CN110971128A - Bidirectional DC/DC system and control method thereof - Google Patents
Bidirectional DC/DC system and control method thereof Download PDFInfo
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- CN110971128A CN110971128A CN201811160693.5A CN201811160693A CN110971128A CN 110971128 A CN110971128 A CN 110971128A CN 201811160693 A CN201811160693 A CN 201811160693A CN 110971128 A CN110971128 A CN 110971128A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Abstract
The invention discloses a bidirectional DC/DC system and a control method thereof, wherein the bidirectional DC/DC system comprises: a power supply module and a load module; the primary side of the bidirectional DC/DC module is connected with the power supply module, and the secondary side of the bidirectional DC/DC module is connected with the load module; the electrical signal acquisition module is used for acquiring electrical signals of the secondary side of the bidirectional DC/DC; and the control module is respectively connected with the control end of the bidirectional DC/DC module and the electric signal acquisition module, and is used for controlling the bidirectional DC/DC module to carry out voltage conversion according to the electric signal. The system can realize the bidirectional transmission of energy, and when the system transmits energy to the power supply module by the load module, the output power can change along with the change of the power of the load module, thereby ensuring that the voltage of the load module is more stable in the energy transmission process, accelerating the dynamic response of the system and improving the product performance.
Description
Technical Field
The present invention relates to the field of electronic technologies, and in particular, to a bidirectional DC/DC system and a method for controlling the bidirectional DC/DC system.
Background
For a bidirectional DC/DC system, in a traditional control mode, when the system works in the forward direction, the system reduces the voltage and takes a low-voltage side electric signal as feedback; when the system works in the reverse direction, the system boosts the voltage and takes the high-voltage side electric signal as feedback. Therefore, when the system works reversely, the state of the power of the load end is not clear, and only the constant power output of the high-voltage side can be controlled.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. Therefore, an object of the present invention is to provide a bidirectional DC/DC system, which can achieve bidirectional transmission of energy, and when the system transmits energy from a load module to a power supply module, output power can change along with the change of the power of the load module, and the voltage of the load module is more stable in the energy transmission process, thereby accelerating the dynamic response of the system and improving the product performance.
Another object of the present invention is to propose a control method of a bidirectional DC/DC system.
To achieve the above object, a first aspect of the present invention provides a bidirectional DC/DC system, comprising: a power supply module and a load module; a bidirectional DC/DC module, a primary side of the bidirectional DC/DC module being connected to the power supply module, a secondary side of the bidirectional DC/DC module being connected to the load module, wherein the bidirectional DC/DC module is configured to enable energy transfer between the power supply module and the load module; an electrical signal acquisition module for acquiring an electrical signal of a secondary side of the bi-directional DC/DC; the control module is respectively connected with the control end of the bidirectional DC/DC module and the electric signal acquisition module, and is used for controlling the bidirectional DC/DC module to carry out voltage conversion according to the electric signal so as to convert the voltage fixed direct current into voltage adjustable direct current when the power supply module supplies power to the load module, and to enable the power output by the primary side to change along with the change of the power input by the secondary side when the load module feeds power to the power supply module.
According to the bidirectional DC/DC system provided by the embodiment of the invention, bidirectional transmission of energy can be realized, and when the system transmits energy to the power supply module from the load module, the output power can change along with the change of the power of the load module, so that the voltage of the load module is more stable in the energy transmission process, the dynamic response of the system is accelerated, and the product performance is improved.
In addition, the bidirectional DC/DC system according to the above embodiment of the present invention may further have the following additional technical features:
according to one embodiment of the present invention, the electric signal acquisition module includes: the current acquisition unit is used for acquiring the current of a secondary side loop of the bidirectional DC/DC module; and/or
A voltage acquisition unit, the voltage acquisition module is used for acquiring the voltage of the secondary side of the bidirectional DC/DC module. Wherein the electrical signal comprises the current and/or the voltage.
According to one embodiment of the invention, the power supply module comprises: a utility grid connected to a supply bus through a first controllable switch to connect with a primary side of the bidirectional DC/DC module through the supply bus; the energy storage unit is connected to the power supply bus through a second controllable switch; the control module is further used for controlling the on-off of the first controllable switch and the second controllable switch.
According to an embodiment of the present invention, the bidirectional DC/DC system further includes: the power supply detection module is used for detecting whether faults exist in the commercial power grid and the energy storage unit; the control module is specifically configured to control the first controllable switch to be in an off state and the second controllable switch to be in an on state when the utility grid fails and the energy storage unit is normal, and control the second controllable switch to be in an off state and the first controllable switch to be in an on state when the energy storage unit fails and the utility grid is normal.
