CN111654197A - Bidirectional isolation type energy conversion system and control method thereof - Google Patents

Bidirectional isolation type energy conversion system and control method thereof Download PDF

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Publication number
CN111654197A
CN111654197A CN202010499972.5A CN202010499972A CN111654197A CN 111654197 A CN111654197 A CN 111654197A CN 202010499972 A CN202010499972 A CN 202010499972A CN 111654197 A CN111654197 A CN 111654197A
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voltage
bridge
low
pwm
voltage side
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韩冰
杨东军
赵许强
甄远伟
张家明
沈壮壮
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CRRC Qingdao Sifang Rolling Stock Research Institute Co Ltd
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CRRC Qingdao Sifang Rolling Stock Research Institute 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
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal 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
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal 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 in a bridge configuration
    • 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
    • B60L1/00—Supplying electric power to auxiliary equipment of vehicles
    • 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
    • B60L50/00—Electric propulsion with power supplied within the vehicle
    • B60L50/50—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells
    • B60L50/60—Electric propulsion with power supplied within the vehicle using propulsion power supplied by batteries or fuel cells using power supplied by batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J9/00—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting
    • H02J9/04—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source
    • H02J9/06—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems
    • H02J9/061—Circuit arrangements for emergency or stand-by power supply, e.g. for emergency lighting in which the distribution system is disconnected from the normal source and connected to a standby source with automatic change-over, e.g. UPS systems for DC powered loads
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • 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
    • 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
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Business, Economics & Management (AREA)
  • Emergency Management (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to a bidirectional isolation type energy conversion system, which comprises a three-phase PWM (pulse-width modulation) rectification circuit and a cascaded bidirectional active bridge DC/DC conversion circuit; the bidirectional active bridge DC/DC conversion circuit comprises a high-voltage side H bridge, an HSLP high-frequency transformer circuit and a low-voltage side H bridge; one side of the high-voltage side H bridge is connected with the three-phase PWM rectifying circuit, and the other side of the high-voltage side H bridge is connected with the high-voltage side of the HSLP high-frequency transformer circuit; and the low-voltage side of the HSLP high-frequency transformer circuit is connected with the low-voltage side H bridge. The system can realize alternating current-direct current bidirectional conversion, is simple in design and realizes lightweight design of equipment; meanwhile, the invention also provides a corresponding control method, a mixed control mode of SVPWM and PWM is adopted, the three-phase PWM rectification circuit adopts SVPWM control, the bidirectional active bridge DC/DC conversion circuit adopts PWM control, the control stability of the system is improved, and the conversion and the control reliability of the system in the full voltage range can be ensured in the mixed control mode.

Description

Bidirectional isolation type energy conversion system and control method thereof
Technical Field
The invention belongs to the technical field of power supply system design, and particularly relates to a bidirectional isolation type energy conversion system and a control method thereof.
Background
Fig. 1 is a conventional power supply topology for a motor train unit, wherein the motor train unit obtains electric energy from 25kV high-voltage power of a power grid through a pantograph on a roof of the motor train unit to perform energy conversion so as to supply power to a traction power supply system and an auxiliary power supply system of the motor train unit. However, when a pantograph fault or a power grid power supply fault of the motor train unit occurs, the motor train unit cannot obtain electric energy, cannot walk, can only stop on a rail temporarily and wait for rescue of other motor train units, and time delay risk is brought to operation of the motor train unit.
Therefore, for the power supply topology of the motor train unit vehicle in an emergency, the charger in the power supply system is replaced by a bidirectional energy conversion system, so that the mutual conversion of AC380V and DC110V is realized, when the motor train unit normally operates, the bidirectional energy conversion system realizes the conversion from AC380V to DC110V, and the battery is positively charged; the motor train unit realizes the conversion from DC110V to AC380V through a bidirectional energy conversion system under the emergency condition, reversely releases the reserved electric energy, provides emergency power supply, and meanwhile increases the electric energy reserve of the motor train unit. Based on the energy conversion system, the invention considers and designs the bidirectional isolation type energy conversion system which is used for replacing a charger in a power supply system of a motor train unit vehicle.
