CN1845435A - Bidirectional multi-level soft switch DC/DC for superconducting energy storage and its voltage side phase-shift controlling method - Google Patents

Abstract

The dual-way multi-level soft switch DC/DC for superconductance energy-storage comprises a voltage unit with voltage level being increased by adding primary winding and number of H-bridge inverter and current level being increased by paralleling with dc output end of H-bridge inverter, a transformer unit, and a current unit with current/voltage level being increased by paralleling/series connected with its dc output respectively. This invention reduces current ripple and requirement to circuit, and lets system work flexible within charge and discharge state.

Description

Superconducting energy storage bidirectional multi-level soft switch DC/DC and voltage side phase-shift controlling method thereof

Technical field

The present invention relates to DC converter and control method thereof that a kind of superconducting energy storage is used, particularly a kind of superconducting energy storage technology bidirectional multi-level soft switch DC/DC and voltage side phase-shift controlling method thereof.

Background technology

In recent years, along with the development of superconductor technology, superconductor more and more obtains people's attention and attention in the utilization of power domain, and countries in the world are carried out the superconducting power Study on Technology one after another.Wherein the superconducting energy storage technology owing to can realize many-sided function such as pulse energy adjustings, power system stability control people's attention extremely, become present unique business-like superconducting power technology.The superconducting energy storage technology generally is divided into two types of voltage-source type and current source types, and wherein voltage-source type is compared with current source type, and technology is more ripe, thereby the main flow that becomes superconductive energy storage system is selected.In the voltage-source type superconducting magnetic energy storage, need discharge and recharge superconducting magnet with DC/DC.DC/DC technology at present commonly used or be to need each cover of charging/discharging apparatus " adopts the superconducting energy storage stabilizing arrangement of charging and discharge DC/DC " as U.S. Pat 005159261; Adopt a covering device to realize the function that discharges and recharges simultaneously, " adopt the not multipleization DC/DC chopper of inphase angle " and U.S. Pat 004695932 " superconducting energy storage circuit " as U.S. Pat 005661646.Though the topological structure that these patents adopt is different, all do not solve the problem of two keys: 1, the soft switch problem of switching tube.These DC/DC realize discharging and recharging of superconducting magnet by hard switching, and the switching tube switch stress is big, and loss is big, have not only shortened the life-span of switching tube greatly, and have reduced the operating efficiency of system.2, the direct voltage terminal voltage is low, and has only a dc terminal voltage interface, can't link to each other with advanced person's voltage with multiple levels source inventer.Fig. 1 is the topology diagram of U.S. Pat 004695932 " superconducting energy storage circuit ", and wherein 10 for being used for the DC/DC chopper that superconducting magnet discharges and recharges.It realizes that by the hard switching of switching tube 17a and 17b the stress of switching tube is big to the discharging and recharging of superconducting magnet, and loss is also big; Simultaneously, it has only a dc terminal voltage interface, the direct voltage interface that electric capacity 9 two ends are as shown in Figure 1 provided, and in order to reduce harmonic wave, the voltage source converter that it can only pass through the form of multipleization of employing links to each other with high-voltage electric power system.And that the voltage source converter of multipleization need use is a plurality of bulky, expensive Industrial Frequency Transformer.Not only increase the volume of system greatly, also increased the cost of system greatly.The volume of Industrial Frequency Transformer and cost all account for more than 40% of whole system.

Summary of the invention

In order to overcome the deficiency of prior art, the invention provides a kind of many level DC/DC that can realize the energy two-way flow, its voltage cell can be as required, by the winding on the former limit of increase transformer and the quantity of H bridge inverter, improve electric pressure, and its current unit can improve current class by form in parallel, the current class of voltage cell also can obtain by the form of H bridge inverter dc output end parallel connection simultaneously, and the electric pressure of current unit also can be obtained by the series connection of its dc output end.Because can reduce the voltage of current unit by transformer, the voltage that is added on the superconducting magnet is relatively low, thereby has reduced the ripple of electric current side, has alleviated the requirement of filter circuit and the A.C.power loss of superconducting magnet.Simultaneously, it can also realize the Zero Current Switch of the whole switching tubes of current unit, and the zero voltage switch of the whole switching tubes of voltage cell has improved operating efficiency.And, by adopting the transformer step-down, make current unit can adopt low and the switching device that current capacity is big of voltage capacity, and the parallel connection of electric current side current source converter (csc) unit module, then further improve the through-current capability of electric current side, thereby improved the energy storage capacity of superconducting magnet effectively.The present invention can also pass through the transformer clamper, externally under the situation of the former limit of input current unanimity and transformer equivalent series resistance unanimity, make the voltage on each H bridge inverter dc terminal capacitor to be consistent automatically, externally the former limit of input current difference and transformer equivalent series resistance exists under the situation of certain error, its dc terminal voltage only has small steady-state error, meet the requirement that engineering is used fully, solved the difficult problem that many level DC/DC dc terminal voltage is difficult to balance, and the dc terminal voltage of the feasible multi-electrical level inverter that is attached thereto has also obtained Balance Control, make the multi-electrical level inverter that surpasses five level apply to high-pressure system and become possibility, thereby avoided adopting the voltage source inverter of multipleization to link to each other, reduced the volume and the cost of system with high-pressure system.The present invention can not only apply to superconductive energy storage system, and can also be as the boost voltage bascule of multi-electrical level inverter, in order to solve the unbalanced problem of multi-electrical level inverter dc terminal voltage.

Topological structure of the present invention is made up of voltage cell, transformer unit and current unit three parts.Wherein the topological structure of direct current pressure side unpack format can be used for connecting cascaded inverter, and the topological structure of direct current pressure side type of attachment can be used for connecting the multi-electrical level inverter of forms such as diode clamp, capacitor clamper.Wherein voltage cell is the H bridge inverter of a plurality of switching tube shunt capacitances, and each switching tube of H bridge inverter is shunt capacitor all.The former limit of the interchange termination transformer winding of H bridge inverter, the dc terminal of H bridge inverter is in parallel with capacitor.Transformer unit is one all has the transformer of a plurality of windings at former limit and secondary, and all on same magnetic core, the equal turn numbers of former limit winding, the number of turn of secondary winding also equate the winding of the former secondary of transformer; Can be common transformer or the tapped transformer of subcarrier band.The structure of current unit is decided according to transformer unit.If common transformer, secondary is the current source inverter of full-bridge form, if be with tapped transformer, secondary is the current source inverter of all-wave form.The dc terminal of current source inverter can be carried out series, parallel or connection in series-parallel as required.Voltage cell as required, also can adopt several H bridge inverters is one group, carries out parallel connection in dc terminal.In order to improve power density, transformer can be used high frequency transformer.In the topological structure of dc terminal unpack format, H bridge inverter dc terminal is separate, do not connect each other, and H bridge inverter dc terminal interconnects up and down in the topological structure of dc terminal type of attachment.

