CN101056070B

CN101056070B - General convertor based on the mixed switch

Info

Publication number: CN101056070B
Application number: CN2007100689550A
Authority: CN
Inventors: 吕征宇; 汪槱生
Original assignee: 吕征宇; 汪槱生
Current assignee: Hangzhou Di Di Electric Technology Co., Ltd.
Priority date: 2007-05-31
Filing date: 2007-05-31
Publication date: 2010-09-08
Anticipated expiration: 2027-05-31
Also published as: CN101056070A

Abstract

The present invention provides a universal convertor based on a mixed type switch. The convertor circuit which is adapted to form a series of new switch power supply convertors almost having no energy saving ability only adopts a spot of all-controlled switches, and common thyristors. Devices derived from the present invention are: a reactive power compensator of electrical power grid, an active electric power filter, a sine inverter, a quasi-square wave inverter, an AC-DC transducer working in four quadrants, a bidirectional AC-DC-AC sine wave transducer, controllable rectifier having a power factor approximating to 1 and the content of harmonic wave approximating to 0, etc. The universal convertor can be applied widely in the fields of power supply of electric automobile, frequency and speed control, electric traction, uninterruption power sources, new energy convertor, electrochemistry power supply, medium frequency power supply, electrical energy quality improvement of electric power system. The device in the present invention has advantages of excellent electric property, reduced material cost, volume and weight, harmonic waves that are almost eliminated comparing to the common technology, and has a high value of application and generalizing.

Description

General convertor based on mixed switch

Technical field

The invention belongs to power rectifier, inversion and frequency control equipment.

Background technology

Three-phase alternating current with DC converting, exchange and the conversion that exchanges, be the basic contents of high-power electric technology.The relevant apparatus of AC/DC conversion mainly comprises rectifier and inverter two classes.The former becomes interchange into direct current, and the latter becomes direct current into interchange.Friendship/alternation changes normally through two friendships/straight conversion, i.e. ac-dc-ac transform; Yet useful friendship/friendship Direct Transform as matrixing, but is not promoted; Loop converter and for example, harmonic content is bigger, and power factor and operating frequency are all lower.

Hand over/directly the citation form of 3-phase power converter is the form of Fig. 1 a of six devices (representing six brachium pontis) composition.Six switch (K among Fig. 1 a _A, K _B, K _C, K _X, K _Y, K _Z) representing six brachium pontis, a, b, c are the three-phase alternating current ends, P, N are respectively the positive and negative ends of direct current.More heterogeneous friendship/straight current transformer form class is same, and brachium pontis quantity is the twice of the number of phases.If AC system has center line o, then also can increase by two brachium pontis (K _On, K _Op), as Fig. 1 b.

The device of forming current transformer at present, mainly be half control device (thyristor) and full control device (power field effect transistor---power MOSFET, insulated gate twin-stage transistor npn npn---IGBT, integrated gate commutated thyristor---IGCT etc., with IGBT is representative), uncontrollable diode can only be made common rectifier.

By thyristor or control the routine that device forms entirely and hand over/straight current transformer, voltage-type and current mode two classes are arranged, generally distinguish name, respectively shown in Fig. 2 a and Fig. 2 b with the operating condition of DC side.Usually, often import/go out inductance L 1 in the DC side serial connection in the current source converter, AC side also connects capacitor C 1; The DC side of voltage-type current transformer also connects capacitor C 2, and inductance L 2 is imported/gone out to the AC side serial connection.The voltage-type current transformer is suitable for adopting against leading type full-control type device, and current source converter is suitable for adopting inverse-impedance type full-control type device.

Use the current transformer of full-controlled switch and can also realize the control of step wave mode (for example: SHE, i.e. special key angle harmonic elimination method), pulse frequency modulated common switch regulating and controlling modes such as (PFM).Some can be used for sinusoidal wave circuit these methods, and some need can be used to the circuit of square type ripple work, as: permanent-magnet brushless DC electric machine driving, quasi-square wave motor-driven, electronic transformer etc.

The current transformer performance that the full-control type device is formed is better than thyristor current transformer usually, but the device of its use is more, and is expensive.Be difficult to satisfy convertor assembly and can integrate high-performance and low-cost requirement simultaneously, and having more advantage aspect the high-power device.

Summary of the invention

The objective of the invention is appropriate design, reach or the approaching complete performance of controlling device, have the advantage of high-power aspect by the device circuit.Controlling device relatively entirely is to reduce production costs significantly, can significantly widen market prospects.

For achieving the above object, the present invention proposes a kind of current mode friendship/straight current transformer that adopts the mixed switch device, comprises DC side and AC side, and thyristor bridge and auxiliary switch are arranged.The present invention adopts mixed switch in current transformer, i.e. unsteady flow bridge in conventional current type friendship/straight current transformer is thyristor bridge BR, and at current transformer the auxiliary BR of shutoff of auxiliary switch is set.The present invention who belongs under this total invention thinking has following 8 kinds of technical schemes that are mutually related:

Scheme I. is referring to Fig. 3 a, Fig. 3 b.In DC side one full control K switch 1 is set and connects with thyristor bridge BR and inductance L 1, other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness to L1; K2 is in parallel with L1, or a termination L1 and the tie point of K1, the dc terminal that another termination BR Different L 1 links to each other with K1; K1 keeps conducting state in the most of the time of switch periods L1, and the turn-off time that is used for the auxiliary BR of shutoff slightly is longer than BR brachium pontis recovery forward blocking required time, complementary conducting of K2 and K1 and shutoff.

Scheme II. is referring to Fig. 4 a.With the K1 among the mixed type dc switch Ks replacement scheme I, Ks connects with BR and L1, Ks by full control K switch 3, control K switch 4 entirely and constitute with thyristor K5, it is in parallel after wherein K4 connects with K5 with K3, the conducting task of Ks is born by K4, K5, the blocking voltage of Ks is born by K5, K3 and K4 play the effect of the auxiliary K5 of shutoff, the conducting K3 of elder generation when needs turn-off Ks, complementary conducting of K4 and K3 and shutoff, cut off the K5 electric current by K4 and make it to turn-off, the turn-off time of K4 slightly is longer than K5 and recovers the forward blocking required time.

