CN114123790A - Large-scale efficient direct-current transformer - Google Patents

Large-scale efficient direct-current transformer Download PDF

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CN114123790A
CN114123790A CN202111388436.9A CN202111388436A CN114123790A CN 114123790 A CN114123790 A CN 114123790A CN 202111388436 A CN202111388436 A CN 202111388436A CN 114123790 A CN114123790 A CN 114123790A
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CN114123790B (en
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张东来
段金沛
谷汝楠
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Harbin Institute of Technology Shenzhen
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/22—Conversion of DC power input into DC power output with intermediate conversion into AC
    • H02M3/24—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters
    • H02M3/28—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
    • H02M3/325—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/3353—Conversion of DC power input into DC power output with intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter

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  • Dc-Dc Converters (AREA)

Abstract

本发明提供了一种大规模高效直流变压器，包括主电路、控制器，所述控制器与所述主电路相连；所述主电路包括子模块，所述子模块数量至少为两个，各所述子模块的输入侧串联，各所述子模块的输出侧并联；所述子模块包括升压电路、隔离型电路，所述升压电路与所述隔离型电路级连；所述控制器分别与各所述子模块的所述升压电路、所述隔离型电路相连，所述控制器用于控制各所述子模块中的前级升压电路从而实现功率流方向或输出电压或输入电压的控制。本发明的有益效果是：1.本发明的大规模高效直流变压器控制结构简单、高效率且易于故障切除；2.本发明的大规模高效直流变压器不仅减少了成本，同时还提高了工作效率。

Figure 202111388436

The present invention provides a large-scale high-efficiency DC transformer, including a main circuit and a controller, the controller is connected to the main circuit; the main circuit includes sub-modules, and the number of the sub-modules is at least two, each of which is The input sides of the sub-modules are connected in series, and the output sides of the sub-modules are connected in parallel; the sub-modules include a booster circuit and an isolation circuit, and the booster circuit and the isolation circuit are cascade-connected; the controllers are respectively Connected with the boost circuit and the isolated circuit of each of the sub-modules, the controller is used to control the front-stage boost circuit in each of the sub-modules to realize the direction of power flow or the output voltage or input voltage. control. The beneficial effects of the present invention are: 1. The large-scale and high-efficiency DC transformer of the present invention has a simple control structure, high efficiency and easy fault removal; 2. The large-scale and high-efficiency DC transformer of the present invention not only reduces costs, but also improves work efficiency.

Figure 202111388436

Description

Large-scale efficient direct-current transformer
Technical Field
The invention relates to the field of transformers, in particular to a large-scale efficient direct-current transformer.
Background
In the occasions of flexible direct current power transmission and distribution, rail transit, ships and warships and the like, the direct current transformer is key equipment for realizing voltage matching, electrical isolation and voltage regulation between the medium-voltage direct current bus and the low-voltage direct current bus. The input-series-output parallel-type combined converter has low voltage resistance and current resistance requirements on a switching device, and has the characteristics of modularization and easy expansibility, so that the input-series-output parallel-type combined converter becomes an ideal direct-current transformer form.
For the input-series output-parallel combined converter, the input voltage equalizing and the output current equalizing among all the sub-modules are ensured to ensure that the whole converter can normally operate. For this purpose, a number of advanced control methods are proposed: same duty cycle control, three-loop control, two-loop control, interconnection-less control, etc. The same duty ratio control is the simplest, but the input voltage-sharing and output current-sharing effects among the submodules are greatly influenced by the consistency of the parameters of the submodules. Therefore, in the document [1] "research on an input-series-output parallel system of a multi-converter module with a natural voltage-sharing characteristic", a two-stage structure of a boost converter cascade LLC-DCX is adopted as a submodule, and a control method with the same duty ratio is adopted to realize the stable operation of the whole direct-current transformer. The scheme improves the input voltage-sharing and output current-sharing degrees among the submodules, but reduces the conversion efficiency of the system. Document [2] "voltage decoupling control of a switched capacitor type ISOP converter" also adopts a two-stage structure, replaces LLC-DCX in document [1] with a phase-shifted full-bridge converter, and adopts voltage decoupling control to realize stable operation of a direct current transformer. The control system needs to adopt the input direct-current link capacitor voltage of each submodule, the cost is increased, and the pre-stage converter of the submodule is only used for fault removal.
