CN114583948A - Energy system of hydrogen fuel vehicle and control method thereof - Google Patents

Energy system of hydrogen fuel vehicle and control method thereof Download PDF

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Publication number
CN114583948A
CN114583948A CN202011378304.3A CN202011378304A CN114583948A CN 114583948 A CN114583948 A CN 114583948A CN 202011378304 A CN202011378304 A CN 202011378304A CN 114583948 A CN114583948 A CN 114583948A
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bridge
converter
switching function
current
target value
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Inventor
陈雄春
陈慧民
梁松
彭再武
沈泽华
马健
刘少春
贺晓昉
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CRRC Electric Vehicle Co Ltd
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CRRC Electric Vehicle 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
    • H02M3/02—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L58/00—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles
    • B60L58/40—Methods or circuit arrangements for monitoring or controlling batteries or fuel cells, specially adapted for electric vehicles for controlling a combination of batteries and fuel cells
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02M3/157—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 with digital control
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries

Abstract

The invention provides an energy system of a hydrogen fuel vehicle and a control method thereof. The energy system comprises a hydrogen fuel cell, a lithium battery, an air compressor and a staggered parallel bidirectional half-bridge DC/DC converter. Wherein the air compressor provides pressure required by reaction for the hydrogen fuel cell; the staggered parallel bidirectional half-bridge DC/DC converter is a stabilized voltage power supply of the air compressor; the hydrogen fuel cell is a main input power supply of the interleaved parallel bidirectional half-bridge DC/DC converter; the lithium battery is an auxiliary input power supply of the staggered parallel bidirectional half-bridge DC/DC converter, and when the hydrogen fuel cell does not work, the lithium battery provides energy for the staggered parallel bidirectional half-bridge DC/DC converter so as to enable the air compressor to work and drive the hydrogen fuel cell to work. The control method controls the staggered parallel bidirectional half-bridge DC/DC converter to provide stable output voltage for the air compressor. According to the present invention, a hydrogen-fueled vehicle energy system can be provided that meets the requirements.

Description

Energy system of hydrogen fuel vehicle and control method thereof
Technical Field
The invention relates to the field of new energy vehicles, in particular to an energy system of a hydrogen fuel automobile and a control method thereof.
Background
The new energy automobile adopts unconventional automobile fuel as a power source (or adopts conventional automobile fuel but adopts a novel vehicle-mounted power device), integrates advanced technologies in the aspects of power control and driving of the automobile, and forms an automobile with advanced technical principle, new technology and new structure. New energy automobile includes: hybrid Electric Vehicles (HEV), electric-only vehicles (BEV), fuel cell vehicles (FCEV), hydrogen engine vehicles, as well as gas vehicles, alcohol ether vehicles, and the like.
Among them, the hydrogen fuel vehicle employs a hydrogen fuel cell as an energy source. In the whole operation process of the hydrogen fuel cell, except for consuming oxygen and air, no other energy is consumed, no oil is added, no charging is carried out, and the energy-saving performance is undoubted. Meanwhile, the hydrogen fuel cell stack only generates water in the process of generating electric energy, so that the maximum advantage is that the aim of zero emission is really realized.
Referring to fig. 1, an electric vehicle power control system using a hydrogen fuel cell as an energy source includes two power supply systems, namely a hydrogen fuel cell and a lithium battery, wherein the hydrogen fuel cell is used as a main power supply of the whole system, and the lithium battery system is used as an auxiliary power supply. In order to realize high-density integration and light-weight design of the hydrogen fuel cell, the output voltage of the hydrogen fuel cell is assumed to be relatively low between 200 and 400V. It is not known to be a stable voltage and the voltage power curve of the hydrogen fuel cell is shown in figure 2. The working voltage of the main drive motor is generally 450-750V, so that a Boost DCDC is arranged between the hydrogen fuel cell and the main drive motor to complete stable voltage and power output conversion. The voltage range of the lithium battery used as the support of the input voltage of the main drive motor is consistent with the required voltage range of the main drive motor, and the lithium battery can also be replaced by a super capacitor. The required voltage range of other high-voltage accessories such as a high-speed air compressor, a hydrogen circulating pump, a water pump and the like is assumed to be 300-400V. Since the air compressor is started first and the output of the voltage of the hydrogen fuel cell is unstable, the hydrogen fuel cell cannot be directly used as a power supply source of the high-speed air compressor and the like, and a step-down converter is required to be additionally arranged to supply power to the high-speed air compressor and the like. And the high-speed air compressor machine deceleration or scram can cause input end voltage to rise rapidly, must release the energy of air compressor machine input rapidly this moment otherwise will have the danger of burning out the air compressor machine.
