltage being limited thus, thereby allow overvoltage to be used as the keep-alive voltage of discharge lamp.Adopt this design, can provide a high keep-alive voltage so that the lighting of lamp to discharge lamp, in case and lamp lighted and can guarantee to avoid overvoltage is added on the lamp, this is the present invention's an another purpose.

Describe preferred embodiment provided by the invention in detail below in conjunction with accompanying drawing, this will make the present invention above-mentioned purpose and favourable characteristic thereof with other more apparent.

Fig. 1 to Fig. 4 is the circuit diagram of explanation power supply prior art;

Fig. 5 is the schematic diagram of explanation according to a power supply of first embodiment of the invention;

Fig. 6 is the circuit diagram of power supply shown in Figure 5;

Fig. 7 A to 7D is the flow through schematic diagram of power circuit shown in Figure 6 of explanation electric current;

Fig. 8 and Fig. 9 A to 9D are the oscillograms of explanation power work principle shown in Figure 6;

Figure 10 is the circuit diagram according to a power supply of second embodiment of the invention;

Figure 11 to Figure 13 is respectively first kind, second kind and the circuit diagram of the third change that explanation is done power supply shown in Figure 10;

Figure 14 is the circuit diagram according to a power supply of third embodiment of the invention;

Figure 15 is the circuit diagram to a kind of change that power supply shown in Figure 14 is done;

Figure 16 is the circuit diagram according to a power supply of four embodiment of the invention;

Figure 17 A to 17D is the flow through schematic diagram of power circuit shown in Figure 16 of explanation electric current;

Figure 18 is the circuit diagram according to a power supply of fifth embodiment of the invention;

Figure 19 is the circuit diagram according to a power supply of sixth embodiment of the invention;

Figure 20 and Figure 21 are the circuit diagrams of first kind and second kind change that power supply shown in Figure 19 is done;

Figure 22 is the circuit diagram according to a power supply of seventh embodiment of the invention;

Figure 23 is the circuit diagram according to a power supply of eighth embodiment of the invention;

Figure 24 is the circuit diagram according to a power supply of ninth embodiment of the invention;

Figure 25 is the circuit diagram according to a power supply of tenth embodiment of the invention;

Figure 26 is the oscillogram of explanation circuit working principle shown in Figure 25.

Referring now to Fig. 5,, its expression is according to the schematic diagram of a power supply of first embodiment of the invention, and this power supply comprises an inverter 20 by fixing direct voltage source E power supply.This inverter 20 comprises switching transistor Q ₁And Q ₂, and a series connection L-C resonant circuit of forming by resonant inductor L and resonant capacitor C, by transistor Q ₁And Q ₂Switching manipulation, provide high-frequency ac voltage to load 3.This power supply also comprises and a pair ofly is connected across impedance component Z on load 3 or the inverter output end with the series connection form ₁And Z ₂, it in order to indicate the output voltage of this inverter, promptly results from the voltage on the L-C resonant circuit in order to a component voltage to be provided.Impedance component Z ₁And Z ₂Between tie point be defined as first tie point.This power supply also comprises a pair of clamping diode D ₁And D ₂, they are connected across on the direct voltage source E with the series connection form, and form the antiparallel relation with it.Clamping diode D ₁And D ₂Between tie point be defined as second tie point.First tie point is connected by lead LN with second tie point, like this,, load 3 increases when breaking away from or present impedance with power supply, and during the too high voltage of one of the corresponding generation of L-C resonant circuit, clamp current will be distinguished along the direction of arrow in the figure, flow through selectively by the first impedance component Z ₁, direct voltage source E, the first diode D ₁With the formed first loop LP1 of lead LN, and by the first impedance component Z ₁, lead LN and the second diode D ₂The formed second loop LP2, the output voltage with inverter is limited under a certain value thus, and this value depends on by impedance component Z ₁And Z ₂The voltage ratio of determined inverter output.

Fig. 6 represents according to one of first embodiment of the invention concrete power circuit diagram.This power supply comprises a diode bridge full-wave rectifier 2, and it is connected to AC power 1, presses in order to provide once commutated direct current, is undertaken smoothly by smmothing capacitor 14 then, and a fixing direct voltage is provided thus.Under this meaning, smmothing capacitor 14 has just determined to offer the direct voltage of inverter 20.Inverter 20 comprises a pair of first and second transistor 21 and the 22(Q ₁And Q ₂), and the series connection L-C resonant circuit of forming by inductor 25 and capacitor 31,32.First and

second transistors

21 and 22 are connected in parallel with first and

second diodes

23 and 24 respectively with antiparallel form.Also comprise output transformer 50 in the circuit, its elementary winding 51 is connected across on capacitor connected in

series

31 and 32, and its secondary winding 52 is connected to load 3.Elementary winding 51 is connected with coupling capacitor 28 and is connected across on the transistor seconds 22, and has determined the output of inverter, and the L-C resonant circuit forms high-frequency ac voltage in response to the switching manipulation of

transistor

21,22 at this.The high-frequency ac voltage that forms is added to load 3 via secondary winding 52, drives its work.The capacitance of coupling capacitor 28 should be selected more much biggerly than the capacitance of

capacitor

31 and 32, make its charging voltage can reach direct voltage on the smmothing capacitor 14 nearly half.Inductor 25 magnetic couplings are on the first and

second feedback windings

26 and 27, and the latter is connected respectively on the base stage of

transistor

21 and 22, and as their self-excitation winding, its details will be discussed afterwards.

Also comprise a starter in the circuit, it is connected across resistor 61 and capacitor 62 on the smmothing capacitor 14 by series connection, and the diac 63 that is connected with them is formed, be added on the first transistor 21 by capacitor 62 in order to start biasing one, when capacitor 62 chargings reach a certain value, at first make the first transistor 21 conductings.Diode 64 is connected in series with transistor 21, and both form relation in parallel with capacitor 62, and the voltage in order on can releasing capacitor 62 after transistor 21 conductings makes inverter thus as long as setover once starting elimination startup immediately.