The existing three-loop control and two-loop control strategies are complex, the input direct-current voltage of each submodule needs to be sampled, and the cost is increased. The interconnection-less control strategy has a softer out-of-output characteristic. The voltage-sharing and current-sharing effect in the same duty ratio control scheme adopting the single-stage structure is greatly influenced by the manufacturing process of the sub-module, and the system efficiency is not high by adopting the two-stage structure (boost + SRC) controlled by the same duty ratio.
Disclosure of Invention
The invention provides a large-scale efficient direct current transformer, which comprises a main circuit and a controller, wherein the controller is connected with the main circuit; the main circuit comprises at least two submodules, the input sides of the submodules are connected in series, and the output sides of the submodules are connected in parallel; the sub-module comprises a booster circuit and an isolated circuit, and the booster circuit is connected with the isolated circuit in a cascade way; the controller is respectively connected with the booster circuit and the isolation circuit of each submodule and is used for controlling a preceding stage booster circuit in each submodule so as to realize the control of the power flow direction or the output voltage or the input voltage;
the controller adopts a digital closed-loop control strategy, the output of the compensator is a modulation signal Vc, and when the large-scale high-efficiency direct-current transformer is in an optimal efficiency mode, the duty ratio of a boost circuit in each sub-module can be determined by judging the output of the modulation signal Vc and the carrier offset and amplitude set by each sub-module; when the large-scale high-efficiency direct current transformer is in a maximum power mode, the duty ratio of the boost circuit in each submodule can be obtained by dividing a modulation signal Vc by the number N of submodules and then sending the result to the carrier wave of each submodule.
As a further improvement of the present invention, the digital closed-loop control strategy comprises:
output voltage closed-loop control strategy: and generating a modulation signal Vc through output voltage closed loop, and generating and controlling the duty ratio of a Boost booster circuit in each submodule after the modulation signal Vc is subjected to carrier modulation, thereby realizing the regulation of the output voltage Vo.
As a further improvement of the present invention, the digital closed-loop control strategy further comprises:
input voltage closed-loop control strategy: and generating a modulation signal Vc through input voltage closed loop, and generating and controlling the duty ratio of a Boost booster circuit in each submodule after the modulation signal Vc is subjected to carrier modulation, thereby realizing the regulation of the input voltage Vin.
As a further improvement of the present invention, the digital closed-loop control strategy further comprises:
output voltage double closed loop control strategy: generating a reference signal i of a current inner loop by an output voltage outer looprefAnd generating a modulation signal Vc through the current inner ring, and generating and controlling the duty ratio of a Boost booster circuit in each submodule after the modulation signal Vc is subjected to carrier modulation, thereby realizing the regulation of the output voltage Vo.
As a further improvement of the present invention, the digital closed-loop control strategy further comprises:
input or output current closed-loop control strategy: and generating a modulation signal Vc through a current closed loop, and generating and controlling the duty ratio of a Boost booster circuit in each submodule after the modulation signal Vc is subjected to carrier modulation, thereby realizing the regulation of input or output current.
As a further improvement of the present invention, the controller includes a computing module and a carrier control module, the computing module is configured to provide a modulation signal to the voltage boost circuit in each of the sub-modules, the carrier control module is configured to provide a carrier to the voltage boost circuit in the sub-module, and the modulation signal and the carrier together form a driving signal of the voltage boost circuit; the controller comprises a fixed duty ratio and fixed frequency PWM generating module, and the fixed duty ratio and fixed frequency PWM generating module is used for providing a driving signal for the isolated circuit; the calculation module is a closed-loop voltage, current or power loop calculation module; the large-scale high-efficiency direct current transformer further comprises a hysteresis function block, and the hysteresis function block is used for preventing the converter from shaking between a maximum power mode and an optimal efficiency mode.
As a further improvement of the invention, the carrier wave will depend on the input power pinSum mode boundary power pboundaryWhen the input power p is greater than the maximum power carrier and the optimum efficiency carrierinIf the boundary power is less than-2 delta, switching from the maximum power mode to the optimal efficiency mode; when the input power pinWhen > mode boundary power-delta, switch from the optimum efficiency mode to the maximum power mode.