In addition, since the hydrogen fuel cell is formed by connecting the hydrogen battery units in series and parallel, the hydrogen fuel cell is quite sensitive to input current ripples, the consistency of the hydrogen battery units is seriously influenced by overlarge current ripples, and even the danger that the single battery of the hydrogen battery unit is too low is possibly caused, so the current ripples must be controlled within the limit range
Existing buck converters include isolated bidirectional DC/DC converters, non-isolated BDCs, i.e., bidirectional half-bridge DC/DC converters, and the like. However, for the isolated bidirectional DC/DC converter, the energy storage transformer has high design requirement, complex control and relatively low efficiency, and is not suitable for the design of the current hydrogen fuel electric system from the economical and practical perspective. For a non-isolated BDC, namely a bidirectional half-bridge DC/DC converter, although the DC/DC bidirectional operation can be realized and the converter can work in a voltage control mode or a current control mode, the converter has the problems that the output ripple is difficult to control, the frequency of a switching power tube is difficult to improve, the dynamic response is slow, the voltage-resistant grade and the overcurrent grade of the power tube are too high during high-power design, and the like.
Therefore, it is highly desirable to add a power supply converter, which can realize a converter with bidirectional energy flow, fast dynamic response speed and satisfactory current ripple fluctuation, so as to provide a satisfactory hydrogen fuel vehicle energy system by controlling the converter.
Disclosure of Invention
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
In order to enable the energy system of the hydrogen fuel vehicle to meet the working requirement, the invention provides an energy system of the hydrogen fuel vehicle, which comprises a hydrogen fuel cell, a lithium battery, an air compressor and a staggered parallel bidirectional half-bridge DC/DC converter; wherein
The air compressor provides air pressure required by reaction for the hydrogen fuel cell;
the staggered parallel bidirectional half-bridge DC/DC converter is a stabilized voltage power supply of the air compressor;
the hydrogen fuel cell is a main input power supply of the interleaved parallel bidirectional half-bridge DC/DC converter;
the lithium battery is the auxiliary input power supply of the staggered parallel bidirectional half-bridge DC/DC converter, and when the hydrogen fuel cell is not in operation, the lithium battery provides energy for the staggered parallel bidirectional half-bridge DC/DC converter so as to enable the air compressor to work and drive the hydrogen fuel cell to work.
In an embodiment of the energy system, optionally, an output current ripple of the interleaved bidirectional half-bridge DC/DC converter is less than 1.5% of a rated current.
In an embodiment of the energy system, optionally, an overshoot amount of the output bus voltage of the interleaved bidirectional half-bridge DC/DC converter is not more than 5%.
In an embodiment of the energy system, optionally, a dynamic response time of the interleaved bidirectional half-bridge DC/DC converter is less than 15 ms.
In an embodiment of the energy system, optionally, two bridge arms of the interleaved bidirectional half-bridge DC/DC converter respectively use integrated silicon carbide MOS modules.
Another aspect of the present invention also provides a control method of an energy system of a hydrogen-fueled vehicle, the power system being the power system described in any one of the above embodiments, the control method including:
collecting input voltage, output voltage and output current of a staggered parallel bidirectional half-bridge DC/DC converter of the power system;
determining a current target value according to the deviation of the output voltage and a stabilized voltage target value;
determining a switching function of a power tube in the interleaved bidirectional half-bridge DC/DC converter according to the deviation between the target current value and the output current;
determining a feed forward quantity according to the input voltage and the output voltage;
correcting the switching function according to the feedforward quantity; and
and controlling the on-off of the power tube based on the corrected switching function so as to control the output voltage of the interleaved parallel bidirectional half-bridge DC/DC converter to be stabilized at the stabilized target value.