Control method of the present invention adopts the trigger impulse of current unit constant, and carries out the method for phase shifting control in voltage cell.According to the phase shifting angle of voltage cell, can make converter be operated in the state of charging and discharge.Adjust the phase shifting angle of voltage cell,, then be in charged state if make current unit dc terminal average value of output voltage greater than zero; Less than zero, then be in discharge condition.This control method is simple, and it is fast to discharge and recharge the speed of conversion.This method is in charging and discharging process simultaneously, and current unit dc terminal output voltage is a kind of unipolar voltage basically, and the ripple of electric current is less relatively, and the A.C.power loss of superconducting magnet is less, and also lower to the requirement of electric current side filter circuit.

Description of drawings

Further specify the present invention below in conjunction with the drawings and specific embodiments.

Fig. 1 is the schematic diagram of prior art U.S. Pat 004695932.

Fig. 2 is the topological structure schematic diagram of three level DC voltage end unpack format of the present invention.Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are switching tube among the figure, D1, D2, D3, D4, D5, D6, D7, D8 are diode, C1, C2, C3, C4, C5, C6, C7, C8 are the shunt capacitor on the respective switch pipe, Cd1, Cd2 are H bridge inverter dc terminal capacitor, Tr is the tapped transformer of subcarrier band, T1, T2 are that electric current can only single-phase mobile switch or the switch of two-way flow and the combination that diode is in series, and L is a superconducting magnet.

Fig. 3 is the topological structure schematic diagram of three level DC voltage end type of attachment of the present invention.Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8 are switching tube among the figure, D1, D2, D3, D4, D5, D6, D7, D8 are diode, C1, C2, C3, C4, C5, C6, C7, C8 are the shunt capacitor on the respective switch pipe, Cd1, Cd2 are H bridge inverter dc terminal capacitor, Tr is the tapped transformer of subcarrier band, T1, T2 are that electric current can only single-phase mobile switch or the switch of two-way flow and the combination that diode is in series, and L is a superconducting magnet.

Fig. 4 is a topological structure schematic diagram of many level DCs of the present invention voltage end unpack format.Wherein C1-Cn is a capacitor, FB-1 ... FB-n is the H bridge inverter of switching tube shunt capacitor, REC-1 ... REC-n is a current source inverter.L1 ... Ln is a current sharing inductor, and L is a superconducting magnet.Wherein current unit adopts form in parallel, as required, also can adopt the form of series connection or connection in series-parallel combination.Voltage cell as required, also can adopt several H bridge inverters is one group, carries out parallel connection in dc terminal.

Fig. 5 is a topological structure schematic diagram of many level DCs of the present invention voltage end type of attachment.Wherein C1-Cn is a capacitor, FB-1 ... FB-n is the H bridge inverter of switching tube shunt capacitor, REC-1 ... REC-n is a current source inverter.L1 ... Ln is a current sharing inductor, and L is a superconducting magnet.Wherein current unit adopts form in parallel, as required, also can adopt the form of series connection or connection in series-parallel combination.Voltage cell as required, also can adopt several H bridge inverters is one group, carries out parallel connection in dc terminal.

Fig. 6 is embodiments of the invention 1.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are thyristor, and L is a superconducting magnet.

Fig. 7 is embodiments of the invention 2.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is a thyristor, and L is a superconducting magnet.

Fig. 8 is embodiments of the invention 3.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are IGBT, and D1, D2 are diode, and L is a superconducting magnet.

Fig. 9 is embodiments of the invention 4.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is IGBT, and D1-D4 is a diode, and L is a superconducting magnet.

Figure 10 is embodiments of the invention 5.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are thyristor, and L is a superconducting magnet.

Figure 11 is embodiments of the invention 6.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is a thyristor, and L is a superconducting magnet.

Figure 12 is embodiments of the invention 7.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are IGBT, and D1, D2 are diode, and L is a superconducting magnet.

Figure 13 is embodiments of the invention 8.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is IGBT, and D1-D4 is a diode, and L is a superconducting magnet.

Figure 14 is the switching sequence figure in the charge cycle.

Figure 15 is the switching sequence figure in the discharge cycle.

Figure 16 is current unit half control type switch and full-controlled switch trigger impulse comparison diagram.

Figure 17 is in the charge switch sequential chart, [t ₃, t ₄] equivalent circuit diagram on the former limit of interior transformer.

Figure 18 is in the discharge switch sequential chart, [t ₂, t ₄] equivalent circuit diagram on the former limit of interior transformer.

Embodiment

Fig. 2 is the topological structure schematic diagram of three level DC voltage end unpack format of the present invention.As shown in Figure 2, topological structure of the present invention is made up of voltage cell, transformer unit and current unit three parts, and its voltage cell is made up of two H bridge inverters.Wherein each switch all has corresponding inverse parallel diode, and in parallel with corresponding capacitor.In first H bridge inverter, switch Q1, Q3 form a brachium pontis, and switch Q2, Q4 form another brachium pontis, and the two ends of two brachium pontis interconnect and be in parallel with capacitor Cd1.Two mid point A1, B1 of brachium pontis link to each other the equal turn numbers of two windings in the former limit of transformer with a winding on the former limit of transformer.The composition mode of second H bridge inverter and first are identical, switch Q5, Q7 form a brachium pontis, switch Q6, Q8 form another brachium pontis, the two ends of two brachium pontis interconnect and are in parallel with capacitor Cd2, and two mid point A2, B2 of its brachium pontis link to each other with another winding on the former limit of transformer.Transformer is the tapped transformer of subcarrier band.Its current unit is the current source inverter that switch transistor T 1, T2 form.The end of T1, T2 links to each other with the two ends of transformer, and the other end interconnects, and links to each other with an end of superconducting magnet.The other end of superconducting magnet L links to each other with the centre tap of transformer.