According to one embodiment of the invention, the load module comprises: a feed motor; one end of the rectifying circuit is connected with the feed motor, and the other end of the rectifying circuit is connected with the secondary side of the bidirectional DC/DC module; when the feed motor is in a power generation state, the feed motor feeds power to the bidirectional DC/DC module through the rectifying circuit.
According to one embodiment of the present invention, the primary side of the bidirectional DC/DC module includes a first arm and a first coil, and the secondary side of the bidirectional DC/DC module includes a second arm and a second coil, wherein an input end of the first arm is connected to the power supply bus, an output end of the first arm is connected to the first coil, an input end of the second arm is connected to the second coil, an output end of the second arm is connected to the load module, and the second coil and the first coil form a mutual inductor; the control module performs pulse width modulation, frequency modulation or mixed modulation on the first bridge arm and the second bridge arm according to the electric signals, wherein the mixed modulation comprises pulse width modulation and frequency modulation.
According to one embodiment of the invention, the primary side of the bidirectional DC/DC module further comprises a third leg and a third coil, and the secondary side of the bidirectional DC/DC module comprises a fourth leg and a fourth coil, wherein an input end of the third leg is connected to the power supply bus, an output end of the third leg is connected to the third coil, an input end of the fourth leg is connected to the fourth coil, an output end of the fourth leg is connected to the load module, and the fourth coil and the third coil form a mutual inductor; the control module selectively controls the first bridge arm and the second bridge arm and/or the third bridge arm and the fourth bridge arm according to the electric signal, and adopts pulse width modulation, frequency modulation or hybrid modulation technology when controlling the third bridge arm and the fourth bridge arm.
According to an embodiment of the present invention, when the control module selectively controls the first leg and the second leg, and/or the third leg and the fourth leg according to the electrical signal, the control module is specifically configured to: when the current is greater than a preset current threshold value and/or the voltage is greater than a preset voltage threshold value, controlling the first bridge arm and the second bridge arm, and controlling the third bridge arm and the fourth bridge arm simultaneously; and when the current is less than or equal to the preset current threshold and/or the voltage is less than or equal to the preset voltage threshold, controlling the first bridge arm and the second bridge arm, or controlling the third bridge arm and the fourth bridge arm.
In order to achieve the above object, a second aspect of the present invention provides a control method for a bidirectional DC/DC system, the bidirectional DC/DC system including a bidirectional DC/DC module, a power supply module, and a load module, a primary side of the bidirectional DC/DC module being connected to the power supply module, a secondary side of the bidirectional DC/DC module being connected to the load module, the control method including the steps of: collecting an electrical signal of a secondary side of the bidirectional DC/DC module; and controlling the bidirectional DC/DC module to perform voltage conversion according to the electric signal so as to convert the voltage fixed direct current into voltage adjustable direct current when the power supply module supplies power to the load module, and to enable the power output by the primary side to change along with the change of the power input by the secondary side when the load module feeds power to the power supply module.
According to the control method of the bidirectional DC/DC system, the bidirectional transmission of energy can be realized, and when the system transmits energy to the power supply module from the load module, the output power can change along with the change of the power of the load module, so that the voltage of the load module is more stable in the energy transmission process, the dynamic response of the system is accelerated, and the product performance is improved.
In addition, the control method of the bidirectional DC/DC system according to the above-described embodiment of the present invention may further have the following additional technical features:
according to an embodiment of the invention, the electrical signal comprises a current of a secondary side loop of the bidirectional DC/DC module, and/or a voltage of a secondary side of the bidirectional DC/DC module.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a block diagram of a bi-directional DC/DC system according to an embodiment of the present invention;
FIG. 2 is a block diagram of a bi-directional DC/DC system according to one embodiment of the present invention;
FIG. 3 is a block diagram of a bi-directional DC/DC system according to another embodiment of the present invention;
FIG. 4 is a topology diagram of a bi-directional DC/DC system according to one embodiment of the present invention;
FIG. 5 is a topology diagram of a bi-directional DC/DC system according to another embodiment of the present invention;
FIG. 6 is a schematic diagram of the operating principle of a bi-directional DC/DC system according to one embodiment of the present invention;
fig. 7 is a flowchart of a control method of a bidirectional DC/DC system according to an embodiment of the present invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
A bidirectional DC/DC system and a control method thereof of an embodiment of the present invention are described below with reference to the accompanying drawings.
Fig. 1 is a block diagram of a bi-directional DC/DC system according to an embodiment of the present invention.
