CN114614670A - Bidirectional DC-DC converter for vehicle-mounted dual power supply system - Google Patents

Bidirectional DC-DC converter for vehicle-mounted dual power supply system Download PDF

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Publication number
CN114614670A
CN114614670A CN202011421175.1A CN202011421175A CN114614670A CN 114614670 A CN114614670 A CN 114614670A CN 202011421175 A CN202011421175 A CN 202011421175A CN 114614670 A CN114614670 A CN 114614670A
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China
Prior art keywords
group
bridge arms
bidirectional
switching tube
converter
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CN202011421175.1A
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Chinese (zh)
Inventor
孟凡刚
殷昕羽
张伟
宫大东
贺洪波
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WEIHAI TONSLOAD POWER-TECH CO LTD
Weihai Tianfan Power Technology Co ltd
Harbin Institute of Technology Weihai
Original Assignee
WEIHAI TONSLOAD POWER-TECH CO LTD
Weihai Tianfan Power Technology Co ltd
Harbin Institute of Technology Weihai
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Priority to CN202011421175.1A priority Critical patent/CN114614670A/en
Publication of CN114614670A publication Critical patent/CN114614670A/en
Pending legal-status Critical Current

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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R16/00—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for
    • B60R16/02—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements
    • B60R16/023—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for transmission of signals between vehicle parts or subsystems
    • B60R16/0231—Circuits relating to the driving or the functioning of the vehicle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R16/00—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for
    • B60R16/02—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements
    • B60R16/03—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for supply of electrical power to vehicle subsystems or for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R16/00—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for
    • B60R16/02—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements
    • B60R16/03—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for supply of electrical power to vehicle subsystems or for
    • B60R16/033—Electric or fluid circuits specially adapted for vehicles and not otherwise provided for; Arrangement of elements of electric or fluid circuits specially adapted for vehicles and not otherwise provided for electric constitutive elements for supply of electrical power to vehicle subsystems or for characterised by the use of electrical cells or batteries
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/14—Arrangements for reducing ripples from dc input or output
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention relates to the technical field of electronics, in particular to a bidirectional DC-DC converter for a vehicle-mounted dual-power system, which is characterized in that a two-phase staggered parallel bidirectional four-switch Buck-Boost circuit is used as a basic topology of the bidirectional DC-DC converter, and the basic topology structure comprises four groups of bridge arm circuits, a first energy storage inductor, a second energy storage inductor, a first power supply, a second power supply, a generator, a first capacitor and a second capacitor; the four groups of bridge arm circuits comprise a first group of bridge arms, a second group of bridge arms, a third group of bridge arms and a fourth group of bridge arms, wherein the first group of bridge arms, a first energy storage inductor and the second group of bridge arms form a first-phase bidirectional DCDC circuit; the third group of bridge arms, the second energy storage inductor and the fourth group of bridge arms form a second-phase bidirectional DCDC circuit; the invention has the characteristic of energy bidirectional flow, improves the power grade of the system, reduces output voltage and current ripples, can automatically realize current sharing, reduces the volume of the system and reduces the complexity of the system.

Description

Bidirectional DC-DC converter for vehicle-mounted dual power supply system
Technical Field
The invention relates to the technical field of electronics, in particular to a bidirectional DC-DC converter for a vehicle-mounted dual-power system, which has the characteristic of energy bidirectional flow, improves the power level of the system, reduces output voltage and current ripples, can automatically realize current sharing, reduces the volume of the system and reduces the complexity of the system.