Use the

capacitor

31 and 32 of forming the L-C resonant circuit with inductor 25 in the present embodiment, determine first tie point between two capacitors, and provide a dividing potential drop, the output voltage of indication inverter at this first tie point place.A pair of first and second clamping diodes 41 and 42 series connection are connected across on the smmothing capacitor 14, and determine second tie point between two diodes.First tie point is connected by lead LN with second tie point, thereby has identical current potential, its objective is that the output impedance when inverter is obviously increased, thereby when making the L-C resonant circuit produce too high voltages, can limit the output voltage of inverter 20.

Before above-mentioned voltage limit principle is discussed,, discuss from exciting converter work under normal operation at first with reference to Fig. 7 A to 7D and Fig. 8.Wherein, load 3 is received on the inverter 20, makes the output of inverter have suitable load impedance.In the case, the magnitude of voltage of above-mentioned two tie points maintains under the magnitude of voltage on the smmothing capacitor 14, therefore, and when inverter two clamping diodes 41 and 42 all not conductings during by the work of the following stated step.

(1) is added to the first transistor 21 when making its conducting when starting biasing, inverter 20 is started working, shown in Fig. 7 A, electric current I L makes coupling capacitor 28 chargings simultaneously from level and smooth capacitor 14 flow through parallel connection combination, inductor 25 and the first transistor 21 of coupling capacitor 28, elementary winding 51 and

capacitor

31 and 32.

(2) when electric current I L reaches it in the degree that the magnetic field that induction around the inductor 25 produces no longer increases, the voltage that forms in the first feedback winding 26 two ends induction reduces thereupon, the first transistor 21 is ended, after this, shown in Fig. 7 B, electric current I L continues to pass through with same direction in the inductor 25, and the flow through second diode 24(rather than transistor 21), the parallel connection combination of capacitor 28 and elementary winding 51 and

capacitor

31,32, progressively weaken in magnetic field simultaneously.

(3) second feedback windings 27 are then in response to this magnetic field of weakening, and forward bias of induction generation is added on the transistor seconds 22 and makes its conducting.At this moment, transistor seconds 22 conductings, electric current I L with the parallel connection combination of transistor seconds 22, inductor 25 and elementary winding 51 and

capacitor

31,32 of flowing through of opposite direction self-capacitance device 28, and turns back to capacitor 28 shown in Fig. 7 C.

(4) when electric current I L reaches it in the degree that the magnetic field that induction around the inductor 25 produces no longer increases, the voltage that forms in the second feedback winding 27 two ends induction reduces thereupon, thereby transistor seconds 22 is ended.Then, shown in Fig. 7 D, inductor 25 still has electric current I L to continue to flow through to flow through parallel connection combination, capacitor 28, smmothing capacitor 14 and first diode 23 of elementary winding 51 and

capacitor

31 and 32.

So repeat above-mentioned steps, resonant circuit can provide the resonance current that flows with two rightabouts, and its operating time is depended on the circuit constant of resonant circuit.

On the other hand, when load 3 and power supply are thrown off, or load impedance value is when being increased to the degree that makes the corresponding generation too high voltages of L-C resonant circuit, the clamp current lead LN that will flow through, and according to flow through selectively a output voltage with the restriction inverter in clamping diode 41 and 42 of the polarity of output AC voltage.To 9C, such a case is discussed referring now to Fig. 7 A to 7D and Fig. 9 A.

(1) at first, when the first transistor 21 conductings, the electric current I L circuit of shown in Fig. 7 A, flowing through, with as shown in FIG. polarity to capacitor 31 chargings.

(2) then, the L-C resonant circuit is so being formed a corresponding bigger potential difference in the corresponding generation overvoltage in elementary winding 51 two ends by container 31 two ends, and the forward bias that adds on first clamping diode 41 than the direct voltage on the smmothing capacitor 14 is also big.Make 41 conductings of first diode thus, allow clamp current ID to press the order shown in Fig. 7 B, and by the direction opposite with electric current I L, first loop of flowing through and forming by capacitor 31, coupling capacitor 28, smmothing capacitor 14, diode 41 and lead LN.At this moment, transistor 21 ends because of the effect of the first feedback winding 26, and after this, inductor 25 makes the electric current I L diode 24 that continues to flow through, capacitor 28 and elementary winding 51, and turn back to inductor 25.Like this, a resultant current IC(IL+ID will be arranged) capacitor 31 of flowing through, shown in Fig. 9 A to 9C.Therefore; the voltage that is produced by clamp current ID; resistance and resistance are by the formed voltage of electric current I L; output voltage is limited under the predetermined value thus; exempt from too high electric current with

protective transistor

21 and 22; otherwise too high electric current will not produce because of there being clamp current, inductor 25 and elementary winding 51 yet clamp current ID does not flow through.

(3) after this, transistor seconds 22 conductings make electric current I L by the circuit of flowing through of opposite direction shown in Fig. 7 C, with opposite polarity to capacitor 31 chargings.

(4) then, the L-C resonant circuit correspondingly produces overvoltage at elementary winding 51 two ends, form a corresponding bigger potential difference thus at capacitor 31 two ends, the forward bias that adds on second clamping diode 42 than the direct voltage on the smmothing capacitor 14 is also big.Make 42 conductings of second diode thus, allow another clamp current ID by the order shown in Fig. 7 D, and by the direction opposite with electric current I L, second loop of flowing through and forming by coupling capacitor 28, capacitor 31, lead LN and diode 42.At this moment, transistor 22 ends because of the effect of the second feedback winding 27, and after this, inductor 25 makes electric current I L continue to flow through elementary winding 51, coupling capacitor 28, smmothing capacitor 14 and diode 23, and turn back to inductor 25.Like this, an identical resultant current IC(IL+ID will be arranged) capacitor 31 of flowing through, shown in Fig. 9 A to 9C.Therefore, revolt and resist, thus output voltage is limited under the predetermined value, exempt from too high electric current with

protective transistor

21 and 22 by the formed voltage of electric current I L by the voltage that clamp current ID is produced.Otherwise too high electric current will not produce because of there being clamp current, clamp current ID do not flow through inductor 25 and elementary winding 51.