As shown in fig. 1, the bi-directional DC/DC system 10 includes: the power supply system comprises a power supply module 1, a load module 2, a bidirectional DC/DC module 11, an electric signal acquisition module 12 and a control module 13.
The primary side of the bidirectional DC/DC module 11 is connected with the power supply module 1, the secondary side of the bidirectional DC/DC module 11 is connected with the load module 2, and the bidirectional DC/DC module 11 is used for realizing energy transmission between the power supply module and the load module; the electric signal acquisition module 12 is used for acquiring an electric signal of the secondary side of the bidirectional DC/DC module 11; the control module 13 is connected to the control end of the bidirectional DC/DC module 11 and the electrical signal acquisition module 12, respectively, and the control module 13 is configured to control the bidirectional DC/DC module 11 to perform voltage conversion according to the electrical signal, so as to convert the voltage-fixed direct current into a voltage-adjustable direct current when the power supply module 1 supplies power to the load module 2, and to change the power output from the primary side along with the change of the power input from the secondary side when the load module 2 feeds power to the power supply module 1. Therefore, the control precision is improved, the voltage stability of the load module is guaranteed, the dynamic response of the system is accelerated, and the product performance is improved.
In one embodiment of the present invention, as shown in fig. 2, the electrical signal acquisition module 12 includes: a current collection unit 121 and/or a voltage collection unit 122.
The current collecting unit 121 is configured to collect a current of a secondary side loop of the bidirectional DC/DC module 11; the voltage collecting unit 122 is used for collecting the voltage of the secondary side of the bidirectional DC/DC module 11.
Specifically, the electrical signal collection module 12 collects voltage and/or current, and then feeds the voltage and/or current back to the control module 13, and the control module 13 controls the bidirectional DC/DC module 11 to perform voltage conversion according to the voltage and/or current.
Therefore, the bidirectional DC/DC system can control the low-voltage side electric signal when the system is boosted and reduced, so that the stability of the voltage of the load end is ensured.
In one embodiment of the present invention, as shown in fig. 3, the power supply module 1 includes: a utility grid 1a and an energy storage unit 1b, wherein the utility grid 1a is connected to a supply bus L through a first controllable switch K1 to be connected to the primary side of the bidirectional DC/DC module 11 through the supply bus L, and the energy storage unit 1b is connected to the supply bus L through a second controllable switch K2.
Alternatively, the energy storage unit 1b may include a rechargeable battery, such as a lithium ion battery, a lead storage battery, or the like.
In this embodiment, the control module 13 is also used to control the on and off of the first controllable switch K1 and the second controllable switch K2.
Further, as shown in fig. 3, the bidirectional DC/DC system 10 further includes a power detection module 14, and the power detection module 14 is configured to detect whether a fault exists in the utility grid 1a and the energy storage unit 1 a.
In this embodiment, the control module 13 is further connected to the power detection module 14, and the control module 13 is specifically configured to control the first controllable switch K1 to be in an open state and the second controllable switch K2 to be in a closed state when the utility grid 1a fails and the energy storage unit 1b is normal, and control the second controllable switch K2 to be in an open state and the first controllable switch K1 to be in a closed state when the energy storage unit 1b fails and the utility grid 1a is normal.
The fault of the utility grid 1a may be a fault of a power supply line of the utility grid 1a, so that a voltage input to the power supply bus L is 0, and the fault may be obtained by detecting the voltage of the utility grid 1 a. The failure of the energy storage unit 1b may be an undervoltage or an overvoltage of the rechargeable battery in the energy storage unit 1b, and the failure may be obtained by detecting the voltage of the energy storage unit 1 b.
In some examples, the control module 13 may also disconnect the connection between the utility grid 1a and the power supply bus L and connect the energy storage unit 1b with the power supply bus L when the supply voltage of the utility grid 1a fluctuates greatly, for example, the fluctuation value is greater than a certain range.
Of course, if the utility grid 1a and the energy storage unit 1b have a fault at the same time, the control module 13 controls both the first controllable switch K1 and the second controllable switch K2 to be in the off state, and does not control the bidirectional DC/DC module 11, and at this time, the bidirectional DC/DC system 10 does not work.
In one embodiment of the present invention, as shown in fig. 3, the load module 2 includes a feed motor M and a rectifying circuit 2a, one end of the rectifying circuit 2a is connected to the feed motor M, and the other end of the rectifying circuit 2a is connected to the secondary side of the bidirectional DC/DC module 11. When the feeding motor M is in a power generation state, the feeding motor feeds power to the bidirectional DC/DC module 11 through the rectifying circuit 2 a.
