CN114583952A - Bidirectional direct current converter for energy storage system and control method thereof - Google Patents

Bidirectional direct current converter for energy storage system and control method thereof Download PDF

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Publication number
CN114583952A
CN114583952A CN202210271739.0A CN202210271739A CN114583952A CN 114583952 A CN114583952 A CN 114583952A CN 202210271739 A CN202210271739 A CN 202210271739A CN 114583952 A CN114583952 A CN 114583952A
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voltage side
low
voltage
switch tube
filter capacitor
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Inventor
秦岭
许兴
张雷
王亚芳
饶家齐
孙诗雨
钱娇
刘宇涵
周磊
段冰莹
钱天泓
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Nantong University
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Nantong University
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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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • 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
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E70/00—Other energy conversion or management systems reducing GHG emissions
    • Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin

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

Abstract

The invention belongs to the technical field of converters, and discloses a bidirectional direct current converter for an energy storage system and a control method thereof, wherein one end of a first inductor is connected with one end of a second inductor and the positive electrode of a low-voltage side filter capacitor; the other end of the first inductor is connected with a drain electrode of the first switch tube and a source electrode of the second switch tube; the other end of the second inductor is connected with the drain electrode of the third switching tube and the positive electrode of the first capacitor; the source electrode of the first switching tube is connected with the cathode of the first capacitor and the source electrode of the fourth switching tube; the drain electrode of the second switching tube is connected with the anode of the high-voltage side filter capacitor; the source electrode of the third switching tube is connected with the drain electrode of the fourth switching tube, the cathode of the low-voltage side filter capacitor and the cathode of the high-voltage side filter capacitor; the positive electrode and the negative electrode of the low-voltage side filter capacitor are respectively connected with the positive electrode and the negative electrode of the low-voltage side direct-current power supply; the positive pole and the negative pole of the high-voltage side filter capacitor are respectively connected with the positive pole and the negative pole of the high-voltage side direct-current power supply, so that the average current of the low-voltage side inductor can be equally divided, the current pulsation of the low-voltage side is reduced, and the high-voltage side filter capacitor is suitable for energy storage systems such as storage batteries.

Description

Bidirectional direct current converter for energy storage system and control method thereof
Technical Field
The invention belongs to the technical field of converters, and particularly relates to a bidirectional direct current converter for an energy storage system and a control method thereof.
Background
Photovoltaic, wind power and other new energy power generation systems must be equipped with energy storage device to store and adjust electric energy, in order to overcome the volatility and the randomness of output, supply power to load (such as direct current converter, inverter, LED, direct current microgrid, etc.) continuous stability. These power generation systems typically require a bi-directional DC-DC converter as an energy storage interface. However, the output voltage of an energy storage device (such as a battery) is low, and the service life of the energy storage device is closely related to the magnitude of the current ripple. Therefore, the bidirectional DC-DC converter is required to have a wide voltage gain range and a small current ripple. At present, bidirectional DC/DC converters are mainly classified into two categories: isolated and non-isolated. In the application without electrical isolation, the non-isolated DC/DC converter has the advantages of simple design and structure, low loss and small volume.
The bidirectional Buck-Boost converter has fewer passive and active elements and is a non-isolated bidirectional DC/DC converter with the simplest structure. However, the Boost capability in Boost mode is limited, and the average current of the low-side inductor is large, resulting in large inductor volume and large loss. The bidirectional converter based on the coupling inductor can obtain stronger boosting capacity by adjusting the turn ratio of the coupling inductor, but leakage inductance energy is difficult to effectively recover, and the conversion efficiency is generally lower. The bidirectional converter based on the switched inductor has a simple structure, does not have the leakage inductance problem, and has small average current of the low-voltage side inductor; but the low-voltage side port current has large pulsation, thereby increasing the capacity of the filter capacitor and increasing the system volume and cost.
