CN113630008A - Boost cascade and switched capacitor bidirectional DC-DC converter and control method - Google Patents

Boost cascade and switched capacitor bidirectional DC-DC converter and control method Download PDF

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CN113630008A
CN113630008A CN202111052804.2A CN202111052804A CN113630008A CN 113630008 A CN113630008 A CN 113630008A CN 202111052804 A CN202111052804 A CN 202111052804A CN 113630008 A CN113630008 A CN 113630008A
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capacitor
boost
voltage side
mode
converter
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CN113630008B (en
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高强
梅军
蔡旭
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Shanghai Jiaotong University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • 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
    • 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
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • 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
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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

Abstract

The invention provides a Boost cascade and switched capacitor bidirectional DC-DC converter, which comprises three groups of cascade Boost circuits and switched capacitor modules connected with the Boost circuits, wherein the switched capacitor modules are positioned on a high-voltage side; the three cascaded sets of Boost circuits are located on a low-voltage side, wherein: the three groups of cascaded Boost circuits enable the converter to have large voltage gain in a cascaded mode, and meanwhile, current is divided into three branches on the low-voltage side, so that current stress borne by the inductor is reduced. In addition, the invention also provides a control method of the converter, and the method is simpler.

Description

Boost cascade and switched capacitor bidirectional DC-DC converter and control method
Technical Field
The invention relates to the technical field of new energy, in particular to a non-isolated bidirectional DC-DC converter and a control method.
Background
The photovoltaic grid-connected system belongs to a new energy grid-connected system, and an energy storage system is usually required to be added in order to enhance the stability of photovoltaic power generation and grid connection. The energy storage system is connected with a direct current bus of the photovoltaic grid-connected system through the bidirectional DC-DC converter, the terminal voltage of the energy storage system is relatively low, and the direct current bus voltage of the photovoltaic grid-connected system is relatively high, so that the bidirectional DC-DC converter is required to have high voltage gain, and the voltage stress of a switching device of the bidirectional DC-DC converter is also small. In addition, if the voltage gain of the converter is high, the energy storage element such as the inductor on the low-voltage side is subjected to high current stress under the same power condition, and thus the current stress of the element such as the inductor on the low-voltage side is required to be not large.
The bidirectional DC-DC has been developed and widely applied in many fields requiring energy to realize bidirectional flow, such as new energy grid connection, energy storage systems of electric vehicles, micro-grids, uninterruptible power supplies, etc., because the bidirectional DC-DC enables energy to flow bidirectionally. The bidirectional DC-DC converter is classified into an isolated type and a non-isolated type according to whether or not electrical isolation is achieved. The isolated bidirectional DC-DC converter adopts a high-frequency isolation transformer, has higher voltage gain, but the design and the manufacture of the high-frequency transformer are more complex, the volume is larger, certain cost is required, and in addition, the high-frequency transformer also causes the problems of leakage inductance and the like. In the non-isolated bidirectional DC-DC converter, the multi-level bidirectional DC-DC converter has high voltage gain, but needs a plurality of switching devices, and the modulation and control strategy is complex. The switch capacitor can effectively improve the voltage gain of the bidirectional DC-DC converter, and simultaneously reduce the voltage stress of the switch device.
The topology of the document H.Ardi, A.Ajami, F.Kardan and S.N.Avilagh, "Analysis and Implementation of a non-ordered bipolar DC-DC Converter With High Voltage Gain," in IEEE Transactions on Industrial Electronics, vol.63, No.8, pp.4878-4888, aug.2016, doi:10.1109/TIE.2016.2552139. the maximum Voltage stress experienced by the switching device is higher than the Voltage on the High Voltage side, and the Voltage Gain thereof is to be improved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a Boost cascade and switched capacitor bidirectional DC-DC converter and a control method.
According to an aspect of the present invention, there is provided a non-isolated bidirectional DC-DC converter, including three sets of cascaded Boost circuits and a switched capacitor module connected thereto, where the three sets of cascaded Boost circuits are located at a low voltage side, and the switched capacitor module is located at a high voltage side, where: three groups of cascade Boost circuits enable the converter to have large voltage gain in a cascade mode. In addition, the three groups of cascaded Boost circuits reduce the current stress on the inductor by dividing the low-voltage side current into three different branches. The switch capacitor module further improves the voltage gain of the converter by using the switch devices and the switch capacitors, and simultaneously reduces the voltage stress born by all the switch devices.