Disclosure of Invention
The invention provides a bidirectional isolation type energy conversion system and a control method thereof.
In order to achieve the above object, the present invention provides a bidirectional isolation type energy conversion system, including: the three-phase PWM rectifying circuit and the cascaded bidirectional active bridge DC/DC conversion circuit;
the bidirectional active bridge DC/DC conversion circuit comprises a high-voltage side H bridge, an HSLP high-frequency transformer circuit and a low-voltage side H bridge; one side of the high-voltage side H bridge is connected with the three-phase PWM rectifying circuit, and the other side of the high-voltage side H bridge is connected with the high-voltage side of the HSLP high-frequency transformer circuit; the low-voltage side of the HSLP high-frequency transformer circuit is connected with the low-voltage side H bridge;
when energy is converted in the forward direction, three-phase alternating current is rectified into high-voltage direct current through the three-phase PWM rectifying circuit, the high-voltage side H bridge inverts the high-voltage direct current into high-frequency alternating current and transmits the high-frequency alternating current to the low-voltage side H bridge through the HSLP high-frequency transformer circuit, and the low-voltage side H bridge rectifies the high-frequency alternating current into low-voltage direct current;
when energy is reversely converted, low-voltage direct current is inverted into high-frequency alternating current through a low-voltage side H bridge and is transmitted to a high-voltage side H bridge through an HSLP high-frequency transformer circuit, and the high-voltage side H bridge rectifies the high-frequency alternating current into high-voltage direct current and then inverts the high-voltage direct current into high-voltage alternating current through a three-phase PWM rectifying circuit.
Preferably, the HSLP high frequency transformer circuit includes two high frequency transformers, high voltage sides of the two high frequency transformers are connected in series to the high voltage side H-bridge, and low voltage sides realize parallel output through the low voltage side H-bridge.
Preferably, the low-voltage side H-bridge comprises two H-bridges connected in parallel, two high-frequency transformers are respectively connected to one H-bridge, and the low-voltage side of each high-frequency transformer is connected to a neutral point of the H-bridge.
Preferably, the high-voltage side H bridge series inductor LsAnd then connected to the HSLP high frequency transformer circuit.
Preferably, the low-voltage side H bridge DC side is connected with a filter capacitor C in parallelo。
Preferably, the three-phase PWM rectification circuit comprises a three-phase rectifier bridge, a three-phase rectifier bridge AC side series reactor L and a DC side parallel filter capacitor Cdc。
The invention also provides a control method of the bidirectional isolation type energy conversion system, the three-phase PWM rectification circuit is controlled by SVPWM, and the bidirectional active bridge DC/DC conversion circuit is controlled by PWM;
after the system is powered on, the energy conversion mode of the system is judged, and the high-voltage direct current voltage U is initializeddcReference value U ofdc_ref；
If the forward energy conversion mode is judged, the SVPWM controls the three-phase PWM rectifying circuit to work in a rectifying mode, and U is useddc_refFor reference voltage, three-phase AC voltage UinRectified to a stable high voltage DC voltage Udc(ii) a PWM adjusts the phase shift angle D of the high-voltage side H bridge and the low-voltage side H bridge to convert UdcConversion to a stable low-voltage DC voltage Uo；
If the reverse energy conversion mode is judged, PWM adjusts the phase shift angle D of the low-voltage side H bridge and the high-voltage side H bridge to Udc_refUsing the low-voltage DC voltage U as a reference voltageoConverted into stable high-voltage direct current voltage Udc(ii) a SVPWM controls a three-phase PWM rectifying circuit to work in an inversion mode to convert high-voltage DC voltage UdcConverted to ac voltage Uin。