Disclosure of Invention
In view of the above, the present invention provides a bidirectional dc converter for an energy storage system and a control method thereof, which can achieve bidirectional flow of energy and uniform average current of a low-voltage side inductor, reduce ripple amplitude of an input current, increase ripple frequency to twice of a switching frequency, reduce filter capacitance of the low-voltage side, have strong boosting capability, and are suitable for energy storage systems such as a storage battery and a super capacitor.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a bidirectional DC converter for energy storage system comprises a low-voltage side filter capacitor CLA first capacitor C1High-voltage side filter capacitor CHA first inductor L1A second inductor L2A first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4；
The first inductor L1And the second inductor L2One end of the low-voltage side filter capacitor CLThe positive electrode of (2) is connected;
the first inductor L1And the other end of the first switch tube S1Drain electrode of (1), the second switching tube S2Is connected to the source of (a);
the second inductor L2And the other end of the third switching tube S3The drain electrode of (1), the first capacitor C1The positive electrode of (1) is connected;
the first switch tube S1And the first capacitor C1Negative pole of (1), the fourth switching tube S4Is connected to the source of (a);
the second switch tube S2And the high-voltage side filter capacitor CHThe positive electrode of (1) is connected;
the third switch tube S3Source electrode of and the fourth switching tube S4Drain electrode of, the low-voltage side filter capacitor CLNegative pole of (2), the high-voltage side filter capacitor CHThe negative electrode of (1) is connected;
the low-voltage side filter capacitor CLPositive pole of and the low-voltage side DC power supply ULThe positive electrode of the low-voltage side filter capacitor C is connected with the positive electrode of the capacitorLNegative pole of and the low-voltage side DC power supply ULThe negative electrode of (1) is connected;
the high-voltage side filter capacitor CHAnd the positive pole of the power supply and the high-voltage side direct current power supply UHThe anode of the filter capacitor C on the high-voltage side is connected withHAnd the negative electrode of the high-voltage side direct-current power supply UHIs connected to the negative electrode of (1).
When the high-voltage side is the DC power supply UHAverage voltage value and low-voltage side DC power supply ULWhen the ratio of the average voltage value of the two-way direct current converter is greater than 4, the invention also provides a control method of the two-way direct current converter, which comprises the following steps:
sampling the high-voltage side end voltage of the bidirectional direct-current converter to obtain a high-voltage side end voltage sampling value uH,fSampling the high-side end voltage uH,fAnd a high side end voltage reference value uH,refComparing to obtain a first error signal delta uH(ii) a The first error signal DeltauHSequentially passes through a voltage controller GuH(s) and a bidirectional amplitude limiting link Lim1 are processed to obtain a low-voltage side port current reference value iL,ref；
For low voltage side port current i of the bidirectional DC converterLSampling to obtain a low-voltage side port current sampling value iL,fSampling the current of the low-voltage side port iL,fAnd a low-voltage side port current reference value iL,refThe comparison is carried out to obtain a second error signal delta iL(ii) a The second error signal Δ iLThrough current controller GiL(s) and a one-way amplitude limiting link Lim2 to obtain a first modulation signalur1；
First modulation signal ur1And amplitude of UcmFirst unipolar triangular carrier uc1Crossing to generate a first switch tube S1Drive signal u ofgs1；
A first switch tube S1Drive signal u ofgs1Obtaining a second switch tube S by inverting2Drive signal u ofgs2；
The first modulation signal ur1Sending to a calculation module by formula ur2＝Ucm-ur1And/2, calculating in real time to obtain a second modulation signal ur2；
Second modulation signal ur2And amplitude of UcmOf the second unipolar triangular carrier uc2Intersecting to generate a third switch tube S3Drive signal u ofgs3；
A third switching tube S3Drive signal u ofgs3Taking the inverse to obtain a fourth switching tube S4Drive signal u ofgs4；
Wherein the first unipolar triangular carrier uc1And a second unipolar triangular carrier uc2Are identical and have a phase difference of 180 deg.
Further, the ideal voltage gain G of the bidirectional direct current converter in the Boost modeBoostAnd ideal voltage gain G in Buck modeBoostRespectively as follows:
Figure BDA0003553656950000021
in the above formula, d1Is the duty cycle of the first drive signal.
Furthermore, the first inductor L of the bidirectional DC converter1And a second inductance L2The average values of the currents of (a) are:
Figure BDA0003553656950000022
in the above formula, the first and second carbon atoms are,IL1and IL2Are respectively a first inductance L1And a second inductance L2The average current value of (a); i isLThe average of the low voltage side port current.