In an embodiment of the control method, optionally, the output current includes a first inductor current and a second inductor current; wherein
Determining the switching function of the power tube further comprises:
determining a first inductance current target value and a second inductance current target value according to the current target value;
determining a first switching function of a power tube of a first bridge arm according to the deviation between the first inductive current target value and the first inductive current; and
and determining a second switching function of the power tube of the second bridge arm according to the second inductive current target value and the deviation of the second inductive current.
In an embodiment of the control method, optionally, the modifying the switching function according to the feed-forward amount further includes:
correcting the first switching function according to the feedforward quantity; and
and correcting the second switching function according to the feedforward quantity.
In an embodiment of the control method, optionally, the first bridge arm and the second bridge arm respectively use integrated silicon carbide MOS modules; wherein
Controlling the power transistor to be on or off based on the corrected switching function further comprises:
controlling the silicon carbide MOS module based on the corrected duty ratio parameter of the first switching function; and
and controlling the silicon carbide MOS module based on the corrected duty ratio parameter of the second switching function.
In an embodiment of the control method, optionally, the first inductor current target value and the second inductor current target value are respectively half of the current target value.
In an embodiment of the control method, optionally, the feedforward amount is a ratio of the input voltage to the output voltage.
In an embodiment of the control method, optionally, modifying the switching function further includes:
and superposing the feedforward quantity and the switching function into a modified switching function.
According to the energy system of the hydrogen fuel vehicle and the control method thereof provided by the invention, the rapid dynamic response of the output low ripple and high-power fluctuation of the interleaved parallel bidirectional half-bridge DC/DC converter and the interleaved parallel active current sharing are realized. According to the control method, the input/output mode-free switching control of the interleaved parallel bidirectional half-bridge DC/DC converter can be realized.
Drawings
The above features and advantages of the present disclosure will be better understood upon reading the detailed description of embodiments of the disclosure in conjunction with the following drawings. In the drawings, components are not necessarily drawn to scale, and components having similar associated characteristics or features may have the same or similar reference numerals.
Fig. 1 shows a configuration of a power control system in which an energy system of a hydrogen-fueled vehicle provided by the present invention is located.
Fig. 2 shows a voltage power curve and a power density curve of a hydrogen fuel cell provided by the present invention.
Fig. 3 shows the output voltage response that can be achieved by the interleaved bi-directional half-bridge DC/DC converter provided by the present invention.
Fig. 4A shows the topology of the interleaved parallel bidirectional half-bridge DC/DC converter provided by the present invention.
Fig. 4B shows an equivalent circuit model of the interleaved parallel bidirectional half-bridge DC/DC converter shown in fig. 4.
Fig. 5A-5D show the flow of operating energy for the interleaved bi-directional half-bridge DC/DC converter provided by the present invention.
Fig. 6 shows the operation timing and output current waveform of the interleaved bidirectional half-bridge DC/DC converter provided by the present invention.
Fig. 7 shows a control circuit structure of the interleaved bidirectional half-bridge DC/DC converter provided by the invention.
Fig. 8 shows the control strategy principle of the interleaved parallel bidirectional half-bridge DC/DC converter provided by the present invention.
Fig. 9 shows a flow chart of a control method of the interleaved parallel bidirectional half-bridge DC/DC converter provided by the invention.
Fig. 10A shows the output total current ripple in the prior art.
Fig. 10B shows the output total current ripple in the present application.
Fig. 11A shows a prior art high power momentary loading of the IBDC output bus voltage.
Fig. 11B shows the IBDC output bus voltage for high power transient loading in the present invention.
Fig. 12A shows prior art IBDC output bus voltage with instantaneous energy feedback.
Fig. 12B shows the IBDC output bus voltage for instantaneous energy feedback in the present invention.