Optionally, the three cascaded sets of Boost circuits are formed by capacitors CL、C1、C2、C4Inductance L1、L2、L3Switching device Q1、Q2、Q3、Q4、Q5、Q6Composition, capacitance CLThe negative electrode of the capacitor C is connected with the negative electrode of the power supplyLIs connected with the positive pole of the voltage side power supply and the inductor L3One terminal of (1), inductance L3The other end of the capacitor C is connected with a capacitor C1Positive electrode of (2), Q2Source electrode of (2) is connected to Q3Source electrode of (1), capacitor C1Is connected to Q2Source and Q of3Between the source electrodes of, Q2The drain electrode of the power supply is connected with the negative electrode of a voltage side power supply; q1Source electrode of (2) is connected with a capacitor CLNegative electrode of (1), Q2Drain electrode, Q4Drain electrode of (1), capacitor C4Is connected to the cathode, the drain is connected to the inductor L3Capacitor C1To (c) to (d); inductor L2One end is connected with a capacitor CLThe anode of the voltage side power supply and the other end of the voltage side power supply are connected with a capacitor C2Positive electrode of (2), Q3Is connected to the inductor L2And a capacitor C2Between, capacitance C2Is connected to Q4、Q5Q of4Source and Q of5Drain electrode connection of, Q4Is connected to the negative pole of the voltage side power supply; inductor L1One end of which is connected with a capacitor CLThe positive pole of the voltage side power supply, and the other end of the voltage side power supply is connected with Q6Source electrode of, Q5Is connected to the inductance L1、Q6And connected to the switched capacitor module; q6Is connected to the switched capacitor module and the capacitor C4Between the positive electrodes of (1), a capacitance C4Is connected to the negative pole of the voltage side power supply.
In the above circuit, S1、S2、S3、S4、S5、S6For driving the switching device during a switching period TSInternal, driving signal S1、S3And S5Same and duty ratio of d, S2、S4And S6Is the same as S1、S3And S5Complementary, duty cycle 1-d, switching frequency fS＝1/TS。
Optionally, the switched capacitor module is composed of a capacitor C3And CHSwitching device Q7And Q8Composition, capacitance C3The negative electrode of the three-group cascade Boost circuit is connected with the Q of the three-group cascade Boost circuit5Drain electrode, Q6Source and inductor L1One terminal of (C), a capacitor3Positive electrode of (2) is connected with Q7Drain electrode of (1) and Q8Source electrode of, Q7Source electrode of (2) is connected to Q6Drain electrode of (1), capacitor C4Positive electrode of (2), Q8The drain of the second transistor is connected with the anode of the high-voltage side power supply.
In the above circuit, S7And S8For switching devices Q7And Q8Driving signal of S7And S1、S3And S5Same, S8And S2、S4And S6The same is true.
According to a second aspect of the present invention, there is provided a control method for the above bidirectional DC-DC converter, where the converter is in Boost operating mode, energy flows from the low voltage side to the high voltage side, the circuit performs Boost operation, and R isHThe Boost mode is divided into a mode 1 and a mode 2 for a high-voltage side load resistor according to the difference of the conduction sequence and the current path of a switching device,
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Forward conduction, Q7Conducting reversely; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Charging and storing energy;capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; high-voltage side load RHFrom CHSupplying power;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting reversely; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; high-voltage side load RHFrom C3And (5) supplying power.
According to a third aspect of the present invention, there is provided another control method for the above bidirectional DC-DC converter, wherein the converter is in Buck mode, energy flows from the high voltage side to the low voltage side, the circuit performs Buck operation, and R is a voltage-controlled rectifierLFor the low-voltage side load resistor, the Buck mode is divided into a mode 1 mode and a mode 2 mode according to the conduction sequence of the switching devices and the difference of current paths:
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Reverse conduction, Q7Conducting in the forward direction; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; low side load RLConsuming energy;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting in the forward direction; inductor L1、L2And L3Charging and storing energy; capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; low side load RLConsuming energy.