Compared with the prior art, the invention has the following technical effects:
1) the power tube is few, the structure is simple, and the cost is low;
2) the voltage rising/reducing capability is strong, and the on-state loss is small;
3) the double inductors divide the current on the low-voltage side equally, the magnetic core has small volume and high conversion efficiency;
4) the pulse rate of the input current is small, the frequency is twice of the switching frequency, and the capacitance and the volume of the low-voltage side filter capacitor are reduced.
Drawings
Fig. 1 is a schematic circuit diagram of a bidirectional dc converter provided in the present application;
FIG. 2 illustrates a method of controlling the bi-directional DC converter of FIG. 1;
fig. 3 is an equivalent diagram of 4 working modes of the bidirectional dc converter shown in fig. 1 in a switching period in a Boost mode;
fig. 4 is an equivalent diagram of 4 working modes of the bidirectional dc converter shown in fig. 1 in a switching period in Buck mode;
FIG. 5 is a waveform illustrating the principal operation of the bi-directional DC converter of FIG. 1 during a switching cycle in two modes;
FIG. 6 is a schematic diagram of an average current equivalent circuit of the bidirectional DC converter shown in FIG. 1 in two modes;
FIG. 7 is a simulated waveform diagram of the bidirectional DC converter shown in FIG. 1 in a Boost mode;
FIG. 8 is a simulated waveform diagram of the bidirectional DC converter shown in FIG. 1 in Buck mode;
fig. 9 is a simulated waveform diagram of two mode switching of the bidirectional dc converter shown in fig. 1.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a bidirectional direct current converter for an energy storage system, and the circuit structure is shown as figure 1. The high-gain converter comprises a low-voltage side filter capacitor CLA first capacitor C1High-voltage side filter capacitor CHA first inductor L1A second inductor L2A first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4(ii) a First inductance L1One end of and the second inductance L2One end of, the low voltage side filter capacitor CLThe positive electrode of (1) is connected; first inductance L1And the other end of the first switch tube S1Drain electrode of (1), second switch tube S2Is connected to the source of (a); second inductance L2The other end of the first switch tube and the third switch tube S3Drain electrode of, first capacitor C1The positive electrode of (1) is connected; first switch tube S1Source electrode of and the first capacitor C1Negative electrode of (1), fourth switching tube S4Is connected to the source of (a); a second switch tube S2Drain and high-side filter capacitor CHThe positive electrode of (1) is connected; third switch tube S3Source electrode and fourth switch tube S4Drain electrode, low voltage side filter capacitor CLNegative electrode and high-voltage side filter capacitor CHThe negative electrode of (1) is connected; low-voltage side filter capacitor CLPositive and low voltage side dc power supply ULIs connected with the positive electrode of the low-voltage side filter capacitor CLNegative pole and low voltage side DC power supply ULIs connected with the negative pole of the anode; high-voltage side filter capacitor CHPositive pole and high voltage side dc power supply UHIs connected with the positive electrode of the high-voltage side filter capacitor CHNegative pole and high voltage side DC power supply UHIs connected to the negative electrode of (1).
When the high-voltage side DC power supply UHAverage voltage value and low-voltage side DC power supply ULWhen the ratio of the average voltage value of (2) is more than 4, the product is obtainedThe invention provides a control method of the bidirectional direct current converter, a control block diagram is shown in fig. 2, and the control method comprises the following steps:
sampling the high-voltage side end voltage of the bidirectional direct current converter to obtain a high-voltage side end voltage sampling value uH,fSampling the high side end voltage uH,fAnd a high side end voltage reference value uH,refComparing to obtain a first error signal delta uH(ii) a First error signal DeltauHSequentially passes through a voltage controller GuH(s) and a bidirectional amplitude limiting link Lim1 are processed to obtain a low-voltage side port current reference value iL,ref；
Low voltage side port current i to bidirectional DC converterLSampling to obtain a current sampling value i of the low-voltage side portL,fSampling the current of the low-voltage side port iL,fAnd a low-voltage side port current reference value iL,refThe comparison is carried out to obtain a second error signal delta iL(ii) a Second error signal Δ iLThrough current controller GiL(s) and a one-way amplitude limiting link Lim2 to obtain a first modulation signal ur1；
First modulation signal ur1And amplitude of UcmFirst unipolar triangular carrier uc1Crossing to generate a first switch tube S1Drive signal u ofgs1(ii) a Drive signal ugs1Duty ratio of d1；
A first switch tube S1Drive signal u ofgs1Inverting to obtain a second switch tube S2Drive signal u ofgs2；
The first modulation signal ur1Sending to a calculation module for calculating the formula ur2＝Ucm-ur12, calculating in real time to obtain a second modulation signal ur2；
Second modulation signal ur2And amplitude of UcmOf the second unipolar triangular carrier uc2Intersecting to generate a third switch tube S3Drive signal u ofgs3Driving signal ugs3Duty ratio of d2；
A third switch tube S3Drive signal u ofgs3Taking the inverse to obtain a fourth switching tube S4Drive signal u ofgs4；
Wherein the first unipolar triangular carrier uc1And a second unipolar triangular carrier uc2Are identical and have a phase difference of 180 deg.