When switching from a maximum power mode to an optimum efficiency mode, a stacked carrier is selected as a carrier for each of the sub-modules; when switching from the optimal efficiency mode to the maximum power mode, a large carrier is selected as a carrier for each of the sub-modules;
the amplitude of the large carrier is the sum of the amplitudes of the laminated carriers of the booster circuits in the submodules; and if the maximum amplitude limit a of the duty ratio of the booster circuit in the submodule is set, the carrier offset of the ith submodule in the laminated carrier is (i-1) aH.
As a further development of the invention, the mode boundary power pboundaryIs about the input voltage vinA rated input power P that can be processed by a single sub-moduleuAnd the expected DC-link capacitance voltage V of a single said sub-moduledcAs shown in the following equation:
Figure BDA0003367861210000031
the isolation circuit has the characteristic of fixed voltage transformation ratio, so that the direct current link voltage Vdc and the output voltage Vo have the relation of fixed transformation ratio, and when the output voltage is stabilized at a desired voltage, the direct current link voltage Vdc is also stabilized at a fixed voltage value;
when the large-scale efficient direct current transformer works in an optimal efficiency mode, the lower tube duty ratio of the booster circuit in part of the submodules is 0.
As a further improvement of the invention, the isolated circuit is a series resonance circuit working under a fixed duty ratio or a phase-shifted full bridge under a fixed phase-shifting angle and fixed frequency or a double-active bridge circuit under a fixed phase-shifting angle and fixed frequency; the isolated circuit can adopt a structure of sharing one transformer magnetic core; the isolated circuit can further adopt a structure of sharing a secondary side rectifier on the basis of adopting a structure of sharing a transformer magnetic core; in the system starting stage of the large-scale high-efficiency direct current transformer, a maximum power mode is selected as a default starting mode, and after the system enters a steady state, the maximum power mode is used as a default starting mode according to input or output power and mode boundary power pboundaryDetermines in which mode the system operates; the input inductances in the boost circuits of the submodules can be combined into one inductance.
As a further improvement of the invention, the large-scale high-efficiency direct current transformer also comprisesWhen the system needs to be switched from the optimal efficiency mode to the expanded power mode, the carrier waves of the area where the modulation signal Vc is located and the carrier waves above the area are fused into a large carrier wave, the carrier waves of modules lower than the modulation signal Vc are kept unchanged, and meanwhile, the system is located in a work partition under different input voltage and input power conditions according to the input power PinAnd merge boundary power line Pfusion_boundary(x,Pu) The relationship of (a) determines whether the number of fused carriers needs to be increased to meet the power requirement;
the fusion boundary power line is a function of the number of carriers of the fusion sub-module and the rated power processed by the single sub-module, and is specifically shown by the following formula:
PFusion_boundary(x,Pu)＝x·Pu(1＜x≤N)，
wherein N is the total number of the submodules;
when the input power Pin> (fuse boundary Power line P)fusion_boundary(x,Pu)-δ1) If so, increasing the number of the fusion carriers to at least (x + 1); when the input power Pin< (fuse boundary power line Pfusion_boundary(x,Pu)-2δ1) And then, the number of the fusion carriers can still meet the power requirement when the number is less than x.
The invention has the beneficial effects that: 1. the large-scale efficient direct-current transformer is simple in control structure, high in efficiency and easy to remove faults; 2. the large-scale efficient direct current transformer not only reduces the cost, but also improves the working efficiency.
Drawings
FIG. 1(a) is a main circuit diagram of the present invention;
FIG. 1(b) is a schematic block diagram of the controller of the present invention;
FIG. 2(a) is a schematic diagram of a stacked carrier of the present invention;
FIG. 2(b) is a schematic diagram of a large carrier according to the present invention;
FIG. 3 is a schematic diagram of a digital closed loop control strategy of the present invention, FIG. 3(a) is a schematic diagram of an output voltage closed loop control; FIG. 3(b) a schematic diagram of input voltage closed loop control; FIG. 3(c) output voltage dual closed loop control schematic; FIG. 3(d) input or output current closed loop control.