Scheme III. is referring to Fig. 4 b.With the K1 among the mixed type dc switch Ks replacement scheme I, Ks connects with BR and L1, and Ks is made of full control K switch 3, low pressure accessory power supply Δ U and thyristor K5, and is in parallel with K5 after wherein K3 connects with Δ U, the conducting task of Ks is born by K5, and K3 and Δ U play the effect of the auxiliary K5 of shutoff; The conducting K3 of elder generation when needs turn-off Ks, the ON time of K3 slightly is longer than K5 and is recovered the forward blocking required time, and then turn-offs K3, makes Ks integral body present off-state.

Scheme IV. is referring to Fig. 4 c.With the K1 among the mixed type dc switch Ks replacement scheme I, Ks connects with BR and L1, Ks is made of thyristor K5, pulse power Up, step-up pulse transformer T, thyristor K6, it is in parallel after wherein the high pressure winding of T is connected with thyristor K6 with K5, the conducting task of Ks is born by K5, and Up plays the effect of the auxiliary K5 of shutoff by T; When needs turn-offed Ks, Up sent out direct impulse, the electric current of the K5 that flows through was originally changed flow to K6 K5 is turn-offed, and Up sends out reverse impulse and turn-offs K6 and make Ks integral body present off-state then.

Plan V. referring to Fig. 5.It is in parallel with thyristor bridge BR in DC side one mixed switch circuit Kp to be set, Kp is used for the auxiliary BR of shutoff, Kp is by thyristor bridge BRa and full control K switch 7, K8, low pressure accessory power supply Δ U1, Δ U2 forms, the AC side port of Kp promptly is the AC side port of BRa, the DC side port of Kp is connected respectively by two DC side ports of BRa and is gone up K7, Δ U1 and K8, form behind the Δ U2, K7, K8 is in the most of the time not conducting of switch periods, K7 or K8 conducting when needing to turn-off BR, the BR device current is incorporated among the BRa, make the BR device realize auxiliary the shutoff, K7, the ON time of K8 slightly is longer than the BR device and is recovered the forward blocking required time, and then turn-offs K7 or K8 makes Kp integral body present off-state.

VI. referring to Fig. 6.K7, the Δ U1 and K8, the Δ U2 that replace Kp in the plan V with two pulse power Up, two step-up pulse transformer T respectively.The most of the time not conducting of BRa switch periods, when needs turn-off the BR respective branch, Up exported positive pulse before this makes BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking, Up exports negative pulse then, boost the back amplitude a little more than the three-phase line voltage peak value through T, the respective branch of BRa is turn-offed and the recovery forward blocking.

VII. referring to Fig. 7.It is in parallel with thyristor bridge BR in DC side one mixed switch circuit Kp to be set, Kp is used for the auxiliary BR of shutoff, Kp by thyristor bridge BRa and thyristor K9, K10, control K switch 11 entirely, low pressure accessory power supply Δ U forms, the AC side port of Kp promptly is the AC side port of BRa, it is in parallel after K11, Δ U connect mutually with the BRa dc terminal, wherein the dc terminal polarity of BRa is opposite with Δ U, forms two ports of Kp on connecting respectively in the two ends after the parallel connection behind K9, the K10, and is in parallel on the contrary with BR port polarity; K9, K10, K11 are in the most of the time not conducting of switch periods, conducting K9 or K10 when needing to turn-off the BR respective branch, and conducting K11, the BR device current is incorporated among the BRa, make the BR device realize auxiliary the shutoff, the ON time of K9, K10, K11 slightly is longer than the BR device and is recovered the forward blocking required time, and then shutoff K11 makes Kp integral body present off-state.

VIII. referring to Fig. 8.Replace Δ U among the plan V II with pulse power Up, step-up pulse transformer T, replace full control K switch 11 with thyristor K12, the low pressure winding of T meets Up, conducting K8 or K9 when needing to turn-off the BR respective branch, and Up sends positive pulse and makes BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking, Up exports negative pulse then, boost the back amplitude a little more than the three-phase line voltage peak value through T, the respective branch of BRa is turn-offed and the recovery forward blocking, make Kp integral body present off-state.

Derived the technical scheme of 2 subordinates by foregoing invention.

The one, referring to Fig. 9 a, Fig. 9 b.The K2 current transformer in parallel among the solution of the present invention I or II or III or the IV with L1, between the tie point of K1 or Ks and L1 and BR (different K 1 or Ks are connected one) dc terminal, increase a full control switch or thyristor or diode Kdc with L1, in the section standby time of assist exchanging circuit, utilize K1 or Ks and Kdc, L1 to carry out DC/DC HF switch unsteady flow function, make whole current transformer become AC/DC dual regulation current transformer.Because of K1 is different with the ordering of connecting between the output at BR with L1, promptly directly connect BR by K1 or L1, this dependent invention has two kinds of DC/DC of Figure 10 a, Figure 10 b to regulate circuit.

The 2nd, referring to Figure 10 a, Figure 10 b.On the basis of technique scheme V or VI or VII or VIII, current transformer of the present invention is provided with a full control K switch 1 in DC side and connects with thyristor bridge BR and L1, and other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness for inductance L 1; K2 is in parallel with L1, or a termination L1 and the tie point of K1, the dc terminal that another termination BR Different L 1 links to each other with K1.Complementary conducting of K2 and K1 and shutoff are used to cut off the DC side electric current when commutation failure or load short circuits, in the section execution standby time of assist exchanging circuit HF switch unsteady flow function.

The general description of foregoing invention content

The current mode of the employing mixed switch device that the present invention proposes is handed over/straight current transformer, can also be extended to a various friendships alternating flow device always by it.Friendship of the present invention/straight current transformer is mainly used in the conversion between direct current and the simple alternating current, but AC side is not limited only to three-phase, can be more than three-phase (for example six phases); It also not necessarily must be sinusoidal wave exchanging output, just needs the output industrial frequency harmonic during for example as active power filtering, just needs output square type ripple during as brshless DC motor.In addition, exchanging also three-phase three-wire system not necessarily, also can be the three-phase four-wire system of band center line, and the C1 in this moment above-mentioned circuit can be connected across between each phase line and the center line.