Fig. 13A shows the current sharing effect of two bridge arm branches in the prior art.
Fig. 13B shows the current sharing effect of the two bridge arm branches in the present invention.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments. It is noted that the aspects described below in connection with the figures and the specific embodiments are only exemplary and should not be construed as imposing any limitation on the scope of the present invention.
The following description is presented to enable any person skilled in the art to make and use the invention and is incorporated in the context of a particular application. Various modifications, as well as various uses in different applications will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without necessarily being limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.
The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
Note that where used, the designations left, right, front, back, top, bottom, positive, negative, clockwise, and counterclockwise are used for convenience only and do not imply any particular fixed orientation. In fact, they are used to reflect the relative position and/or orientation between the various parts of the object. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
It is noted that, where used, further, preferably, still further and more preferably is a brief introduction to the exposition of the alternative embodiment on the basis of the preceding embodiment, the contents of the further, preferably, still further or more preferably back band being combined with the preceding embodiment as a complete constituent of the alternative embodiment. Several further, preferred, still further or more preferred arrangements of the belt after the same embodiment may be combined in any combination to form a further embodiment.
The invention is described in detail below with reference to the figures and specific embodiments. It is noted that the aspects described below in connection with the figures and the specific embodiments are only exemplary and should not be construed as imposing any limitation on the scope of the present invention.
In order to meet the operating requirements of the hydrogen fuel vehicle energy system, one aspect of the invention provides a hydrogen fuel vehicle energy system, and the energy system provided by the invention and the power system thereof are understood with reference to fig. 1. The energy system provided by the invention comprises a hydrogen fuel cell, a lithium battery, an air compressor and a staggered parallel bidirectional half-bridge DC/DC converter; wherein the air compressor supplies a reaction gas to the hydrogen fuel cell; the staggered parallel bidirectional half-bridge DC/DC converter is a stabilized voltage power supply of the air compressor; the hydrogen fuel cell is a main input power supply of the interleaved parallel bidirectional half-bridge DC/DC converter; the lithium battery is an auxiliary input power supply of the staggered parallel bidirectional half-bridge DC/DC converter, and when the hydrogen fuel cell does not work, the lithium battery provides energy for the staggered parallel bidirectional half-bridge DC/DC converter so as to enable the air compressor to work and drive the hydrogen fuel cell to work.
In practical application, considering the narrow input voltage range requirement of an air compressor, the requirement of a hydrogen fuel cell (hydrogen stack for short) for low output ripple, the large current and the high-power follow-up characteristic (namely uncertain load power disturbance) of a hydrogen fuel electric system, the converter provided by the invention adopts a non-isolated IBDC topological structure, as shown in fig. 4A. The invention provides a staggered parallel bidirectional half-bridge DC/DC converter (hereinafter referred to as IBDC) which adopts a design scheme of a SiC integrated power module and provides a novel control strategy of output voltage feedforward of an IBDC voltage outer ring-parallel current inner ring. The scheme realizes the rapid dynamic response of low output ripple and high-power fluctuation of the IBDC and the active current sharing in staggered parallel connection. Meanwhile, the input/output mode-free switching control is realized through a DSP software algorithm.
That is, the IBDC provided by the present invention has the following characteristics:
(1) IBDC low ripple: less than 1.5% of rated current;
(2) the closed loop response speed of the IBDC output terminal voltage is high, and the closed loop response speed comprises the steps of responding to instant load pulling and instant energy feedback;
(3) outputting parallel branch inductive current sharing;
(4) input/output mode-less switching control.
For the second point, the fast response speed not only requires the response time, but also requires the response amplitude, i.e. the overshoot of the voltage, i.e. the overshoot cannot exceed 5%. As will be understood in conjunction with FIG. 3, assume the difference between the maximum and minimum input voltage ranges of the air compressor<100V, and the output side voltage delta V is taken as a safety range in consideration of the bidirectional energy flow of the IBDC1、ΔV2The fluctuation is limited within +/-35V, and the response time delta t1、Δt2Within 15ms, the response of the instantaneous pull load and instantaneous energy feedback is as shown in fig. 3.