FIG. 4 is a schematic diagram of the system operating region for different input voltages and input powers of the present invention;
FIG. 5 is a series resonant circuit diagram of the present invention;
FIG. 6 is a circuit diagram of a dual active bridge of the present invention;
FIG. 7 is a phase-shifted full-bridge circuit diagram of the present invention;
FIG. 8 is a main circuit diagram of the common input inductor of the present invention;
FIG. 9 is a schematic diagram of the system operating region for different input voltages and input powers of the present invention;
fig. 10 is a schematic diagram of the fusion of carriers of two sub-modules of the present invention.
Detailed Description
As shown in fig. 1, the invention discloses a large-scale high-efficiency direct current transformer, wherein a main circuit in the invention is shown in fig. 1(a), the main circuit at least comprises two sub-modules, the input sides of the sub-modules are connected in series, the output sides of the sub-modules are connected in parallel, and each sub-module is formed by cascading a booster circuit and an isolation circuit.
Fig. 1(b) is a schematic block diagram of a control structure. The isolated circuit is a series resonance circuit working under a fixed duty ratio or a phase-shifted full bridge under a fixed phase-shifting angle and a fixed frequency or a double-active circuit under a fixed phase-shifting angle and a fixed frequency.
The invention realizes the control of the power flow direction or the output voltage or the input voltage by controlling the preceding stage booster circuit in each submodule through the controller.
The carrier in the present invention will depend on the input power pinSum mode boundary power pboundaryThe size relationship of (c) is switched between the maximum power carrier and the optimum efficiency carrier. By introducing a hysteresis block, the converter can be prevented from dithering between the maximum power mode and the optimum efficiency mode. When the input power < (boundary power-2 δ), then switching from the maximum power mode to the optimum efficiency mode, the stacked carriers as in fig. 2(a) are selected as the carriers for the respective sub-modules; when the input power is > (mode boundary power-delta), then from the optimal efficiency modeSwitching to the maximum power mode, a large carrier such as that of fig. 2(b) is selected as the carrier for each sub-module.
And the amplitude of the large carrier is the sum of the amplitudes of the laminated carriers of the boosting circuits of the submodules. And the amplitude of the carrier wave of each sub-module booster circuit in the laminated carrier wave is H. The carrier offset of the ith sub-module is (i-1) × H. And if the maximum amplitude limit a of the duty ratio of the booster circuit in the submodules is set, the carrier offset of the ith submodule in the laminated carrier is (i-1) a H.
The control strategy of the present invention is schematically illustrated in fig. 3. Fig. 3(a) is a schematic diagram of an output voltage closed-loop control strategy. And generating a modulation signal Vc through output voltage closed loop, and generating and controlling the duty ratio of a Boost booster circuit in each submodule after the modulation signal Vc is subjected to carrier modulation, thereby realizing the regulation of the output voltage Vo.
Fig. 3(b) is a schematic diagram of an input voltage closed-loop control strategy. The modulation signal Vc is generated through input voltage closed loop, and the modulation signal Vc is generated after carrier modulation to control the duty ratio of a Boost circuit in each submodule, so that the regulation of the input voltage Vin is realized.
Fig. 3(c) is a schematic diagram of an output voltage outer loop input or output current inner loop control strategy. Generating a reference signal i of a current inner loop by an output voltage outer looprefAnd a modulation signal Vc is generated through the current inner ring, and the modulation signal Vc is generated after carrier modulation to control the duty ratio of a Boost circuit in each submodule, so that the regulation of the output voltage Vo is realized.
FIG. 3(d) is a schematic diagram of an input or output current closed-loop control strategy. The modulation signal Vc is generated through current closed loop, and the modulation signal Vc is generated after carrier modulation to control the duty ratio of a Boost circuit in each submodule, so that the regulation of input or output current is realized.
When digital closed-loop control is adopted, the output of the compensator is a modulation signal Vc. When the system is in the optimal efficiency mode, the duty ratio of the boost circuit in each sub-module can be determined by judging Vc and the carrier offset and amplitude set by each sub-module. When the system is in a maximum power mode, the duty ratio of the boost circuit in each submodule can be obtained by dividing the modulation signal Vc by the number N of submodules and then sending the result to the carrier of each submodule (removing direct current bias), and the duty ratios of the modules are the same, so that the duty ratio can be conveniently and quickly calculated.