Preferably, when the energy is converted in the forward direction, the voltage is lower than the DC voltage UoThe low-voltage load of the power supply is changed, and the SVPWM is regulated to control the direct-current voltage UdcThe change is not changed; PWM adjusts phase shift angle D to stabilize low voltage DC voltage Uo(ii) a When the phase shift angle D reaches a given reference value D_ref1I.e. D.gtoreq.D_ref1When D is set to D ═ D_ref1While increasing Udc_refThe SVPWM and PWM regulation process is repeated to output stable low-voltage direct-current voltage Uo。
Preferably, when the energy is converted reversely, if the alternating voltage U isinThe AC load of the power supply changes, PWM adjusts the phase shift angle D, stabilizes the DC voltage Udc(ii) a SVPWM adjusts high-voltage direct current voltage UdcConverted to a stable alternating voltage Uin(ii) a When the phase shift angle D is lower than a given reference value D_ref2I.e. D.ltoreq.D_ref2When D is set to D ═ D_ref2Repeating the PWM and SVPWM regulation processes to output stable AC voltage Uin。
Preferably, the high pressure side H bridge and the low pressure side H bridgeHas a PWM phase shift angle of D, D_ref1＞0，D_ref2< 0, and D_ref1＝-D_ref2。
Preferably, the PWM duty ratio of the high-voltage side H bridge is set to be 50%, PWM pulse waveforms are complementary on an upper bridge arm and a lower bridge arm of the H bridge, and diagonal bridge arms are synchronous; the two H bridges in the low-voltage side H bridge correspond to switching tubes in PWM synchronization, the PWM duty ratio in each H bridge is 50%, PWM pulse waveforms are complementary on the upper bridge arm and the lower bridge arm of the H bridge, and diagonal bridge arms are synchronous.
Compared with the prior art, the invention has the advantages and positive effects that:
the invention provides a bidirectional isolation type energy conversion system and a control method thereof, which can be used for a power supply system of a motor train unit. According to the bidirectional isolation type energy conversion system, a three-phase PWM (pulse width modulation) rectifying circuit is arranged to be cascaded with a bidirectional active bridge DC/DC converting circuit, so that when a train normally runs, energy is converted in a forward direction, three-phase alternating current is rectified into high-voltage direct current through the three-phase PWM rectifying circuit, the high-voltage direct current is inverted into high-frequency alternating current by a high-voltage side H bridge and is transmitted to a low-voltage side H bridge through an HSLP (high speed Linear Power) high-frequency transformer circuit, the high-frequency alternating current is rectified into low-voltage direct current by the; under the emergency condition of the train, the energy is reversely converted, low-voltage direct current is inverted into high-frequency alternating current through a low-voltage side H bridge and is transmitted to a high-voltage side H bridge through an HSLP high-frequency transformer circuit, the high-voltage side H bridge rectifies the high-frequency alternating current into high-voltage direct current and then is inverted into high-voltage alternating current through a three-phase PWM (pulse width modulation) rectification circuit, and the stored electric energy is reversely released to provide emergency power supply. Meanwhile, the system adopts a high-frequency transformer to realize electrical isolation, so that the weight and the volume of the product are greatly reduced, and the lightweight design is realized.
Meanwhile, the system adopts a mixed control mode combining SVPWM and PWM, and controls a phase shift angle D within a certain range D according to the change of a direct current load during forward energy conversion_ref1D is more than or equal to 0, and the high-voltage direct current voltage U rectified by the three-phase rectification circuit is keptdcAnd is not changed. When the reverse energy is changed, according to the change of the AC load, the phase shift angle D is controlled to be more than or equal to D and more than or equal to D within a certain range from 0_ref2Maintaining the high voltage DC voltage U after DC/DC conversiondcConstant, PWM regulationThe flow works in a reverse inversion mode to realize the stability of reverse conversion. The control method has very high control stability for the two-way isolation type HSLP energy conversion system of the motor train unit, and can ensure that the conversion of the system in the voltage full range keeps the control reliability.