In a preferred embodiment, two arms of the IBDC respectively employ integrated silicon carbide MOS modules. The SiC MOS has the advantages of high voltage resistance and low on-resistance. Compared with the IGBT, the SiC MOS has no current tailing in the turn-off process, and can work at higher switching frequency in the application occasions of high voltage and large current. The SiC packaging module is adopted, so that the control of the circuit of IDBC in parallel connection in a staggered mode is facilitated.
The flapping structure of the IBDC is shown in fig. 4A, and the IBDC is designed to work in a continuous current mode, i.e., a CCM mode, according to the requirements of high power and large current of the system.
Fig. 5A-5D illustrate the energy bi-directional operation of the above-described IBDC at duty cycles D < 0.5. Please refer to fig. 6 together to understand the operation timing, the output current waveform and the energy flow in the operation process of the IBDC when the duty ratio D < 0.5. The duty cycle D is 0.5 or D >0.5 is similar to that of D < 0.5.
As shown in fig. 5A, at t0～t1Power tube Q of branch 1 in time period1Turn-on, inductance L1Storing energy; power tube Q of branch 23Off, diode D3Follow current, inductance L2And (4) discharging energy.
As shown in fig. 5B, at t1～t2Power tube Q of branch 1 and branch 2 in time period1、Q3Are all turned off, diode D1、D3Follow current, inductance L1、L2And (4) discharging energy.
As shown in fig. 5C, at t2～t3Power tube Q of branch 1 in time period1Off, diode D1Follow current, inductance L1Continuing discharging energy; power tube Q of branch 23Open, inductance L2And (4) storing energy.
As shown in fig. 5B, at t3～t4Power tube Q of branch 1 and branch 2 in time period1、Q3Are all turned off, diode D1、D3Follow current, inductance L1、L2Discharge, followed by periodic cycling.
Another aspect of the present invention also provides a control method of an energy system of a hydrogen-fueled vehicle, the above-described power system being the power system described in any one of the above embodiments,
for the above-mentioned IBDC, for convenience of control, the IBDC in fig. 4A may be equivalent to the topology as in fig. 4B, as illustrated in fig. 4B. As shown in fig. 4B, the equivalent inductance and the equivalent input-output gain M therein can be expressed by the following equations 1 and 2.
Figure BDA0002807783040000081
Figure BDA0002807783040000082
In addition, in order to operate the IBDC in the continuous current mode, the following equation 3 needs to be satisfied for the energy storage inductor L.
Figure BDA0002807783040000083
Wherein, IoutTo average output current, DminThe duty cycle is designed for minimum.
Similarly, for the output capacitance, the following equation 4 needs to be satisfied.
Figure BDA0002807783040000091
Wherein, tauRCIs a constant, Δ iLIs ripple current, VrIs the ripple voltage, Δ tminFor dynamic variation of time, Δ VmaxIn order to achieve the maximum dynamic change amplitude, a mode of connecting large and small capacitors in parallel is adopted in the practical application process.
The invention also provides a control method of the IBDC. To implement the control method described above, the control circuit of the IBDC may be as shown in fig. 7, in which the power main circuit, i.e., the IBDC described above, inputs the power supply, i.e., the output of the hydrogen fuel cell after passing through the boost converter. The auxiliary power supply is a lithium battery, the output load is high-voltage accessories such as an air compressor, a hydrogen circulating pump, a water pump and the like, and the drive circuit of the IBDC is controlled by the control of the DSP through sampling input voltage, output voltage and current so as to drive the main power circuit to work.
Calculation of the control parameters and parameter correction are subsequently performed. According to the IBDC small signal model calculation, a transfer function G of duty ratio to output voltage and inductive current can be obtainedvd(s)、Gid(s) as shown in the following equations 5 and 6.