DC power supply U at high voltage side for the bidirectional DC converter shown in FIG. 1HAverage voltage value and low-voltage side DC power supply ULThe operation when the ratio of the average voltage values of (a) is greater than 4 will be described.
To simplify the analysis, the following assumptions were made: first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4Low voltage side filter capacitor CLA first capacitor C1High-voltage side filter capacitor CHA first inductor L1A second inductor L2Are all ideal devices; low-voltage side filter capacitor CLA first capacitor C1High-voltage side filter capacitor CHLarge enough that voltage ripple is negligible; first inductance L1A second inductor L2The current of (2) is continuous; low-voltage side DC power supply ULIs a zero potential reference point.
Based on the assumptions, the working principle and the steady-state characteristics in the Boost mode and the Buck mode are analyzed:
1) boost mode
In Boost mode, after entering steady state, the bidirectional DC converter is in a switching period TsThe working process in the system can be divided into 4 modes, and the equivalent circuit of each mode is shown in fig. 3. The main waveforms in one switching cycle are shown in fig. 5 (a).
t0Before the moment, the first switch tube S1And a fourth switching tube S4Conducting; a second switch tube S2And a third switching tube S3And (6) turning off.
Mode 1[ t ]0,t1](the equivalent circuit is shown in FIG. 3 (a))
t0At the moment, the third switch tube S3Opening, fourth switch tube S4And (6) turning off. Low-voltage side DC power supply ULAnd a first capacitor C1Through a first switch tube S1And a third switching tube S3To the first inductor L1Charging; at the same time, the low-voltage side DC power supply ULThrough a third switch tube S3To the second inductance L2And (6) charging. First inductance L1And a second inductance L2Are subject to a forward voltage. During this time, there are:
Figure BDA0003553656950000031
in the formula, L1And L2Are respectively a first inductance L1And a second inductance L2The inductance value of (a); i.e. iL1And iL2Are respectively a first inductance L1And a second inductance L2The current value of (a); u shapeC1Is a first capacitor C1Terminal voltage of ULIs the terminal voltage of the low-side dc power supply.
t1At the moment, the first switch tube S1Off, modality 1 ends and modality 2 begins.
Mode 2[ t ]1,t2](the equivalent circuit is shown in FIG. 3 (b))
t1At the moment, the first switch tube S1Off, the second switching tube S2And conducting. Low-voltage side DC power supply ULAnd a first inductance L1Through a second switching tube S2DC power supply U to high voltage sideHAnd (5) supplying power. At the same time, the low-voltage side DC power supply ULThrough a third switch tube S3To the second inductance L2And (6) charging. First inductance L1Subject to reverse voltage, second inductance L2Subject to a forward voltage. During this time, there are:
Figure BDA0003553656950000041
in the formula of UHIs the terminal voltage of the high-side dc power supply.
t2At the moment, the second switch tube S2Off, mode 2 ends, mode 3And starting.
Mode 3[ t ]2,t3](the equivalent circuit is shown in FIG. 3 (c))
t2At the moment, the second switch tube S2Turn off, first switch tube S1And conducting. First inductance L1And a second inductance L2The current expression of (c) is the same as mode 1.
t3At the moment, the third switch tube S3Shutdown, modality 3 ends, and modality 4 begins.