Fig. 3 is the topological structure schematic diagram of three level DC voltage end type of attachment of the present invention.Its topological structure is almost completely identical with Fig. 1, and unique difference is that the lower end of its first H bridge inverter dc terminal capacitor C d1 links to each other with the upper end of second H bridge inverter dc terminal capacitor C d2.Other connected mode is owing to identical with Fig. 1, so repeat no more here.

Fig. 4 is a topological structure schematic diagram of many level DCs of the present invention voltage end unpack format.Voltage cell is made up of a plurality of H bridge inverters; Transformer unit is one all has the transformer of a plurality of windings at former limit and secondary, and all on same magnetic core, the equal turn numbers of former limit winding, the number of turn of secondary winding also equate the winding of the former secondary of transformer; Current unit is made up of a plurality of current source inverters.C wherein ... Cn is a capacitor, FB-1 ... FB-n is the H bridge inverter of switching tube shunt capacitor, and the ac output end of each H bridge inverter all with a winding on the former limit of transformer links to each other; REC-1 ... REC-n is a current source inverter, and its alternating current end links to each other with the winding of transformer secondary; L1 ... Ln is a current sharing inductor, their end and current source inverter REC-1 ... one end of the dc output end of REC-n links to each other, and the other end links to each other with the end of superconducting magnet L.The other end of superconducting magnet L and current source inverter REC-1 ... the other end of REC-n dc output end links to each other.Current source inverter REC-1 ... the other end of REC-n dc output end interconnects.In this topological structure, current unit adopts form in parallel, as required, also can adopt the form of series connection or connection in series-parallel combination.Voltage cell as required, also can adopt several H bridge inverters is one group, carries out parallel connection in dc terminal.

Fig. 5 is a topological structure schematic diagram of many level DCs of the present invention voltage end type of attachment.Its topological structure is almost completely identical with Fig. 4, different is, the H bridge inverter FB-1 of switching tube shunt capacitor ... among the FB-n, the upper end of each H bridge inverter dc terminal capacitor C 1-Cn links to each other with a last H bridge inverter dc terminal electric capacity lower end, and the lower end of each H bridge inverter dc terminal capacitor C 1-Cn links to each other with the upper end of next H bridge inverter dc terminal electric capacity.The upper end of two H bridge inverter dc terminal capacitor C 1 and the lower end of Cn are not connected end to end.In this topological structure, current unit adopts form in parallel, as required, also can adopt the form of series connection or connection in series-parallel combination.Voltage cell as required, also can adopt several H bridge inverters is one group, carries out parallel connection in dc terminal.

Fig. 6 is embodiments of the invention 1.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are thyristor, and L is a superconducting magnet.Its connected mode and Fig. 2 are identical, and different is that it replaces perfect switch with actual switch.Wherein IGBT can be 1MBI600PX-120, and thyristor can be KA1200.

Fig. 7 is embodiments of the invention 2.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is a thyristor, and L is a superconducting magnet.Its voltage cell connected mode and Fig. 6 are identical, repeat no more here.Its transformer secondary is not with centre tap.Current unit is the current source inverter that T1-T4 forms, and T1 and T3 constitute one of them brachium pontis, and T2 and T4 constitute wherein another brachium pontis.The two ends of two brachium pontis interconnect and are in parallel with the superconducting magnet two ends, and the mid point of two brachium pontis links to each other with the two ends of transformer secondary.Wherein IGBT can be 1MBI600PX-120, and thyristor can be KA1200.

Fig. 8 is embodiments of the invention 3.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is the tapped transformer of subcarrier band, and T1, T2 are IGBT, and D1, D2 are diode, and L is a superconducting magnet.Its connected mode is almost completely identical with accompanying drawing 6, and unique difference is, it interconnects with IGBT and diode does as a wholely, replaces a thyristor in the accompanying drawing 6.Wherein IGBT can be 1MBI600PX-120, and diode can be MDN 600C20.

Fig. 9 is embodiments of the invention 4.Q1-Q8 is IGBT among the figure, and C1-C8 is the shunt capacitor on the respective switch pipe, and Cd1, Cd2 are H bridge inverter dc terminal capacitor, and Tr is a transformer, and T1-T4 is IGBT, and D1-D4 is a diode, and L is a superconducting magnet.Its connected mode is almost completely identical with Fig. 7, and unique difference is, it interconnects with IGBT and diode does as a wholely, replaces a thyristor in the accompanying drawing 7.Wherein IGBT can be 1MBI600PX-120, and diode can be MDN 600C20.

Figure 10,11,12,13 is almost completely identical with Fig. 6,7,8,9 connected mode respectively.Unique difference is that the lower end of their first H bridge inverter dc terminal electric capacity links to each other with the upper end of second H bridge inverter dc terminal electric capacity.

Concrete operation principle of the present invention and process are as follows:

The present invention can be operated in charging and discharge two states.

In charged state, converter of the present invention has 8 kinds of switch mode a switch periods, corresponds respectively to [t ₀, t ₁], [t ₁, t ₂], [t ₂, t ₃], [t ₃, t ₄], [t ₄, t ₅], [t ₅, t ₆], [t ₆, t ₇], [t ₇, t ₈], the switching sequence figure of its three level form is as shown in figure 14.[t wherein ₀, t ₄] be the preceding half period, [t ₄, t ₈] be the later half cycle.Below in conjunction with accompanying drawing 2 (establishing wherein, the switching device of current unit is half control type switches such as thyristor), describe its course of work in detail, wherein U _A1B1For first H bridge inverter exchanges end output voltage, U _A2B2Be that the 2nd H bridge inverter exchanges the end output voltage.U _sBe transformer secondary output voltage.I _P1For first H bridge inverter exchanges end output current, I _P2Be that second H bridge inverter exchanges the end output current.U _oBe current source inverter dc terminal output voltage.The no-load voltage ratio of transformer is K.I _Tr1For flowing through the electric current of first thyristor, I _Tr2For flowing through the electric current of second thyristor.