The background art comprises the following steps:
with the vigorous development of the logistics transportation industry, modern commercial vehicles and logistics transport vehicles become essential transportation and distribution tools in the logistics industry, and people not only put forward higher requirements on the practicability and reliability of the transportation and distribution tools, but also put forward further requirements on the comfort degree of drivers. Because the former car storage battery still is the thin polar plate storage battery that is applicable to the vehicle and starts, can't be adapted to the heavy current deep discharge state when high-power consumer (air conditioner, electromagnetism stove etc.) moves, seriously influences the life of battery, consequently add lithium cell group in traditional on-vehicle single power supply system and constitute dual supply system and can effectively reduce discharge current, promote the life of former car storage battery. And a core part of a vehicle-mounted double power supply system, namely a bidirectional DC-DC converter, is required to be inserted between the original vehicle storage battery and the lithium battery pack, so that the bidirectional flow of energy is realized. The DC-DC converter is a device for converting one kind of direct current into another kind of fixed or adjustable direct current, is also called as a DC-DC converter, and is widely applied to occasions such as hybrid electric vehicle driving, storage battery energy storage systems and the like. In the prior art, most of DC-DC converters are unidirectional, namely, only unidirectional voltage boosting or voltage reduction can be performed. For the unidirectional boost DC-DC converter, after direct current is input at one end, direct current with higher voltage level is output at the other end; for a unidirectional step-down DC-DC converter, after direct current is input at one end, direct current with lower voltage level is output at the other end. The energy flow direction of such a unidirectional DC-DC converter is fixed and not reversible.
For the occasion that energy needs to flow in two directions, if two unidirectional DC-DC converters are connected in parallel in the opposite direction, the energy can flow in two directions by switching two working states, although the method is easy to control, the complexity of the system is increased, the power level of the system is low, and the volume and the weight of the system are increased, so that the waste of resources is caused. The prior patent literature: 201711406600.8 discloses a bidirectional DC-DC topology structure, which can realize bidirectional flow of energy, and has various conversion modes, but has large ripple of output voltage and current, needs to consider current sharing problem and has low fault tolerance.
The invention content is as follows:
aiming at the defects and shortcomings in the prior art, the invention provides the bidirectional DC-DC converter for the vehicle-mounted dual-power system, which has the characteristic of bidirectional flow of energy, solves the problem that the traditional DC-DC converter can only realize unidirectional flow of energy in a single working mode, improves the power grade of the system, reduces output voltage and current ripples, can automatically realize current sharing, simultaneously reduces the volume of the system and reduces the complexity of the system.
In order to achieve the purpose, the invention provides the following technical scheme:
a bidirectional DC-DC converter for a vehicle-mounted dual-power system is characterized in that a two-phase staggered parallel bidirectional four-switch Buck-Boost circuit is used as a basic topology of the bidirectional DC-DC converter, and the basic topology structure comprises four groups of bridge arm circuits, a first energy storage inductor, a second energy storage inductor, a first power supply, a second power supply, a generator, a first capacitor and a second capacitor; the four groups of bridge arm circuits comprise a first group of bridge arms, a second group of bridge arms, a third group of bridge arms and a fourth group of bridge arms, wherein the first group of bridge arms, a first energy storage inductor and the second group of bridge arms form a first-phase bidirectional DCDC circuit; the third group of bridge arms, the second energy storage inductor and the fourth group of bridge arms form a second-phase bidirectional DCDC circuit;
the first group of bridge arms consists of switching tubes VT1 and VT2, the second group of bridge arms consists of switching tubes VT3 and VT4, the third group of bridge arms consists of switching tubes VT5 and VT6, the fourth group of bridge arms consists of switching tubes VT7 and VT8,
a source electrode of the switching tube VT1 is connected with a drain electrode of the switching tube VT2, and is used as a common end of a first group of bridge arms to be connected with a first end of the first energy storage inductor, a drain electrode of the switching tube VT1 is used as a first end of the first group of bridge arms to be connected with a first end of the first capacitor and a first end of the generator, and a source electrode of the switching tube VT2 is used as a second end of the first group of bridge arms to be connected with a second end of the first capacitor and a second end of the generator;
the drain electrode of the switching tube VT3 is connected with the source electrode of the switching tube VT4, and is used as the common end of the second group of bridge arms to be connected with the second end of the second energy storage inductor, the drain electrode of the switching tube VT4 is used as the first end of the second group of bridge arms to be connected with the first end of the second capacitor, and the source electrode of the switching tube VT3 is used as the second end of the second group of bridge arms to be connected with the second end of the second capacitor;
the source electrode of the switching tube VT5 is connected with the drain electrode of the switching tube VT6, and is used as the common end of the third group of bridge arms to be connected with the first end of the second energy storage inductor, the drain electrode of the switching tube VT5 is used as the first end of the third group of bridge arms to be connected with the first end of the first capacitor and the first end of the generator, and the source electrode of the switching tube VT5 is used as the second end of the third group of bridge arms to be connected with the first capacitor and the second end of the generator;
the drain electrode of the switching tube VT7 is connected with the source electrode of the switching tube VT8, and is used as the common terminal of the fourth group of bridge arms to be connected with the second end of the second energy storage inductor, the drain electrode of the switching tube VT8 is used as the first end of the fourth group of bridge arms to be connected with the first end of the second capacitor, and the source electrode of the switching tube VT7 is used as the second end of the fourth group of bridge arms to be connected with the second end of the second capacitor.