Mode 4[ t ]3,t4](the equivalent circuit is shown in FIG. 4 (d))
t3At the moment, the third switch tube S3Turn-off, fourth switch tube S4And conducting. Low-voltage side DC power supply ULAnd a second inductance L2Through a fourth switching tube S4To the first capacitor C1And (6) charging. At the same time, the low-voltage side DC power supply ULThrough a first switch tube S1And a fourth switching tube S4To the first inductor L1And (6) charging. First inductance L1Bearing forward voltage, second inductance L2Subject to a reverse voltage. During this time, there are:
Figure BDA0003553656950000042
t4at the moment, the fourth switching tube S4And (4) turning off, ending the mode 4 and entering the next switching period.
The steady state behavior in Boost mode is analyzed as follows:
according to the first inductance L1A second inductor L2The voltage-second balance of (a) can be obtained:
Figure BDA0003553656950000043
the voltage gain G of the bidirectional DC-DC converter in Boost mode can be obtained by the formula (4)BoostComprises the following steps:
Figure BDA0003553656950000044
the voltage stress of the power tube is as follows:
Figure BDA0003553656950000045
in the above formula, US1、US2、US3And US4Are respectively a first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4The voltage stress experienced.
After the steady state is entered, the average current of the capacitor is zero, so that an average current equivalent circuit schematic diagram of the bidirectional direct current converter in the Boost mode can be obtained, as shown in fig. 6 (a). From FIG. 6, it can be seen that:
Figure BDA0003553656950000051
in the above formula, IS1、IS2、IS3And IS4Are respectively a first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4The average current value of (a); I.C. ALAverage value of low voltage side port current, IHThe average of the high voltage side port current.
2) Buck mode
In the Buck mode, after entering the steady state, the working process of the converter in one switching period can be divided into 4 modes, and the equivalent circuits of the modes are respectively shown in fig. 4. The main waveform in one switching cycle is shown in fig. 5 (b).
t0Before the moment, the first switch tube S1And a fourth switching tube S4Conducting; a second switch tube S2And a third switching tube S3And (6) turning off.
Mode 1[ t ]0,t1](the equivalent circuit is shown in FIG. 4 (a))
t0Time of day, third switchPipe S3Opening, fourth switch tube S4And (6) turning off. First inductance L1Through a first switch tube S1And a third switching tube S3DC power supply U to low voltage sideLAnd a first capacitor C1Charging; at the same time, the second inductance L2Through a third switch tube S3DC power supply U to low voltage sideLAnd (6) charging. First inductance L1And a second inductance L2Are subject to a forward voltage. During this time, there are:
Figure BDA0003553656950000052
t1at the moment, the first switch tube S1Off, modality 1 ends and modality 2 begins.
Mode 2[ t ]1,t2](the equivalent circuit is shown in FIG. 4 (b))
t1At the moment, the first switch tube S1Off, the second switching tube S2And conducting. High-voltage side DC power supply UHThrough a second switch tube S2DC power supply U to low voltage sideLAnd a first inductance L1And (5) supplying power. At the same time, the second inductance L2Through a third switch tube S3DC power supply U to low voltage sideLAnd (6) charging. First inductance L1Bearing reverse voltage, second inductance L2Subject to a forward voltage. During this time, there are:
Figure BDA0003553656950000053
t2at the moment, the second switch tube S2Off, modality 2 ends and modality 3 begins.
Mode 3[ t ]2,t3](the equivalent circuit is shown in FIG. 4 (c))
t2At the moment, the second switch tube S2Turn off, first switch tube S1And conducting. First inductance L1And a second inductance L2The current expression of (c) is the same as mode 1.
t3At the moment, the third switch tube S3Shutdown, modality 3 ends, and modality 4 begins.
Mode 4[ t ]3,t4](the equivalent circuit is shown in FIG. 4 (d))
t3At the moment, the third switch tube S3Turn-off, fourth switch tube S4And conducting. A first capacitor C1Through a fourth switching tube S4DC power supply U to low voltage sideLAnd a second inductance L2And (6) charging. At the same time, the first inductance L1Through a first switch tube S1And a fourth switching tube S4DC power supply U to low voltage sideLAnd (6) charging. First inductance L1Bearing forward voltage, second inductance L2Subject to a reverse voltage. During this time, there are:
Figure BDA0003553656950000054
t4at the moment, the fourth switching tube S4And (4) turning off, finishing the mode 4 and entering the next switching period.
Based on the above working principle of the bidirectional DC-DC converter of the present invention in the Buck mode, the steady-state characteristics thereof are analyzed below.