Can carry out the conventional unsteady flow function of PWM (for example SPWM or SVPWM etc.) at current transformer of the present invention, dual mode is adopted in shutoff at pwm pulse thyristor in the cycle: the one, and by triggering the thyristor that need open, the thyristor that needs to turn-off is turn-offed by alternate back-pressure because of bearing back-pressure (alternate counter voltage); The 2nd, before triggering the thyristor that need open, real in the auxiliary shutoff of commutation brachium pontis by full control switch or mixed type dc switch.The former must work as and alternately could turn-off when counter voltage occurring, and the latter is then no matter voltage between phases is that plus or minus all can turn-off.In order to make full use of auxiliary turn-off function, reach and simplify the control purpose in the controlling Design, can in switch periods, arrange the auxiliary switch synchronization action, and alternate back-pressure turn-off function is used for the adjusting of pulse.

About further specifying of 8 kinds of concrete technical schemes under same invention thinking:

1) about scheme I

When the auxiliary shutoff of needs, cut off the current path of thyristor bridge by full control K switch 1, the thyristor that needs to turn-off is turn-offed naturally because of losing electric current, recovers forward blocking required time (for example doubling latter's required time) as long as interruption duration is slightly larger than thyristor.The electric current of inductance L 1 comes afterflow by full control switch or thyristor or diode K2 when direct current is cut off.K1, K2 be counteragent always, another shutoff when a conducting.Since in each switch periods the auxiliary time of turn-offing very short, it will be very little controlling the current effective value that K switch 2 passes through entirely.According to the connection difference of K2, two kinds of circuits are arranged.

First kind of connection is shown in Fig. 3 a, and application is limited to when DC side and connects electric capacity or voltage source or ohmic load.Afterflow control switch K2 can use thyristor in some applications except with the full control switch, and K2 had a process that is in reverse voltage naturally when prerequisite was the K1 conducting.But can not use diode.The advantage of this connection is to keep the electric current of L1 constant in the commutation course as far as possible, can adopt when direct current side joint voltage source or electric capacity, then can not adopt when charged inductive load of DC side or current source.

Second kind of connection is shown in Fig. 3 b, and this circuit K2 not only can use full control switch or thyristor, when current transformer can also use diode during for rectifier.This circuit allows direct current termination inductive load or current source.

Full control number of devices is one or two in the circuit of this programme, and wherein the current rating of K2 can significantly be lower than full control K switch 1, and all the other devices are thyristor.

2) about scheme II

Full-controlled switch K1 among the scheme I is in conducting state basically in switch periods, need bear whole power.Scheme II then is the function that realizes full-controlled switch K1 by mixed type dc switch Ks, referring to Fig. 4 a.Bear the conducting function by thyristor K5 among the Ks, assist by the conducting of full control K switch 3 and turn-off K5, and then turn-off K3; Consider that K3 has conduction voltage drop, also be not enough to turn-off K5,, force K3 to turn-off by the shutoff of the full control K switch 4 of connecting with K5.The conducting of K3 and K4, shutoff action are complementary, and the turn-off time of K4 slightly is longer than K5 and recovers forward blocking required time (for example doubling the latter).

K4 can use low pressure and low power MOSFET device, does not have very big voltage drop by big electric current the time, and price is not high yet.K3 can use devices such as IBGT, owing to do not need by very big average current, the capacity requirement of device is minimized.

3) about scheme III

Dispose the thinking of mixed switch similar with scheme II, different is when needs shutoff mixed switch Ks, guarantees that by introducing accessory power supply Δ U electric current can transfer on the full control K switch 3, referring to Fig. 4 b from thyristor K5.This independent current source can constitute with high frequency switch power, voltage requirements not high (for example 6-12V), in addition conduction time very short, so desired volume is very little.

4) about scheme IV

Basic identical from the thinking of overall control principle and disposal mixed switch with scheme III, be the high pressure version of scheme III, referring to Fig. 4 c.The solution thinking of scheme IV is to reduce the requirement of withstand voltage of the device that constitutes pulse power Up with step-up transformer.For example step-up ratio is 2: 1, and the requirement of withstand voltage of related device nearly just reduces half.The negative pulse amplitude of the pulse power Up here should be a little more than the three-phase line voltage peak value after T boosts, and forward voltage did not need very high (for example 12V gets final product) originally, but consider that the positive negative pulse stuffing that T sends needs magnetic balance, can get the part that the direct impulse amplitude is a negative pulse (for example 1/10th).Pulse power Up can produce by the circuit that is made of full control device.

5) about plan V

Referring to Fig. 5.Basic identical with scheme I from overall control principle, the thinking of disposing mixed switch is similar to scheme III, and different is by the auxiliary cutoff thyristor bridge BR that cuts off of ac circuit.All only by short-time current, the device rated capacity does not need very big full control device K7, K8 in this scheme.

6) about plan V I

Referring to Fig. 6.Overall control principle is basic identical with plan V, is the high pressure version of plan V.The thinking of disposing mixed switch is similar to scheme IV.For simplifying circuit, two step-up transformer T among the plan V I also can piece together with one in actual applications, and promptly T contains a former limit and two secondary.

7) about plan V II

Referring to Fig. 7.Control principle is basic identical with plan V, utilizes K9 and the K10 control passage of change of current brachium pontis up and down among the plan V II, thereby only needs a full control switch of cover and low pressure accessory power supply to realize assist exchanging circuit.

8) about plan V III

Referring to Fig. 8.Overall control principle is basic identical with plan V II, is the high pressure version of plan V II.The thinking of disposing mixed switch is similar to scheme IV.

9) about the change of current acceleration problem of scheme I, II, III, V

Among current transformer scheme I of the present invention or II or III or the IV, when K1 or Ks shutoff, the brachium pontis on the BR does not bear reverse voltage, and its turn-off time can be long.The last controlled false impulse power supply Ua in parallel of BR can add that to it reverse voltage makes it fast and reliable and recovers the forward blocking ability in the turn off process of BR, referring to Figure 11.The power of Ua does not need very big, and polarity is identical with BR, and voltage disconnects when stream does not change a little more than the controlled false impulse power supply of alternating voltage peak.When the needs change of current, the brachium pontis electric current of BR is by K1 or Ks blocking-up, and making alive is a little more than alternating voltage peak Ua more after a while, and the reverse current of BR brachium pontis is very little.Ua can be made of high frequency switch power independently and full control switch, as long as the Ua pulse can be kept the forward blocking recovery time (for example tens of microsecond) of being longer than brachium pontis.