Drawings
FIG. 1 is a prior art power supply topology for a multiple unit vehicle;
FIG. 2 is a topology of a bi-directional isolated energy conversion system of the present invention;
FIG. 3 is a flow chart of a control method of the bidirectional isolated energy conversion system of the present invention.
Detailed Description
The following further describes embodiments of the present invention with reference to the accompanying drawings.
The invention considers that a charger in the existing vehicle power supply system is replaced by a bidirectional energy conversion system to realize the mutual conversion of alternating current and direct current, so that the bidirectional energy conversion system realizes AC/DC conversion when a train normally runs and charges a battery in the forward direction; under emergency, DC/AC conversion is realized through a bidirectional energy conversion system, and the stored electric energy is released in the reverse direction to provide emergency power supply. Based on this, the embodiment of the invention designs a bidirectional isolation type energy conversion system which is used for replacing a charger in a power supply system of a motor train unit vehicle, and as shown in fig. 2, the bidirectional isolation type energy conversion system comprises a three-phase PWM (pulse width modulation) rectification circuit and a cascaded bidirectional active bridge DC/DC conversion circuit. The method specifically comprises the following steps:
the three-phase PWM rectifying circuit comprises a three-phase rectifying bridge, switching tubes s1, s2, s3, s4, s5 and s6 form the three-phase rectifying bridge, a reactor L is connected in series at the alternating current side of the rectifying bridge, and a filter capacitor C is connected in parallel at the direct current side of the rectifying bridgedc. When the energy is converted in the forward direction, the three-phase alternating current passes through a three-phase reactor L to balance the voltage, a three-phase rectifier bridge to rectify the alternating current and a filter capacitor CdcAfter filtering, rectifying the three-phase alternating current into high-voltage direct current; when the energy is reversely converted, the high-voltage direct current is reversely converted into three-phase alternating current.
The bidirectional active bridge DC/DC conversion circuit comprises a high-voltage side H bridge, an HSLP high-frequency transformer circuit and a low-voltage side H bridge. Wherein the switching tubes s7, s8, s9 and s10 form a high-voltage side H bridgeOne side of the H bridge is connected with a three-phase PWM rectification circuit, and the other side of the H bridge is connected with the high-voltage side of an HSLP high-frequency transformer circuit; during energy forward conversion, the high-voltage side H bridge inverts the high-voltage side direct-current voltage into high-frequency alternating-current voltage; the high-voltage side H bridge rectifies high-frequency alternating-current voltage into direct-current voltage during energy reverse conversion. The HSLP high-frequency transformer circuit comprises two high-frequency transformers T1 and T2, wherein the high-voltage sides of the high-frequency transformers T1 and T2 are connected to a high-voltage side H bridge in series, the low-voltage sides of the high-frequency transformers T1 and T2 are connected with a low-voltage side H bridge in parallel, and parallel output is achieved through the low-voltage side H bridge. The HSLP high-frequency transformer circuit realizes the functions of electrical isolation and high-frequency power conversion, and transmits energy from the high-voltage side H bridge to the low-voltage side H bridge during forward conversion of the energy; when the energy is reversely converted, the energy is transferred from the low-pressure side H bridge to the high-pressure side H bridge. The low-voltage side H bridge comprises two H bridges connected in parallel, wherein: s11, s12, s13 and s14 form an H bridge of an upper bridge arm, and the neutral point of the H bridge is connected to the low-voltage side of the high-frequency transformer T1; s15, s16, s17 and s18 form an H bridge of a lower bridge arm, the neutral point of the H bridge is connected to the low-voltage side of a high-frequency transformer T2, and the direct-current side of the H bridge at the low-voltage side is also connected with an independent filter capacitor C in parallelo. When the energy is converted in the forward direction, the low-voltage side H bridge rectifies the high-frequency alternating voltage into direct-current voltage; when the energy is reversely converted, the low-voltage side H bridge inverts the low-voltage side direct-current voltage into high-frequency alternating-current voltage.