Mode boundary power pboundaryIs about the input voltage vinRated input power P that can be handled by individual submodulesuAnd expected dc-link capacitor voltage V for a single submoduledcAs shown in the following equation:
Figure BDA0003367861210000061
since the isolated circuit in the sub-module operates at a fixed frequency or a fixed moving angle with a fixed duty ratio, the isolated circuit has a characteristic of a fixed voltage transformation ratio, and therefore the direct-current link voltage Vdc and the output voltage Vo have a fixed transformation ratio relation. When the output voltage is stabilized at a desired voltage, the dc link voltage Vdc is also stabilized at a fixed voltage value.
When the input power of the direct current transformer is smaller than the mode boundary power, the whole direct current transformer works in the optimal efficiency mode, the lower tube duty ratio of the booster circuit in part of the sub-modules is 0, and therefore switching loss and reverse recovery loss in the main circuit are reduced.
The isolated circuit in the submodule may select a series resonant circuit as shown in fig. 5, which operates at a fixed duty cycle and a fixed frequency.
The isolated circuit in the sub-module may be selected as a dual active bridge circuit as shown in fig. 6, which operates at a fixed frequency with a fixed shift to the corner.
The isolated circuits in the submodules may be selected as phase-shifted full-bridge circuits as shown in fig. 7, which operate at a fixed frequency with a fixed shift to the angle.
The input inductors in each sub-module boost circuit may also be combined into one inductor, as shown in fig. 8.
The isolated circuits in each submodule can also adopt a structure of sharing one transformer magnetic core, so that the power density of the system can be improved.
The isolated circuits in the submodules can further share the structure of the secondary rectifier on the basis of the structure of sharing one transformer magnetic core, so that the power density is further improved.
In the system starting phase, the maximum power mode is selected as the default starting mode. When the system enters a steady state, the system starts to determine the mode in which the system operates according to the relation between the input or output power and the mode boundary power.
In addition, more detailed region division can be performed in the original maximum power region, but this will complicate system control, but will further improve system efficiency. Fig. 9 shows another working partition where the system is located under different input voltage and input power conditions. Wherein, the mode I is an extended power mode, and the mode II is still an optimal efficiency mode.
When the system needs to be switched from the optimal efficiency mode to the extended power mode, all modules do not share one large carrier wave for modulation any more, but the carrier wave in the area where the modulation signal Vc is located and the carrier waves above the area are fused into the large carrier wave, and the carrier waves of all modules lower than the modulation signal Vc are kept unchanged. At the same time, according to the input power PinAnd merge boundary power line Pfusion_boundary(x,Pu) The relationship determines whether the number of fused carriers needs to be increased to meet the power requirement. Fig. 10 shows a schematic diagram of the carrier fusion of two sub-modules, and the remaining carriers are unchanged.
The fused boundary power line is a function of the number of carriers of the fused sub-modules and the rated power processed by the single sub-module, and is shown by the following formula:
PFusion_boundary(x,Pu)＝x·Pu (1＜x≤N)，
wherein N is the total number of sub-modules.
In the extended power mode, the system can be prevented from jittering between adjacent fusion states by introducing a hysteresis function block. When the input power Pin> (fuse boundary Power line P)fusion_boundary(x,Pu)-δ1) Then the carriers are fusedThe number is increased to at least (x + 1); when the input power Pin< (fuse boundary power line Pfusion_boundary(x,Pu)-2δ1) And then, the number of the fusion carriers can still meet the power requirement when the number is less than x.
The invention has the beneficial effects that: 1. the large-scale efficient direct-current transformer is simple in control structure, high in efficiency and easy to remove faults; 2. the large-scale efficient direct current transformer not only reduces the cost, but also improves the working efficiency.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.