Specifically, the feed motor M can work in an electric state and a power generation state, and when the feed motor M is in the electric state, traction force can be provided for the rail vehicle; when the feeding motor M is in a power generation state, power can be fed to the power supply module 1 through the rectifying line and the bidirectional DC/DC module 11. When the rail vehicle brakes or brakes, the feed motor M can work in a power generation state.
In one embodiment of the present invention, as shown in fig. 4 and 5, the primary side of the bidirectional DC/DC module 11 includes a first arm M1 and a first coil L1, and the secondary side of the bidirectional DC/DC module 11 includes a second arm M2 and a second coil L2, wherein the input end of the first arm M1 is connected to the power supply bus L, the output end of the first arm M1 is connected to the first coil L1, the input end of the second arm M2 is connected to the second coil L2, the output end of the second arm M2 is connected to the load module 2, and the second coil L2 and the first coil L1 form a mutual inductor. In this embodiment, control module 13 performs pulse width modulation, frequency modulation, or hybrid modulation on first leg M1 and second leg M2 according to the electrical signals, where the hybrid modulation includes pulse width modulation and frequency modulation.
The pulse width modulation means that the switching period T is kept unchanged, and the on-time ton of the switch is adjusted; the frequency modulation means that the on-time ton of the switch is kept unchanged, and the switching period T is changed; hybrid modulation means that both ton and T are adjustable, causing the duty cycle to change.
In this embodiment, as shown in fig. 4 and 5, the primary side of the bidirectional DC/DC module 11 further includes a first capacitor C1.
One end of the first capacitor C1 is connected to the first output end of the power supply module 1, and the other end of the first capacitor C1 is connected to the second output end of the power supply module 1; the first bridge arm M1 comprises first to fourth switching tubes Q1 to Q4, a first end of the first switching tube Q1 is connected with one end of a first capacitor C1, a second end of the first switching tube Q1 is connected with a first end of the second switching tube Q2 and forms a first node d1, a third end of the first switching tube Q1 is connected with the control module 13, a second end of the second switching tube Q2 is connected with the other end of the first capacitor C1, a third end of the second switching tube Q2 is connected with the control module 13, a first end of the third switching tube Q3 is connected with one end of the first capacitor C1, a second end of the third switching tube Q3 is connected with a first end of the fourth switching tube Q4 and forms a second node d2, a third end of the third switching tube Q3 is connected with the control module 13, a third end of the fourth switching tube 4 is connected with the other end of the first capacitor C24, a third end of the fourth switching tube Q4 is connected with the control module Q599, and a bidirectional control module Q5911/DC 5911 is connected with the fourth switching tube Q68611, a bidirectional control module (ii) a One end of the first coil L1 is connected to the first node d1, and the other end of the first coil L1 is connected to the second node d 2.
Referring to fig. 4 and 5, the secondary side of the bidirectional DC/DC module 11 further includes: a second capacitor C2.
One end of the second capacitor C2 is connected to the first power supply end of the load module 2, and the other end of the second capacitor C2 is connected to the second power supply end of the load module 2; the second bridge arm M2 includes fifth to sixth switching tubes Q5 to Q6, a first end of the fifth switching tube Q5 is connected to one end of a second capacitor C2, a second end of the fifth switching tube Q5 is connected to a first end of the sixth switching tube Q6 and forms a third node d3, a third end of the fifth switching tube Q5 is connected to the control module 13, a second end of the sixth switching tube Q6 is connected to the other end of the second capacitor C2, a third end of the sixth switching tube Q6 is connected to the control module 13, a first end of the seventh switching tube Q7 is connected to one end of the second capacitor C2, a second end of the seventh switching tube Q7 is connected to a first end of the eighth switching tube Q8 and forms a fourth node d 635, a third end of the seventh switching tube Q7 is connected to the control module 13, a second end of the eighth switching tube Q8 is connected to a second end of the eighth switching tube Q4624, a second end of the eighth switching tube Q599 is connected to the eighth switching tube Q599, and further includes bidirectional switching tubes DC 5911 and DC 5911/Q5911 and a bidirectional switching tube Q359 A terminal; one end of the second coil L2 is connected to the third node d3, and the other end of the second coil L2 is connected to the fourth node d4, wherein the second coil L2 and the first coil L1 form a mutual inductor.