Therefore, in the embodiment, a three-phase PWM rectification circuit is arranged to cascade a bidirectional active bridge DC/DC conversion circuit, so that when the train normally operates, energy is converted in the forward direction, three-phase alternating current is rectified into high-voltage direct current through the three-phase PWM rectification circuit, the high-voltage side H bridge inverts the high-voltage direct current into high-frequency alternating current and transmits the high-frequency alternating current to the low-voltage side H bridge through the HSLP high-frequency transformer circuit, and the low-voltage side H bridge rectifies the high-frequency alternating current into low-voltage direct current, which supplies power to; under the emergency condition of the train, the energy is reversely converted, low-voltage direct current is inverted into high-frequency alternating current through a low-voltage side H bridge and is transmitted to a high-voltage side H bridge through an HSLP high-frequency transformer circuit, the high-voltage side H bridge rectifies the high-frequency alternating current into high-voltage direct current and then is inverted into high-voltage alternating current through a three-phase PWM (pulse width modulation) rectification circuit, and the stored electric energy is reversely released to provide emergency power supply.
Referring further to fig. 2, in this embodiment, the H-bridge on the high voltage side is also connected in series with a single bridgeVertical inductance LsThen connected to HSLP high frequency transformer circuit to connect the series inductor LsThe energy storage element is placed on the high-voltage side and is connected with the HSLP high-frequency transformer circuit in series on the high-voltage side to realize energy transmission, so that the problem of uneven power distribution on the low-voltage side due to inconsistent inductance parameters when a plurality of inductors are connected in series on the low-voltage side can be solved; meanwhile, the current at the high-voltage side is small, and the design realization difficulty of the inductor can be reduced.
Meanwhile, the bidirectional energy converter system in the embodiment realizes electrical isolation through the internal high-frequency transformer, has the switching frequency of 15kHz, and greatly reduces the weight and the volume of a product compared with the electrical isolation of a traditional 50Hz power frequency transformer, and realizes lightweight design. Meanwhile, the two High-frequency transformers adopt a mode that High-voltage sides are connected in series and low-voltage sides are connected in Parallel (HSLP), and compared with a mode that a single High-frequency transformer is combined with a low-voltage side H bridge, the mode selection of a low-voltage side H bridge switching tube is facilitated on a High-power occasion, so that power can be shared by a plurality of H bridges under the same power, the power of a single H bridge is small, the switching tube with small current capacity can be selected, and the research and development cost is effectively reduced.
Aiming at the designed bidirectional isolation type energy conversion system, the invention further provides a control mode of the system, and provides a hybrid control method based on the control of the PWM rectification circuit and the double-active DC/DC circuit, wherein the three-phase PWM rectification circuit adopts SVPWM control, and three-phase voltage, three-phase current and C are acquireddcHigh voltage U on capacitordcSVPWM decoupling control is adopted under a d-q rotating coordinate system, and three-phase alternating current is converted into stable high-voltage direct current U during energy forward conversiondc(ii) a High-voltage direct current U during energy reverse conversiondcConverted into stable three-phase alternating current. The bidirectional active bridge DC/DC conversion circuit adopts PWM control, the PWM duty ratio of a high-voltage side H bridge is defined to be 50%, PWM pulse waveforms are complementary on an upper bridge arm and a lower bridge arm of the H bridge, and diagonal bridge arms are synchronous; PWM synchronization is carried out on corresponding switching tubes of two H bridges