In the invention, each switch tube is provided with a diode which is reversely connected in parallel with the switch tube and plays the role of afterflow; the eight switching tubes are NMOS tubes; the parameters of the first capacitor and the second capacitor are the same; the parameters of the first energy storage inductor and the second energy storage inductor are the same.
The first power supply adopts a lead storage battery, namely a storage battery of an original vehicle, and the second power supply adopts a lithium battery pack.
The bidirectional DC-DC converter in the vehicle-mounted dual power supply system can work in six working modes such as a bidirectional Boost mode, a bidirectional Buck-Boost mode and the like: when the bidirectional DC-DC converter works in a forward Boost mode, the switching tubes VT1 and VT5 are switched on, and the switching tubes VT2 and VT6 are switched off; the switching tubes VT3, VT4, VT7 and VT8 respectively work at a certain duty ratio; the bidirectional DC-DC converter can be equivalent to a form that two-phase forward Boost circuits are connected in parallel in a staggered mode;
when the bidirectional DC-DC converter works in a reverse Buck mode, the switching tubes VT1 and VT5 are conducted, the switching tubes VT2 and VT6 are turned off, the switching tubes VT4 and VT8 work at a certain duty ratio, and the switching tubes VT3 and VT7 work at a complementary duty ratio with dead time. The bidirectional DC-DC converter can be equivalent to a form that two-phase reverse Buck circuits are connected in parallel in an interleaving mode.
When the bidirectional DC-DC converter works in a forward Buck-Boost mode, the switching tubes VT1, VT3, VT5 and VT7 work at a certain duty ratio, and the switching tubes VT2, VT4, VT6 and VT8 work at a complementary duty ratio with dead time. The bidirectional DC-DC converter can be equivalent to two circuit structures that a first-phase Buck converter and a second-phase Boost converter are connected in parallel in an interlaced mode or the first-phase Boost converter and the second-phase Buck converter are connected in parallel in an interlaced mode.
When the bidirectional DC-DC converter works in a reverse Buck-Boost mode, the switching tubes VT2, VT4, VT6 and VT8 work at a certain duty ratio, and the switching tubes VT1, VT3, VT5 and VT7 work at a complementary duty ratio with dead time. Therefore, the bidirectional DC-DC converter can be equivalent to two circuit structures that the first-phase Boost converter and the second-phase Buck converter are connected in parallel in an interlaced mode or the first-phase Buck converter and the second-phase Boost converter are connected in parallel in an interlaced mode.
When the bidirectional DC-DC converter works in a reverse Boost mode, the switching tubes VT4 and VT8 are conducted, the switching tubes VT3 and VT7 are turned off, and the switching tubes VT1, VT5, VT2 and VT6 respectively work at certain duty ratios. The bidirectional DC-DC converter can be equivalent to a form that two-phase reverse Boost circuits are connected in parallel in an interleaving mode.
When the bidirectional DC-DC converter works in a forward Buck mode, the switching tubes VT4 and VT8 are switched on, the switching tubes VT3 and VT7 are switched off, and the switching tubes VT1, VT2, VT5 and VT6 respectively work at a certain duty ratio. The bidirectional DC-DC converter can be equivalent to a two-phase forward Buck circuit interleaving parallel connection mode.
