CN113691139B - Intermittent method for avoiding saturation of high-frequency transformer in power electronic transformer - Google Patents

Intermittent method for avoiding saturation of high-frequency transformer in power electronic transformer Download PDF

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CN113691139B
CN113691139B CN202111023074.3A CN202111023074A CN113691139B CN 113691139 B CN113691139 B CN 113691139B CN 202111023074 A CN202111023074 A CN 202111023074A CN 113691139 B CN113691139 B CN 113691139B
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intermittent
transformer
frequency transformer
power electronic
converter
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CN113691139A (en
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范建华
徐鹏飞
李健勋
邵康
于晓强
王庆园
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Qingdao Topscomm Communication Co Ltd
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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
    • H02M3/33569—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 several active switching elements
    • H02M3/33576—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 several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to the field of power electronics, and particularly discloses an intermittent method for avoiding saturation of a high-frequency transformer in a power electronics transformer, which comprises the steps of firstly judging peak exciting current of the high-frequency transformer, and judging whether the peak exciting current can provide enough energy to enable parasitic capacitance of a switching tube to complete charging and discharging; judging whether the high-frequency transformer parallel inductor is additionally arranged according to the result; secondly, designing a corresponding intermittent program according to the result of the steps; finally, the accumulation of unbalanced volt-second products is avoided by a method of driving the upper pipe and the lower pipe to be exchanged in adjacent intermittent periods. The invention avoids the saturation problem of the transformer in the intermittent process, simultaneously avoids the overcurrent problem and unstable working condition in the intermittent process, and further improves the operation efficiency and stability of the power electronic transformer under the air-light load condition.