in the low-voltage side H bridge, the PWM duty ratio in each H bridge is 50%, PWM pulse waveforms are complementary on upper and lower bridge arms of the H bridges, and diagonal bridge arms are synchronous; high side H bridge and lowThe PWM phase shift angle of the voltage side H bridge is D, and the phase shift angle range is as follows: d is more than or equal to-0.5 and less than or equal to 0.5. By collecting CdcHigh voltage U on capacitordcAnd a low-side capacitor CoUpper low voltage UoControlling the magnitude of the phase shift angle D to perform bidirectional energy conversion; when the forward energy is converted, the high-voltage side H bridge PWM waveform leads the low-voltage side H bridge PWM waveform, and the phase shift angle D is positive; when the energy is reversely converted, the low-voltage side H bridge PWM waveform leads the high-voltage side H bridge PWM waveform, and the phase shift angle D is negative. The specific flow of the control method is shown in fig. 3:
after the system is powered on, the energy conversion mode of the system is judged, and the high-voltage direct current voltage U is initializeddcReference value U ofdc_ref；
If the forward energy conversion mode is judged, the SVPWM controls the three-phase PWM rectifying circuit to work in a rectifying mode, and U is useddc_refFor reference voltage, three-phase AC voltage UinRectified to a stable high voltage DC voltage Udc(ii) a PWM adjusts the phase shift angle D of the high-voltage side H bridge and the low-voltage side H bridge to convert UdcConversion to a stable low-voltage DC voltage Uo(ii) a If low voltage DC voltage UoThe low-voltage load of the power supply is changed, and the SVPWM is regulated to control the direct-current voltage UdcThe change is not changed; PWM adjusts phase shift angle D to stabilize low voltage DC voltage Uo(ii) a When the phase shift angle D reaches a given reference value D_ref1I.e. D.gtoreq.D_ref1When D is set to D ═ D_ref1And D is_ref1∈ (0, 0.5), while increasing Udc_refThe SVPWM and PWM regulation process is repeated to output stable low-voltage direct current voltage Uo。
If the reverse energy conversion mode is judged, PWM adjusts the phase shift angle D of the low-voltage side H bridge and the high-voltage side H bridge to Udc_refUsing the low-voltage DC voltage U as a reference voltageoConverted into stable high-voltage direct current voltage Udc(ii) a SVPWM controls a three-phase PWM rectifying circuit to work in an inversion mode to convert high-voltage DC voltage UdcConverted to ac voltage Uin. If the alternating voltage UinThe AC load of the power supply changes, PWM adjusts the phase shift angle D, stabilizes the DC voltage Udc(ii) a SVPWM adjusts high-voltage direct current voltage UdcConverted to a stable alternating voltage Uin(ii) a When the phase shift angle D is lower than a given reference value D_ref2I.e. D.ltoreq.D_ref2When D is set to D ═ D_ref2，D_ref2∈ (-0.5, 0) and D_ref2＝-D_ref1Repeating the PWM and SVPWM regulation processes to output stable AC voltage Uin。
Therefore, the control method controls the phase shift angle D of the double-active DC/DC circuit within a certain range D according to the change of the DC load during the forward energy conversion by a mixed control mode combining SVPWM and PWM_ref1D is more than or equal to 0, and the high-voltage direct current voltage U after PWM rectification is maintaineddcConstant and out of range, using constant phase shift angle D ═ D_ref1And then the high-voltage direct current voltage U after PWM rectification is adjusteddcThe stabilization of the forward transform is achieved. When the reverse energy is converted, according to the change of the alternating current load, the phase shift angle D of the double-active DC/DC circuit is controlled to be more than or equal to D and more than or equal to D within a certain range_ref2Maintaining high voltage DC voltage UdcAnd the stability of reverse conversion is realized only by regulating the PWM rectification to work in a reverse inversion mode. The control method has very high control stability for the two-way isolation type HSLP energy conversion system of the motor train unit, and can ensure that the conversion of the system in the voltage full range keeps the control reliability.