In order to make transformer 50 that required output voltage is provided,

capacitor

31 and 32 can be selected the suitable capacitance that differs from one another.

Figure 10 represents a power supply according to second embodiment of the invention, except additional capacitors device 29 of cross-over connection and

transistor

21A and 22A on elementary winding 51A are controlled by one drive circuit, outside making it alternate conduction and ending, it is identical with above-mentioned first embodiment basically.This capacitor 29 is in parallel with the tandem compound of

capacitor

31A and 32A, and forms the L-C resonant circuit of connecting with inductor 25A.As hereinbefore element is with identical reference number back word adding mother " A " expression in the circuit.The operation principle of this circuit is identical with first embodiment, so do not remake the explanation of repetition.Transistor 21A and 21B can resemble among first embodiment produce self-oscillation.

Figure 11 represents first kind of change to above-mentioned second embodiment, except the resistor 31B that connects with pair of series and 32B as impedance component, replacing

capacitor

31A and 32A is connected across on the elementary winding 51B, providing outside the output voltage that dividing potential drop represents inverter 20B, it and second embodiment are basic identical.The operation principle of this circuit is identical with first embodiment, therefore, not be used in this and makes repetition of explanation.Components identical is represented with identical reference number back word adding mother " B " in the circuit.

Figure 12 represents above-mentioned second second kind of change that embodiment did, except the inductor 31C that connects with pair of series and 32C as impedance component, replacing

capacitor

31A and 32A is connected across on the elementary winding 51C, to provide outside the output voltage that dividing potential drop represents inverter 20C, it is identical with second embodiment.Its operation principle is identical with first embodiment, thereby, not be used in this and make repetition of explanation.Components identical is represented with identical reference number back word adding mother " C " in the circuit.

Figure 13 represents above-mentioned second the third change that embodiment did, except the inductor 31D that connects with pair of series and capacitor 32D as impedance component, replacing

capacitor

31A and 32A is connected across on the elementary winding 51C, to provide outside the output voltage that dividing potential drop represents inverter 20D, it is identical with second embodiment.Its operation principle is identical with first embodiment, thereby, also not be used in this and make repetition of explanation.And components identical is represented with identical reference number back word adding mother " D " in the circuit.

Figure 14 represents a power supply according to third embodiment of the invention, adopt the form of the leakage transformer that contains leakage inductance except output transformer 50E, in order to replace inductor 25, outside capacitor 31E and 32E formed the similar L-C of series connection resonant circuit, it was identical with first embodiment.And, in the present embodiment, also alternately conducting and ending of

transistor

21E and 22E by the control of drive circuit.Its operation principle is identical with first embodiment, so also not be used in the explanation that this does repetition.And components identical is represented with identical reference number back word adding mother " E " in the circuit.

Figure 15 represents above-mentioned the 3rd a kind of change that embodiment did, on the secondary winding 52F that is connected across output transformer 50F except capacitor 31F that pair of series is connected and 32F, to provide a dividing potential drop to represent outside the output voltage of inverter, it is identical with above-mentioned the 3rd embodiment.Its operation principle is identical with first embodiment, makes repetition of explanation so not be used in this.Components identical is represented with identical reference number back word adding mother " F " in the circuit.

Figure 16 represents a power supply according to four embodiment of the invention, except load 3G directly is connected across on the capacitor 29G, do not insert output transformer therebetween, and

capacitor

31G and 32G that pair of series is connected are connected across on the inductor 25G, providing outside the output voltage that dividing potential drop represents inverter 20G, it and second embodiment are similar.Present embodiment can limit the output voltage of inverter equally, promptly can be by shown in Figure 17 A to 17D, according to the polarity of output AC voltage, make same clamp current ID flow through selectively

clamping diode

41G and 42G.

Specifically, when load impedance increases, when the first transistor 21G conducting, electric current I L is flow through shown in Figure 17 A like that, and capacitor 31G is charged by the polarity shown in the figure, and the L-C resonant circuit of being made up of inductor 25G and capacitor 29G forms a corresponding bigger potential difference at capacitor 31G two ends when producing too high voltage, and the forward bias that adds the first clamping diode 41G than the direct voltage on the smmothing capacitor 14G is also big.At this moment, the first clamping diode 41G conducting makes clamp current ID flow through capacitor 31G, capacitor 28G, smmothing capacitor 14G, diode 41G and lead LN shown in Figure 17 B.

On the other hand, when load impedance increases, when transistor seconds 22G conducting, electric current I L is flow through shown in Figure 17 C like that, and capacitor 31G is charged by the opposite polarity shown in Fig. 4, and the L-C resonant circuit produces when having the too high voltages of opposite polarity, forms a corresponding bigger potential difference at capacitor 31G two ends, and the forward bias that adds the second clamping diode 42G than the direct voltage on the smmothing capacitor 14 is also big.At this moment, the second clamping diode 42G conducting makes clamp current ID flow through like that capacitor 31G, lead LN, diode 42G, capacitor 28G and capacitor 29G shown in Figure 17 D.Like this, clamp current ID is limited under the predetermined value output voltage of inverter, and exempts from excessive electric current in order to

protective transistor

21G and 22G and flow through (otherwise will inevitable).Note, adopt this kind connected mode, the clamp current ID inductor 25G that will can not flow through, thus make inductor 25G can avoid generating heat because of clamp current flows through.Although in the present embodiment,

capacitor

31G and 32G as impedance component, are constituted the voltage divider of inverter output voltage, but the resistor that equally also can connect with pair of series, or the inductor of pair of series connection, or the inductor that pair of series connects constitutes identical voltage divider with capacitor.