Specifically, when the power supply module 1 starts to supply power to the load module 2, the control module 13 outputs a corresponding PWM control signal according to the electrical signal to control the switching frequency and/or the duty ratio of the first to eighth switching tubes Q1 to Q8. When the first switching tube Q1 and the fourth switching tube Q4 are turned on and the second switching tube Q2 and the third switching tube Q3 are turned off, the first end of the first capacitor C1 (i.e., one end of the power supply module 1) is connected to the second end of the first capacitor C1 through the first switching tube Q1 in the first bridge arm M1, the first coil L1 and the fourth switching tube Q4 in the first bridge arm M1; when the fifth switch tube Q5 and the eighth switch tube Q8 are turned on and the sixth switch tube Q6 and the seventh switch tube Q7 are turned off, the first end of the second capacitor C2 (i.e., the end of the load module 2) is connected to the second end of the second capacitor C2 through the fifth switch tube Q5, the second coil L2 and the eighth switch tube Q8, and at this time, the first capacitor C1 is discharged.
Further, as shown in fig. 4 and 5, the primary side of the bidirectional DC/DC module 11 further includes a third leg M3 and a third coil L3, and the secondary side of the bidirectional DC/DC module 11 includes a fourth leg M4 and a fourth coil L4, wherein an input end of the third leg M3 is connected to the power supply bus L, an output end of the third leg M3 is connected to the third coil L3, an input end of the fourth leg M4 is connected to the fourth coil L4, an output end of the fourth leg M4 is connected to the load module 2, and the fourth coil L4 and the third coil L3 form a mutual inductor. In this embodiment, control module 13 selectively controls first leg M1 and second leg M2, and/or third leg M3 and fourth leg M4 according to electrical signals, and employs pulse width modulation, frequency modulation, or a hybrid modulation technique when controlling third leg M3 and fourth leg M4.
Specifically, when selectively controlling first leg M1 and second leg M2, and/or third leg M3 and fourth leg M4 according to the electrical signals, control module 13 is specifically configured to: when the current is greater than a preset current threshold value and/or the voltage is greater than a preset voltage threshold value, controlling the first bridge arm M1 and the second bridge arm M2, and controlling the third bridge arm M3 and the fourth bridge arm M4; when the current is less than or equal to a preset current threshold value and/or the voltage is less than or equal to a preset voltage threshold value, the first bridge arm M1 and the second bridge arm M2, or the third bridge arm M3 and the fourth bridge arm M4 are controlled.
In this embodiment, as shown in fig. 4 and 5, the primary side of the bidirectional DC/DC module may further include: a third capacitor C3.
Wherein the third capacitor C3 is connected between the first capacitor C1 and the second output terminal of the power supply module 1; the third bridge arm comprises ninth switching tube Q9 to twelfth switching tube Q12, the first end of the ninth switching tube Q9 is connected with one end of the third capacitor C3, the second end of the ninth switching tube Q9 is connected with the first end of the tenth switching tube Q10 and forms a fifth node d5, the third end of the ninth switching tube Q9 is connected with the control module 13, the second end of the tenth switching tube Q10 is connected with the other end of the third capacitor C3, the third end of the tenth switching tube Q10 is connected with the control module 13, the first end of the eleventh switching tube Q11 is connected with one end of the third capacitor C3, the second end of the eleventh switching tube Q11 is connected with the first end of the twelfth switching tube Q12 and forms a sixth node d6, the third end of the eleventh switching tube Q11 is connected with the control module 13, the second end of the twelfth switching tube Q12 is connected with the other end of the third capacitor C6327, and the twelfth switching tube Q12 is connected with the control module 13, the control end of the bidirectional DC/DC module 11 further includes third ends of a ninth switching tube Q9-a twelfth switching tube Q12; one end of the third coil L3 is connected to the fifth node d5, and the other end of the third coil L3 is connected to the sixth node d 6.
As shown in fig. 4 and 5, the secondary side of the bidirectional DC/DC module 11 further includes: a fourth capacitor C4.
One end of the fourth capacitor C4 is connected to the first power supply end of the load module 2, and the other end of the fourth capacitor C4 is connected to the second power supply end of the load module 2; the fourth bridge arm M4 includes thirteenth to sixteenth switching tubes Q13 to Q16, a first end of the thirteenth switching tube Q13 is connected to one end of a fourth capacitor C4, a second end of the thirteenth switching tube Q13 is connected to a first end of a fourteenth switching tube Q13 and forms a seventh node d7, a third end of the thirteenth switching tube Q13 is connected to the control module 13, a second end of the fourteenth switching tube Q14 is connected to the other end of the fourth capacitor C4, a third end of the fourteenth switching tube Q14 is connected to the control module 13, a first end of the fifteenth switching tube Q15 is connected to one end of a fourth capacitor C4, a second end of the fifteenth switching tube Q15 is connected to a first end of the sixteenth switching tube Q16 and forms an eighth node d8, a third end of the fifteenth switching tube Q15 is connected to the control module 13, a second end of the sixteenth switching tube Q16 is connected to the other end of the sixteenth switching tube Q4, the control end of the bidirectional DC/DC module 11 further includes third ends of a thirteenth switching tube Q13-a sixteenth switching tube Q16; one end of the fourth coil L4 is connected to the seventh node d7, and the other end of the fourth coil L4 is connected to the eighth node d8, wherein the fourth coil L4 and the third coil L3 constitute a mutual coil.