According to the first inductance L1A second inductor L2The voltage-second balance of (a) can be obtained:
Figure BDA0003553656950000061
from equation (11), the voltage gain G of the invented bidirectional DC-DC converter in Buck mode can be obtainedBuckComprises the following steps:
Figure BDA0003553656950000062
the voltage stress of the power tube is as follows:
Figure BDA0003553656950000063
after entering the steady state, the average current of the capacitor is zero, so that an equivalent circuit diagram of the average current of the bidirectional dc converter in the Buck mode can be obtained, as shown in fig. 6 (b). From FIG. 6, it can be seen that:
Figure BDA0003553656950000064
the bidirectional direct current converter has the same steady-state characteristics in a Boost mode and a Buck mode, so the parameter design process is the same. For this reason, the parameter design is performed by taking the Boost mode as an example.
The design indexes of the bidirectional direct current converter are as follows: switching frequency fs100kHz, input voltage U L40V, maximum output power Po,max250W, output voltage UH＝400V。
From the above index, the duty ratio d can be obtained from the equation (5)1Satisfies the following conditions:
Figure BDA0003553656950000065
the duty ratio d can be obtained from equation (15)1Comprises the following steps:
d1＝0.8 (16)
usually, the inductance L of the inductor and the current pulsation Δ I of the inductorinductorSatisfies the following conditions:
Figure BDA0003553656950000066
in the formula of UinductorThe value of the forward or reverse voltage borne by the inductor, t is the forward or reverse voltage U borne by the inductor in one switching periodinductorThe time of (c).
It is generally required that the maximum current ripple allowed by the inductor does not exceed 30% of its maximum average current, i.e. the first inductor L1Of electric currentPulsating quantity Δ IL1And a first inductance L1Maximum average current I ofL1,maxSatisfies the following conditions: delta IL1≤0.3IL1,maxIn conjunction with fig. 5 and equation (17), there are:
Figure BDA0003553656950000071
similarly, the second inductor L2Pulsating quantity of current Δ IL2A second inductor L2Maximum average current I ofL2,maxSatisfies the following conditions: delta IL2≤0.3IL2,maxIn conjunction with fig. 5 and equation (17), there are:
Figure BDA0003553656950000072
capacitance C of a normal capacitor and voltage fluctuation DeltaU of the capacitorcapacitorSatisfies the following conditions:
Figure BDA0003553656950000073
in the formula IcapacitorThe average current value for charging or discharging the capacitor, and t is the time for charging or discharging the capacitor in one switching period.
Typically, the capacitor voltage pulse rate is required to be less than 1%, and in conjunction with fig. 6 and equation (20), it can be seen that:
Figure BDA0003553656950000074
Figure BDA0003553656950000075
based on the modal analysis, the working condition analysis and the parameter design of the bidirectional direct current converter, the bidirectional direct current converter is subjected to simulation verification as follows:
in order to verify the correctness of the theoretical analysis,according to the parameter design, Saber simulation software is used for carrying out simulation verification on the bidirectional direct current converter, and specific values are as follows: a first capacitor C 120 muF, first inductance L10.8mH, second inductance L20.3mH, low-voltage side filter capacitor C L20 muF, high side filter capacitance CH＝20μF。
In Boost mode, the low-voltage side direct current power supply ULDC power supply U to high voltage sideHEnergy is delivered. Fig. 7 shows simulation waveforms of the bidirectional dc converter in Boost mode according to the present invention. It can be seen that the drive signal ugs1And ugs2Complementary, drive signals ugs3And ugs4Complementary, drive signals ugs1And ugs3The phase difference is 180 degrees; when the driving signal ugs1Duty ratio d of1DC power supply U with 0.8 and low voltage sideLDrive signal u of the converter mentioned at 40Vgs3Duty ratio d of2Approximately equals 0.6, and the high-voltage side direct-current power supply is UHApproximately equal to 400V, and the actually measured voltage gain is UH/U L400/40 ≈ 10, with the theoretical value GBoost＝2/(1-d1) 2/(1-0.8) ≈ 10. At the same time, it can also be seen that IL≈IL1+IL23.1A +3.1A ═ 6.2A, first inductance L1And a second inductor L2Current i of low-voltage side DC power supply is equally dividedL(ii) a And the frequency of the input current is twice of the switching frequency, and the ripple rate delta i of the input current isL/IL0.9/6.2 ≈ 14.5%, far less than the first inductance L1Ripple rate Δ i ofL1/IL10.9/3.1 ≈ 29% and a second inductance L2Ripple rate Δ i ofL2/IL20.7/3.1 ≈ 23%, consistent with theory.