10) about the explanation of multiple convertor scheme

At this moment current transformer of the present invention can adopt the multiple scheme in parallel of the invention described above current transformer because of adopting thyristor bridge BR operating frequency often lower, and the switch motion of each unit was staggered at interval mutually by equal time in switch periods, and circuit is referring to Figure 23.In high-power converter, utilize the amplitude of multipleization reduction switch periods pulsating current, can make the operating frequency of device require further to reduce, very be suitable for the super high power unsteady flow and use.

11) about the explanation of soft switch solution

Above-mentioned full control switch is carried out proper handling, just can utilize distributed constant or add the small parameter passive component, realize soft switch at an easy rate.For example full control K switch 1 is carried out to close afterwards earlier with full control K switch 2 and is opened in current transformer, promptly utilizes distributed constant to make it to bear voltage from zero progressively raising in a full control switch turn off process therein, and another is controlled switch entirely and just can open when the voltage natural zero-crossing.

Figure 24 is the soft switch solution of extra resonance electric capacity.At the dc output end of thyristor bridge resonant capacitance C4 in parallel, can make the dc terminal voltage of thyristor bridge BR change more regular in the commutation course, the resonance of current cut-off stage energy utilization finally and thyristor bridge and AC side load Distribution inductance, the half control device that turn-offs to needs provides more stable reverse voltage, and its harmonic period generally need be more than 10 microseconds.On the full control switch in full control switch or mixed switch and connect resonant capacitance, and meet resonant capacitance C5 can easier realization Zero-voltage soft switch condition, its harmonic period is generally in the microsecond level.Resonant capacitance C5 is the soft switch resonance that participates in full control switch, and above-mentioned resonant capacitance C4 is the shutoff resonance that participates in the half control switch, and both effects are distinguishing.

12) about reducing the explanation of full control switch requirement of withstand voltage scheme

Device such as K1, K2 can be connected by a plurality of devices, or many level circuit commonly used reduces the requirement of withstand voltage of individual devices.But K2 has the scheme of more simple and reliable reduction requirement of withstand voltage, for example by bearing a part of voltage (at this moment the current requirements of K2 can descend and the inverse ratio rising with voltage) on the L2 in the tap that is connected in parallel on L.Figure 25 is another dividing potential drop scheme of K2, is connected in parallel on waiting in the sub-winding of L respectively by a plurality of devices, has good dividing potential drop effect.

About further specifying of dependent invention

Dependent invention 1.Referring to Fig. 9 a and Fig. 9 b.The K2 current transformer in parallel among current transformer scheme I of the present invention or II or III or the IV with L1, increase a full control switch or thyristor or diode Kdc, in the section standby time of assist exchanging circuit, can utilize K1 or Ks and Kdc, L1 to carry out DC/DC HF switch unsteady flow function.Controlling schemes can adopt general pulse modulation scheme, and its switching frequency generally is higher than the change of current frequency of BR, thereby has formed the dual regulation function with the commutation switch of AC side.This regulatory function is the current transformer advantageous particularly of quasi-square wave for interchange, promptly regulates change of current frequency, the DC side amplitude of accommodation by AC side respectively.

Because of K1 is different with the ordering of connecting between the output at BR with L1, promptly directly connect BR by K1 or L1, this dependent invention has Fig. 9 a and two kinds of DC/DC of Fig. 9 b to regulate circuit, and its buck adjusting direction is opposite.When DC/DC regulated work, K2 was in not on-state.

For the circuit of Fig. 9 a, when current transformer only was used for rectification, Kdc can use diode, and the DC adjustment function is equivalent to BUCK (step-down) circuit, the step-down of control from the AC side to the DC side.When current transformer was inverter, Kdc must adopt full control switch or half control switch, and the DC adjustment function is equivalent to BOOST (boosting) circuit, control boosting from the DC side to the AC side.

For the circuit of Fig. 9 b, when current transformer was used for rectification, the DC adjustment function was equivalent to BOOST (boosting) circuit, control boosting from the AC side to the DC side.When current transformer was inverter, Kdc can use diode, and the DC adjustment function is equivalent to BUCK (step-down) circuit, the step-down of control from the DC side to the AC side.

This dependent invention 1 is to utilize full control switch of increase or thyristor or diode Kdc to realize the DC adjustment function.For K2 current transformer not in parallel among the present invention program I or II or III or the IV with L1, then need not increase switch, in the section standby time of assist exchanging circuit, also can utilize K1 or Ks and K2, L1 to carry out DC/DC HF switch unsteady flow function.When current transformer only was used for rectification, K2 can use diode, and the DC adjustment function is equivalent to BUCK (step-down) circuit, the step-down of control from the AC side to the DC side.When current transformer was inverter, K2 must adopt full control switch or half control switch, the complementary conducting of K2 and K1 or Ks, and the DC adjustment function is equivalent to BOOST (boosting) circuit, control boosting from the DC side to the AC side.

Dependent invention 2.Referring to Figure 10 a, Figure 10 b.Be scheme I and the combining of plan V or VI or VII or VIII, change of current task realizes that by plan V or VI or VII or VIII the protection the when K1 among the scheme I, K2 then are used for commutation failure or load short circuits is to improve reliability.Figure 10 a, Figure 10 b are dependent invention 3 examples based on plan V, have wherein adopted the KP in the plan V; For dependent invention 3 examples, as long as will in Figure 10 a, Figure 10 b, change corresponding Kp based on plan V I or VII or VIII.

K2 current transformer not in parallel in this dependent invention 2 with L1, in the section standby time of assist exchanging circuit, itself just can utilize K1 and K2, L1 to carry out DC/DC HF switch unsteady flow function, controlling schemes can adopt general pulse modulation scheme, its switching frequency generally is higher than the change of current frequency of BR, thereby has formed the dual regulation function with the commutation switch of AC side.