Switch mode 1 is (corresponding to [t ₀, t ₁]).t ₀Constantly, U _AB1, U _AB2For negative, I _P1, I _P2For negative, the T2 conducting, T1 turn-offs, and the voltage that loads the superconducting magnet two ends is identical with sense of current, and the electric current on the superconducting magnet increases.Primary current I _P1The flow direction be Q2-B1-A1-Q3, primary current I _P2The flow direction be Q6-B2-A2-Q7.t ₀Constantly, Q3, Q7 turn-off, so because C3, C7 are arranged is that no-voltage is turn-offed.Primary current I _P1To the C3 charging, the C1 discharge; Primary current I _P2To the C7 charging, the C5 discharge.After charge and discharge process finished, C1, the voltage on the C5 were zero, and the voltage on C3, the C7 is the voltage on capacitor Cd1, the Cd2.Primary current I _P1The flow direction be Q2-B1-A1-D1, primary current I _P2The flow direction be Q6-B2-A2-D5.U _A1B1, U _A2B2Be zero, converter neither charges and does not also discharge.

Switch mode 2 is (corresponding to [t ₁, t ₂]).t ₁Constantly, Q1, Q5 are open-minded, because the voltage on C1, the C5 is zero, institute thinks that no-voltage is open-minded.Flowing to of primary current is constant, U _A1B1, U _A2B2Still be zero, converter neither charges and does not also discharge.

Switch mode 3 is (corresponding to [t ₂, t ₃]).t ₂Constantly, Q2, Q6 turn-off, so because C2, C6 are arranged is that no-voltage is turn-offed.Primary current I _P1To the C2 charging, the C4 discharge; Primary current I _P2To the C6 charging, the C8 discharge.After charge and discharge process finished, C4, the voltage on the C8 were zero, and the voltage on C2, the C6 is the voltage on capacitor Cd1, the Cd2.Primary current I _P1The flow direction be D4-B1-A1-D1, primary current I _P2The flow direction be D8-B2-A2-D5.U _A1B1, U _A2B2For just, opposite with the direction of primary current, the electric current on the superconducting magnet reduces.

Switch mode 4 is (corresponding to [t ₃, t ₄).t ₃Constantly, apply trigger impulse to T1, because positive voltage is born at the T1 two ends, under the effect of trigger impulse, T1 is open-minded, because there is leakage inductance in transformer, the electric current that flows through T1 increases gradually, and T1 has realized zero current turning-on.And this moment, T2 bears reverse voltage, and under the effect of reverse voltage, the electric current that flows through T2 reduces to zero gradually, the T2 zero-crossing switching, thus realized zero-current switching.T2 closes and has no progeny the output voltage U of controlled rectification circuit _oOn the forward superconducting magnet, the electric current on the superconducting magnet increases.

More than be the switching process in first cycle of charged state,, do not giving unnecessary details here because operation principle and first cycle in second cycle are identical.

In discharge condition, converter of the present invention has 10 kinds of switch mode a switch periods, corresponds respectively to [t ₀, t ₁], [t ₁, t ₂], [t ₂, t ₃], [t ₃, t ₄], [t ₄, t ₅], [t ₅, t ₆], [t ₆, t ₇], [t ₇, t ₈], [t ₈, t ₉], [t ₉, t ₁₀] (seeing accompanying drawing 15).[t wherein ₀, t ₅] be the preceding half period, [t ₅, t ₁₀] be the later half cycle.

Switch mode 1 is (corresponding to [t ₀, t ₁]).t ₀Constantly, U _AB1, U _AB2For just, I _P1, I _P2For just, the T1 conducting, T2 turn-offs, and the voltage that loads the superconducting magnet two ends is identical with sense of current, the electric current increase on the superconducting magnet.Primary current I _P1The flow direction be Q1-A1-B1-Q4, primary current I _P2The flow direction be Q5-A2-B2-Q8.t ₀Constantly, Q1, Q5 turn-off, owing on Q1, the Q5 shunt capacitor C1, C5 are arranged, are that no-voltage is turn-offed.Primary current I _P1To the C1 charging, the C3 discharge; Primary current I _P2To the C5 charging, the C7 discharge.After charge and discharge process finished, C3, the voltage on the C7 were zero, and the voltage on C1, the C5 is the voltage on capacitor Cd1, the Cd2.Primary current I _P1The flow direction be D3-A1-B1-Q4, primary current I _P2The flow direction be D7-A2-B2-Q8.U _A1B1, U _A2B2Be zero, converter neither charges and does not also discharge.

Switch mode 2 is (corresponding to [t ₁, t ₂]).t ₁Constantly, Q3, Q7 are open-minded, because the voltage on C3, the C7 is zero, so be that no-voltage is open-minded.Flowing to of primary current is constant, U _A1B1, U _A2B2Still be zero, converter neither charges and does not also discharge.

Switch mode 3 is (corresponding to [t ₂, t ₃]).t ₂Constantly, Q4, Q8 turn-off, because C4, C8 are arranged, are that no-voltage is turn-offed.Primary current I _P1To the C4 charging, the C2 discharge; Primary current I _P2To the C8 charging, the C6 discharge.After charge and discharge process finished, C2, the voltage on the C6 were zero, and the voltage on C4, the C8 is the voltage on capacitor Cd1, the Cd2.Primary current I _P1The flow direction be D3-A1-B1-D2, primary current I _P2The flow direction be D7-A2-B2-D6.U _A1B1, U _A2B2For negative, opposite with the direction of primary current, superconducting magnet discharge, capacitor Cd1, Cd2 charging.

Switch mode 4 is (corresponding to [t ₃, t ₄]).t ₃Constantly, Q2, Q6 are open-minded, because the voltage on C2, the C6 is zero, so be that no-voltage is open-minded.Primary current flows to constant, U _A1B1, U _A2B2For still negative, operating state is identical with switch mode 4.

Switch mode 5 is (corresponding to [t ₄, t ₅]).T ₄Constantly, apply trigger impulse to T2, because positive voltage is born at the T2 two ends, under the effect of trigger impulse, T2 is open-minded, because there is leakage inductance in transformer, the electric current that flows through T2 increases gradually, and T2 has realized zero current turning-on.And this moment, T1 bears reverse voltage, and under the effect of reverse voltage, the electric current that flows through T1 reduces to zero gradually, the T1 zero-crossing switching, thus realized zero-current switching.T1 closes and has no progeny the output voltage U of controlled rectification circuit _oOn the forward superconducting magnet, the electric current on the superconducting magnet increases.Primary current I after commutation is finished _P1The flow direction be Q2-B1-A1-Q3, primary current I _P2The flow direction be Q6-B2-A2-Q7.

More than be the switching process in first cycle of discharge condition,, do not giving unnecessary details here because operation principle and first cycle in second cycle are identical.

From above-mentioned charge and discharge process, this converter has been realized the zero voltage switch of voltage cell and the Zero Current Switch of current unit fully, has very high operating efficiency.