Description

Intermittent method for avoiding saturation of high-frequency transformer in power electronic transformer
Technical Field
The invention relates to the technical field of power electronics, in particular to an intermittent method for avoiding saturation of a high-frequency transformer in a power electronic transformer.
Background
Along with the proposal of the carbon neutralization concept and the development and popularization and application of the related technology of the intelligent power grid in China, the proportion of renewable energy sources such as wind energy, photovoltaic and the like in the existing energy system is continuously improved. In the whole energy internet, as the proportion of distributed energy sources is gradually increased, the method is very important for comprehensive management and treatment of various energy sources. Because the whole energy system gradually tends to be intelligent and decentralized, the traditional transformer cannot realize the functions aiming at the application scene. Under the whole energy development trend, related products and concepts such as an energy router, an electric energy router and the like are gradually developed, and a power electronic transformer is the most central link.
The power electronic transformer performs voltage conversion of different voltage classes through a power electronic topology, the power electronic transformer comprises a rectifying stage converter and a DC/DC stage converter, the rectifying stage converter generally realizes a CHB or MMC mode according to application scenes and converts high-voltage alternating current into multiport low-voltage direct current or a public direct current bus, the DC/DC stage converter generally adopts a phase-shifting full bridge or a resonant converter to perform voltage class conversion to form the low-voltage direct current bus, and the rectifying stage converter converts direct current voltage into high-frequency alternating current through high-frequency switching signals and then rectifies the high-frequency alternating current into direct current so as to realize voltage class conversion. Such power electronics can be driven in an intermittent manner, i.e. pulsed switching signals.
In the power electronic transformer, the design capacity of the high-frequency transformer is larger, and the saturation induction intensity is generally smaller. Under the premise of comprehensively considering cost and volume, the magnetic induction strength is not too large when the design of the common high-frequency transformer meets the condition of a continuous mode. The intermittent control mode is gradually applied to the power electronic transformer, so that the loss of air-load light load is reduced. Meanwhile, when the intermittent control is applied to a power electronic transformer, the voltage-second product of a high-frequency transformer is unbalanced easily, so that the saturation problem of the transformer is caused, the overcurrent problem of a DC/DC converter is extremely easy to be caused, and the whole system is stopped in a fault mode.
Disclosure of Invention
Aiming at the defects and the shortcomings existing in the prior art, the invention provides an intermittent method for avoiding the saturation of a high-frequency transformer in a power electronic transformer, a specific intermittent implementation mode is designed according to the actual working condition of the high-frequency transformer in the power electronic transformer, the unbalanced accumulation of the volt-second product in the intermittent process is avoided, the transformer saturation problem generated in the intermittent process is avoided through specific intermittent control, the overcurrent problem or the unstable condition generated in the intermittent process is correspondingly avoided, and the operation efficiency and the stability of the power electronic transformer under the air-light load condition are further improved.
In order to achieve the above object, the present invention provides an intermittent method for avoiding saturation of a high frequency transformer in a power electronic transformer, comprising the steps of:
s1: judging peak exciting current I of high-frequency transformer max If so, S3 is entered, otherwise S2 is entered;
s2: according to the cost requirement, selecting whether to add the high-frequency transformer parallel inductor L p If the DC/DC converter is additionally arranged, enough turn-off current can be provided to realize zero voltage conduction in the DC/DC converter, S3 is entered, otherwise S4 is entered; the method comprises the steps of carrying out a first treatment on the surface of the
S3: the first drive duty cycle in the batch process is adjusted from 50% to 25%, defined as drive A, and S5 is entered
S4: the first driving duty ratio in the intermittent process is kept unchanged by 50%, and is defined as driving B, and S5 is entered;
s5: in the intermittent process, the upper pipe and the lower pipe of adjacent intermittent periods are driven to be exchanged, so that the intermittent operation is completed.
Further, the success condition formula judged in the step 1 is as follows:
Figure BDA0003242388530000021
wherein I is max The peak exciting current of the high-frequency transformer of the DC/DC level converter is obtained, fs is the switching frequency of the DC/DC level converter, U in Is the input voltage of the DC/DC level converter, C oss Output capacitance of H-bridge switching tube of DC/DC stage converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
Further, the determination formula of adding the parallel inductor in the step 2 is as follows:
Figure BDA0003242388530000022
wherein L is p Parallel inductance for added high-frequency transformer, U in Is the input voltage of the DC/DC level converter, C oss Output capacitance of H-bridge switching tube of DC/DC stage converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
Further, the intermittent period in the step 5 is divided into a continuous driving time T on And a stop driving time T off The two-stage time proportion formula is:
Figure BDA0003242388530000023
wherein i is L I is the load current under the current load condition Lh The load current at the highest efficiency point of the measured power electronic transformer.
The beneficial technical effects of the invention are as follows: according to the method, by designing a specific intermittent control mode, the saturation problem of the transformer in the intermittent process can be avoided, the overcurrent shutdown fault generated by the saturation of the transformer in the operation process of the power electronic transformer is eliminated, the operation efficiency and stability of the power electronic transformer under the air-light load condition are further improved, and the method has good engineering practicability.
Drawings
Fig. 1 is a basic topology of a power electronic transformer of the present invention for an intermittent method of avoiding high frequency transformer saturation in the power electronic transformer.
Fig. 2 is a block diagram of the design steps of the intermittent method of the present invention for avoiding saturation of high frequency transformers in a power electronic transformer.
Fig. 3 is a DC/DC converter topology of the intermittent method of the invention for avoiding high frequency transformer saturation in a power electronic transformer.
Fig. 4 is a topology diagram of the present invention after adding parallel inductors to a DC/DC converter of an intermittent method of avoiding high frequency transformer saturation in a power electronic transformer.
Fig. 5 is a waveform diagram of an intermittent drive a of the intermittent method of the present invention for avoiding saturation of a high frequency transformer in a power electronic transformer.
Fig. 6 is a waveform diagram of an intermittent drive B of the intermittent method of the present invention for avoiding saturation of a high frequency transformer in a power electronic transformer.
Fig. 7 is a waveform diagram of an intermittent drive process of the intermittent method of avoiding saturation of a high frequency transformer in a power electronic transformer according to the present invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Fig. 1 is a basic topology of a power electronic transformer according to the present invention. With reference to fig. 2, a batch method for high frequency transformer saturation in a power electronic transformer comprises the steps of:
s1: judging the peak exciting current of the high-frequency transformer, judging whether the peak exciting current can provide enough energy to enable the parasitic capacitance of the switching tube to complete charging and discharging, wherein a topological diagram is shown in fig. 3, the process mainly judges whether the exciting current has enough energy to support the follow current process of 25% of switching period after the driving is finished, and the judging conditions for completing the whole process are as follows:
Figure BDA0003242388530000031
wherein I is max The peak exciting current of the high-frequency transformer of the DC/DC level converter is obtained, fs is the switching frequency of the DC/DC level converter, U in Is the input voltage of the DC/DC level converter, C oss Output capacitance of H-bridge switching tube of DC/DC stage converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
If the above process can be completed, at the end of intermittent driving, since the exciting current is at a positive peak value or a negative peak value, the exciting current will flow through the H-bridge diode to continue freewheeling, resulting in 25% more switching period of the voltage applied across the transformer.
S2: when the exciting inductance design of the DC/DC converter high-frequency transformer in the power electronic transformer is larger, the exciting current peak value is smaller, the complete charge and discharge of the parasitic capacitance of the switching tube cannot be completed in dead time under the condition, and when intermittent driving is finished, the exciting current is a positive peak value or a negative peak value, but insufficient to support a follow current link, and the voltage applied to the two ends of the transformer is normally finished. At this time, the parallel inductance of the high-frequency transformer can be added, the topological diagram is shown in fig. 4, enough turn-off current is provided to realize zero voltage conduction in the DC/DC converter, and the determination formula of the parallel inductance is as follows:
Figure BDA0003242388530000032
wherein L is p Parallel inductance for added high-frequency transformer, U in Is the input voltage of the DC/DC level converter, C oss Output capacitance of H-bridge switching tube of DC/DC stage converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
For the case described in this step, adding parallel inductors can improve overall efficiency to some extent, but can create additional costs that require the user to further evaluate both alternatives.
S3: if the step S1 process can be completed or the parallel inductor in the step S2 can be optionally added, the first driving duty ratio in the intermittent process should be adjusted from 50% to 25% to ensure that the volt-second product applied to both ends of the transformer in each intermittent period remains balanced, which is defined as driving a, as shown in fig. 5.
S4: otherwise, the first drive duty cycle during the batch should remain 50% unchanged, defined as drive B, as shown in fig. 6.
S5: in the intermittent process, even if a specific intermittent driving program is designed for different working conditions, due to the influences of hardware implementation, device parameter difference and the like, voltage volt-second product deviation can still be generated in each intermittent period, and the accumulation of the deviation can also lead to saturation of a transformer, so that the driving program is further designed, the upper and lower tube driving of the adjacent intermittent periods is subjected to the exchange, and the accumulation of volt-second product deviation generated in the adjacent intermittent periods is eliminated, and an intermittent driving waveform is shown as a driving A for example, and is shown in fig. 7.
The above embodiments are illustrative of the specific embodiments of the present invention, and not restrictive, and various changes and modifications may be made by those skilled in the relevant art without departing from the spirit and scope of the invention, so that all such equivalent embodiments are intended to be within the scope of the invention.