According to a third aspect of the present invention, there is provided an electronic terminal comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor is configured to execute the method for controlling the Boost cascade and switched capacitor bidirectional DC-DC converter when executing the program.
According to a fourth aspect of the invention, a computer-readable storage medium is provided, on which a computer program is stored which, when being executed by a processor, is adapted to carry out the method of Boost cascade and switched capacitor bidirectional DC-DC converter as described.
Compared with the prior art, the embodiment of the invention has at least one of the following beneficial effects:
according to the bidirectional DC-DC converter composed of the three groups of cascade Boost circuits and the switched capacitor module, a new group of Boost circuits and the switched capacitor module are introduced, so that the voltage gain of the converter is increased, the voltage stress borne by a switching device is reduced, the bidirectional DC-DC converter has high voltage gain and lower voltage stress of the switching device, and the current stress of a low-voltage side inductor is smaller and is easy to control.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
FIG. 1 is a circuit diagram of a non-isolated bi-directional DC-DC converter in accordance with a preferred embodiment of the present invention;
FIG. 2 is a diagram of the Boost mode of operation of the converter and its current path in a preferred embodiment of the present invention;
FIG. 3 is a block diagram of the Buck mode of operation of the converter and its current path in a preferred embodiment of the present invention;
FIG. 4 shows an inductor L in Boost mode in a preferred embodiment of the present invention1、L2And L3The current waveform at (c);
FIG. 5 is a low-side current waveform in Boost mode in a preferred embodiment of the present invention;
FIG. 6 is a graph showing the output high side voltage waveform in Boost mode in a preferred embodiment of the present invention;
FIG. 7 shows an inductor L in Buck mode in a preferred embodiment of the present invention1、L2And L3The current waveform at (c);
FIG. 8 is a low side current waveform in Buck mode according to a preferred embodiment of the present invention;
FIG. 9 is a voltage waveform of Buck output low side in a preferred embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
The invention provides a novel non-isolated bidirectional DC-DC converter which is provided with three groups of cascaded bidirectional Boost circuits and a switched capacitor module and has the characteristics of high voltage gain, low voltage stress of a switching device and the like. The current is divided into three branches at the low-voltage side, so that the current stress borne by the inductor is reduced. In addition, the control method is simple.
FIG. 1 is a non-isolated bidirectional DC-DC converter with three cascaded bidirectional Boost circuits on the low-voltage side, where the voltage on the low-voltage side is V, according to a preferred embodiment of the present inventionL。
The three cascaded sets of Boost circuits comprise three sets of Boost circuits. The first group of Boost circuits is composed of a capacitor CL、C1Inductance L3Switching device Q1、Q2Composition of wherein CLIs a low side capacitance. Second group of Boost powerRouting capacitor C2Inductance L2Switching device Q3、Q4And (4) forming. The third group of Boost circuits is composed of a capacitor C4Inductance L1Switching device Q5、Q6And (4) forming. And the third group of Boost circuits are newly added Boost circuits.
Capacitor CLThe negative electrode of the capacitor C is connected with the negative electrode of the power supplyLIs connected with the positive pole of the voltage side power supply and the inductor L3One terminal of (1), inductance L3The other end of the capacitor C is connected with a capacitor C1Positive electrode of (2), Q2Source electrode of (2) is connected to Q3Source electrode of (1), capacitor C1Is connected to Q2Source and Q of3Between the source electrodes of, Q2The drain electrode of the power supply is connected with the negative electrode of a voltage side power supply; q1Source electrode of (2) is connected with a capacitor CLNegative electrode of (1), Q2Drain electrode, Q4Drain electrode of (1), capacitor C4Is connected to the cathode, the drain is connected to the inductor L3Capacitor C1To (c) to (d); inductor L2One end is connected with a capacitor CLThe anode of the voltage side power supply and the other end of the voltage side power supply are connected with a capacitor C2Positive electrode of (2), Q3Is connected to the inductor L2And a capacitor C2Between, capacitance C2Is connected to Q4、Q5Q of4Source and Q of5Drain electrode connection of, Q4Is connected to the negative pole of the voltage side power supply; inductor L1One end of which is connected with a capacitor CLThe positive pole of the voltage side power supply, and the other end of the voltage side power supply is connected with Q6Source electrode of, Q5Is connected to the inductance L1、Q6And connected to the switched capacitor module; q6Is connected to the switched capacitor module and the capacitor C4Between the positive electrodes of (1), a capacitance C4Is connected to the negative pole of the voltage side power supply.