More than adopt the operation principle of half control type device such as thyristor for current unit.For the form that current unit adopts full-controlled switch to connect with diode, its control method is almost completely identical, unique different be the trigger impulse of current unit, both pulses contrast as shown in figure 16.Wherein T1, T2 are the trigger impulse of half control type switch, and S1, S2 are the trigger impulse of full-controlled switch.For half control type switch, t ₀Constantly, give the T1 trigger impulse, be added in voltage on the T1 this moment greater than zero, because transformer has leakage inductance, the electric current that flows through T1 increases gradually, the T1 zero current turning-on, and be added in voltage on the T2 less than zero, the electric current that flows through T2 reduces gradually, and the T2 zero-crossing switching realizes zero-current switching.For full-controlled switch, t ₀Constantly, give the S1 trigger impulse, be added in voltage on the S1 this moment greater than zero, because transformer has leakage inductance, the electric current that flows through S1 increases gradually, the S1 zero current turning-on, and be added in voltage on the S2 less than zero, and the electric current that flows through S2 is reduced to zero gradually, after S2 is reduced to zero, and t ₁Constantly, turn-off S2, thereby realize zero-current switching.

The transformer clamper principle that regards to three level formal argument devices (n=2) down describes, and the operation principle of expanded circuit (n＞2) is basic identical in it.So-called transformer clamper is the former limit of transformer winding N _P1, N _P2On same magnetic core, if N _P1, N _P2The number of turn identical, winding N so _P1, N _P2Both end voltage keep identical constantly.In like manner, if secondary has a plurality of windings equally, as long as the number of windings is identical, the voltage at its two ends is also identical.

Be that example describes below with the charging process.If half switch periods is T.Charging process can be divided into three phases, and the one, energy is transmitted to secondary in the former limit of transformer; The 2nd, the former secondary voltage of transformer is zero (converter is in nought state); The 3rd, the switch of former secondary-side switch pipe and commutation process.Wherein the three phases time very short, can ignore.Second stage primary current is in the internal flow of H bridge inverter, and H bridge inverter dc terminal electric capacity does not participate in whole process.So can H bridge dc terminal voltage balance depend on first stage.First stage time corresponding is T1, [the t in the respective figure 14 ₃, t ₄], i.e. T ₁=t ₄-t ₃, its equivalent circuit diagram as shown in figure 17, r wherein ₁Be first H bridge switch pipe, lead, the former limit of transformer winding N _P1All-in resistance, r wherein ₂Be second H bridge switch pipe, lead, the former limit of transformer winding N _P2All-in resistance, E _P11, E _P12Be the terminal voltage on the former limit of transformer, i _P11, i _P12Be the electric current on the former limit of transformer, i ₁For external circuit injects the electric current of first H bridge inverter dc terminal, i ₂Be the electric current of second H bridge inverter dc terminal of external circuit injection, the leakage inductance of transformer is very little, can ignore.The terminal voltage that other establishes this stage transformer secondary is E _S11, E _S12, the electric current of transformer secondary is i _S11, i _S12, order $d=\frac{T_1}{T}.$

Two dc terminal voltage sums are 2U, are located under the external disturbance, and first dc terminal output voltage is U+ Δ U, and second dc terminal output voltage is U-Δ U, and the number of turn of transformer secondary is N _S1, N _S2, the former secondary turn ratio is K.

Have according to constant-linkage theorem:

${\mathrm{<figure-callout\; id="11"\; label="E\; p"\; filenames="A20061001191000191.png"\; state="\{\{state\}\}">E</figure-callout>}}_p=N_{p1}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}},E_{p12}=N_{p2}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}$

$E_{s11}=N_{s1}\frac{\mathrm{d\&Phi;}1}{\mathrm{dt}},E_{s12}=N_{s2}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}$

Make N _P1=N _P2=N _p, N _S1=N _S2=N _s(1)

Have

E _p1＝E _p11＝E _p12＝KE _s11＝KE _s12＝KE _s1

By principle of conservation of energy as can be known:

$N_{p1}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}*i_{\mathrm{<figure-callout\; id="11"\; label="p"\; filenames="A20061001191000191.png"\; state="\{\{state\}\}">p</figure-callout>}11}+N_{p2}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}*i_{p12}=N_{s1}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}*i_{s11}+N_{s2}\frac{d{\mathrm{\&Phi;}}_1}{\mathrm{dt}}*i_{s12}$

Substitution (1)

N _p* (i _P11+ i _P12)=N _s* (i _S11+ i _S12)=N _s* I ₀(I wherein ₀Be the electric current in the superconducting magnet)

Thereby have: $i_{\mathrm{<figure-callout\; id="11"\; label="p"\; filenames="A20061001191000191.png"\; state="\{\{state\}\}">p</figure-callout>}11}+i_{p12}=\frac{I_0}{K}...\left(2\right)$ (is reference direction with the flow direction shown in Figure 17)

As shown in Figure 17

$i_{\mathrm{<figure-callout\; id="11"\; label="p"\; filenames="A20061001191000191.png"\; state="\{\{state\}\}">p</figure-callout>}11}=\frac{(U+\mathrm{\&Delta;U})-E_{p1}}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_1},...\left(3\right)$

$i_{p12}=\frac{(U-\mathrm{\&Delta;U})-E_{p1}}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}...\left(4\right)$

Get by (2), (3), (4)

$\frac{(U+\mathrm{\&Delta;U})-E_{p1}}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_1}+\frac{(U-\mathrm{\&Delta;U})-E_{p1}}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}=\frac{I_0}{K}$

$\frac{[(U+\mathrm{\&Delta;U})-E_{p1}]{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2+[(U-\mathrm{\&Delta;U})-E_{p1}]r_1}{r_1{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}=\frac{I_0}{K}$

Make r ₁=R, r ₂=R+ Δ R (5)

:

$\frac{[(U+\mathrm{\&Delta;U})-E_{p1}](R+\mathrm{\&Delta;R})+[(U-\mathrm{\&Delta;U})-E_{p1}]R}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

$\frac{(U-E_{p1})(2R+\mathrm{\&Delta;R})+\mathrm{\&Delta;U\&Delta;R}}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

Ignore high-order event Δ U Δ R,

$\frac{(U-E_{p1})(2R+\mathrm{\&Delta;R})}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