Claims (10)

1.一种大规模高效直流变压器，其特征在于：包括主电路、控制器，所述控制器与所述主电路相连；所述主电路包括子模块，所述子模块数量至少为两个，各所述子模块的输入侧串联，各所述子模块的输出侧并联；所述子模块包括升压电路、隔离型电路，所述升压电路与所述隔离型电路级连；所述控制器分别与各所述子模块的所述升压电路、所述隔离型电路相连，所述控制器用于控制各所述子模块中的前级升压电路从而实现功率流方向或输出电压或输入电压的控制；1. A large-scale high-efficiency DC transformer is characterized in that: comprising a main circuit and a controller, and the controller is connected to the main circuit; the main circuit comprises sub-modules, and the number of the sub-modules is at least two, The input side of each of the sub-modules is connected in series, and the output side of each of the sub-modules is connected in parallel; the sub-module includes a booster circuit and an isolation circuit, and the booster circuit is cascaded with the isolation circuit; the control The controller is respectively connected to the booster circuit and the isolated circuit of each of the sub-modules, and the controller is used to control the front-stage booster circuit in each of the sub-modules to realize the power flow direction or output voltage or input voltage control; 所述控制器采用数字闭环控制策略，补偿器的输出为调制信号Vc，当该大规模高效直流变压器处于最优效率模式时，通过判断输出为调制信号Vc与各所述子模块设定的载波偏置与幅值，即可决定各子模块中boost升压电路的占空比大小；当该大规模高效直流变压器处于最大功率模式时，通过将调制信号Vc除以子模块数N，然后将这一结果送入各所述子模块的载波，即可得到各所述子模块中boost升压电路的占空比大小。The controller adopts a digital closed-loop control strategy, and the output of the compensator is the modulation signal Vc. When the large-scale high-efficiency DC transformer is in the optimal efficiency mode, the output is determined by the modulation signal Vc and the carrier set by each of the sub-modules. The bias and amplitude can determine the duty cycle of the boost circuit in each sub-module; when the large-scale high-efficiency DC transformer is in the maximum power mode, the modulation signal Vc is divided by the number of sub-modules N, and then the This result is sent to the carrier of each of the sub-modules, and the duty ratio of the boost circuit in each of the sub-modules can be obtained. 2.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述数字闭环控制策略包括：2. The large-scale high-efficiency DC transformer according to claim 1, wherein the digital closed-loop control strategy comprises: 输出电压闭环控制策略：通过输出电压闭环生成调制信号Vc，调制信号Vc经过载波调制后生成控制各所述子模块中Boost升压电路的占空比，从而实现输出电压Vo的调节。Output voltage closed-loop control strategy: The modulation signal Vc is generated through the output voltage closed-loop, and the modulation signal Vc is modulated by the carrier to generate and control the duty cycle of the boost circuit in each of the sub-modules, so as to realize the adjustment of the output voltage Vo. 3.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述数字闭环控制策略还包括：3. The large-scale high-efficiency DC transformer according to claim 1, wherein the digital closed-loop control strategy further comprises: 输入电压闭环控制策略：通过输入电压闭环生成调制信号Vc，调制信号Vc经过载波调制后生成控制各所述子模块中Boost升压电路的占空比，从而实现输入电压Vin的调节。Input voltage closed-loop control strategy: The modulation signal Vc is generated through the input voltage closed-loop, and the modulation signal Vc is modulated by the carrier to generate and control the duty cycle of the boost circuit in each of the sub-modules, so as to realize the adjustment of the input voltage Vin. 4.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述数字闭环控制策略还包括：4. The large-scale high-efficiency DC transformer according to claim 1, wherein the digital closed-loop control strategy further comprises: 输出电压双闭环控制策略：通过输出电压外环生成电流内环的参考信号iref，经过电流内环生成调制信号Vc，调制信号Vc经过载波调制后生成控制各所述子模块中Boost升压电路的占空比，从而实现输出电压Vo的调节。Output voltage double closed-loop control strategy: the reference signal i ref of the current inner loop is generated through the output voltage outer loop, the modulation signal Vc is generated through the current inner loop, and the modulation signal Vc is modulated by the carrier to generate and control the boost circuit in each of the sub-modules , so as to realize the regulation of the output voltage Vo. 5.