Figure BDA0002807783040000092
Figure BDA0002807783040000093
Substituting the control parameters, the system is stable, but the high frequency greatly disturbs the system, and compensation is needed. The system can be designed with compensation based on the proposed control strategy as shown in fig. 8. In the proposed control strategy, the inner current loop is designed first and then the outer loop is designed because the response speed of the inner current loop is faster than that of the outer voltage loop, so that the cutoff frequency f after compensation of the inner loop can be designedic500Hz, outer loop cut-off frequency fvcAnd finally, obtaining a compensation parameter, namely 100 Hz.
Please further refer to fig. 9 to understand the control method of the present invention. As shown in fig. 9, the control method of the present invention includes:
1. input voltage U of interleaved parallel bidirectional half-bridge DC/DC converter of acquisition power systemiOutput voltage UoOutput current (i)LIs iL1And iL2Sum);
2. according to the output voltage UoAnd a stabilized voltage target value Uo_refDetermining a current target value;
3. determining a switching function of a power tube in the interleaved bidirectional half-bridge DC/DC converter according to the deviation between the target current value and the output current;
4. determining a feedforward quantity U based on the input voltage and the output voltagedff；
5. Correcting the switching function according to the feedforward quantity; and
and 6, controlling the on-off of the power tube based on the corrected switching function so as to control the output voltage of the interleaved parallel bidirectional half-bridge DC/DC converter to be stabilized at the stabilized target value.
In the step 2, please refer to fig. 8, according to the output voltage UoAnd a regulated target value Uo_refDetermining the target current value comprises determining the output voltage UoAnd a stabilized voltage target value Uo_refObtaining i after PI proportion regulationL_PI. It will be appreciated that due to the output current iLIncluding a first inductor current iL1And a second inductor current iL2Thus will iL_PII is obtained by an amplifier with an amplification factor of 0.5L_PI_out. Then, for iL_PI_outCarrying out amplitude limiting processing to obtain a first inductive current target value iL1_refAnd a second inductor current target value iL2_ref. That is, the first inductor current target value iL1_refAnd the second inductor current target value iL2_refRespectively, half of the current target value.
In step 3, please refer to fig. 8, according to the first inductor current target value iL1_refAnd a first inductor current iL1Determining a first switching function of a power tube of the first bridge arm; and according to the second inductor current target value and the second inductor current iL2Determines a second switching function of the power transistors of the second leg.
Further, the first switching function is obtained by setting the first inductor current target value iL1_refAnd a first inductor current iL1The deviation is obtained after PI proportion adjustment. Similarly, the second switching function is performed by applying a second inductor current target value iL2_refAnd a first inductor current iL2Is subjected to PI proportion regulation to obtainIn (1).
The first and second switching functions described above include the duty cycles of the power transistors Q1-Q4 for the first and second legs. Furthermore, in order to improve the accuracy of the voltage stabilization of the system, the control method provided by the invention further comprises the step of forming feed-forward control by using the input voltage and the output voltage. Specifically, in step 3, the input voltage U can be calculatediAnd an output voltage UoTo determine the feedforward quantity Udff. The feed forward amount described above can be seen to be approximately equal to the duty cycle.
Thus, as shown in fig. 8, when having been based on the first inductor current target value iL1_refAnd a first inductor current iL1Determines a first switching function of the power transistor of the first leg already based on the second inductor current target value and the second inductor current iL2After determining the second switching function of the power transistor of the second bridge arm, in step 5, the feedforward quantity U is respectively superimposed on the first switching function and the second switching functiondffThe switching function is modified, i.e. the final duty cycle is obtained.
Then, in step 6, the corrected switching function can control the on/off of the power tube. In the control system, the corrected duty ratio is used as the transfer function G of the duty ratio to the inductive currenti1d(s)、Gi2d(s) obtaining a first inductor current and a second inductor current iL1And iL2Then superimposed as an output current iL. The output voltage is then derived via a current-to-voltage transfer function.
In summary, the control method provided by the invention is a voltage outer ring-parallel current inner ring-output voltage feedforward control method, so that the quick dynamic response of low-ripple and high-power fluctuation of output of the IBDC and the active current sharing in staggered parallel connection can be realized.