In summary, the invention provides a bidirectional isolation type energy conversion system and a control method thereof, which can be used for a power supply system of a motor train unit. According to the bidirectional isolation type energy conversion system, a three-phase PWM (pulse width modulation) rectifying circuit is arranged to be cascaded with a bidirectional active bridge DC/DC converting circuit, so that when a train normally runs, energy is converted in a forward direction, three-phase alternating current is rectified into high-voltage direct current through the three-phase PWM rectifying circuit, the high-voltage direct current is inverted into high-frequency alternating current by a high-voltage side H bridge and is transmitted to a low-voltage side H bridge through an HSLP (high speed Linear Power) high-frequency transformer circuit, the high-frequency alternating current is rectified into low-voltage direct current by the; under the emergency condition of the train, energy is reversely converted, low-voltage direct current is inverted into high-frequency alternating current through a low-voltage side H bridge and is transmitted to a high-voltage side H bridge through an HSLP high-frequency transformer circuit, the high-voltage side H bridge rectifies the high-frequency alternating current into high-voltage direct current and then the high-voltage direct current passes through a transformerThe phase PWM rectifying circuit is inverted into high-voltage alternating current, stored electric energy is reversely released, emergency power supply is provided, system design is simple, and light-weight design can be achieved. Meanwhile, the system adopts a mixed control mode combining SVPWM and PWM, and controls a phase shift angle D within a certain range D according to the change of a direct current load during forward energy conversion_ref1D is more than or equal to 0, and the high-voltage direct current voltage U rectified by the three-phase rectification circuit is keptdcAnd is not changed. When the reverse energy is changed, according to the change of the AC load, the phase shift angle D is controlled to be more than or equal to D and more than or equal to D within a certain range from 0_ref2Maintaining the high voltage DC voltage U after DC/DC conversiondcAnd the PWM rectification is regulated to work in a reverse inversion mode to realize the stability of reverse conversion without change. The control method has very high control stability for the two-way isolation type HSLP energy conversion system of the motor train unit, and can ensure that the conversion of the system in the voltage full range keeps the control reliability.
The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.

Claims (11)

1. A bi-directional isolated energy conversion system, comprising: the three-phase PWM rectifying circuit and the cascaded bidirectional active bridge DC/DC conversion circuit;
the bidirectional active bridge DC/DC conversion circuit comprises a high-voltage side H bridge, an HSLP high-frequency transformer circuit and a low-voltage side H bridge; one side of the high-voltage side H bridge is connected with the three-phase PWM rectifying circuit, and the other side of the high-voltage side H bridge is connected with the high-voltage side of the HSLP high-frequency transformer circuit; the low-voltage side of the HSLP high-frequency transformer circuit is connected with the low-voltage side H bridge;
when energy is converted in the forward direction, three-phase alternating current is rectified into high-voltage direct current through the three-phase PWM rectifying circuit, the high-voltage side H bridge inverts the high-voltage direct current into high-frequency alternating current and transmits the high-frequency alternating current to the low-voltage side H bridge through the HSLP high-frequency transformer circuit, and the low-voltage side H bridge rectifies the high-frequency alternating current into low-voltage direct current;
when energy is reversely converted, low-voltage direct current is inverted into high-frequency alternating current through a low-voltage side H bridge and is transmitted to a high-voltage side H bridge through an HSLP high-frequency transformer circuit, and the high-voltage side H bridge rectifies the high-frequency alternating current into high-voltage direct current and then inverts the high-voltage direct current into high-voltage alternating current through a three-phase PWM rectifying circuit.
2. The bi-directional isolated energy conversion system of claim 1, wherein the HSLP high frequency transformer circuit comprises two high frequency transformers, the high voltage sides of the two high frequency transformers are connected in series to the high voltage side H-bridge, and the low voltage sides are connected in parallel for output through the low voltage side H-bridge.
3. The bi-directional isolated energy conversion system of claim 2, wherein the low-side H-bridge comprises two parallel H-bridges, two high-frequency transformers are connected to one H-bridge each, and the low-side of the high-frequency transformers are connected to the H-bridge neutral point.
4. The bi-directional isolated energy conversion system of any of claims 1-3, wherein the high side H-bridge series inductance LsAnd then connected to the HSLP high frequency transformer circuit.