In conclusion, the invention has the following beneficial effects: (1) the invention adopts the two-phase staggered parallel synchronous four-switch Buck-Boost circuit, can perform bidirectional flow of energy according to the charge-discharge requirement of the original vehicle battery, and can also perform mode conversion according to the states of the accessed original vehicle battery and the lithium battery pack, thereby realizing bidirectional flow of energy. (2) The bidirectional Buck-Boost converter can work in a bidirectional Buck-Boost mode, namely under the condition that voltages at two ends of the bidirectional DC-DC converter are close, the conversion modes are various. (3) The invention adopts a staggered parallel connection mode, can effectively reduce the discharge current when high-power electric equipment in the system runs, and improves the power grade and the working efficiency of the system; meanwhile, the invention adopts a staggered parallel connection mode, can reduce output voltage and current ripples and improve the dynamic response speed of the system. (4) The invention adopts a staggered parallel connection mode, the system fault tolerance is higher, and when one-phase bidirectional DC-DC converter fails, the other-phase bidirectional DC-DC converter can still continue to work.
Description of the drawings:
fig. 1 is a circuit diagram of the present invention.
Fig. 2 is a working mode diagram when the forward Boost mode D is less than 0.5 in the embodiment of the present invention, where fig. 2(1) is a mode diagram from t0 to t1, fig. 2(2) is a mode diagram from t1 to t2, fig. 2(3) is a mode diagram from t2 to t3, and fig. 2(4) is a mode diagram from t3 to t 4.
Fig. 3 is a working mode diagram of the embodiment of the present invention when the forward Boost mode D is 0.5, where fig. 3(1) is a mode diagram from t0 to t1, and fig. 3(2) is a mode diagram from t1 to t 2.
Fig. 4 is a mode diagram of operation when the forward Boost mode D >0.5 in the embodiment of the present invention, where fig. 4(1) is a mode diagram from t0 to t1, fig. 4(2) is a mode diagram from t1 to t2, fig. 4(3) is a mode diagram from t2 to t3, and fig. 4(4) is a mode diagram from t3 to t 4.
Fig. 5 is a mode diagram of the reverse Buck mode D <0.5 in the embodiment of the present invention, where fig. 5(1) is a mode diagram from t0 to t1, fig. 5(2) is a mode diagram from t1 to t2, fig. 5(3) is a mode diagram from t2 to t3, and fig. 5(4) is a mode diagram from t3 to t 4.
Fig. 6 is a working mode diagram of the embodiment of the present invention when the reverse Buck mode D is 0.5, where fig. 6(1) is a mode diagram from t0 to t1, and fig. 6(2) is a mode diagram from t1 to t 2.
Fig. 7 is a mode diagram of the reverse Buck mode D >0.5 in the embodiment of the present invention, where fig. 7(1) is a mode diagram from t0 to t1, fig. 7(2) is a mode diagram from t1 to t2, fig. 7(3) is a mode diagram from t2 to t3, and fig. 7(4) is a mode diagram from t3 to t 4.
Fig. 8 is a circuit diagram of a forward Buck-Boost mode alternate parallel connection of an up-link Boost converter and a down-link Buck converter in the embodiment of the invention.
Fig. 9 is a circuit diagram of a forward Buck-Boost mode alternate parallel connection of an up-link Buck converter and a down-link Boost converter in the embodiment of the invention.
Fig. 10 is a working mode diagram of the forward Buck-Boost mode in the embodiment of the present invention, where fig. 10(1) is a mode diagram from t0 to t1, fig. 10(2) is a mode diagram from t1 to t2, fig. 10(3) is a mode diagram from t2 to t3, and fig. 10(4) is a mode diagram from t3 to t 4.
Reference numerals: the bridge comprises a first group of bridge arms 1, a second group of bridge arms 2, a third group of bridge arms 3, a fourth group of bridge arms 4, a first energy storage inductor 5, a second energy storage inductor 6, a first capacitor 7, a second capacitor 8, a first power supply 9, a second power supply 10 and a generator 11.