$U-{\mathrm{<figure-callout\; id="1"\; label="E\; p"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">E</figure-callout>}}_p=\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}...\left(6\right)$

If i _P1, i _P2Be the average current of two transformer outputs up and down, then:

$i_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">p</figure-callout>}1}=\frac{\frac{(U+\mathrm{\&Delta;U})-E_{p1}}{r_1}{T}_1}{T}$

$=\frac{(U+\mathrm{\&Delta;U})-E_{p1}}{r_1}d...\left(7\right)$

In like manner can get:

$i_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{(U-\mathrm{\&Delta;U})-E_{p1}}{r_2}d...\left(8\right)$

${\mathrm{\&Delta;i}}_p=i_{p1}-{\mathrm{<figure-callout\; id="2"\; label="i\; p"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">i</figure-callout>}}_p$

$=\frac{[(U+\mathrm{\&Delta;U})-E_{p1}]r_2-[(U-\mathrm{\&Delta;U})-E_{p1}]r_1}{r_1{r}_2}d$

Generation (5)

$\mathrm{\&Delta;}{i}_p=\frac{[(U+\mathrm{\&Delta;U})-E_{p1}](R+\mathrm{\&Delta;R})-[(U-\mathrm{\&Delta;U})-E_{p1}]R}{R(R+\mathrm{\&Delta;R})}d$

$\mathrm{\&Delta;}{i}_p=\frac{2\mathrm{\&Delta;UR}+(U+\mathrm{\&Delta;U}-E_{p1})\mathrm{\&Delta;R}}{R(R+\mathrm{\&Delta;R})}d$

$=\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}(U-E_{p1})+\mathrm{\&Delta;R\&Delta;U}}{R(R+\mathrm{\&Delta;R})}d$

Ignore high-order event Δ R Δ U, then following formula can be reduced to:

$\mathrm{\&Delta;}{i}_p=\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}(U-E_{p1})}{R(R+\mathrm{\&Delta;R})}d...\left(9\right)$

Substitution (6) can get:

$\mathrm{\&Delta;}{i}_p=\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d$

If flowing into the electric current of Cd1, Cd2 is i _Cd1, i _Cd2, then

i _Cd1=i ₁-i _P1, i _Cd2=i ₂-i _P2, difference between the two is:

Δi _Cd＝i ₁-i _p1-(i ₂-i _p2)＝Δ _i-Δi _p

$\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=i_1-i_2-\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d...\left(10\right)$

If Δ i _Cd＞0 representative flows into the electric current of the electric current of Cd1 greater than inflow Cd2, and the voltage on the Cd1 increases with respect to Cd2; If Δ i _Cd＜0 representative flows into the electric current of the electric current of Cd1 less than inflow Cd2, and the voltage on the Cd1 reduces with respect to Cd2.

If i ₁=i ₂, promptly the voltage of two dc terminal of external circuit inflow voltage cell equates, this situation sees and adopts cascaded inverter or adopt other forms of multi-electrical level inverter and the null situation of its zero-sequence component; And Δ R=0, promptly the all-in resistance of each H bridge switch pipe, lead, the former limit of transformer winding is equal fully, then $\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=\frac{-2\mathrm{\&Delta;U}}{R}d.$ If Δ U＞0, promptly the voltage of upside dc terminal is greater than downside, then Δ i _Cd＜0 because R is very little, the voltage of upside dc terminal with respect to the rapid minimizing of downside until Δ U=0.If Δ U=1V, R=0.01 Ω, $d=\frac{1}{2},$ Δ i then _Cd=-100A, as seen, a small change in voltage can both cause the great variety that flows into the capacitance current difference, makes dc terminal voltage restore balance rapidly.In like manner, if Δ U＜0, promptly the voltage of upside dc terminal is less than downside, then Δ i _Cd＞0, the voltage of upside dc terminal increases sharply until Δ U=0 with respect to downside.

If Δ R ≠ 0, promptly there is certain difference in the all-in resistance of H bridge switch pipe, lead, the former limit of transformer winding, and i ₁=i ₂Still set up, then $\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d.$ Suppose that disturbance appears in dc terminal, make Δ i _Cd≠ 0, system is through Δ i after the dynamic adjustments _Cd=0, promptly

$-\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d=0$

$\mathrm{\&Delta;U}=-\mathrm{\&Delta;R}\frac{I_0(R+\mathrm{\&Delta;R})}{2K(2R+\mathrm{\&Delta;R})}$

$\mathrm{\&Delta;U}=-\mathrm{\&Delta;R}\frac{I_0(1+\frac{\mathrm{\&Delta;R}}{R})}{2K(2+\frac{\mathrm{\&Delta;R}}{R})}$

If R=0.01 is Ω, $\frac{\mathrm{\&Delta;R}}{R}=10\%,$ K＝2，I ₀＝1000A

ΔU＝-0.131V

As seen, though o'clock there is certain steady-state error in Δ R ≠ 0,, because R is very little, the absolute value of steady-state error is also very little, can control within the acceptable range.

If i ₁≠ i ₂, i.e. Δ i ≠ 0, and Δ R=0, then $\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=i_1-{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">i</figure-callout>}}_2+\frac{-2\mathrm{\&Delta;U}}{R}d,$ System still can do dynamic reaction to the disturbance of dc terminal voltage, suppose that disturbance appears in dc terminal, makes Δ i _Cd≠ 0, system is through Δ i after the dynamic adjustments _Cd=0, promptly

$i_1-{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">i</figure-callout>}}_2+\frac{-2\mathrm{\&Delta;U}}{R}d=0$

$\mathrm{\&Delta;i}+\frac{-2\mathrm{\&Delta;U}}{R}d=0$

$\mathrm{\&Delta;U}=\frac{\mathrm{R\&Delta;i}}{2d}...\left(15\right)$

If R=0.01 is Ω, Δ i=100A, $d=\frac{1}{2}$

Δ U=1V then

As seen, even the having a long way to go of input current, the dc terminal steady state voltage is still very little.