In a preferred embodiment, the first and second legs of the IBDC provided by the present invention each employ integrated silicon carbide MOS modules. Due to the fact that the integrated silicon carbide MOS module is adopted, control over duty ratio of 4 power tubes can be converted into control over duty ratio parameters of 2 silicon carbide MOS modules, and therefore the integrated silicon carbide MOS module has the advantages of being high-voltage resistant, low in on-resistance, capable of working at higher switching frequency under application occasions of high voltage and high current, meanwhile, control complexity can be reduced, and control efficiency is improved.
In addition, it can be understood that, because the control method provided by the invention is a voltage outer loop-parallel current inner loop-output voltage feedforward control method, the input/output mode-free switching control can be realized by writing a corresponding digital processing chip C/C + + control program and a DSP software algorithm. That is, the input voltage U can be directly obtained from the acquisitioniOutput voltage UoOutput current (i)LIs iL1And iL2Sum) to perform compensation processing of duty ratio and response without performing additional judgment and conversion of input/output modes, thereby further improving response speed.
According to the energy system of the hydrogen fuel vehicle and the control method thereof provided by the invention, the following three effects can be achieved:
(a) the output current ripple is extremely small, so that the stable output of the hydrogen stack current is ensured;
(b) the dynamic response is rapid, the fluctuation of the bus voltage is small, and the device is suitable for severe working conditions;
(c) the branch current has good current equalizing effect, and the design requirements of a power module, an energy storage inductor and the like can be reduced.
Please refer to fig. 10A, 10B, 11A, 11B, 12A, 12B, 13A, and 13B to verify the practical application effect of the solution provided by the present invention.
Where fig. 10A shows the output total current ripple in the prior art and fig. 10B shows the output total current (lower light grey pattern) ripple in the present application. Comparing fig. 10A and 10B, it can be seen that the output total current ripple can be effectively controlled according to the technical scheme of the present application, thereby achieving the effects of extremely small output current ripple and ensuring stable output of the hydrogen stack current.
Fig. 11A shows the prior art high power transient load IBDC output bus voltage (upper line) and fig. 11B shows the high power transient load IBDC output bus voltage (upper line) of the present invention. Comparing fig. 11A and 11B, it can be seen that the external high-power instantaneous loading can be quickly and dynamically responded according to the technical scheme of the present application, thereby ensuring that the bus voltage fluctuation is small and being capable of adapting to severe working conditions.
Fig. 12A shows the total current of the IBDC output of the instantaneous energy feedback in the prior art, and fig. 12B shows the total current of the IBDC output of the instantaneous energy feedback in the present invention. Comparing fig. 12A and 12B, it can be seen that according to the technical scheme of the present application, the external instantaneous energy feedback can be quickly and dynamically responded, and the transition of the output total current is stable, so that the fluctuation of the bus voltage is small, and the bus voltage can be adapted to severe working conditions.
Fig. 13A shows the current sharing effect of two bridge arm branches in the prior art, and fig. 13B shows the current sharing effect of two bridge arm branches in the present invention. Comparing fig. 13A and 13B, it can be seen that better branch current flow equalizing effect can be achieved according to the technical scheme of the present application, so that design requirements of power modules, energy storage inductors, and the like can be reduced, and hardware requirements can be reduced.
The present invention has been described in detail with reference to the embodiments of the present invention. According to the energy system of the hydrogen fuel vehicle and the control method thereof provided by the invention, the rapid dynamic response of the output low ripple and high-power fluctuation of the interleaved parallel bidirectional half-bridge DC/DC converter and the interleaved parallel active current sharing are realized. According to the control method, the control of the non-input/output mode switching of the interleaved parallel bidirectional half-bridge DC/DC converter can be realized.
The various illustrative logical modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. It is to be understood that the scope of the invention is to be defined by the appended claims and not by the specific constructions and components of the embodiments illustrated above. Those skilled in the art can make various changes and modifications to the embodiments within the spirit and scope of the present invention, and these changes and modifications also fall within the scope of the present invention.