The specific implementation mode is as follows:
the technical solution of the present invention will be fully and clearly described below with reference to the accompanying drawings and examples.
Example (b):
the invention provides a bidirectional DC-DC converter for a vehicle-mounted dual-power system, which is used for realizing bidirectional flow of energy, effectively reducing ripples of output voltage and current, automatically realizing current sharing and improving the power grade and the working efficiency of the system.
As shown in fig. 1, the present invention includes four sets of bridge arms (a first set of bridge arm 1, a second set of bridge arm 2, a third set of bridge arm 3, and a fourth set of bridge arm 4, respectively), a first energy storage inductor 5, a second energy storage inductor 6, a first power supply 9, a second power supply 10, a generator 11, a first capacitor 7, and a second capacitor 8, where the first set of bridge arm 1 includes switching tubes VT1 and VT2, the second set of bridge arm 2 includes switching tubes VT3 and VT4, the third set of bridge arm 3 includes switching tubes VT5 and VT6, the fourth set of bridge arm 4 includes switching tubes VT7 and VT8, and eight switching tubes are all connected in parallel with one diode in reverse direction to play a role of freewheeling; eight switching tubes of the four groups of bridge arms are NMOS tubes;
the specific connection relation of the four groups of bridge arm circuits is as follows:
the source electrode of a switching tube VT1 in the first group of bridge arms 1 is connected with the drain electrode of the switching tube VT2, and is used as the common end of the first group of bridge arms 1 to be connected with the first end of a first energy storage inductor 5, the drain electrode of a switching tube VT1 is used as the first end of the first group of bridge arms 1 to be connected with the first end of a first capacitor 7, and the source electrode of a switching tube VT2 is used as the second end of the second group of bridge arms 2 to be connected with the second end of the first capacitor 7;
the drain of the switch tube VT3 in the second group of bridge arms 2 is connected with the source of the switch tube VT4 and serves as the common end of the second group of bridge arms 2 to be connected with the second end of the first energy storage inductor 5, the drain of the switch tube VT4 serves as the first end of the second group of bridge arms 2 to be connected with the first end of the second capacitor 8, and the source of the switch tube VT5 serves as the second end of the second group of bridge arms 2 to be connected with the second end of the second capacitor 8;
the drain of the switching tube VT5 in the third group of bridge arms 3 is connected to the source of the switching tube VT6, and is connected to the first end of the second energy storage inductor 6 as the common end of the third group of bridge arms 3, the drain of the switching tube VT5 is connected to the first end of the first capacitor 7 as the first end of the third group of bridge arms 3, and the source of the switching tube VT6 is connected to the second end of the first capacitor 7 as the second end of the third group of bridge arms 3;
the drain of the switching tube VT7 in the fourth group of bridge arms 4 is connected to the source of the switching tube VT8, and is connected to the second end of the second energy storage inductor 6 as the common terminal of the fourth group of bridge arms 4, the drain of the switching tube VT8 is connected to the first end of the second capacitor 8 as the first end of the fourth group of bridge arms 4, and the source of the switching tube VT7 is connected to the second end of the second capacitor 8 as the second end of the fourth group of bridge arms 4;
the first end and the second end of the first capacitor 7 are respectively connected with the anode and the cathode of a first power supply 9, and the first end and the second end of the second capacitor 8 are respectively connected with the anode and the cathode of a second power supply 10.
In this example, when the bidirectional DC-DC converter for the vehicle-mounted dual power supply system operates, the converter can operate in six operating modes, such as a bidirectional Boost mode, a bidirectional Buck mode, and a bidirectional Buck-Boost mode, and the following detailed description will be given of the selection of the conduction and duty ratio of the switching tube controlled by the driving circuit, where it should be noted that, because there are cases with similar analysis methods between the six operating modes, the following analysis only includes three operating modes:
1. bidirectional DC-DC converter working in forward Boost mode
When the bidirectional DC-DC converter works in a forward Boost mode, the switching tubes VT1 and VT5 are kept on, the switching tubes VT2 and VT6 are kept off, and the switching tubes VT3, VT4, VT7 and VT8 respectively work at a certain duty ratio. According to the duty ratio D of the switching tubes VT3 and VT7, the forward Boost mode can be divided into three states, namely D <0.5, D is 0.5, and D > 0.5.