If Δ i ≠ 0, and Δ R ≠ 0, then $\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=\mathrm{\&Delta;i}-\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d$ , system still can do dynamic reaction to the disturbance of dc terminal voltage, suppose that disturbance appears in dc terminal, makes Δ i _Cd≠ 0, system is through Δ i after the dynamic adjustments _Cd=0, promptly

$\mathrm{\&Delta;i}-\frac{2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d=0$

$\mathrm{\&Delta;U}=\frac{(R+\mathrm{\&Delta;R})\mathrm{\&Delta;i}}{2d}-\mathrm{\&Delta;R}\frac{I_0(1+\frac{\mathrm{\&Delta;R}}{R})}{2K(2+\frac{\mathrm{\&Delta;R}}{R})}$

If R=0.01 is Ω, $\frac{\mathrm{\&Delta;R}}{R}=10\%,$ K＝2，I ₀＝1000A， $d=\frac{1}{2},$ Δi＝100A

ΔU＝-0.131+1.1＝0.969V

As seen, though Δ R ≠ 0, and the bigger gap of input current existence, its steady-state error is still very little.

Discharge condition can be divided into three phases equally, and the one, the transformer secondary transmits energy to former limit; The 2nd, the former secondary voltage of transformer is zero (converter is in nought state); The 3rd, the switch of former secondary-side switch pipe and commutation process.What work remains first stage, and first stage time corresponding is T ₁, [the t among corresponding Figure 15 ₂, t ₄], i.e. T ₁=t ₄-t ₂, its equivalent circuit diagram as shown in figure 18, r wherein ₁Be first H bridge switch pipe, lead, the former limit of transformer winding N _P1All-in resistance, r wherein ₂Be second H bridge switch pipe, lead, the former limit of transformer winding N _P2All-in resistance, E _P21, E _P22Be the terminal voltage on the former limit of transformer, i _P21, i _P22Be the electric current on the former limit of transformer, i ₁For external circuit injects the electric current of first H bridge inverter dc terminal, i ₂Be the electric current of second H bridge inverter dc terminal of external circuit injection, the leakage inductance of transformer is very little, can ignore.The terminal voltage that other establishes this stage transformer secondary is E _S21, E _S22, the electric current of transformer secondary is i _S21, i _S22, order $d=\frac{T_1}{T}.$

Two dc terminal voltage sums are 2U, are located under the external disturbance, and first dc terminal output voltage is U+ Δ U, and second dc terminal output voltage is U-Δ U, and the number of turn of transformer secondary is N _S1, N _S2, the former secondary turn ratio is K.

Have according to constant-linkage theorem:

$E_{p21}=N_{p1}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}},E_{p22}=N_{p2}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}$

$E_{s21}=N_{s1}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}},E_{s22}=N_{s2}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}$

Make N _P1=N _P2=N _p, N _S1=N _S2=N _s

Have

E _p2＝E _p21＝E _p22＝KE _s21＝KE _s22＝KE _s2

By principle of conservation of energy as can be known:

$N_{p1}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}*i_{p21}+N_{p2}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}*i_{p22}=N_{s1}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}*i_{s21}+N_{s2}\frac{d{\mathrm{\&Phi;}}_2}{\mathrm{dt}}*i_{s22}$

Substitution (1)

N _p* (i _P21+ i _P22)=N _s* (i _S21+ i _S22)=N _s* I ₀(I wherein ₀Be the electric current in the superconducting magnet) thus have: $i_{p21}+i_{p22}=\frac{I_0}{K}...\left(16\right)$ (is reference direction with the flow direction shown in the accompanying drawing 18)

By Figure 11,12 as can be known

$i_{p21}=\frac{E_{p2}-(U+\mathrm{\&Delta;U})}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_1},...\left(17\right)$

$i_{p22}=\frac{E_{p2}-(U-\mathrm{\&Delta;U})}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}...\left(18\right)$

Get by (16), (17), (18)

$\frac{E_{p2}-(U+\mathrm{\&Delta;U})}{{\mathrm{<figure-callout\; id="1"\; label="r"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_1}+\frac{E_{p2}-(U-\mathrm{\&Delta;U})}{{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}=\frac{I_0}{K}$

$\frac{[E_{p2}-(U+\mathrm{\&Delta;U})]{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2+[E_{p2}-(U-\mathrm{\&Delta;U})]r_1}{r_1{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">r</figure-callout>}}_2}=\frac{I_0}{K}$

Make r ₁=R, r ₂=R+ Δ R (19)

:

$\frac{[E_{P2}-(U+\mathrm{\&Delta;U})](R+\mathrm{\&Delta;R})+[E_{P2}-(U-\mathrm{\&Delta;U})]R}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

$\frac{(E_{P2}-U)(2R+\mathrm{\&Delta;R})-\mathrm{\&Delta;U\&Delta;R}}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

Ignore high-order event Δ U Δ R,

$\frac{(E_{p2}-U)(2R+\mathrm{\&Delta;R})}{R(R+\mathrm{\&Delta;R})}=\frac{I_0}{K}$

$E_{p2}-U=\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}...\left(20\right)$

If i _P1, i _P2Be the average current of two transformer outputs up and down, then:

$i_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20061001191000192.png,A20061001191000202.png"\; state="\{\{state\}\}">p</figure-callout>}1}=\frac{\frac{E_{p2}-(U+\mathrm{\&Delta;U})}{r_1}{T}_1}{T}$

$=\frac{E_{p2}-(U+\mathrm{\&Delta;U})}{r_1}d...\left(21\right)$

In like manner can get:

$i_{\mathrm{<figure-callout\; id="2"\; label="p"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">p</figure-callout>}2}=\frac{E_{p2}-(U-\mathrm{\&Delta;U})}{r_2}d...\left(22\right)$

$\mathrm{\&Delta;}{i}_p=i_{p1}-{\mathrm{<figure-callout\; id="2"\; label="i\; p"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">i</figure-callout>}}_p$

$=\frac{[E_{p2}-(U+\mathrm{\&Delta;U})]r_2-[E_{p2}-(U-\mathrm{\&Delta;U})]r_1}{r_1{r}_2}d$

Generation (5)

$\mathrm{\&Delta;}{i}_p=\frac{[E_{p2}-(U+\mathrm{\&Delta;U})](R+\mathrm{\&Delta;R})-[E_{p2}-(U-\mathrm{\&Delta;U})]R}{R(R+\mathrm{\&Delta;R})}d$

$\mathrm{\&Delta;}{i}_p=\frac{-2\mathrm{\&Delta;UR}+[E_{p2}-(U+\mathrm{\&Delta;U})]\mathrm{\&Delta;R}}{R(R+\mathrm{\&Delta;R})}d$