5. The bi-directional isolated energy conversion system of any of claims 1-3, wherein the low side H bridge DC side is connected in parallel with a filter capacitor Co。
6. The bidirectional isolated energy conversion system according to any one of claims 1 to 3, wherein the three-phase PWM rectification circuit comprises a three-phase rectifier bridge, a series reactor L on an AC side of the three-phase rectifier bridge, and a filter capacitor C on a DC side of the three-phase rectifier bridgedc。
7. A control method of a bidirectional isolation type energy conversion system adopts the bidirectional isolation type energy conversion system of any one of claims 1 to 6, the three-phase PWM rectification circuit adopts SVPWM control, and the bidirectional active bridge DC/DC conversion circuit adopts PWM control; the method is characterized in that:
after the system is powered on, the energy conversion mode of the system is judged, and the high-voltage direct current voltage U is initializeddcReference value U ofdc_ref；
If the forward energy conversion mode is judged, the SVPWM controls the three-phase PWM rectifying circuit to work in a rectifying mode, and U is useddc_refFor reference voltage, three-phase AC voltage UinRectified to a stable high voltage DC voltage Udc(ii) a PWM adjusts the phase shift angle D of the high-voltage side H bridge and the low-voltage side H bridge to convert UdcConversion to a stable low-voltage DC voltage Uo；
If the reverse energy conversion mode is judged, PWM adjusts the phase shift angle D of the low-voltage side H bridge and the high-voltage side H bridge to Udc_refUsing the low-voltage DC voltage U as a reference voltageoConverted into stable high-voltage direct current voltage Udc(ii) a SVPWM controls a three-phase PWM rectifying circuit to work in an inversion mode to convert high-voltage DC voltage UdcConverted to ac voltage Uin。
8. The control method of the bidirectional isolated energy conversion system according to claim 7, wherein the low voltage DC voltage is U if the energy conversion is performed in the forward directionoThe low-voltage load of the power supply is changed, and the SVPWM is regulated to control the direct-current voltage UdcThe change is not changed; PWM adjusts phase shift angle D to stabilize low voltage DC voltage Uo(ii) a When the phase shift angle D reaches a given reference value D_ref1I.e. D.gtoreq.D_ref1When D is set to D ═ D_ref1While increasing Udc_refThe SVPWM and PWM regulation process is repeated to output stable low-voltage direct-current voltage Uo。
9. The control method of the bidirectional isolated energy conversion system according to claim 7 or 8, wherein the alternating voltage U is provided when the energy is converted in the reverse directioninThe AC load of the power supply changes, PWM adjusts the phase shift angle D, stabilizes the DC voltage Udc(ii) a SVPWM adjusts high-voltage direct current voltage UdcConverted to a stable alternating voltage Uin(ii) a When the phase shift angle D is lower than a given reference value D_ref2I.e. D.ltoreq.D_ref2When D is set to D ═ D_ref2Repeating the PWM and SVPWM regulation processes to output stable AC voltage Uin。
10. The control method of a bi-directional isolated energy conversion system according to claim 9, wherein the PWM phase shift angles of the high-side H-bridge and the low-side H-bridge are D, D_ref1＞0，D_ref2< 0, and D_ref1＝-D_ref2。
11. The control method of the bidirectional isolated energy conversion system according to claim 7, wherein the PWM duty ratio of the high-voltage side H bridge is set to 50%, PWM pulse waveforms are complementary on the upper bridge arm and the lower bridge arm of the H bridge, and diagonal bridge arms are synchronous; the two H bridges in the low-voltage side H bridge correspond to switching tubes in PWM synchronization, the PWM duty ratio in each H bridge is 50%, PWM pulse waveforms are complementary on the upper bridge arm and the lower bridge arm of the H bridge, and diagonal bridge arms are synchronous.
CN202010499972.5A 2020-06-04 2020-06-04 Bidirectional isolation type energy conversion system and control method thereof Pending CN111654197A (en)

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Application publication date: 20200911