Fig. 2 is a diagram of an operation mode when the duty ratio D is less than 0.5 in the forward Boost mode. At t0-t1, the driving circuit controls the switching tubes VT3 and VT8 to be switched on, VT4 and VT7 to be switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; the driving circuit controls the switching tubes VT3 and VT7 to be turned off at t1-t2, the VT4 and VT8 to be turned on, the first inductor 5 and the second inductor 6 release energy, the driving circuit controls the switching tubes VT3 and VT8 to be turned off at t2-t3, the VT4 and VT7 are turned on, the first inductor 5 releases energy, and the second inductor 6 stores energy; the switching process from t3 to t4 is the same as that from t1 to t 2.
Fig. 3 is an operation mode diagram when the duty ratio D is 0.5 in the forward Boost mode. At t0-t1, the driving circuit controls the switching tubes VT3 and VT8 to be switched on, the switching tubes VT7 and VT4 are switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; and at t1-t2, the driving circuit controls the switching tubes VT3 and VT8 to be turned off, the switching tubes VT7 and VT4 to be turned on, the first inductor 5 releases energy, and the second inductor 6 stores energy.
Fig. 4 is a diagram of an operation mode when the duty ratio D >0.5 in the forward Boost mode. At t0-t1, the driving circuit controls the switching tubes VT3 and VT7 to be switched on, VT4 and VT8 are switched off, and the first inductor 5 and the second inductor 6 store energy; at t1-t2, the driving circuit controls the switching tubes VT3 and VT8 to be switched on, VT4 and VT7 to be switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; the switching processes of t2-t3 and t1-t2 are the same; and at t3-t4, the driving circuit controls the switching tubes VT3 and VT8 to be turned off, VT4 and VT7 to be turned on, the first inductor 5 releases energy, and the second inductor 6 stores energy.
2. The bidirectional DC-DC converter operates in a reverse Buck mode.
When the bidirectional DC-DC converter works in a reverse Buck mode, the switching tubes VT1 and VT5 are kept on, the VT2 and VT6 are kept off, the VT4 and the VT8 work at a certain duty ratio, and the VT3 and the VT7 work at a complementary duty ratio with dead time. According to the conditions of the switching tubes VT4 and VT8 duty ratio D, the Buck mode can be divided into three states: d <0.5, D ═ 0.5, D > 0.5.
Fig. 5 is a diagram of the operation mode of the reverse Buck mode with duty ratio D < 0.5. At t0-t1, the driving circuit controls the switching tubes VT4 and VT7 to be switched on, the switching tubes VT3 and VT8 are switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; the driving circuit controls the switching tubes VT4 and VT8 to be turned off at t1-t 2; the switching tubes VT3 and VT8 are conducted, and the first inductor 5 and the second inductor 6 release energy; at t2-t3, the driving circuit controls the switching tubes VT3 and VT8 to be switched on, VT4 and VT7 to be switched off, the first inductor 5 releases energy, and the second inductor 6 stores energy; the switching process from t3 to t4 is the same as that from t1 to t 2.
Fig. 6 is an operation mode diagram when the duty ratio D is 0.5 in the reverse Buck mode. At t0-t1, the driving circuit controls the switching tubes VT4 and VT7 to be switched on, the switching tubes VT3 and VT8 are switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; and at t1-t2, the driving circuit controls the switching tubes VT3 and VT8 to be turned off, VT4 and VT7 to be turned on, the first inductor 5 releases energy, and the second inductor 6 stores energy.