Figure 18 represents a power supply according to fifth embodiment of the invention, it comprise same as described above, in order to the rectifier 2H of smooth dc voltage to be provided to smmothing capacitor 14H, and have two couples of transistor 21H that connect with the full-bridge form, 33 and 22H, 34 inverter 20H.Connect a series connection L-C resonant circuit of forming by the capacitor 31H and the 32H of inductor 25H and pair of series between the above-mentioned electric bridge output.Diode 43 and 44 is connected across on

transistor

33 and 34 respectively in antiparallel mode.Be connected to output transformer 50H in the circuit, its elementary winding 51H is connected across on a pair of capacitor 31H and the 32H, and secondary winding 52H is connected on the

load 3H.Capacitor

31H and 32H form voltage divider, in order to the dividing potential drop of the output voltage of representing inverter 20H to be provided, then determine first tie point between capacitor 31H and the 32H.Clamping diode 41H and 42H connect in antiparallel mode on the

transistor

21H and 22H that is connected across pair of series, determine second tie point between diode 41H and the 42H, and it is connected to first tie point that is positioned between

capacitor

31H and 32H by lead LN.And, in the present embodiment, when as long as the L-C resonant circuit is tending towards producing too high voltage because of load impedance increases, the tie point that is positioned between

capacitor

31H and 32H promptly is clamped on input direct voltage no better than, or on the magnitude of voltage that provides by smmothing capacitor 14H, thus, by as shown in FIG., make clamp current flow through selectively loop LP1 and LP2, and output voltage is limited under the predetermined value.Wherein, loop LP1 and LP2 comprise among clamping diode 41H and the 42H separately, and in diode 43 and 44 one.

That is, when

transistor

21H and 33 conductings and load impedance increase, allow clamp current to flow through and comprise the loop LP1 of diode 41H, smmothing capacitor 14H and diode 43.On the other hand, when

transistor

22H and 34 conductings and load impedance increase, then allow clamp current to flow through to comprise the loop LP2 of diode 44, smmothing capacitor 14H and diode 42H.In addition, can know that clamp current neither flows through inductor 25H, also not flow through the elementary winding 51H of output transformer, like this, just can not cause any undesired heating problem there according to figure.

Figure 19 represents a power supply according to sixth embodiment of the invention, it comprise same as described above, in order to the rectifier 2J of smooth dc voltage to be provided on smmothing capacitor 14J, and the inverter 20J with single transistor 21J, this transistor 21J connects with a L-C resonant circuit in parallel of being made up of capacitor 35 and inductor 36 and is connected across on the smmothing capacitor 14J.Inverter comprises a series connection L-C resonant circuit of being made up of inductor 25J and capacitor 29J, and this series connection L-C resonant circuit is connected with coupling capacitor 28J, is connected across on the above-mentioned L-C resonant circuit in parallel.Load 3J is connected across on the capacitor 29J.Transistor 21 is controlled conducting by drive circuit and is ended, so that provide a high-frequency ac output voltage at the capacitor 31J and the 32J two ends of a pair of serial connection.Capacitor 31J and 32J series connection are connected across on the capacitor 29J, constitute a voltage divider, and a dividing potential drop in order to expression inverter 20J output voltage is provided, and determine first tie point between two capacitors.A pair of

clamping diode

41J and 42J are connected across on the smmothing capacitor 14J in antiparallel mode, and determine one second tie point between two diodes, and it is connected to first tie point by lead LN.Therefore, in the present embodiment, as long as when the L-C resonant circuit is tending towards producing too high voltage because of load impedance increases, tie point between capacitor 31J and 32J, also be clamped on no better than smmothing capacitor 14J and go up on the input direct voltage value, like this, by as shown in FIG., make clamp current flow through selectively loop LP1 and LP2, the output voltage of inverter can be limited under the predetermined value.Wherein, loop LP1 and LP2 respectively comprise among clamping diode 41J and the 42J one.

Figure 20 represents the 6th first kind of change that embodiment did, except the series connection L-C resonant circuit of being made up of inductor 25K and capacitor 29K is connected across transistor 21K, and in circuit, adopt beyond the output transformer 50K, it is identical with the 6th embodiment.Wherein, the elementary winding 51K of output transformer 50K is connected across on the capacitor 29K, and its secondary winding 52K is connected on the load 3K.Components identical is represented with identical reference number back word adding mother " K " in the circuit.The operation principle of this change circuit, similar with embodiment shown in Figure 19.When clamp current is flowed through loop LP1 and LP2 as shown in FIG. selectively, the output voltage of inverter can be limited under the predetermined value, its clamping action is identical.Wherein, loop LP1 and LP2 respectively comprise among diode 41K and the 42K one.

Figure 21 represents the 6th second kind of change that embodiment did, except the series connection L-C resonant circuit of being made up of inductor 25M and capacitor 29M is connected across on the transistor 21M, in circuit, adopt an output transformer 50M, and capacitor 31M and 32M series connection is connected across inductor 25M goes up constituting outside the identical voltage divider, it and the 6th embodiment are similar.Wherein, the elementary winding of transformer 50M is connected across on the capacitor 29M, and its secondary winding 52M is connected on the load 3M.Components identical is represented with identical reference number back word adding mother " K " in the circuit.The operation principle of this change circuit, for example the clamp principle is identical with embodiment shown in Figure 19.When clamp current is flowed through loop LP1 and LP2 as shown in FIG. selectively, the output voltage of inverter can be limited under the predetermined value.Wherein, loop LP1 and LP2 respectively comprise among diode 41M and the 42M one.

In the circuit shown in Figure 19 to 21, can connect the inductor of resistor, pair of series connection or inductor and the capacitor that pair of series connects with pair of series equally, the capacitor of replacing the pair of series connection provides the expression dividing potential drop that inverter is exported.

