CN111600487A - Control strategy for improving DCDC efficiency of charging station energy router system - Google Patents

Control strategy for improving DCDC efficiency of charging station energy router system Download PDF

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Publication number
CN111600487A
CN111600487A CN202010178529.8A CN202010178529A CN111600487A CN 111600487 A CN111600487 A CN 111600487A CN 202010178529 A CN202010178529 A CN 202010178529A CN 111600487 A CN111600487 A CN 111600487A
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dcdc
current
resonant
charging station
zero crossing
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CN111600487B (en
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李健勋
李鸿儒
范建华
徐鹏飞
赵新举
王庆园
纪华丽
金立亭
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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
    • H02M3/33584—Bidirectional converters
    • 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
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • 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

Abstract

The invention provides a control strategy for improving DCDC efficiency of a charging station energy router system, and belongs to the field of medium and high voltage electric vehicle charging stations. The invention collects the resonance current ir1Signal to dynamically adjust IGBT by software logic to determine zero crossing point of resonant current1、S2、S3、S4、S5、S6、S7、S8) And the switching-off moment solves the problem of hard switching phenomenon caused by the fact that parameters of a capacitor and an inductor change along with the temperature, the current and the service life when the series resonance type isolation DCDC topology is actually operated. The zero current switch in the full load range of the DCDC converter is realized while the energy bidirectional flow capacity is ensured, the switching loss of the system is reduced, the overall efficiency of the electric vehicle charging station is improved, and the dynamic response of the system is ensured.