Under Buck mode, the high-voltage side direct current power supply UHDC power supply U to low voltage sideLEnergy is delivered. Fig. 8 shows simulation waveforms of the bidirectional dc converter of the present invention in Buck mode. It can be seen that the drive signal ugs1And ugs2Complementary, drive signals ugs3And ugs4Complementary, drive signals ugs1And ugs3The phase difference is 180 degrees; when driving informationNumber ugs1Duty ratio d of1High-voltage side DC power supply U with a value of 0.8H400V, the driving signal u of the convertergs3Duty ratio d of2DC power supply U with 0.6 and low voltage sideLApproximately equals 40V, and the actually measured voltage gain is UL/U H40/400 ≈ 0.1 with the theoretical value GBuck＝(1-d1) The ratio of/2 to (1-0.8)/2 to 0.1 is basically identical. At the same time, it can also be seen that IL≈IL1+IL23.1A +3.1A ═ 6.2A, first inductance L1And a second inductor L2Current i of low-voltage side DC power supply is equally dividedL(ii) a And the frequency of the input current is twice of the switching frequency, and the ripple rate delta i of the input current isL/IL0.9/6.2 ≈ 14.5%, far less than the first inductance L1Ripple rate Δ i ofL1/IL10.9/3.1 ≈ 29% and a second inductance L2Ripple rate Δ i ofL2/IL20.7/3.1 ≈ 23%, consistent with theory.
Fig. 9 is a dynamic regulation process of the bidirectional dc converter shown in fig. 1 when switching from Boost mode to Buck mode, and it can be seen that after about 44ms, the low-side dc power current iLThe current is changed from +6.2A to-6.2A, and the high-voltage side direct-current power supply current iHThe current is changed from +0.62A to-0.62A, the energy flow direction of the converter is changed, and the working mode is switched from a Boost mode to a Buck mode; before and after mode switching, the high-voltage side voltage U of the converterHAre all stabilized at 400V, and are consistent with theory, thereby verifying the feasibility of the control scheme provided by the invention.
The bidirectional direct current converter provided by the invention can be applied to an energy storage system and has the following advantages: (1) the voltage gain in Boost mode is 2/(1-d)1) The voltage gain in Buck mode is (1-d)1) 2, the voltage rising/reducing capability is strong, and the on-state loss is small; (2) first inductance L1A second inductor L2The current at the low-voltage side is equally divided, and the magnetic core is small in size; the first inductance L is reduced1A second inductor L2A first switch tube S1A second switch tube S2A third switch tube S3The current stress and the on-state loss are reduced, thereby being beneficial to improving the conversion efficiency; (3) power deviceThe quantity is small, and the structure is simple; (4) the pulse rate of the input current is small, the frequency is twice of the switching frequency, and the capacitance and the volume of the low-voltage side filter capacitor are reduced.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea, and not to limit it. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall into the protection scope of the present invention.

Claims (4)

1. A bidirectional DC converter for an energy storage system is characterized by comprising a low-voltage side filter capacitor CLA first capacitor C1High-voltage side filter capacitor CHA first inductor L1A second inductor L2A first switch tube S1A second switch tube S2A third switch tube S3And a fourth switching tube S4；
The first inductor L1And the second inductor L2One terminal of, the low-voltage side filter capacitor CLThe positive electrode of (1) is connected;
the first inductor L1To another one ofEnd of the first switch tube S1Drain electrode of (1), the second switching tube S2Is connected to the source of (a);
the second inductor L2And the other end of the third switching tube S3The drain electrode of (1), the first capacitor C1The positive electrode of (1) is connected;
the first switch tube S1And the first capacitor C1Negative pole of (1), the fourth switching tube S4Is connected with the source electrode of the transistor;
the second switch tube S2And the high-voltage side filter capacitor CHThe positive electrode of (1) is connected;
the third switch tube S3Source electrode of and the fourth switching tube S4Drain electrode of, the low-voltage side filter capacitor CLNegative pole of (2), the high-voltage side filter capacitor CHThe negative electrode of (1) is connected;
the low-voltage side filter capacitor CLPositive pole of and the low-voltage side DC power supply ULThe positive pole of the low-voltage side filter capacitor CLNegative pole of and the low-voltage side DC power supply ULThe negative electrode of (1) is connected;
the high-voltage side filter capacitor CHAnd the positive pole of the power supply and the high-voltage side direct current power supply UHThe anode of the filter capacitor C on the high-voltage side is connected withHAnd the negative electrode of the high-voltage side direct-current power supply UHIs connected to the negative electrode of (1).