Figure 22 represents a power supply according to seventh embodiment of the invention, and it is suitable for the gaseous discharge lamp 3N of rotating band negative electrode 4.

This power supply is identical with first embodiment basically.But further comprise a tracer 7; this tracer can reporting to the police to abnormal conditions; comprise that gaseous discharge lamp 3N throws off from power supply; or discharge lamp 3N is when increasing significantly because of performance becomes bad its impedance; for example, discharge lamp keeps work (at the end take place through regular meeting this useful life at discharge lamp) when having only a negative electrode, and the half-wave discharge situation that electric current only flows with a direction.Components identical is represented with identical reference number back word adding mother " N " in the circuit.The operation principle of this inverter is identical with first embodiment with the clamp operation principle, so this is not done the explanation that repeats.

Only there is clamp current (this clamp current produces in response to abnormal conditions, and it is in order to the output of restriction inverter) in tracer 7 and works in inverter.For this purpose, connect a transformer in circuit, its elementary winding 45 is inserted among the lead LN that connects first and second tie points, and when clamp current was flowed through lead LN, it can respond to a correspondent voltage on secondary winding 46.Secondary winding 46 is connected to capacitor 49 by diode 47 and resistor 48 and to its charging, makes tracer 7 actions.Therefore, tracer 7 only takes place just to work when flowing because of abnormal conditions when clamp current.When discharge lamp 3N becomes bad because of performance, impedance increases and when abnormal conditions took place, tracer 7 was in order to reduce the turn-on cycle of transistor 21N, thereby reduce the output voltage of inverter, make lamp 3N deepening, thus, notify the user to have abnormal conditions, and require the user to change this lamp.

Tracer 7 comprises first 70 and second portion 90.Wherein, first 70 is in order to the turn-on cycle of control minimizing transistor 21N, and second portion 90 only just makes first's 70 actions by capacitor 49 power supplies when clamp current flows in response to abnormal conditions.First 70 is connected to first of inductor 25 couplings with A, B, 3 of C respectively feeds back winding 26N, auxiliary winding 71 and 72.First 70 comprises transistor 73, and it is connected on the first transistor 21N of inverter 20N, with so that it ends, when abnormal conditions take place, can reduce the energising cycle of inverter.Transistor 73 and smmothing capacitor 74 cross-over connection mutually.The latter provides operating voltage by winding 71 and by capacitor 49 by second portion 90 and diode 95.The base stage of transistor 73 is connected with the output of comparator 75, and the latter's inverting input is connected on the dividing point between resistor 76 and 77, and resistor 76 and 77 is in series and cross-over connection in capacitor 74.The in-phase input end of comparator 75 is connected on the dividing point between resistor 78 and the capacitor 79, and resistor 78 and capacitor 79 also cross-over connection in capacitor 74.Capacitor 79 transistors 80 in parallel, transistor 81 in parallel again between the latter's the base-emitter.The base stage of transistor 81 is connected to winding 72 by resistor 82, and connects a diode 83 between its base-emitter.The winding direction of winding 72 should be and ought flow through inductor 25N because of electric current is arranged by the first feedback winding 26N, and when the first transistor 21N provided a biasing to make its conducting, winding 72 should provide a biasing to make its conducting to transistor 81.I.e. transistor 81 conductings simultaneously when the first transistor 21N conducting, and transistor 81 also ends when the first transistor 21N ends.When transistor 81 conductings, transistor 80 ends, and the electric current of origin self-capacitance device 74 to capacitor 79 charging, thus, provides a correspondent voltage to the in-phase input end of comparator 75 through resistor 78.The voltage that provides when capacitor 79 surpasses when being sent to the threshold voltage of comparator 75 end of oppisite phase, and high level output of comparator 75 corresponding generations makes transistor 73 conductings, and the first transistor 21N is ended.

Threshold voltage should be able to change between a high level and a low level.Wherein, high level only depends on resistor 76 and 77, and low level then not only depends on resistor 76 and 77, but also depends on the resistor 94 that is arranged in the second portion.Just as will be discussed, this threshold voltage is arranged on high level usually, only when detecting to such an extent that just be reduced to low level during ordinary situation.This high level should be selected to such an extent that make the threshold voltage that is no more than comparator 75 from the voltage of capacitor 79, transistor 73 is kept ended, thereby the first transistor 21N is not ended.On the other hand, this low level should be selected to such an extent that make the voltage from capacitor 79 can surpass this threshold voltage.Promptly when threshold voltage was arranged on the corresponding low level of abnormal conditions, capacitor 79 should be able to provide a voltage that surpasses this threshold level through charging in a time interval.The above-mentioned time interval is depended on the time constant of resistor 78 and capacitor 79, and it is from moment that transistor 80 ends in response to the conducting of the first transistor 21N.This time interval should be selected less than normally phase of the first transistor 21N, like this, capacitor 79 just like one in order to reduce the first transistor 21N timer of conducting phase, be that the charging voltage one of capacitor 79 surpasses when being arranged on low level threshold voltage, the first transistor 21N promptly ends to being forced to property.

Second portion 90 comprises by resistor 91 and being connected with 92 and a voltage divider forming that its accepts the voltage from capacitor 49, is used for providing a high level voltage to inverter 93, and the latter then produces a low-voltage that is defined as the circuit ground level.Just because resistor 94 is being inserted in inverter 93 and between the tie point between resistor 76 and 77, so when second portion 90 receives voltage from capacitor 49, resistor 94 becomes with resistor 77 and is connected in parallel, the result reduces the current potential of the tie point between resistor 76 and 77, thereby the threshold voltage of comparator 75 is reduced to low level.Therefore, when capacitor 49 forms voltage because of the clamp current lead LN that flows through, when expression had abnormal conditions to take place, tracer promptly moved to reduce the conducting phase of the first transistor 21N.And the output voltage of inverter 20N is reduced.When no abnormal situation, capacitor 49 does not charge, and the threshold voltage of comparator 75 remains on high level, and like this, tracer just can not move conducting phase of minimizing the first transistor 21N.Note, adopt this kind connected mode, deliver on the capacitor 74 by diode 95 from the voltage of capacitor 49, like this, the voltage that is produced by clamp current just can be used for providing operating voltage for first best.