Fig. 7 is a diagram of the operation mode when the duty ratio D >0.5 in the reverse Buck mode. And at t0-t1, the driving circuit controls the switching tubes VT4 and VT8 to be switched on, the switching tubes VT3 and VT7 to be switched off, and the first inductor 5 and the second inductor 6 store energy. At t1-t2, the driving circuit controls the switching tubes VT4 and VT7 to be switched on, the switching tubes VT3 and VT8 are switched off, the first inductor 5 stores energy, and the second inductor 6 releases energy; the switching processes of t2-t3 and t0-t1 are the same; and at t3-t4, the driving circuit controls the switching tubes VT4 and VT7 to be turned off, VT3 and VT8 to be turned on, the first inductor 5 releases energy, and the second inductor 6 stores energy.
3. The bidirectional DC-DC converter works in a forward Buck-Boost mode.
The switching tubes VT1, VT3, VT5 and VT7 work with a certain duty ratio, and VT2, VT4, VT6 and VT8 work with a complementary duty ratio with dead time. Fig. 8 is an equivalent circuit diagram of an up-link Boost converter and a down-link Boost converter which are connected in parallel in a staggered manner when a bidirectional DC-DC converter works in a forward Buck-Boost mode in the embodiment of the present invention, and fig. 9 is an equivalent circuit diagram of an up-link Boost converter and a down-link Boost converter which are connected in parallel in a staggered manner when a bidirectional DC-DC converter works in a forward Buck-Boost mode in the embodiment of the present invention.
It should be noted that, according to the sizes of the first power supply 9 and the second power supply 10, the forward Buck-Boost mode can be divided into two cases, that is, V1> V2 and V1< V2, for avoiding redundant description, the duty ratios D1 of VT1 and VT5 are only equal, and D1>0.5, and VT2 and VT6 operate with complementary duty ratios with dead time; VT3, VT7 duty cycles D2 are equal, and D2<0.5, VT4, VT8 operate with complementary duty cycles with dead time, i.e., V1> V2, for example, analyzing the forward Buck-Boost mode. The remaining duty cycle combinations are similar to their switching process.
When V1> V2, the bidirectional DC-DC converter is switched from the forward Buck mode to the forward Buck-Boost mode. Fig. 10 is a diagram of the operation mode of the forward Buck-Boost mode. When the voltage is t0-t1, the first phase circuit is in a Buck discharge mode, the driving circuit controls the switching tube VT1 to be switched off, the VT2 is switched on, the first inductor 5 releases energy, the second phase circuit is in a Boost charge mode, the driving circuit controls the switching tube VT7 to be switched on, the VT8 is switched off, and the second inductor 6 stores energy; when the voltage is t1-t2, the first phase circuit is in a Buck charging mode, the driving circuit controls the switching tube VT1 to be switched on, the VT2 is switched off, the first inductor 5 stores energy, the second phase circuit is in a Boost discharging mode, the driving circuit controls the switching tube VT7 to be switched off, the VT8 is switched on, and the second inductor 6 still stores energy as V1 is greater than V2; when the voltage is t2-t3, the first phase circuit is in a Boost charging mode, the driving circuit controls the switching tube VT3 to be switched on, the VT4 is switched off, the first inductor 5 stores energy, the second phase circuit is in a Buck discharging mode, the driving circuit controls the switching tube VT5 to be switched off, the VT6 is switched on, and the second inductor 6 releases energy; and at t3-t4, the first phase circuit is in a Boost discharge mode, the driving circuit controls the switching tube VT4 to be switched on, the VT3 is switched off, the first inductor 5 still releases energy due to V1 being larger than V2, the second phase circuit is in a Buck charging mode, the driving circuit controls the switching tube VT6 to be switched off, the VT5 is switched on, and the second inductor 6 stores energy.
In the above detailed description of the bidirectional DC-DC converter for a vehicle-mounted dual power supply system provided by the present invention, relational terms such as first and second, and the like are used only to distinguish two different entities, and there is no requirement that a practical order exist between these entities or operations.