Explanation about current mode of the present invention and voltage-type current transformer problem

Friendship of the present invention/straight current transformer is a current source converter, and this circuit presents the voltage source characteristic in AC side, and presents current source characteristic in DC side, and these are the port Impedance character of its high-frequency converter.When the port of the impedance property of power supply or load and current transformer was identical, the capacitor C1 of current transformer port or inductance L 1 all allowed to omit.The present invention can change port character by adding filter.As Figure 12, wherein the AC/DC current transformer in the square frame is a current mode, but after the periphery added filters such as inductance L f and capacitor C f, whole port character had just become to voltage-type.

About the unidirectional and explanation bi-directional configuration problem

For convenience of description, many illustrations of specification have all used single-way switch to introduce the present invention program.The present invention program's embodiment has also mostly used unidirectional device, if need the four quadrant running performance, can use device, accessory power supply direction all opposite two overlap the circuit parallel runnings.Need only in some schemes of current transformer of the present invention and adopt the bidirectional switch device just can realize four quadrant running.

At present thyristor have two-way, and often the constituting of actual full control bidirectional switch by two single-way switch and diode etc. are compound.Figure 13 is that the four-quadrant that adopts bidirectional thyristor, two-way full control switch is handed over/straight current transformer.

Polarity problems about thyristor bridge and other switches

For the purpose of explanation the present invention program is convenient, in Figure of description on the thyristor bridge block diagram mark "+" "-" number, positive and negative end is exported in the rectification of corresponding thyristor bridge respectively.The positive and negative polarity of the output of current transformer in the accompanying drawings, i.e. " P ", " N " are unified according to the rectification function mark for the sake of simplicity, actual polarity is conversely during as inverter.

About auxiliary explanation of turn-offing the pulse power

Utilize full control device to constitute the auxiliary pulse power that turn-offs easily.Figure 14 a is that circuit takes place Up; Figure 14 b is that circuit takes place Ua, and its DC/DC high frequency switch power provides little electric current, high-tension DC source, sends pulse voltage by IGBT, and diode is used to stop pouring in down a chimney of high-tension current.

Beneficial effect of the present invention

Current transformer of the present invention possesses the function of common full control device current transformer, only uses a small amount of full control device, and most devices all are with high speed thyristor device (KK pipe), have remarkable price advantage.For example adopt the AC/DC current transformer of invention scheme I, only use the asymmetric full control device K1 of a rated capacity; K2 promptly uses full control device, and its current rating also can be more much smaller than K1.At present the high speed thyristor operating frequency just can reach 3000 hertz, can be fit to apparatus of the present invention use, and the price of high speed thyristor and triode thyristor (KP pipe) is more or less the same, far below IGBT, and high tension apparatus especially.Consider that C1, L1 are high frequency capacitance, inductance, current transformer does not use the favorable factor of the big electric capacity of low frequency, inductance, the cost of apparatus of the present invention even can be lower than the triode thyristor current transformer.

Device of the present invention has stronger cost advantage in high pressure, vast capacity field.In high pressure such as electric power system and electric traction, vast capacity application scenario, in the conventional current transformer full control device cost will occupy whole device very at high proportion, and be not easy buying; And the present invention only needs to use seldom full control device (the contour withstand voltage device of IGCT that need adopt constant volume in full of the full control device K1 among the scheme I only, if all the other schemes of employing are then by adopting step-up pulse transformer to reduce the requirement of full control device withstand voltage), can reach the effect that the device of device is controlled in whole employings entirely again.

Be used for the scheme of permanent-magnet brushless DC electric machine one class load or quasi-square wave power supply, the voltage of AC side or current waveform are the lower quasi-square wave of frequency.Interchange of the present invention, direct current dual regulation function can solve commutation and voltage regulation function simultaneously, and very helping brshless DC motor, quasi-square wave motor, electronic transformer etc. needs the device of quasi-square wave power supply to simplify circuit, reduce cost.

As all adjustable controlled rectification of power factor and output current, inverter and ac-dc-ac frequency converter cheaply, the present invention can apply in fields such as general Electric Drive, electric traction, solar power generation, direct current transportation, quality of power supply processing, hybrid vehicle, variable frequency power supply, induction heating power, charge in batteries power supply, electrochemical power sources.The present invention can be two-way and the alternating current-direct current current transformer of four quadrant running, be particularly suitable for hybrid vehicle, fuel cell car, fuel cell power generation, superconduction poultry can, application such as UPS (uninterruption power source) field of etc.ing.

In sum, the convertor assembly that manufactures and designs with the present invention program can be realized the superior function of full-control type current transformer, and significantly conservation, significantly reduce production costs, have huge Application and Development potentiality.

Description of drawings

Accompanying drawing 1a is existing phase three-wire three unsteady flow bridge; Accompanying drawing 1b is existing three-phase and four-line unsteady flow bridge.

Accompanying drawing 2a hands over/straight current transformer for existing current mode; Accompanying drawing 2b hands over/straight current transformer for existing voltage-type.

Accompanying drawing 3a is first kind of connection of current transformer scheme I; Accompanying drawing 3b is second kind of connection of current transformer scheme I.

Accompanying drawing 4a is current transformer scheme II; Accompanying drawing 4b is current transformer scheme III; Accompanying drawing 4c is current transformer scheme IV.

Accompanying drawing 5 is the current transformer plan V; Accompanying drawing 6 is current transformer plan V I.

Accompanying drawing 7 is current transformer plan V II; Accompanying drawing 8 is current transformer plan V III.

Accompanying drawing 9a is the first kind of connection of dual regulation current transformer scheme that adds switch;

Accompanying drawing 9b is the second kind of connection of dual regulation current transformer scheme that adds switch.

First kind of connection of accompanying drawing 10a current transformer change of current protection; Second kind of connection of accompanying drawing 10b current transformer change of current protection.

Accompanying drawing 11 is that scheme is turn-offed in the acceleration of controlled false impulse power supply.

The current transformer of accompanying drawing 12 band edge port filters.

The two-way friendship of accompanying drawing 13 current modes/straight current transformer case.

Accompanying drawing 14a pulse Up produces circuit; Accompanying drawing 16b pulse Ua produces circuit;

One of accompanying drawing 15a invention scheme I embodiment;

Two of accompanying drawing 15b invention scheme I embodiment.

Three of accompanying drawing 15c invention scheme I embodiment.

Accompanying drawing 16 invention scheme II embodiment.