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述数字闭环控制策略还包括：5. The large-scale high-efficiency DC transformer according to claim 1, wherein the digital closed-loop control strategy further comprises: 输入或输出电流闭环控制策略：通过电流闭环生成调制信号Vc，调制信号Vc经过载波调制后生成控制各所述子模块中Boost升压电路的占空比，从而实现输入或输出电流的调节。Input or output current closed-loop control strategy: The modulation signal Vc is generated through the current closed-loop, and the modulation signal Vc is modulated by the carrier to generate and control the duty cycle of the boost circuit in each of the sub-modules, so as to realize the adjustment of the input or output current. 6.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述控制器包括计算模块、载波控制模块，所述计算模块用于向各所述子模块中的所述升压电路提供调制信号，所述载波控制模块用于向所述子模块中的所述升压电路提供载波，所述调制信号、所述载波用于生成所述升压电路的驱动信号；所述控制器包括固定占空比、固定频率PWM发生模块，所述固定占空比、固定频率PWM发生模块用于向所述隔离型电路提供驱动信号；所述计算模块为闭环电压、电流或功率环计算模块；该大规模高效直流变压器还包括滞回功能块，所述滞回功能块用于防止变换器在最大功率模式和最优效率模式间抖动。6 . The large-scale high-efficiency DC transformer according to claim 1 , wherein the controller comprises a calculation module and a carrier control module, and the calculation module is used to provide the boost circuit in each of the sub-modules. 7 . providing a modulated signal, the carrier control module is configured to provide a carrier wave to the boost circuit in the sub-module, the modulated signal and the carrier wave are used to generate a drive signal of the boost circuit; the controller It includes a fixed duty cycle and a fixed frequency PWM generation module, and the fixed duty cycle and fixed frequency PWM generation module is used to provide a drive signal to the isolated circuit; the calculation module is a closed-loop voltage, current or power loop calculation module ; The large-scale high-efficiency DC transformer further includes a hysteresis function block for preventing the converter from jittering between the maximum power mode and the optimum efficiency mode. 7.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述载波会根据输入功率pin和模式边界功率pboundary的大小关系在最大功率载波和最优效率载波间切换，当输入功率pin＜边界功率-2δ时，则从最大功率模式切换到最优效率模式；当输入功率pin＞模式边界功率-δ时，则从最优效率模式切换到最大功率模式；当从最大功率模式切换到最优效率模式时，层叠载波被选择作为各所述子模块的载波；当从最优效率模式切换到最大功率模式时，大载波被选择作为各所述子模块的载波；7. The large-scale high-efficiency DC transformer according to claim 1, wherein the carrier can be switched between the maximum power carrier and the optimal efficiency carrier according to the magnitude relationship between the input power p in and the mode boundary power p boundary , when When the input power p in < boundary power -2δ, switch from the maximum power mode to the optimal efficiency mode; when the input power p in > the mode boundary power - δ, then switch from the optimal efficiency mode to the maximum power mode; When switching from the maximum power mode to the optimal efficiency mode, the stacked carrier is selected as the carrier of each of the sub-modules; when switching from the optimal efficiency mode to the maximum power mode, the large carrier is selected as the carrier of each of the sub-modules; 其中，大载波的幅值是各所述子模块中所述升压电路的层叠载波幅值之和；层叠载波中各所述子模块中所述升压电路的载波幅值为H，第i个所述子模块的载波偏置量为(i-1)*H，如果设置所述子模块中的所述升压电路占空比的最大限幅a，则层叠载波中第i个所述子模块的载波偏置量为(i-1)*a*H。Wherein, the amplitude of the large carrier is the sum of the amplitudes of the stacked carriers of the booster circuits in each of the submodules; the carrier amplitude of the booster circuits in each of the submodules in the stacked carrier is H, and the ith The carrier offset of each of the sub-modules is (i-1)*H. If the maximum limit a of the duty cycle of the booster circuit in the sub-module is set, the ith in the stacked carrier The carrier offset of the sub-module is (i-1)*a*H. 8.根据权利要求7所述的大规模高效直流变压器，其特征在于：所述模式边界功率pboundary是关于输入电压vin、单个所述子模块可处理的额定输入功率Pu和单个所述子模块的预期直流链电容电压Vdc的函数，如下公式所示：8 . The large-scale high-efficiency DC transformer according to claim 7 , wherein the mode boundary power p boundary is related to the input voltage v in , the rated input power P u that can be handled by a single sub-module and the single A function of the expected DC link capacitor voltage V dc of the submodule as follows:
Figure FDA0003367861200000031
Figure FDA0003367861200000031
 其中，因所述隔离型电路呈现出固定电压变比的特性，因此直流链电压Vdc与输出电压Vo具有固定变比的关系，当输出电压稳定在一期望电压时，直流链电压Vdc也稳定在一固定电压值；Wherein, because the isolated circuit exhibits the characteristic of a fixed voltage transformation ratio, the DC link voltage Vdc and the output voltage Vo have a fixed transformation ratio relationship. When the output voltage is stable at a desired voltage, the DC link voltage Vdc is also stable at a fixed voltage value; 当该大规模高效直流变压器工作于最优效率模式时，部分所述子模块中所述升压电路的下管占空比为0。When the large-scale high-efficiency DC transformer works in the optimal efficiency mode, the duty cycle of the lower tube of the boost circuit in some of the sub-modules is 0. 9.根据权利要求1所述的大规模高效直流变压器，其特征在于：所述隔离型电路为工作在固定占空比下的串联谐振电路或者固定移相角固定频率下的移相全桥或固定移相角固定频率下的双有源桥电路；所述隔离型电路可以采用共用一个变压器磁芯的结构；所述隔离型电路可以在采用共用一个变压器磁芯的结构基础上，进一步采用共用副边整流器的结构；在该大规模高效直流变压器的系统启动阶段，选择最大功率模式作为默认启动模式，当系统进入稳态后，根据输入或输出功率与模式边界功率pboundary的关系决定系统运行于何种模式；各所述子模块的所述升压电路中的输入电感能合并成一个电感。9 . The large-scale high-efficiency DC transformer according to claim 1 , wherein the isolated circuit is a series resonant circuit operating under a fixed duty cycle or a phase-shifted full bridge or a fixed-phase-shift angle and a fixed frequency. 10 . A dual active bridge circuit with a fixed phase shift angle and a fixed frequency; the isolated circuit can adopt a structure of sharing a transformer magnetic core; the isolated circuit can further use a common transformer core structure on the basis of using a common transformer core structure. The structure of the secondary side rectifier; in the system startup stage of the large-scale high-efficiency DC transformer, the maximum power mode is selected as the default startup mode. When the system enters a steady state, the system operation is determined according to the relationship between the input or output power and the mode boundary power p boundary In which mode; the input inductances in the boost circuit of each of the sub-modules can be combined into one inductance. 10.根据权利要求9所述的大规模高效直流变压器，其特征在于：该大规模高效直流变压器还包括在不同输入电压与输入功率情况系统所处的工作分区，当系统需要从最优效率模式切换到扩展功率模式时，将调制信号Vc所在区域的载波及以上载波融合成大载波，低于调制信号Vc的各模块载波保持不变，同时根据输入功率Pin与融合边界功率线Pfusion_boundary(x,Pu)的关系决定是否需要增加融合载波的数量以满足功率要求；10. The large-scale high-efficiency DC transformer according to claim 9, characterized in that: the large-scale high-efficiency DC transformer also includes a work zone where the system is located under different input voltage and input power conditions, when the system needs to change from the optimal efficiency mode When switching to the extended power mode, the carrier in the area where the modulated signal Vc is located and the carrier above it are fused into a large carrier, and the carrier of each module lower than the modulated signal Vc remains unchanged. The relationship between x, P u ) determines whether it is necessary to increase the number of fused carriers to meet the power requirements; 融合边界功率线是关于融合子模块的载波个数和单个子模块处理的额定功率的函数，具体如下公式所示：The fusion boundary power line is a function of the number of carriers of the fusion sub-module and the rated power processed by a single sub-module, as shown in the following formula: PFusion_boundary(x,Pu)＝x·Pu(1＜x≤N)，P Fusion_boundary (x,P u )=x·P u (1<x≤N), 其中，N为总共的所述子模块数；Wherein, N is the total number of sub-modules; 当输入功率Pin＞(融合边界功率线Pfusion_boundary(x,Pu)-δ1)时，则融合载波个数增加到至少(x+1)个；当输入功率Pin＜(融合边界功率线Pfusion_boundary(x,Pu)-2δ1)时，则融合载波个数在少于x个时仍可以满足功率要求。When the input power P in >(the fusion boundary power line P fusion_boundary (x,P u )-δ 1 ), the number of fusion carriers is increased to at least (x+1); when the input power P in <(the fusion boundary power When the line P fusion_boundary (x,P u )-2δ 1 ) is used, the power requirement can still be met when the number of fusion carriers is less than x.
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