So the tracer 70 that constitutes can be applied among other embodiments of the invention and the various change thereof equally.In addition, can find that above-mentioned tracer 70 can comprise an additional warning circuit, this warning circuit can be by the clamp current of the lead LN that flows through, or the voltage drive that provides by capacitor 49 and provide the indication of reporting to the police, for example light alarm lamp or send alarm sound.This kind warning circuit may be used solely to report abnormal conditions, and does not reduce the output of inverter.

Figure 23 represents a power supply according to eighth embodiment of the invention, and this power supply is except increasing a chopper 10, and it is similar to the 7th embodiment.Above-mentioned chopper 10 can with by AC power 1P through the direct voltage that identical rectifier 2P provides, offer inverter 20P after the rising.Tracer in the present embodiment is used for reducing the output voltage of chopper 10, thus the output of corresponding reduction inverter.Similar elements is represented with identical reference number back word adding mother " P " in the circuit.Chopper 10 comprises a metal-oxide-semiconductor field effect transistor (MOSFET) 11, and it connects the back cross-over connection in rectifier 2P with inductor 12.MOSFET11 drives conducting by chopper controller 100 and ends, on capacitor 14, also has pulsating dc voltage from rectifier 2P, in order to an interrupted direct voltage to be provided, this direct voltage is delivered to smmothing capacitor 14P to gather a smooth dc voltage that raises by blocking diode 13; Above-mentioned voltage conduct fixedly direct voltage offers inverter 20P.Chopper controller 100 adopts common design, and it is with so that MOSFET11 conducting repeatedly and ending, and obtains its operating voltage from auxiliary winding 15, and auxiliary winding 15 is coupled to inductor 12, produces an induced voltage when electric current is flowed through inductor 12.This induced voltage is fed on the capacitor 18 by diode 16 and resistor 17 and to its charging, and capacitor 18 then is connected to controller 100 and to its power supply.

Tracer comprises a transformer, and its elementary winding 45P inserts among the lead LN that connects first and second tie points, and when clamp current was flowed through lead LN because of the abnormal load situation, level winding 46P went up correspondent voltage of induction secondarily.Secondary winding 46P is connected to capacitor 49P by diode 47P and resistor 48P, and to its charging, capacitor 49P then is connected to transistor 102 by resistor 101, for it provides a biasing.Connect transistor 102 like this it is connected in parallel on by the two ends of capacitor 18 to a voltage supply road warp of chopper controller,, can be used to the work of stop control 100 when transistor 102 during because of the conducting of abnormal load situation.Therefore, when the abnormal load situation took place, controller 100 just lost efficacy, and the MOSFET11 that is working is quit work, thereby no longer provided an additional voltage by chopper 10 to inverter 20P.Thus, make inverter 20P work in lowered direct voltage, this direct voltage only directly is added on the smmothing capacitor 14P by rectifier 2P, has so just reduced the output of inverter.Reduced the voltage of smmothing capacitor 14P in case this thing happens, the also corresponding reduction of the voltage of the tie point between capacitor 31P and 32P, thereby clamp current can flow suitably, when even the abnormal load situation more or less alleviates, also can guarantee to limit the output of inverter.

Figure 24 represents a power supply according to ninth embodiment of the invention, and except a pair of secondary winding 111 and 112 were arranged, it was similar to embodiment shown in Figure 22.Winding 111 and 112 is coupled on the elementary winding 45R, heats in order to each negative electrode 4R to discharge lamp 3R, rather than is used for making the tracer action.Components identical is represented with identical reference number back word adding mother " R " in the circuit.Start moment at discharge lamp 3R, discharge lamp 3R presents the impedance of an increase, at this moment, clamp current will be flowed through and will be connected on lead LN between first tie point (between capacitor 31R and the 32R) and second tie point (between clamping diode 41R and the 42R), thereby produce an induced voltage by elementary winding 45R at each winding 111 and 112.Consequent induced voltage is added on the negative electrode 4R of discharge lamp 3R by

diode

113 and 114 respectively, and to its heating, so that make igniting of discharge lamp more convenient.In other words, when discharge lamp 3R starting moment, the overvoltage that forms because of its high impedance can be used for best to the negative electrode heating of discharge lamp, thereby can accelerate lighting of lamp.

Figure 25 represents a power supply according to tenth embodiment of the invention.Except an additional timer 120, the embodiment with shown in Figure 22 is identical basically for it.This timer 120 only can not limit the output of inverter in order to behind inverter startup in short time interval.Components identical is with identical representing with reference to back word adding mother " S " in the circuit.Timer 120 is by the power voltage supply that accumulates on the capacitor 121, and capacitor 121 then with after diode 122 and resistor 123 are connected is connected across on the input direct voltage E of inverter.Timer 120 is connected to a normally closed relay 130, the latter has excitation wire Figure 131 and switch 132, wherein, switch 132 and elementary winding 45S are in series to insert and are connected among the lead LN of first tie point (between capacitor 31S and the 32S) and second tie point (between clamping diode 41S and the 42S), elementary winding 45S is coupled to secondary winding 46S, it is in response to the abnormal load situation, adopt and identical mode embodiment illustrated in fig. 22, make and the tracer action of being formed by 70S of first and second portion 90S limit the output of inverter by the conducting phase that reduces the first transistor 21S.Wherein, except the first transistor 21S, the 70S of first can also design the conducting phase that is used for reducing transistor seconds 22S.