Description

Control strategy for improving DCDC efficiency of charging station energy router system
Technical Field
The invention relates to the field of medium and high voltage electric vehicle charging stations, in particular to a control strategy for improving the DCDC efficiency of a medium and high voltage electric vehicle charging station.
Background
The medium-high voltage electric vehicle charging station adopts an input-series output-parallel topology scheme, so that the switching frequency and the device withstand voltage level of a single module at the alternating current side are reduced, and the alternating current side can be directly merged into a medium-high voltage power grid; the rear stage of the circuit is usually in a series resonance type isolation DCDC topology, the transformation ratio relation of the input and output voltages can be input and output by using open loop control, soft switching in a full power range can be realized, and the efficiency is improved, so that the circuit is widely applied. However, when the traditional open-loop control scheme realizes the energy bidirectional flow function, the parameters of the capacitor and the inductor can change along with the temperature, the current and the service life influence in the actual operation, so that the inherent resonant frequency point shifts, the resonant frequency and the switching frequency can not accurately correspond, the hard switching phenomenon is caused, and the system loss is increased.
Disclosure of Invention
Aiming at the defects and the requirements, the invention provides a control strategy for improving the DCDC efficiency of the energy router system of the charging station, solves the problem of hard switching caused by the change of system capacitance and inductance parameters on the premise of ensuring the bidirectional flow function of the DCDC isolation level energy, and is simple and easy to realize. The invention provides the following technical scheme:
the alternating current side of the medium-high voltage charging station adopts N H-bridge cascade structures to be directly merged into a medium-high voltage alternating current power grid, so that AC-DC conversion is realized; and a series resonance type isolation converter is connected behind each H-bridge structure to realize DCDC conversion and isolation. The outputs of the 3N DCDC converters are connected in parallel to form a low-voltage direct-current bus for a low-voltage direct-current charging pile to use; the cascade H bridge realizes the control of active component and reactive component; the intermediate DCDC link realizes the characteristic of a direct current transformer by adjusting the duty ratio and the switching period of the original secondary side IGBT, and ensures that the ratio of output voltage to input voltage and output voltage is not the ratio of transformation of the transformer; when a vehicle is connected to perform charging operation, the system is started, the DCDC link samples the resonant current, and the zero crossing point time t of the resonant current is carried out0Judging; according toThe determined zero crossing point moment and the switching-on moment t of the switching tube in the half switching periodsCalculating the resonant frequency f of the resonant currentresComparing with the resonant current frequency limiting condition to judge whether the zero crossing point is a real zero crossing point, and if the condition is met, determining the zero crossing point time as t0The drive signals of all the IGBTs are immediately updated and the output is repeated in the last cycle switching manner if the condition is not satisfied.
Further, as a preferred technical solution of the present invention: series resonance type isolation converter DCDC links S1, S4, S5 and S8 are first group of IGBTs, S2, S3, S6 and S7 are second group of IGBTs, the driving signals of the two groups of IGBTs are complementary, and the level of each group of switches is switched by detecting the zero-crossing time.
Further, as a preferred technical solution of the present invention: the method for judging the zero crossing point of the resonant current is to sample a current resonant current sample value ir1And the sampling value i of the resonant current at the last momentr1_1Multiplication, if the product is less than or equal to zero, the current sampling time t0Are possible zero crossing times.
Further, as a preferred technical solution of the present invention: the resonant current frequency limiting condition is fresGreater than or equal to 0.8fres *And is less than or equal to 1.2fres *The correct current zero crossing is considered, where fres *Is the natural resonant frequency of the system, and the formula is:
Figure BDA0002411659920000021
in the formula, L and C are respectively equivalent series inductance and series capacitance in series resonant DCDC topology.
Further, as a preferred technical solution of the present invention: the updating mode for immediately updating the driving signals of all IGBTs after obtaining the correct zero-crossing point time is to invert the driving signals
Compared with the prior art, the invention has the advantages and positive effects that:
the scheme of the invention is simple and easy to implement, the control scheme has low complexity, the DCDC energy flow bidirectional flow function can be realized, the hard switching phenomenon caused by the change of inductance and capacitance parameters is solved, the system efficiency is improved, and the volume of the radiator is reduced.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate exemplary embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application
FIG. 1 is a topological diagram of a medium and high voltage electric vehicle charging station;
FIG. 2 is a series resonant isolated DCDC topology;
FIG. 3 is a flow chart of a control strategy proposed by the present invention;
fig. 4(a) is a main waveform diagram of the series resonant isolated DCDC circuit after the main circuit inductance or capacitance parameter changes;
fig. 4(b) is a main waveform diagram of the series resonant isolated DCDC circuit after the inductance or capacitance parameter of the main circuit is changed by using the control strategy provided by the present invention.
Detailed Description
Hereinafter, embodiments of the present invention will be further described with reference to the accompanying drawings.
The topological diagram of the medium-high voltage electric vehicle charging station applied by the invention is shown in figure 1, the alternating current side of the medium-high voltage charging station adopts N H-bridge cascade structures to be directly merged into a medium-high voltage alternating current power grid and a high-voltage alternating current power grid, and AC-DC conversion is realized; and a series resonance type isolation converter is connected behind each H-bridge structure to realize DCDC conversion and isolation. The outputs of the 3N DCDC converters are connected in parallel to form a low-voltage direct-current bus for a low-voltage direct-current charging pile to use; the cascade H bridge realizes the control of active component and reactive component; the series resonance type DCDC circuit topology is shown in FIG. 2, wherein S1, S4, S5 and S8 are a first group of IGBTs, S2, S3, S6 and S7 are a second group of IGBTs, driving signals of the two groups of IGBTs are complementary, the direct current transformer characteristic is realized by adjusting the duty ratio and the switching period of the original secondary side IGBT, and the ratio of output voltage to input voltage to output voltage is guaranteed not to be changed by a transformer.
The flow chart of the control strategy of the adopted DCDC is shown in FIG. 3:when an automobile is connected to carry out charging operation, the system is started, the DCDC link samples the resonant current, the zero crossing point time t0 of the resonant current is judged, and the sampling value i of the resonant current at the current time is obtainedr1And the sampling value i of the resonant current at the last momentr1_1Multiplication, if the product is less than or equal to zero, the current sampling time t0Are possible zero crossing times.
According to the determined zero crossing point moment and the switching-on moment t of the switching tube in the half switching periodsCalculating the resonant frequency f of the resonant current by taking the reciprocal of the difference and dividing by 2resThe resonant current frequency limiting condition is fresGreater than or equal to 0.8fres *And is less than or equal to 1.2fres *The correct current zero crossing is considered, where fres *Is the natural resonant frequency of the system, and the formula is:
Figure BDA0002411659920000041
in the formula, L and C are respectively equivalent series inductance and series capacitance in series resonant DCDC topology.
And immediately inverting the driving signals of all the IGBTs after acquiring the correct zero-crossing time, and repeatedly outputting the driving signals according to the last period of switching mode if the conditions are not met.
When the inductance or capacitance parameter in the DCDC main circuit changes, the main waveform diagram of the series resonance type isolation DCDC circuit is shown in fig. 4(a), and it can be seen from the diagram that the circuit is in a hard turn-off state;
after the control strategy provided by the invention is adopted, when the main circuit inductance or capacitance parameter changes, the main waveform of the series resonance type isolation DCDC circuit is shown in fig. 4(b), thus realizing soft turn-off and improving the system efficiency.
The above detailed description is intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above detailed description is only exemplary of the present invention and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (5)