2. A method for controlling a bidirectional dc converter according to claim 1, wherein the method is applied to a high-side dc power supply UHAverage voltage value and low-voltage side DC power supply ULWhere the ratio of the average voltage values of (a) is greater than 4, the control method includes:
sampling the high-voltage side end voltage of the bidirectional direct-current converter to obtain a high-voltage side end voltage sampling value uH,fSampling the high-side end voltage uH,fAnd a high side end voltage reference value uH,refComparing to obtain a first error signal delta uH(ii) a The first error signal DeltauHPassing through the voltage in turnController GuH(s) and a bidirectional amplitude limiting link Lim1 are processed to obtain a low-voltage side current reference value iL,ref；
For low voltage side port current i of the bidirectional DC converterLSampling to obtain a low-voltage side port current sampling value iL,fSampling the low voltage side port current iL,fAnd a low-voltage side port current reference value iL,refThe comparison is carried out to obtain a second error signal delta iL(ii) a The second error signal Δ iLThrough current controller GiL(s) and a one-way amplitude limiting link Lim2 to obtain a first modulation signal ur1；
First modulation signal ur1And amplitude of UcmFirst unipolar triangular carrier uc1Crossing to generate a first switch tube S1Drive signal u ofgs1；
A first switch tube S1Drive signal u ofgs1Inverting to obtain a second switch tube S2Drive signal u ofgs2；
The first modulation signal ur1Sending to a calculation module by formula ur2＝Ucm-ur12, calculating in real time to obtain a second modulation signal ur2；
Second modulation signal ur2And amplitude of UcmOf the second unipolar triangular carrier uc2Intersecting to generate a third switch tube S3Drive signal u ofgs3；
A third switch tube S3Drive signal u ofgs3Inverting to obtain a fourth switching tube S4Drive signal u ofgs4；
Wherein the first unipolar triangular carrier uc1And a second unipolar triangular carrier uc2Are identical in frequency and are 180 deg. out of phase with each other.
3. Control method according to claim 2, characterized in that the ideal voltage gain G of the bidirectional DC converter in Boost modeBoostAnd ideal voltage gain G in Buck modeBoostRespectively as follows:
Figure FDA0003553656940000011
in the above formula, d1Is the duty cycle of the first drive signal.
4. The control method of claim 2, wherein said first inductor L of said bi-directional dc converter1And a second inductance L2The average values of the currents of (a) are:
Figure FDA0003553656940000012
in the above formula, IL1And IL2Are respectively a first inductance L1And a second inductance L2The average current value of (a); i isLThe average of the low voltage side port current.
CN202210271739.0A 2022-03-18 2022-03-18 Bidirectional direct current converter for energy storage system and control method thereof Withdrawn CN114583952A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115242093A (en) * 2022-09-21 2022-10-25 香港中文大学（深圳） High-gain switch direct current booster circuit
CN116191884A (en) * 2023-04-26 2023-05-30 深圳市恒运昌真空技术有限公司 Boost-buck bidirectional converter
CN118367780A (en) * 2024-04-26 2024-07-19 山东艾诺智能仪器有限公司 Circuit for reducing filter inductance of bidirectional direct current power supply and modulation method

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115242093A (en) * 2022-09-21 2022-10-25 香港中文大学（深圳） High-gain switch direct current booster circuit
CN116191884A (en) * 2023-04-26 2023-05-30 深圳市恒运昌真空技术有限公司 Boost-buck bidirectional converter
CN118367780A (en) * 2024-04-26 2024-07-19 山东艾诺智能仪器有限公司 Circuit for reducing filter inductance of bidirectional direct current power supply and modulation method

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