Alternatively, the first to sixteenth switching tubes Q1 to Q16 may be MOS (Metal oxide semiconductor, MOS) tubes (in the figure, N-channel enhancement type MOS tubes), or IGBT (Insulated Gate Bipolar Transistor).
Alternatively, the first coil L1, the second coil L2, the third coil L3 and the fourth coil L4 may be inductive coils.
Therefore, the control module performs pulse width modulation, frequency modulation or mixed modulation on the switching tubes in the first bridge arm M1, the second bridge arm M2, the third bridge arm M3 and the fourth bridge arm M4 according to the electric signals, so that voltage rising and voltage falling are realized by controlling the states of the switching tubes in the first bridge arm M1, the second bridge arm M2, the third bridge arm M3 and the fourth bridge arm M4, the first capacitor C1-the fourth capacitor C4 can play a good role in filtering in the voltage rising and voltage falling process, and when the voltage changes, the voltages at two ends cannot change suddenly due to the charging effect of the capacitors, so that the voltage stability is ensured. In addition, the output power can be increased by connecting two bidirectional DC/DC in parallel, the upper and lower groups of bidirectional DC/DC can control the driving frequency of the PWM1-PWM16 through the electric signal of the secondary side so as to change the output power, and the upper and lower groups of bidirectional DC/DC can be independently controlled.
In one embodiment of the present invention, as shown in fig. 5, the primary side of the bidirectional DC/DC module 11 further comprises: a fifth capacitor C5 and a fifth coil L5 connected in series, a sixth capacitor C6 and a sixth coil L6 connected in series.
Wherein the series connection of the fifth capacitor C5 and the fifth coil L5 is connected in series between the first node d1 and one end of the first coil L1; a sixth capacitor C6 and a sixth coil L6 connected in series, and a sixth capacitor C6 and a sixth coil L6 connected in series are connected between a fifth node d5 and one end of the third coil L3.
Therefore, the fifth capacitor C5 and the fifth coil L5 connected in series, and the sixth capacitor C6 and the sixth coil L6 connected in series constitute a band-pass filter, which is connected in a circuit and has a frequency-selecting function of allowing only a part of frequencies to pass, thereby forming a stable frequency as required.
In one embodiment of the present invention, referring to fig. 5, the primary side of the bidirectional DC/DC module 11 further comprises: a seventh coil L7, an eighth coil L8.
Wherein the seventh coil L7 is connected in parallel with the first capacitor C1; the eighth coil L8 is connected in parallel with the third capacitor C3.
Therefore, the seventh coil L7 and the eighth coil L8 are connected in parallel to both ends of the first capacitor C1 and the third capacitor C3, respectively, and function as a protection circuit.
Referring to fig. 5, when the rail vehicle is braked or braked such that the feeding motor M is in a power generation state, the load module 2 feeds power to the power supply module 1. With the change of the braking power of the rail vehicle, the voltage input to the secondary side of the bidirectional DC/DC module 11 changes, at this time, an electrical signal (including a current signal and/or a voltage signal) at the secondary side of the bidirectional DC/DC module 11 may be acquired, and then the control module 13 may perform pulse width modulation, frequency modulation or hybrid modulation on the switching tubes in the first bridge arm M1, the second bridge arm M2, the third bridge arm M3 and the fourth bridge arm M4 according to the electrical signal, so that the boost power of the system 10 (i.e., the power output from the primary side of the bidirectional DC/DC module 11) changes along with the change of the braking power (i.e., the power input from the secondary side), and the first capacitor C1 to the fourth capacitor C4 may play a good filtering role in the boost process, and when the voltage changes, the voltage at both ends cannot change suddenly due to the charging role of the capacitors.
In the above-described configuration, the voltage of the primary-side output obtained at the time of boosting is not necessarily stable, that is, the voltage of the power supply bus L is not necessarily stable, and therefore, the energy storage unit 1b is provided to stabilize the voltage of the power supply bus L by stabilizing the voltage of the power supply bus L.