Only in the interbody spacer TS of as shown in figure 26 weak point, it is logical to produce an ON(in timer 120 design) signal, with cut-off switch 132, export thereby can not limit inverter by tracer.Otherwise, just do not produce the ON signal, and continue to make switch 132 closures, make tracer can limit the output of inverter.Time interval TS postpones to occur after a period of time after can being chosen in power on circuitry, and the negative electrode 4S to discharge lamp in the time delay before it occurs carries out preheating.Then, when switch disconnects, allow inverter only in short time interval TS, an overvoltage is added on the discharge lamp 3S as starting voltage, so that the igniting of lamp 3S.After this, promptly recover the effect of tracer restriction inverter output, make it when generation abnormal load situation, can be used for protective transistor.

Certainly, also can carry out suitable combination, thereby can realize a kind of more senior and more effective circuit structure above-mentioned each embodiment and feature that various change possessed thereof.

Claims

1, a kind of power supply is characterized in that comprising:

Fixing direct voltage source;

Inverter by described DC-voltage supply, output at described inverter provides a high-frequency ac voltage, described inverter comprises at least one switch element and a L-C resonant circuit, described switch element is through driving and conducting and ending, and producing described high-frequency ac voltage with output that described L-C resonant circuit is engaged in described inverter, described high-frequency ac voltage is added in the load that is coupled in described inverter output end in order to drive this load;

Cross-over connection is in first and second clamping diodes that are connected in series of described direct voltage source, and described first and second diodes and described direct voltage source are antiparallel relation, and by determining one first tie point between described first and second diodes;

First and second impedance components that pair of series connects, the described impedance component in the place in circuit are in order to providing the dividing potential drop of the described inverter output voltage of expression, and by determining one second tie point between described first and second impedance components;

Described first and second tie points interconnect, so that the output voltage of described inverter is limited in below the predetermined value.

2, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in first and second switch elements of described direct voltage, described L-C resonant circuit comprises the resonant inductance apparatus harmony capacitor device that shakes, and described L-C resonant circuit and described coupling capacitor are in series and are connected across on the element of described first and second switch elements, to determine a series connection L-C resonant circuit, described resonant capacitance apparatus comprises a pair of first and second capacitors, these first and second capacitor cross-over connections that are connected in series are in the output of described inverter, to determine described first and second impedance components.

3, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in first and second switch elements of described direct voltage source, described L-C resonant circuit comprises resonant inductance apparatus and capacitor device, and described L-C resonant circuit is connected cross-over connection on an element of described first and second switch elements with described coupling capacitor, to determine a series connection L-C resonant circuit, determine the output of described inverter by the two ends of described resonant capacitance apparatus, described first and second impedance means adopt the form of first and second capacitors respectively, and the described first and second capacitors in series cross-over connections are in described resonant capacitance apparatus.

4, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in described direct voltage source first and second switch elements, described L-C resonant circuit comprises resonant inductance apparatus and capacitor device, and described L-C resonant circuit is connected cross-over connection on an element of described first and second switch elements with described coupling capacitor, to determine a series connection L-C resonant circuit, determine the output of described inverter by the two ends of described resonant capacitance apparatus, described first and second impedance means adopt the form of first and second resistors respectively, and the described first and second resistor in series cross-over connections are in described resonant capacitance apparatus.

5, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in first and second switch elements of described direct voltage source, described L-C resonant circuit comprises the resonant inductance apparatus harmony capacitor device that shakes, and described L-C resonant circuit and described coupling capacitor are in series cross-over connection in an element of described first and second switch elements, to determine a series connection L-C resonant circuit, determine the output of described inverter by the two ends of described resonant capacitance apparatus, described first and second impedance means adopt the form of first and second inductors respectively, and described first and second inductors series connection cross-over connection is in described resonant capacitance apparatus.

6, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in first and second switch elements of described direct voltage source, described L-C resonant circuit comprises resonant inductance apparatus and capacitor device, and described L-C resonant circuit is connected cross-over connection in an element of described first and second switch elements with described coupling capacitor, to determine a series connection L-C resonant circuit, determine the output of described inverter by the two ends of described resonant capacitance apparatus, described first and second impedance means adopt the form of an inductor and a capacitor respectively, and described inductor and capacitors in series cross-over connection are in described resonant capacitance apparatus.

7, power supply as claimed in claim 1, it is characterized in that, described inverter comprises the output transformer with elementary winding and secondary winding, described elementary winding is connected in the circuit, determine the output of described inverter by its two ends, and described output is coupled in the described load by described secondary winding.

8, power supply as claimed in claim 7 is characterized in that, described output transformer is the leakage transformer with leakage inductance, is defined as described inductor arrangement by it, and cooperates the described L-C resonant circuit of formation with the resonant capacitance apparatus.

9, power supply as claimed in claim 1, it is characterized in that, described inverter comprises the output transformer with elementary winding and secondary winding, described elementary winding is connected in the circuit, and thus the two ends of described secondary winding being defined as the output of described inverter, the described first and second impedance component cross-over connections are in described secondary winding.

10, power supply as claimed in claim 1, it is characterized in that, described inverter comprises that a coupling capacitor and a pair of cross-over connection are in first and second switch elements of described direct voltage source, described L-C resonant circuit comprises resonant inductance apparatus and capacitor device, and described L-C resonant circuit is connected cross-over connection on an element of described first and second switch elements with described coupling capacitor, to determine a series connection L-C resonant circuit, described first and second impedance components are connected cross-over connection in described resonant inductance apparatus, and are defined as the output of described inverter by the two ends of described resonant capacitance apparatus.

11, power supply as claimed in claim 1, it is characterized in that, described inverter comprises four switch elements that are provided with by the full-bridge form, its electric bridge input cross-over connection is in described direct voltage source, its electric bridge output cross-over connection is in described L-C resonant circuit, described L-C circuit comprises the resonant inductance apparatus harmony that is connected in series between the described electric bridge output capacitor device that shakes, described inverter further comprises the output transformer with elementary winding and secondary winding, described elementary winding is connected across on the described resonant capacitance apparatus, and be the relation of connecting with described resonant inductance apparatus, and be defined as the output of described inverter by the two ends of described elementary winding, described resonant capacitance apparatus comprises first and second capacitors that pair of series connects, and described first and second capacitors are defined as described first and second impedance components respectively.