Claims (6)

1. A bidirectional DC-DC converter for a vehicle-mounted dual-power system is characterized in that a two-phase staggered parallel bidirectional four-switch Buck-Boost circuit is used as a basic topology of the bidirectional DC-DC converter, and the basic topology structure comprises four groups of bridge arm circuits, a first energy storage inductor, a second energy storage inductor, a first power supply, a second power supply, a generator, a first capacitor and a second capacitor; the four groups of bridge arm circuits comprise a first group of bridge arms, a second group of bridge arms, a third group of bridge arms and a fourth group of bridge arms, wherein the first group of bridge arms, a first energy storage inductor and the second group of bridge arms form a first-phase bidirectional DCDC circuit; the third group of bridge arms, the second energy storage inductor and the fourth group of bridge arms form a second-phase bidirectional DCDC circuit;
the first group of bridge arms consists of switching tubes VT1 and VT2, the second group of bridge arms consists of switching tubes VT3 and VT4, the third group of bridge arms consists of switching tubes VT5 and VT6, the fourth group of bridge arms consists of switching tubes VT7 and VT8,
the source electrode of the switching tube VT1 is connected with the drain electrode of the switching tube VT2, and is used as the common end of a first group of bridge arms to be connected with the first end of the first energy storage inductor, the drain electrode of the switching tube VT1 is used as the first end of the first group of bridge arms to be connected with the first end of the first capacitor and the first end of the generator, and the source electrode of the switching tube VT2 is used as the second end of the first group of bridge arms to be connected with the second end of the first capacitor and the second end of the generator;
the drain electrode of the switching tube VT3 is connected with the source electrode of the switching tube VT4, and is used as the common end of the second group of bridge arms to be connected with the second end of the second energy storage inductor, the drain electrode of the switching tube VT4 is used as the first end of the second group of bridge arms to be connected with the first end of the second capacitor, and the source electrode of the switching tube VT3 is used as the second end of the second group of bridge arms to be connected with the second end of the second capacitor;
a source electrode of the switching tube VT5 is connected to a drain electrode of the switching tube VT6, and is connected to a first end of the second energy storage inductor as a common terminal of a third group of bridge arms, a drain electrode of the switching tube VT5 is connected to a first end of the first capacitor and a first end of the generator as a first end of the third group of bridge arms, and a source electrode of the switching tube VT5 is connected to a second end of the first capacitor and a second end of the generator as a second end of the third group of bridge arms;
the drain electrode of the switching tube VT7 is connected with the source electrode of the switching tube VT8, and is used as the common terminal of the fourth group of bridge arms to be connected with the second end of the second energy storage inductor, the drain electrode of the switching tube VT8 is used as the first end of the fourth group of bridge arms to be connected with the first end of the second capacitor, and the source electrode of the switching tube VT7 is used as the second end of the fourth group of bridge arms to be connected with the second end of the second capacitor.
2. The bidirectional DC-DC converter for the vehicle-mounted dual power supply system according to claim 1, wherein each switching tube has a diode connected in inverse parallel therewith to function as a freewheeling diode.
3. The bidirectional DC-DC converter for the vehicle-mounted dual power supply system according to claim 1, wherein each of the eight switching tubes is an NMOS tube.
4. The bidirectional DC-DC converter for the vehicle-mounted dual power supply system according to claim 1, wherein the parameters of the first capacitor and the second capacitor are the same.
5. The bidirectional DC-DC converter for the vehicle-mounted dual power supply system according to claim 1, wherein parameters of the first energy storage inductor and the second energy storage inductor are the same.
6. The bidirectional DC-DC converter for the vehicle-mounted dual-power system as recited in claim 1, wherein the first power source adopts a lead storage battery, namely a primary vehicle battery, and the second power source adopts a lithium battery pack.
CN202011421175.1A 2020-12-08 2020-12-08 Bidirectional DC-DC converter for vehicle-mounted dual power supply system Pending CN114614670A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118232696A (en) * 2024-05-23 2024-06-21 西安图为电气技术有限公司 Current limit control method, electronic device and computer readable storage medium

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118232696A (en) * 2024-05-23 2024-06-21 西安图为电气技术有限公司 Current limit control method, electronic device and computer readable storage medium

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