In one embodiment of the invention, as shown in fig. 6, the control module 13 is configured to control the bidirectional DC/DC module 11 to convert a voltage of 1500V DC source into a supply voltage of 750V load, or to convert an output voltage of 750V load into a voltage of 1500V DC source.
Specifically, when the system 10 is used for rail transit, when the system 10 is stepped down, the bidirectional DC/DC module 11 works in the forward direction, and converts 1500V voltage into 750V voltage to supply power to the whole vehicle, the control module 13 obtains voltage and current sampled at the 750V side to respectively control the bridge arms M1 and M2 and the bridge arms M3 and M4, so that the voltage input to the load module 2 at the 750V side is stable, and the feed motor M in the load module 2 works in an electric state at this time to provide traction power for the rail vehicle; when the rail vehicle brakes and feeds back, the feed motor M works in a power generation state, the bidirectional DC/DC module 11 boosts the voltage of the reverse working system 10, the voltage output by the 750V load is boosted and then fed back to the 1500V direct-current source, and the control module 13 still obtains the voltage and the current sampled at the 750V side to respectively control the bridge arms M1 and M2 and the bridge arms M3 and M4, so that the power input to the 1500V direct-current source changes along with the change of the output power of the 750V load.
When the system 10 is in boost operation, the bidirectional DC/DC module 11 is not controlled to output 1500V voltage, and the voltage of the power supply bus L can be stabilized at 1500V by the power supply module 1. When the whole railway vehicle brakes or brakes, the voltage of the load module 2 rises along with the increase of the braking power, and at the moment, the power can be output to the high-voltage side (namely 1500V side) according to the magnitude of the braking load, because the voltage of the low-voltage side (namely 750V side) rises along with the rise of the braking power of the load, when the load is increased, the voltage of the low-voltage side rises, the load is increased, and the boosting power of the system also changes along with the control. If the high-voltage side is controlled, the low-voltage side voltage power supply is unstable, and the braking power of the low-voltage side cannot be absorbed according to the power change of the load module 2.
In summary, according to the bidirectional DC/DC system of the embodiment of the present invention, not only can bidirectional transmission of energy be achieved, but also when the system transmits energy from the load module to the power supply module, the output power can change along with the change of the power of the load module, the voltage of the load module is more stable in the energy transmission process, the dynamic response of the system is accelerated, and the product performance is improved.
Further, the invention provides a control method of the bidirectional DC/DC system.
In this embodiment, the bidirectional DC/DC system comprises a bidirectional DC/DC module, the primary side of which is connected to the supply module and the secondary side of which is connected to the load module.
Fig. 7 is a flowchart of a control method of a bidirectional DC/DC system according to one embodiment of the present invention. As shown in fig. 7, the control method includes the steps of:
and S1, acquiring the electric signal of the secondary side of the bidirectional DC/DC module.
And S2, controlling the bidirectional DC/DC module to perform voltage conversion according to the electric signal so as to convert the voltage fixed direct current into voltage adjustable direct current when the power supply module supplies power to the load module, and to make the power output by the primary side change along with the change of the power input by the secondary side when the load module feeds power to the power supply module.
In one embodiment of the invention, the electrical signal comprises a current of a secondary side loop of the bidirectional DC/DC module.
In one embodiment of the invention, the electrical signal comprises a voltage of the secondary side of the bi-directional DC/DC module.
It should be noted that, for other implementation manners of the control method of the bidirectional DC/DC system according to the embodiment of the present invention, reference may be made to the specific implementation manner of the bidirectional DC/DC system according to the above embodiment of the present invention.
According to the control method of the bidirectional DC/DC system, the bidirectional transmission of energy can be realized, and when the system transmits energy to the power supply module from the load module, the output power can change along with the change of the power of the load module, so that the voltage of the load module is more stable in the energy transmission process, the dynamic response of the system is accelerated, and the product performance is improved.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (10)
1. A bi-directional DC/DC system, comprising:
a power supply module and a load module;
a bidirectional DC/DC module, a primary side of the bidirectional DC/DC module being connected to the power supply module, a secondary side of the bidirectional DC/DC module being connected to the load module, wherein the bidirectional DC/DC module is configured to enable energy transfer between the power supply module and the load module;
an electrical signal acquisition module for acquiring an electrical signal of a secondary side of the bi-directional DC/DC;
the control module is respectively connected with the control end of the bidirectional DC/DC module and the electric signal acquisition module, and is used for controlling the bidirectional DC/DC module to carry out voltage conversion according to the electric signal so as to convert the voltage fixed direct current into voltage adjustable direct current when the power supply module supplies power to the load module, and to enable the power output by the primary side to change along with the change of the power input by the secondary side when the load module feeds power to the power supply module.