In FIG. 1, S1、S2、S3、S4、S5、S6Are switching devices Q, respectively1、Q2、Q3、Q4、Q5、Q6In a switching period TSInternal, driving signal S1、S3And S5Same and duty ratio of d, S2、S4And S6Is the same as S1、S3And S5Complementary, duty cycle 1-d, switching frequency fS＝1/TS。
The high-voltage side of the converter comprises a switched capacitor module consisting of a capacitor C3And a capacitor CHSwitching device Q7And Q8Composition of wherein CHIs a high side capacitance. Capacitor C3The negative electrode of the three-group cascade Boost circuit is connected with the Q of the three-group cascade Boost circuit5Drain electrode, Q6Source and inductor L1One terminal of (C), a capacitor3Positive electrode of (2) is connected with Q7Drain electrode of (1) and Q8Source electrode of, Q7Source electrode of (2) is connected to Q6Drain electrode of (1), capacitor C4Positive electrode of (2), Q8The drain of the second transistor is connected with the anode of the high-voltage side power supply.
In FIG. 1, S7And S8For switching devices Q7And Q8Driving signal of S7And S1、S3And S5Same, S8And S2、S4And S6The same is true. i.e. iL1For flowing through the inductance L1Current of (i)L2For flowing through the inductance L2Current of (i)L3For flowing through the inductance L3The current of (2). i.e. iLIs a low side current, iHIs the high side current. I isL1、IL2、IL3、IL、IHIs iL1、iL2、iL3、iL、iHAverage value of the switching period of (a). i.e. iC1、iC2、iC3、iC4And iCHTo flow through a capacitor C1、C2、C3And CHThe current of (2). VC1、VC2、VC3、VC4And VHIs a capacitor C1、C2、C3、C4And CHVoltage of where VHI.e. the high side voltage of the converter.
In the above embodiments of the present invention, the three sets of cascaded Boost circuits enable the converter to have a large voltage gain in a cascaded manner. Meanwhile, the three groups of cascaded Boost circuits divide the low-voltage side current into three different branches, so that the current stress on the inductor is reduced. The switch capacitor module further improves the voltage gain of the converter by using the switch devices and the switch capacitors, and simultaneously reduces the voltage stress born by all the switch devices.
Based on the Boost cascade and switched capacitor bidirectional DC-DC converter, in another embodiment, the invention also provides a control method of the converter, specifically, when the converter is in a Boost working mode, energy flows from a low-voltage side to a high-voltage side, a circuit realizes Boost operation, and R isHThe Boost mode is divided into a mode 1 and a mode 2 for a high-voltage side load resistor according to the difference of the conduction sequence and the current path of a switching device,
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Forward conduction, Q7Conducting reversely; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Charging and storing energy; capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; high-voltage side load RHFrom CHSupplying power;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting reversely; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; high-voltage side load RHFrom C3And (5) supplying power.
In addition, when the converter is in a Buck working mode, energy flows from the high-voltage side to the low-voltage side, the circuit realizes step-down operation, and R isLFor the low-voltage side load resistor, the Buck mode is divided into a mode 1 mode and a mode 2 mode according to the conduction sequence of the switching devices and the difference of current paths:
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Reverse conduction, Q7Conducting in the forward direction; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; low side load RLConsuming energy;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting in the forward direction; inductor L1、L2And L3Charging and storing energy; capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; low side load RLConsuming energy.
The control method in the embodiment of the invention can increase the voltage gain of the converter, reduce the voltage stress born by the switching device, has high voltage gain and lower voltage stress of the switching device, and has smaller current stress of the low-voltage side inductor, thereby being easy to control.