Claims (4)

1. A batch process for avoiding saturation of a high frequency transformer in a power electronic transformer, comprising the steps of:
s1: judging peak exciting current I of high-frequency transformer max If so, S3 is entered, otherwise S2 is entered;
s2: according to the cost requirement, selecting whether to add the high-frequency transformer parallel inductor L p If the DC/DC converter is additionally arranged, enough turn-off current can be provided to realize zero voltage conduction in the DC/DC converter, S3 is entered, otherwise S4 is entered;
s3: the first driving duty ratio in the intermittent process is adjusted from 50% to 25%, which is defined as driving A, and S5 is entered;
s4: the first driving duty ratio in the intermittent process is kept unchanged by 50%, and is defined as driving B, and S5 is entered;
s5: in the intermittent process, the upper pipe and the lower pipe of adjacent intermittent periods are driven to be exchanged, so that the intermittent operation is completed.
2. An intermittent method for avoiding saturation of a high frequency transformer in a power electronic transformer according to claim 1, wherein the conditional formula of the judgment is:
Figure FDA0004218765790000011
wherein I is max Peak exciting current of high-frequency transformer for DC/DC converter, fs being switch operated by DC/DC converterFrequency, U in Is the input voltage of the DC/DC converter, C oss Output capacitance of H-bridge switching tube of DC/DC converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
3. The intermittent method for avoiding saturation of a high frequency transformer in a power electronic transformer according to claim 1, wherein the determination formula of the shunt inductance of the high frequency transformer is:
Figure FDA0004218765790000012
wherein L is p Parallel inductance for added high-frequency transformer, U in Is the input voltage of the DC/DC converter, C oss Output capacitance of H-bridge switching tube of DC/DC converter, v ds The voltage is the drain-source voltage of the mosfet switch tube in the charge-discharge process.
4. A batch process for avoiding saturation of high frequency transformers in power electronic transformers according to claim 1, said batch period being divided into a continuous driving time T on And a stop driving time T off The two-stage time proportion formula is:
Figure FDA0004218765790000013
wherein i is L I is the load current under the current load condition Lh The load current at the highest efficiency point of the measured power electronic transformer.
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CN114825905A (en) * 2022-06-28 2022-07-29 青岛鼎信通讯股份有限公司 Voltage phase intermittence method of power electronic transformer

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CN112491277A (en) * 2020-11-25 2021-03-12 青岛鼎信通讯股份有限公司 Method for improving efficiency of power electronic transformer through dead time self-adaption
CN112701882A (en) * 2020-12-22 2021-04-23 杰华特微电子（杭州）有限公司 Control circuit and control method of flyback converter
CN112994472A (en) * 2021-04-12 2021-06-18 华中科技大学 Optimal dead zone calculation method and variable dead zone control method for high-frequency LLC resonant converter

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KR100547289B1 (en) * 2005-05-18 2006-01-26 주식회사 피에스텍 Synchronous rectifier type series resonant converter for operating in intermittence mode

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112491277A (en) * 2020-11-25 2021-03-12 青岛鼎信通讯股份有限公司 Method for improving efficiency of power electronic transformer through dead time self-adaption
CN112701882A (en) * 2020-12-22 2021-04-23 杰华特微电子（杭州）有限公司 Control circuit and control method of flyback converter
CN112994472A (en) * 2021-04-12 2021-06-18 华中科技大学 Optimal dead zone calculation method and variable dead zone control method for high-frequency LLC resonant converter

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