12, power supply as claimed in claim 1, it is characterized in that, described L-C resonant circuit, it comprises the resonant inductance apparatus harmony capacitor device that shakes, described inverter also comprises additional L-C resonant circuit in parallel, described L-C resonant circuit in parallel comprises secondary inductor and secondary capacitor, and connects cross-over connection in described direct voltage source with described switch element, described series connection L-C resonant circuit then cross-over connection on described L-C resonant circuit in parallel or on the described switch element.

13, power supply as claimed in claim 12, it is characterized in that, described inverter comprises the output transformer with elementary winding and secondary winding, described elementary winding and described resonant capacitance apparatus are connected in parallel and are connected in series with described resonant inductance apparatus, be defined as the output of described inverter by the two ends of described elementary winding, and be coupled in described load by described secondary winding, described first and second impedance components adopt the form of first and second capacitors respectively, and both connect cross-over connection in described elementary winding.

14, a kind of power supply is characterized in that comprising:

Fixing direct voltage source;

Inverter by described DC-voltage supply, output at described inverter provides a high-frequency ac voltage, described inverter comprises at least one switch element and a L-C resonant circuit, described switch element is through driving and conducting and ending, and producing described high-frequency ac voltage with output that described L-C resonant circuit is engaged in described inverter, described high-frequency ac voltage is added in the load that is coupled in described inverter output end in order to drive this load; Described L-C resonant circuit comprises the resonant inductance apparatus harmony capacitor device that shakes;

Cross-over connection is in first and second clamping diodes that are connected in series of described direct voltage source, and described first and second diodes and described direct voltage source are the antiparallel relation, and the tie point between described first and second diodes is defined as first tie point;

Cross-over connection is in first and second impedance components that are connected in series of described resonant inductance apparatus, described impedance component is in order to provide a dividing potential drop, be illustrated in the output voltage that described inverter output end produces, tie point between described first and second impedance components is defined as second tie point, and

15, power supply as claimed in claim 14 is characterized in that, described first and second impedance components adopt the form of first and second capacitors respectively, and two capacitors are in series also cross-over connection on described resonant inductor.

16, power supply as claimed in claim 14, it is characterized in that, described L-C resonant circuit is series connection L-C resonant circuit, it comprises described inductor arrangement and described capacitor device, described inverter also comprises additional L-C resonant circuit in parallel, it comprises secondary inductor and secondary capacitor, and they are connected with described switch element, and also cross-over connection is in described direct voltage source, and the cross-over connection of described series connection L-C resonant circuit is on described L-C resonant circuit in parallel or described switch element.

17, as claim 1 or 14 described power supplys, it is characterized in that further comprising a tracer, described tracer is only when described L-C resonant circuit produces a too high voltage, the electric current that just is connected in by flowing through in the lead between described first and second tie points makes it action, described tracer comprises at least one warning device and control device, described warning device is in order to indicate described superpotential generation, and described control device is controlled the described switch element of described inverter to reduce the output voltage of described inverter.

18, power supply as claimed in claim 17, it is characterized in that, described tracer is by having the transformer coupled in described lead of elementary winding and secondary winding, described elementary winding is plugged in described lead, be plugged in described lead to induce one at described secondary winding two ends with this winding of flowing through, to induce an electric current correspondent voltage with this lead of flowing through at described secondary winding two ends, described secondary winding is connected to described tracer by a rectifier, when described current response is flowed through described lead in described overvoltage that described L-C resonant circuit produced, produce a direct current voltage and make described tracer action thus.

19, as claim 1 or 14 described power supplys, it is characterized in that further comprising a rectifier and a chopper, described rectifier provides the direct voltage through rectification from alternating-current voltage source, described chopper provides described direct voltage source by described direct voltage through rectification, described chopper comprise with inductor be in series and cross-over connection in the chopper switches element of described rectifier, the conducting repeatedly and ending of described chopper switches element by the chopper controller drives, in order to an interrupted voltage to be provided, described interrupted voltage is undertaken smoothly by smmothing capacitor, described smmothing capacitor carries out the level and smooth smooth voltage the direct voltage that is directly provided by described whole device except having, also form a smooth voltage that boosts at its two ends, thus described smmothing capacitor is defined as described direct voltage source, it offers described inverter to described fixedly direct voltage; And described power supply further comprises a tracer, described tracer is only when described L-C resonant circuit produces a too high voltage, the electric current that just is connected in by flowing through in the lead between described first and second tie points makes it action, described tracer is connected to described chopper controller, on the conducting of the described chopper switches element that stops and cutting, reduce described direct voltage thus and and then reduce the output of inverter in response to described superpotential generation.

20, as claim 1 or 14 described power supplys, it is characterized in that, described load is the gaseous discharge lamp with a target, described inverter comprises the transformer with an elementary winding and a pair of secondary winding, described elementary winding is inserted in the lead that is connected between described first and second tie points, produce a too high voltage in order to only to work as described L-C resonant circuit, and when making an electric current flow through described lead, produce voltage in the induction of the two ends of described secondary winding respectively, described secondary winding is connected respectively on the described negative electrode, and the voltage that produces by induction on described secondary winding respectively heats described negative electrode.

21, as claim 1 or 14 described power supplys, it is characterized in that, described load is a gaseous discharge lamp, and described power supply further comprises a timer and a switch that is inserted in the lead that is connected between described first and second tie points, described timer connects into and only just makes described switch disconnect one period scheduled time after the zero-time of preheating discharge lamp negative electrode, thus, only in the described time, just interrupt the work of export-restriction below described predetermined value, light this discharge lamp on the described discharge lamp with an interior overvoltage is added between allowing at this moment with described inverter.