Accompanying drawing 17 invention scheme III embodiment.

Accompanying drawing 18 invention scheme IV embodiment.

Accompanying drawing 19 invention plan V embodiment.

Accompanying drawing 20 invention plan V I embodiment.

Accompanying drawing 21a extra switch makes interchange, the direct current dual regulation current transformer of dc terminal step-down.

Accompanying drawing 21b extra switch makes and exchanges interchange, the direct current dual regulation current transformer that end boosts.

Interchange, direct current dual regulation current transformer that accompanying drawing 21c extra switch is boosted dc terminal.

Accompanying drawing 21d extra switch makes interchange, the direct current dual regulation current transformer that exchanges the end step-down.

Accompanying drawing 22 four-quadrant AC-DC-AC two way convertor embodiment.

Accompanying drawing 23 multiple convertor schemes

The soft switch solution of accompanying drawing 24 current transformers

The dividing potential drop scheme of accompanying drawing 25K2

Embodiment

The embodiment of invention scheme I

The examples of implementation of scheme I as shown in figure 15.Figure 15 a can be used for rectification and inversion, wherein thyristor bridge BR device all adopts the quick crystal brake tube of inverse-impedance type, K1, the common asymmetric IGBT of employing, K2 is made of fast diode of the less common asymmetric IBGT of capacity (only considering that transient current has certain allowance to get final product) series connection, and K2 also can directly adopt inverse-impedance type IGBT.Usually, when handling three-phase symmetrical current, voltage problem, the parameter of C1 and L1 requires design according to the filtering high-frequency impulse.If during problems such as needs processing unsymmetrical current, voltage, can increase the inductance value of L1.

Figure 15 b, Figure 15 c are that the K2 position is different with the difference of Figure 15 a.The current transformer of Figure 15 b has used diode, can only be used for rectification when implementing the DC side regulatory function; The current transformer of Figure 17 c then can be used for inversion, because wherein K1 has replaced the BOOST diode, K1, K2 need complementary conducting and shutoff.

The embodiment of invention scheme II

The examples of implementation of scheme II as shown in figure 16.Different with scheme I is that scheme II has replaced original K1 with mixed switch Ks, wherein K4 is low pressure and low power MOSFET (can constitute with the less power MOSFET of a plurality of electric currents is in parallel), K5 is quick crystal brake tube, and K3 is asymmetric IGBT (current rating requires lower than scheme I).

The embodiment of invention scheme III

The examples of implementation of scheme III as shown in figure 17.The formation of different with scheme II is scheme II mixed switch Ks is different, and K5 is quick crystal brake tube, and K3 is asymmetric IGBT (current rating requires lower than scheme I), and Δ U is the low pressure independent current source.

The embodiment of invention scheme IV

The examples of implementation of scheme IV as shown in figure 18.The formation of different with scheme III is scheme III mixed switch Ks is different, is the high pressure version of scheme III, and K5, K6 are quick crystal brake tubes, and Up is the pulse power, and T is step-up pulse transformer (low pressure side joint K3).When needs turn-off K5, Up exported positive pulse (pulse of opening of K6 arrives simultaneously) before this makes the current transfer of K5 to K6, keeping a period of time makes K5 recover forward blocking, and Up output negative pulse (boosting the back amplitude a little more than the three-phase line voltage peak value through T) is turn-offed K6 then.K5 need be by the rated direct current of device, and the capacity of K6 can be lower than K5.K2 has adopted the device IGCT that inverse-impedance type can turn-off in the circuit of Figure 18.The circuit embodiments that produces clock as shown in figure 14, if the step-up ratio of T gets 2, the device withstand voltage that then produces clock just requires nearly to hang down half than K5.

The embodiment of invention plan V

The examples of implementation of plan V as shown in figure 19, wherein the device of thyristor bridge BR, auxiliary cutoff thyristor bridge BRa all adopts the quick crystal brake tube of inverse-impedance type, full control K switch 7, K8 adopt asymmetric IGBT, and low pressure accessory power supply Δ U1, Δ U2 adopt independent high frequency switch power.The amplitude of low pressure accessory power supply should be able to guarantee that electric current needs the branch road of the change of current to shift the respective branch (about for example desirable 12V) of BRa from BR.K7, K8 needn't be limited to switch motion simultaneously, can independently control according to the needs of change of current branch road.Average current by BRa is very little, and the device capacity can be lower than BR.

The embodiment of invention plan V I

The examples of implementation of plan V I as shown in figure 20, the formation of different with plan V is plan V I mixed switch Kp is different, is the corresponding high pressure version of plan V I.Two Up are pulse powers, and two T are step-up pulse transformer (low pressure side joint pulse powers).When needs turn-off the BR respective branch, Up exported positive pulse before this makes BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking, Up output negative pulse (boosting the back amplitude a little more than the three-phase line voltage peak value through T) is turn-offed the Bra respective branch then.

The embodiment of invention plan V II

The examples of implementation of plan V II as shown in Figure 7, wherein the device of thyristor bridge BR, auxiliary cutoff thyristor bridge Bra, K9, K10 all adopts the quick crystal brake tube of inverse-impedance type, full control K switch 11 adopts asymmetric IGBT, and low pressure accessory power supply Δ U adopts independent high frequency switch power.The amplitude of low pressure accessory power supply should be able to guarantee that electric current needs the branch road of the change of current to shift the respective branch (about for example desirable 12V) of BRa from BR.When the brachium pontis that connects direct current+end of BR needs the change of current, open K9 and K11, otherwise open K10 and K11, make BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking; K11 turn-offs then, and K9 or K10 are turn-offed.Average current by Bra, K9, K10, K11 is very little, and the device capacity can be lower than BR.

The examples of implementation of plan V III as shown in Figure 8, different with plan V II is to have replaced the full control K switch 11 among Fig. 7 with step-up pulse transformer T and pulse power Up among the plan V III, is the corresponding high pressure version of plan V III.When needs turn-off the BR respective branch, Up exported positive pulse before this makes BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking, Up output negative pulse (boosting the back amplitude a little more than the three-phase line voltage peak value through T) is turn-offed the Bra respective branch then.

The embodiment of dependent invention 1 as shown in figure 21.