For simplicity of analysis, assuming that the capacitor, inductor and switching device are ideal components, the circuit operates in steady state and the capacitor voltage remains constant during a switching cycle. In addition, when the bidirectional DC-DC converter in the embodiment of the invention works, different voltage gains can be realized by controlling the duty ratio d by one variable, and the modulation and control method is simple. As described in the above method, the converter can be divided into two operation modes, i.e., Boost and Buck, according to the difference of the energy flow direction. The following detailed analysis was performed for these two modes of operation:
(1) boost mode steady state operating condition analysis
In the working mode, energy flows from the low-voltage side to the high-voltage side, and the circuit realizes boosting operation. RHIs a high-side load resistor. The Boost mode can be divided into two modes, mode 1 and mode 2, according to the conduction sequence of the switching device and the difference of the current path, as shown in fig. 2.
Mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSIn fig. 2, (a) is an equivalent circuit diagram of the switching device in this mode, and the driving signal S is1S2S3S4＝1010,S5S6S7S8＝1010。Q1、Q3And Q5Forward conduction, Q7And conducting in the reverse direction. Q2、Q4、Q6And Q8And (6) turning off. Inductor L1、L2And L3Charge and store energy. Capacitor C1、C2、C4And CHDischarge, capacitance C3And (6) charging. High-voltage side load RHFrom CHAnd (5) supplying power.
Mode 2: when the time is at dTS≤t≤TSIn fig. 2, (b) is an equivalent circuit diagram of the switching device in this mode, and the driving signal S is1S2S3S4＝0101,S5S6S7S8＝0101。Q1、Q3、Q5And Q7And (6) turning off. Q2、Q4、Q6And Q8And conducting in the reverse direction. Inductor L1、L2And L3Discharges and releases energy. Capacitor C1、C2、C4And CHCharging, capacitance C3And (4) discharging. High-voltage side load RHFrom C3And (5) supplying power.
(2) Buck mode steady state operating condition analysis
In the working mode, energy flows from the high-voltage side to the low-voltage side, and the circuit realizes voltage reduction operation. RLIs a low-side load resistor. The Buck mode can be divided into two modes, mode 1 and mode 2, according to the conduction sequence of the switching device and the difference of the current path, as shown in fig. 3.
Mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSIn fig. 3, (a) is an equivalent circuit diagram of the switching device in this mode, and the driving signal S is1S2S3S4＝1010,S5S6S7S8＝1010。Q1、Q3And Q5Reverse conduction, Q7And conducting in the forward direction. Q2、Q4、Q6And Q8And (6) turning off. Inductor L1、L2And L3Discharges and releases energy. Capacitor C1、C2、C4And CHCharging, capacitance C3And (4) discharging. Low side load RLConsuming energy.
Mode 2: when the time is at dTS≤t≤TSIn fig. 3, (b) is an equivalent circuit diagram of the switching device in this mode, and the driving signal S is1S2S3S4＝0101,S5S6S7S8＝0101。Q1、Q3、Q5And Q7And (6) turning off. Q2、Q4、Q6And Q8And conducting in the forward direction. Inductor L1、L2And L3Charge and store energy. Capacitor C1、C2、C4And CHDischarge, capacitance C3And (6) charging. Low side load RLConsuming energy.
(3) Converter voltage and current relationship analysis
Voltage relation: in a switching period TSTo the inductance L1、L2And L3Applying volt-second balance principle and kirchhoff's voltage law to all loops, equations (1) to (5) can be obtained, equation (1) represents the ratio of the low-side voltage and the high-side voltage of the converter,i.e., voltage gain, and equations (2), (3), (4), and (5) give the capacitance C1To C4The voltage of (c).
Figure BDA0003253503930000081
Figure BDA0003253503930000082
Figure BDA0003253503930000083
Figure BDA0003253503930000084
Figure BDA0003253503930000085
The current relationship: by a capacitor C1The ampere-second balance of (2) is an example to illustrate the ampere-second balance theorem, as shown in equation (6):
Figure BDA0003253503930000086
equation (6) illustrates that during a switching cycle, the capacitor C is in steady state1And the charge and discharge balance is realized. Likewise, in a switching period TSInternal pair of capacitors CL、C1、C2、C4And CHThe ampere-second balance theorem is applied and the current paths are analyzed in Boost and Buck modes, so that the current relation can be obtained as shown in formulas (7) to (10):
Figure BDA0003253503930000087
Figure BDA0003253503930000088
Figure BDA0003253503930000089
Figure BDA00032535039300000810
the equations (7) to (10) show that the low-voltage side is influenced by the introduction of a current into the inductor L1、L2And L3The three different branches reduce the current stress on the inductor.