$=\frac{-2\mathrm{\&Delta;URd}+\mathrm{\&Delta;R}(E_{p2}-U)d-\mathrm{\&Delta;R\&Delta;U}}{R(R+\mathrm{\&Delta;R})}$

Ignore high-order event Δ R Δ U, then following formula can be reduced to:

$\mathrm{\&Delta;}{i}_p=\frac{-2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}(E_{p2}-U)}{R(R+\mathrm{\&Delta;R})}d...\left(23\right)$

Substitution (6) can get:

$\mathrm{\&Delta;}{i}_p=\frac{-2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d$

If flowing into the electric current of Cd1, Cd2 is i _Cd1, i _Cd2, then

i _Cd1=i ₁+ i _P1, i _Cd2=i ₂+ i _P2, difference between the two is:

Δi _Cd＝i ₁+i _p1-(i ₂+i _p2)＝Δi+Δi _p

$\mathrm{\&Delta;}{i}_{\mathrm{Cd}}=i_1-{\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="A20061001191000191.png,A20061001191000202.png"\; state="\{\{state\}\}">i</figure-callout>}}_2+\frac{-2\mathrm{\&Delta;UR}+\mathrm{\&Delta;R}\frac{I_{0}R(R+\mathrm{\&Delta;R})}{K(2R+\mathrm{\&Delta;R})}}{R(R+\mathrm{\&Delta;R})}d$

$=\mathrm{\&Delta;i}+$ $\frac{-2\mathrm{\&Delta;U}+\mathrm{\&Delta;R}\frac{I_0(1+\frac{\mathrm{\&Delta;R}}{R})}{K(2+\frac{\mathrm{\&Delta;R}}{R})}}{(R+\mathrm{\&Delta;R})}$ $d...\left(24\right)$

In like manner as can be known according to following formula, though Δ i ≠ 0, and Δ R ≠ 0, its steady-state error is still very little, can satisfy engineering demand.The process of comprehensive charging and discharge as can be known, even still can make dc terminal that small steady-state error is only arranged under the situation of this converter and control method inner parameter Δ R ≠ 0 thereof, under the situation of Δ i ≠ 0, if d is very little, can cause certain error, so this converter and control method relatively are fit to adopt the form of dc terminal separation and link to each other with cascaded inverter, this moment Δ i=0, thereby can make steady-state error in any situation can both be controlled at minimum scope.

Claims (3)

1, a kind of superconducting energy storage bidirectional multi-level soft switch DC/DC is characterized in that it is made up of voltage cell, transformer unit and current unit three parts; Wherein voltage cell is made up of a plurality of H bridge inverters, and each switching tube of H bridge inverter is shunt capacitor all, and the dc terminal of H bridge inverter also connects capacitor, and the two ends of capacitor provide the interface with external circuit; The interchange of H bridge inverter terminates on the winding on the former limit of transformer; Transformer unit is one all has the transformer of a plurality of windings at former limit and secondary, and all on same magnetic core, the equal turn numbers of former limit winding, the number of turn of secondary winding also equate the winding of the former secondary of transformer; The structure of current unit is decided according to transformer unit, if common transformer, secondary is the current source inverter of full-bridge form, if be with tapped transformer, secondary is the current source inverter of all-wave form; The dc terminal of current source inverter can be carried out series, parallel or connection in series-parallel as required; It is one group that voltage cell also can adopt several H bridge inverters, carries out parallel connection in dc terminal.

2,, it is characterized in that having the separation of direct current pressure side and be connected two kinds of topological structure forms according to the described superconducting energy storage of claim 1 bidirectional multi-level soft switch DC/DC:

The three level DC voltage end separates, and its voltage cell is made up of two H bridge inverters, and wherein each switch all has corresponding inverse parallel diode, and in parallel with corresponding capacitor; In first H bridge inverter, switch [Q1], [Q3] form a brachium pontis, and switch [Q2], [Q4] form another brachium pontis, and the two ends of two brachium pontis interconnect and be in parallel with capacitor [Cd1]; Two mid points [A1] of brachium pontis, [B1] link to each other with a winding on the former limit of transformer; Switch [Q5], [Q7] form a brachium pontis in second H bridge inverter, switch [Q6], [Q8] form another brachium pontis, the two ends of two brachium pontis interconnect and are in parallel with capacitor [Cd2], and two mid points [A2] of brachium pontis, [B2] link to each other with another winding on the former limit of transformer; Transformer is the tapped transformer of subcarrier band; Current unit is the current source inverter that switching tube [T1], [T2] form, and the end of switching tube [T1], [T2] links to each other with the two ends of transformer, and the other end interconnects, and links to each other with an end of superconducting magnet; The other end of superconducting magnet links to each other with the centre tap of transformer;

The three level DC voltage end connects, and the lower end of its first H bridge inverter dc terminal electric capacity links to each other with the upper end of second H bridge inverter dc terminal electric capacity;

Many level DCs voltage end separates, the H bridge inverter [FB-1 of switching tube shunt capacitor ... FB-n] the mid point of each H bridge inverter all with a winding on the former limit of transformer link to each other; Current source inverter [REC-1 ... REC-n] the alternating current end link to each other with the winding of transformer secondary; Current sharing inductor [L1 ... Ln] an end and current source inverter [REC-1 ... REC-n] an end of dc output end link to each other, the other end links to each other with an end of superconducting magnet, the other end of superconducting magnet links to each other with the other end of current source inverter dc output end; Current source inverter [REC-1 ... REC-n] other end of dc output end interconnects; Current unit adopts form in parallel, also can adopt the form of series connection or connection in series-parallel combination, and it is one group that voltage cell also can adopt several H bridge inverters, carries out parallel connection in dc terminal;

In the topological structure that many level DCs voltage end connects, the upper end of each H bridge inverter dc terminal electric capacity links to each other with a last H bridge inverter dc terminal electric capacity lower end, and the lower end of each H bridge inverter dc terminal electric capacity links to each other with the upper end of next H bridge inverter dc terminal electric capacity; The upper end of two H bridge inverter dc terminal electric capacity [C1] is not connected with the lower end of [Cn] end to end.

3, be applied to the described superconducting energy storage of claim 1 bidirectional multi-level soft switch DC/DC voltage side phase-shift controlling method, it is characterized in that adopting the voltage cell phase shifting control, adjust the phase shifting angle of voltage cell, make current unit dc terminal average value of output voltage greater than zero the time, converter is operated in charged state, less than zero the time, converter is operated in discharge condition.

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