Claims (12)

1. The energy system of the hydrogen fuel vehicle is characterized by comprising a hydrogen fuel cell, a lithium battery, an air compressor and a staggered parallel bidirectional half-bridge DC/DC converter; wherein
The air compressor provides pressure required by reaction to the hydrogen fuel cell;
the staggered parallel bidirectional half-bridge DC/DC converter is a stabilized voltage power supply of the air compressor;
the hydrogen fuel cell is a main input power supply of the interleaved parallel bidirectional half-bridge DC/DC converter;
the lithium battery is an auxiliary input power supply of the staggered parallel bidirectional half-bridge DC/DC converter, and when the hydrogen fuel cell does not work, the lithium battery provides energy for the staggered parallel bidirectional half-bridge DC/DC converter, so that the air compressor works and drives the hydrogen fuel cell to work.
2. The energy system of claim 1 wherein the output current ripple of the interleaved bi-directional half bridge DC/DC converters is less than 1.5% of rated current.
3. The energy system of claim 1, wherein the overshoot of the output bus voltage of said interleaved bi-directional half-bridge DC/DC converter is no more than 5%.
4. The energy system of claim 1, wherein a dynamic response time of said interleaved bi-directional half-bridge DC/DC converter is less than 15 ms.
5. The energy system of claim 1, wherein two legs of said interleaved bi-directional half-bridge DC/DC converter each employ integrated silicon carbide MOS modules.
6. A control method of an energy system of a hydrogen-fueled vehicle, characterized in that the power system is the power system according to any one of claims 1 to 5, the control method comprising:
collecting input voltage, output voltage and output current of a staggered parallel bidirectional half-bridge DC/DC converter of the power system;
determining a current target value according to the deviation of the output voltage and a voltage stabilization target value;
determining a switching function of a power tube in the interleaved bidirectional half-bridge DC/DC converter according to the deviation between the current target value and the output current;
determining a feed-forward quantity according to the input voltage and the output voltage;
correcting the switching function according to the feedforward quantity; and
and controlling the on-off of the power tube based on the corrected switching function so as to control the output voltage of the interleaved parallel bidirectional half-bridge DC/DC converter to be stabilized at the stabilized target value.
7. The control method of claim 6, wherein the output current comprises a first inductor current and a second inductor current; wherein
Determining the switching function of the power tube further comprises:
determining a first inductive current target value and a second inductive current target value according to the current target value;
determining a first switching function of a power tube of a first bridge arm according to the first inductive current target value and the deviation of the first inductive current; and
and determining a second switching function of the power tube of the second bridge arm according to the second inductive current target value and the deviation of the second inductive current.
8. The control method of claim 7, wherein modifying the switching function based on the feed forward amount further comprises:
correcting the first switching function according to the feed-forward quantity; and
and correcting the second switching function according to the feedforward quantity.
9. The control method of claim 8, wherein the first leg and the second leg each employ integrated silicon carbide MOS modules; wherein
Controlling the power transistor to be on or off based on the modified switching function further comprises:
controlling the silicon carbide MOS module based on the corrected duty ratio parameter of the first switching function; and
and controlling the silicon carbide MOS module based on the corrected duty ratio parameter of the second switching function.
10. The control method of claim 7, wherein the first inductor current target value and the second inductor current target value are each half of the current target value.
11. The control method of claim 6, wherein the feed forward quantity is a ratio of the input voltage to the output voltage.
12. The control method of claim 6, wherein modifying the switching function further comprises:
and superposing the feed-forward quantity and the switching function into a modified switching function.
CN202011378304.3A 2020-11-30 2020-11-30 Energy system of hydrogen fuel vehicle and control method thereof Pending CN114583948A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116683773A (en) * 2023-06-01 2023-09-01 同济大学 Isolated DCDC converter topology structure for fuel cell system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116683773A (en) * 2023-06-01 2023-09-01 同济大学 Isolated DCDC converter topology structure for fuel cell system
CN116683773B (en) * 2023-06-01 2024-02-20 同济大学 Isolated DCDC converter topology structure for fuel cell system

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