2. The bi-directional DC/DC system of claim 1, wherein the electrical signal acquisition module comprises:
the current acquisition unit is used for acquiring the current of a secondary side loop of the bidirectional DC/DC module; and/or
A voltage acquisition unit, the voltage acquisition module being configured to acquire a voltage of a secondary side of the bidirectional DC/DC module;
wherein the electrical signal comprises the current and/or the voltage.
3. The bi-directional DC/DC system of claim 1, wherein the power supply module comprises:
a utility grid connected to a supply bus through a first controllable switch to connect with a primary side of the bidirectional DC/DC module through the supply bus;
the energy storage unit is connected to the power supply bus through a second controllable switch;
the control module is further used for controlling the on-off of the first controllable switch and the second controllable switch.
4. The bi-directional DC/DC system of claim 3, further comprising:
the power supply detection module is used for detecting whether faults exist in the commercial power grid and the energy storage unit;
the control module is specifically configured to control the first controllable switch to be in an off state and the second controllable switch to be in an on state when the utility grid fails and the energy storage unit is normal, and control the second controllable switch to be in an off state and the first controllable switch to be in an on state when the energy storage unit fails and the utility grid is normal.
5. The bi-directional DC/DC system of claim 1, wherein the load module comprises:
a feed motor;
one end of the rectifying circuit is connected with the feed motor, and the other end of the rectifying circuit is connected with the secondary side of the bidirectional DC/DC module;
when the feed motor is in a power generation state, the feed motor feeds power to the bidirectional DC/DC module through the rectifying circuit.
6. The bi-directional DC/DC system of claim 2, wherein the primary side of the bi-directional DC/DC module comprises a first leg and a first coil, and the secondary side of the bi-directional DC/DC module comprises a second leg and a second coil, wherein the input end of the first leg is connected to the supply bus, the output end of the first leg is connected to the first coil, the input end of the second leg is connected to the second coil, the output end of the second leg is connected to the load module, and the second coil and the first coil form a mutual coil;
the control module performs pulse width modulation, frequency modulation or mixed modulation on the first bridge arm and the second bridge arm according to the electric signals, wherein the mixed modulation comprises pulse width modulation and frequency modulation.
7. The bi-directional DC/DC system of claim 6, wherein the primary side of the bi-directional DC/DC module further comprises a third leg and a third coil, and the secondary side of the bi-directional DC/DC module comprises a fourth leg and a fourth coil, wherein an input end of the third leg is connected to the supply bus, an output end of the third leg is connected to the third coil, an input end of the fourth leg is connected to the fourth coil, an output end of the fourth leg is connected to the load module, and the fourth coil and the third coil form a mutual inductor;
the control module selectively controls the first bridge arm and the second bridge arm and/or the third bridge arm and the fourth bridge arm according to the electric signal, and adopts pulse width modulation, frequency modulation or hybrid modulation technology when controlling the third bridge arm and the fourth bridge arm.
8. The bi-directional DC/DC system of claim 7, wherein the control module, when selectively controlling the first leg and the second leg, and/or the third leg and the fourth leg according to the electrical signal, is specifically configured to:
when the current is greater than a preset current threshold value and/or the voltage is greater than a preset voltage threshold value, controlling the first bridge arm and the second bridge arm, and controlling the third bridge arm and the fourth bridge arm simultaneously;
and when the current is less than or equal to the preset current threshold and/or the voltage is less than or equal to the preset voltage threshold, controlling the first bridge arm and the second bridge arm, or controlling the third bridge arm and the fourth bridge arm.
9. A method of controlling a bidirectional DC/DC system, the bidirectional DC/DC system comprising a bidirectional DC/DC module, a power supply module and a load module, a primary side of the bidirectional DC/DC module being connected to the power supply module and a secondary side of the bidirectional DC/DC module being connected to the load module, the method comprising the steps of:
collecting an electrical signal of a secondary side of the bidirectional DC/DC module;
and controlling the bidirectional DC/DC module to perform voltage conversion according to the electric signal so as to convert the voltage fixed direct current into voltage adjustable direct current when the power supply module supplies power to the load module, and to enable the power output by the primary side to change along with the change of the power input by the secondary side when the load module feeds power to the power supply module.
10. The method of claim 9, wherein the electrical signal comprises a current of a secondary side loop of the bidirectional DC/DC module, and/or a voltage of a secondary side of the bidirectional DC/DC module.
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