Figure 21 a is a rectification current transformer, and Kdc just adopts diode, constitutes common DC/DC step-down (BUCK) circuit by K1, Kdc and L1, makes the dc terminal step-down.

Figure 21 b is an inverter/converter, and Kdc just adopts asymmetric IGBT to connect with diode, constitutes DC/DC (BOOST) circuit that boosts by K1, Kdc and L1, makes to exchange end and boost.Because K1 has replaced the BOOST diode among Figure 21 b, when Kdc turn-offs, need the conducting of control K1.

Figure 21 c is a rectification current transformer, and Kdc just adopts asymmetric IGBT to connect with diode, constitutes DC/DC (BOOST) circuit that boosts by K1, Kdc and L1, and dc terminal is boosted.Because K1 has replaced the BOOST diode among Figure 21 c, when Kdc turn-offs, need the conducting of control K1.

Figure 21 d is an inverter/converter, and Kdc just adopts diode, constitutes DC/DC step-down (BUCK) circuit by K1, Kdc and L1, makes to exchange the end step-down.

In the circuit of Figure 21 d, when load is a voltage source or when containing back-emf, allow to omit K2, only the afterflow by Kdc exhausts the electric current of L1 also and can realize assist exchanging circuit, just the assist exchanging circuit action is rapid not as the circuit that contains K2.

Dependent invention 2 is scheme I and the combining of plan V or VI or VII or VIII, and wherein the embodiment of scheme I and plan V or VI or VII or VIII is please respectively referring to above-mentioned each scheme embodiment.

The present invention is based on the AC-DC-AC two way convertor of hybrid switch

Use circuit of the present invention and can constitute the AC-DC-AC two way convertor, specific practice is to overlap AC/DC current transformer of the present invention in the DC side cascade, i.e. the wherein positive and negative terminal inverse parallels of two cover current transformers with two.It can be applied to the field such as electronic transformer, electric energy regulator, wind power generation, interchange transmission, electric traction, variable frequency power supply of electrical power trans mission/distribution system.For electric power system three-phase imbalance situation, can suitably strengthen the inductance value of inductance L 1, be used to handle unbalanced fundamental frequency or harmonic energy.For the electric power quality adjuster, suitably the inductance that strengthens can be used for the adjusting of the transient process of electric power system.

The embodiment of formation AC-DC-AC two way convertor as shown in figure 22.For the sake of simplicity, the friendship in the illustration/straight current transformer has adopted the present invention program I, and it is a cover that wherein original independent two L1, K1, K2 assemblies that overlap are merged saving." a " " b " " c " is two groups respectively with " a ' " " b ' " " c ' " and independently exchanges port among the figure.

Constitute the AC-DC-AC two way convertors for the two cover current transformers that adopt scheme I, II, III, IV, and when adopting K2, two overlap L1 and K1 or Ks, the K2 circuit can be economized a slightly cover with the L1 parallel way.But sometimes in order to isolate the two phase mutual interference of buing or get by illegal means on the current control, at the circuits cascading place of two cover invention schemes, i.e. DC link positive and negative terminal, a last capacitor in parallel; At this moment, two of L1 and K1 or Ks, K2 cover circuits can not be merged into a cover.If allow this electric capacity suitably bear the low frequency energy storage, can make device have the ability of handling three-phase unbalance system too, also can be used for electric power quality and regulate.

The present invention can be applicable to two kinds of reactive power compensations and Active Power Filter-APF

Current transformer of the present invention, high frequency capacitance in the dc terminal parallel connection just can be as exchanging reactive power compensation and the use of APF current transformer, under electric power system three-phase imbalance situation, maybe need to handle the zero sequence composition the time, can suitably add high capacitance.As the present invention program's enforcement special case, all control switchs of current transformer all adopt unidirectional device, DC side short circuit, just become the reactive power compensation and the Active Power Filter-APF that do not have big electric capacity.Because dc terminal does not have power to inject or output (but still holding current passes through), each phase current energy of AC side shifts mutually.Therefore this device can be used for the active static passive compensation device of high efficiency electric power system; Because this convertor assembly also can be handled for symmetrical industrial frequency harmonic, therefore can be used as the electric power system active filter and use.Under electric power system three-phase imbalance situation, maybe need to handle the zero sequence composition the time, can suitably strengthen the inductance value of inductance L 1.

Claims

1. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is characterized in that in DC side one full control K switch 1 being set connects with thyristor bridge BR and inductance L 1, other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness to L1; K2 is in parallel with L1, or a termination L1 and the tie point of K1, the dc terminal that another termination BR Different L 1 links to each other with K1; K1 keeps conducting state in the most of the time of switch periods, and the turn-off time that is used for the auxiliary BR of shutoff slightly is longer than BR brachium pontis recovery forward blocking required time, complementary conducting of K2 and K1 and shutoff; This current transformer can be carried out the conventional unsteady flow function of PWM.

2. current transformer according to claim 1, a kind of in parallel of K2 wherein with L1, between the tie point of K1 and L1 and a dc terminal that BR different K 1 is connected with L1, increase a full control switch or thyristor or diode Kdc, in the section standby time of assist exchanging circuit, utilize K1 and Kdc, L1 to carry out DC/DC HF switch unsteady flow function, make whole current transformer become AC/DC dual regulation current transformer; Different at BR according to K1 with the ordering of connecting between the output with L1, promptly directly connect BR by K1 or L1, this dependent invention has two kinds of DC/DC to regulate circuit.

3. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is characterized in that in DC side one mixed type dc switch Ks being set connects with thyristor bridge BR and inductance L 1, other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness to L1; K2 is in parallel with L1, or a termination L1 and the tie point of Ks, the dc terminal that another termination BR Different L 1 links to each other with Ks; Ks keeps conducting state in the most of the time of switch periods, and the turn-off time that is used for the auxiliary BR of shutoff slightly is longer than BR brachium pontis recovery forward blocking required time, complementary conducting of K2 and Ks and shutoff; This current transformer can be carried out the conventional unsteady flow function of PWM;

Described Ks connects with BR and L1, Ks by full control K switch 3, control K switch 4 entirely and constitute with thyristor K5, it is in parallel after wherein K4 connects with K5 with K3, the conducting task of Ks is born by K4, K5, and the blocking voltage of Ks is born by K5, and K3 and K4 play the effect of the auxiliary K5 of shutoff, the conducting K3 of elder generation when needs turn-off Ks, the complementary conducting of K4 and K3 is cut off the K5 electric current by K4 and is made it to turn-off, and the turn-off time of K4 slightly is longer than K5 and recovers the forward blocking required time.

4. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is characterized in that in DC side one mixed type dc switch Ks being set connects with thyristor bridge BR and inductance L 1, other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness to L1; K2 is in parallel with L1, or a termination L1 and the tie point of Ks, the dc terminal that another termination BR Different L 1 links to each other with Ks; Ks keeps conducting state in the most of the time of switch periods, and the turn-off time that is used for the auxiliary BR of shutoff slightly is longer than BR brachium pontis recovery forward blocking required time, complementary conducting of K2 and Ks and shutoff; This current transformer can be carried out the conventional unsteady flow function of PWM;

Described Ks connects with BR and L1, and Ks is made of full control K switch 3, low pressure accessory power supply Δ U and thyristor K5, and in parallel with K5 after wherein K3 connects with Δ U, the conducting task of Ks is born by K5, and K3 and Δ U play the effect of the auxiliary K5 of shutoff; The conducting K3 of elder generation when needs turn-off Ks, the ON time of K3 slightly is longer than K5 and is recovered the forward blocking required time, and then turn-offs K3, makes Ks integral body present off-state.

5. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is characterized in that in DC side one mixed type dc switch Ks being set connects with thyristor bridge BR and inductance L 1, other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness to L1; K2 is in parallel with L1, or a termination L1 and the tie point of Ks, the dc terminal that another termination BR Different L 1 links to each other with Ks; Ks keeps conducting state in the most of the time of switch periods, and the turn-off time that is used for the auxiliary BR of shutoff slightly is longer than BR brachium pontis recovery forward blocking required time, complementary conducting of K2 and Ks and shutoff; This current transformer can be carried out the conventional unsteady flow function of PWM;

Described Ks connects with BR and L1, Ks is made of thyristor K5, pulse power Up, step-up pulse transformer T, thyristor K6, in parallel with K5 after wherein the high pressure winding of T is connected with thyristor K6, the conducting task of Ks is born by K5, and Up plays the effect of the auxiliary K5 of shutoff by T; When needs turn-offed Ks, Up sent out direct impulse, the electric current of the K5 that flows through was originally changed flow to K6 K5 is turn-offed, and Up sends out reverse impulse and turn-offs K6 and make Ks integral body present off-state then.

6. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is in parallel with thyristor bridge BR to it is characterized in that in DC side one mixed switch circuit Kp being set, Kp is used for the auxiliary BR of shutoff, Kp is by thyristor bridge BRa and full control K switch 7, K8, low pressure accessory power supply Δ U1, Δ U2 forms, the AC side port of Kp promptly is the AC side port of BRa, the DC side port of Kp is connected respectively by two DC side ports of BRa and is gone up K7, Δ U1 and K8, form behind the Δ U2, K7, K8 is in the most of the time not conducting of switch periods, K7 or K8 conducting when needing to turn-off BR, the BR device current is incorporated among the BRa, make the BR device realize auxiliary the shutoff, K7, the ON time of K8 slightly is longer than the BR device and is recovered the forward blocking required time, and then turn-offs K7 or K8 makes Kp integral body present off-state.

7. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is in parallel with thyristor bridge BR to it is characterized in that in DC side one mixed switch circuit Kp being set, Kp is used for the auxiliary BR of shutoff, Kp is by thyristor bridge BRa and two pulse power Up, two step-up pulse transformer T form, the AC side port of Kp promptly is the AC side port of BRa, the DC side port of Kp is respectively connected by two DC side ports of BRa and is formed after the combination of a last Up and T, T is in the most of the time not conducting of switch periods, T conducting when needing to turn-off BR, the BR device current is incorporated among the BRa, make the BR device realize auxiliary the shutoff, the ON time of T slightly is longer than the BR device and is recovered the forward blocking required time, and then shutoff T makes Kp integral body present off-state;

The most of the time not conducting of described BRa switch periods, when needs turn-off the BR respective branch, Up exported positive pulse before this makes BR need the device current of the change of current to transfer on the respective branch of BRa, and keep a period of time and make the BR respective branch recover forward blocking, Up exports negative pulse then, boost the back amplitude a little more than the three-phase line voltage peak value through T, the respective branch of BRa is turn-offed and the recovery forward blocking.

8. one kind is adopted the current mode of mixed switch device to hand over/straight current transformer, comprise DC side and AC side, thyristor bridge and auxiliary switch are arranged, it is in parallel with thyristor bridge BR to it is characterized in that in DC side one mixed switch circuit Kp being set, Kp is used for the auxiliary BR of shutoff, Kp is by thyristor bridge BRa and thyristor K9, K10, full control K switch 11, low pressure accessory power supply Δ U forms, the AC side port of Kp promptly is the AC side port of BRa, K11, it is in parallel after Δ U connects mutually with the BRa dc terminal, wherein the dc terminal polarity of BRa is opposite with Δ U, connect respectively and go up K9 in two ends after the parallel connection, form two ports of Kp behind the K10, in parallel on the contrary with BR port polarity; K9, K10, K11 are in the most of the time not conducting of switch periods, conducting K9 or K10 when needing to turn-off the BR respective branch, and conducting K11, the BR device current is incorporated among the BRa, make the BR device realize auxiliary the shutoff, the ON time of K9, K10, K11 slightly is longer than the BR device and is recovered the forward blocking required time, and then shutoff K11 makes Kp integral body present off-state.

9. current transformer according to claim 6 is provided with a full control K switch 1 in DC side and connects with thyristor bridge BR and L1, and other is provided with full control switch or thyristor or diode K2 and makes afterflow usefulness for inductance L 1; K2 is in parallel with L1, or a termination L1 and the tie point of K1, the dc terminal that another termination BR Different L 1 links to each other with K1; Complementary conducting of K2 and K1 and shutoff are used to cut off the DC side electric current when commutation failure or load short circuits, in the section standby time of assist exchanging circuit, carry out HF switch unsteady flow function.