1. A control strategy for improving DCDC efficiency of a charging station energy router system, the method comprising the steps of:
the alternating current side of the medium-high voltage charging station adopts N H-bridge cascade structures to be directly merged into a medium-high voltage alternating current power grid, so that AC-DC conversion is realized; and a series resonance type isolation converter is connected behind each H-bridge structure to realize DCDC conversion and isolation. The outputs of the 3N DCDC converters are connected in parallel to form a low-voltage direct-current bus for a low-voltage direct-current charging pile to use; the cascade H bridge realizes the control of active component and reactive component; the intermediate DCDC link realizes the characteristic of a direct current transformer by adjusting the duty ratio and the switching period of the original secondary side IGBT, and ensures that the ratio of output voltage to input voltage and output voltage is not the ratio of transformation of the transformer; when a vehicle is connected to perform charging operation, the system is started, the DCDC link samples the resonant current, and the zero crossing point time t of the resonant current is carried out0Judging; calculating the resonant frequency f of the resonant current according to the determined zero crossing point timeresComparing with the resonant current frequency limiting condition to judge whether the zero crossing point is a real zero crossing point, and if the condition is met, determining the zero crossing point time as t0The drive signals of all the IGBTs are immediately updated and the output is repeated in the last cycle switching manner if the condition is not satisfied.
2. The control strategy for improving the efficiency of the charging station energy router system DCDC according to claim 1, wherein said series resonant type isolation converter DCDC link S1, S4, S5, S8 is a first group of IGBTs, S2, S3, S6, S7 is a second group of IGBTs, the driving signals of the two groups of IGBTs are complementary, and the level of each group of switches is switched by detecting the zero-crossing time.
3. The control strategy for improving the DCDC efficiency of the charging station energy router system as claimed in claim 1, wherein said method for determining the zero crossing point of the resonant current is implemented by sampling the current time of the resonant current ir1And the sampling value i of the resonant current at the last momentr1_1Multiplication, if the product is less than or equal to zero, the current sampling time t0Are possible zero crossing times.
4. The control strategy according to claim 1, wherein the resonant current frequency limiting condition is fresGreater than or equal to 0.8fres *And is less than or equal to 1.2fres *The correct current zero crossing is considered, where fres *Is the natural resonant frequency of the system, and the formula is:
Figure FDA0002411659910000011
in the formula, L and C are respectively equivalent series inductance and series capacitance in series resonant DCDC topology.
5. The control strategy for improving the efficiency of the charging station energy router system DCDC according to claim 1, wherein the updating of the driving signals of all IGBTs immediately after obtaining the correct zero-crossing point is performed by inverting the driving signals.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112968610A (en) * 2021-02-24 2021-06-15 北京交通大学 Bidirectional isolation type DC/DC converter

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JP2017209015A (en) * 2017-09-04 2017-11-24 株式会社東芝 Power supply circuit for driving creeping discharge element
CN109728633A (en) * 2019-01-17 2019-05-07 中国科学院电工研究所 A kind of direct resonance frequency Phase Tracking control method of contactless power supply device
CN110190751A (en) * 2019-05-17 2019-08-30 中南大学 A kind of perseverance gain bi-directional DC-DC controlled resonant converter and its control method
CN110336320A (en) * 2019-07-10 2019-10-15 上海交通大学 A kind of new-energy grid-connected or on-site elimination system based on electric energy router
CN110361596A (en) * 2019-06-18 2019-10-22 上海宝准电源科技有限公司 A kind of Resonance detector strategy based on zero-crossing examination

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102023286A (en) * 2010-11-30 2011-04-20 中国工程物理研究院流体物理研究所 Zero current detection circuit for series resonance charging source and design method thereof
JP2017209015A (en) * 2017-09-04 2017-11-24 株式会社東芝 Power supply circuit for driving creeping discharge element
CN109728633A (en) * 2019-01-17 2019-05-07 中国科学院电工研究所 A kind of direct resonance frequency Phase Tracking control method of contactless power supply device
CN110190751A (en) * 2019-05-17 2019-08-30 中南大学 A kind of perseverance gain bi-directional DC-DC controlled resonant converter and its control method
CN110361596A (en) * 2019-06-18 2019-10-22 上海宝准电源科技有限公司 A kind of Resonance detector strategy based on zero-crossing examination
CN110336320A (en) * 2019-07-10 2019-10-15 上海交通大学 A kind of new-energy grid-connected or on-site elimination system based on electric energy router

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112968610A (en) * 2021-02-24 2021-06-15 北京交通大学 Bidirectional isolation type DC/DC converter

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