Voltage stress of the switching device: switching device Q1To Q8Subjected to a voltage stress of VQ1、VQ2、VQ3、VQ4、VQ5、VQ6、VQ7And VQ8The relationship is shown in formulas (11) to (15):
Figure BDA0003253503930000091
Figure BDA0003253503930000092
Figure BDA0003253503930000093
Figure BDA0003253503930000094
Figure BDA0003253503930000095
general formula (11)In (15), the maximum voltage stress to which the switching device is subjected is equal to VC3Since 0 < d < 1, formula (16) can be obtained:
Figure BDA0003253503930000096
from equation (16), the maximum voltage stress of the switching device is reduced, which is less than the high-side voltage VH。
The invention is proved to be feasible through simulation verification. The parameters of the main circuit in the simulation are shown in table 1.
TABLE 1 simulation model parameters
Boost mode low side voltage VL 24V Boost mode duty cycle d 0.2
Buck mode high side voltage VH 329V Buck mode duty cycle d 0.4
Switching frequency fs 20kHz Capacitor CL、C1、C2 360μF
Inductor L1 1000μH Capacitor C3、C4、CH 240μF
Inductor L2 600μH Low side load RL 0.8Ω
Inductor L3 300μH High-voltage side load RH 50.39Ω
(1) Simulation waveform in Boost mode
As shown in fig. 4-6, wherein fig. 4 is the inductor L in Boost mode1、L2And L3Fig. 5 is a low-voltage-side current waveform in the Boost mode, and fig. 6 is a high-voltage-side voltage waveform output in the Boost mode.
In the Boost mode, the duty ratio d is 0.2, and the high-side load R isH50.38 omega, the low-voltage side is an ideal voltage source with a voltage value VL24V. FIG. 4 shows an inductor L1、L2And L3Current i ofL1、iL2And iL3The simulated waveform of (2). FIG. 5 shows the low side current iLThe simulated waveform of (2). FIG. 6 shows the high-side output voltage VHThe simulated waveform of (2). i.e. iL1、iL2、iL3、iLAnd VHThe average switching period of (a) is shown in table 2.
(2) Simulation waveform in Buck mode
As shown in fig. 7-9, wherein fig. 7 shows the inductance L in Buck mode1、L2And L3Fig. 8 shows a low-voltage side current waveform in the Buck mode, and fig. 9 shows a low-voltage side voltage waveform of the Buck output.
In the Buck mode, the duty ratio d is 0.4, and the low-side load R is lowL0.8 omega, the high-voltage side is an ideal voltage source VH329V. FIG. 7 shows an inductor L1、L2And L3Current i ofL1、iL2And iL3The simulated waveform of (2). FIG. 8 shows the low side current iLThe simulated waveform of (2). FIG. 9 shows the low-side output voltage VLThe simulated waveform of (2). i.e. iL1、iL2、iL3、iLAnd VLThe average switching period of (a) is shown in table 2.
(3) Average value of switch period of inductive current and capacitor voltage
Table 2 shows the average values of the switching periods of the current and voltage variations of this bidirectional DC-DC converter operating in Boost mode and in Buck mode. From fig. 4 to 9, and table 2, it can be concluded that: the bidirectional DC-DC converter has correct steady-state theoretical analysis result and has the advantages of high voltage gain, lower voltage stress of a switching device, lower inductive current stress and the like.
Table 2 simulation calculated switching period average for two operating modes
Figure BDA0003253503930000101
Figure BDA0003253503930000111
Based on the same technical concept, another embodiment of the present invention further provides an electronic terminal, which includes a memory, a processor, and a computer program stored in the memory and capable of running on the processor, wherein the processor is configured to execute the control method for the Boost cascade and the switched capacitor bidirectional DC-DC converter when executing the program.
Based on the same technical concept, another embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, is configured to perform the method for the Boost cascade and switched capacitor bidirectional DC-DC converter.
The embodiment of the invention relates to a bidirectional DC-DC converter which is composed of three groups of cascade Boost circuits and a switched capacitor module, has high voltage gain and lower voltage stress of a switching device, and simultaneously reduces the current stress of an inductor.
According to the invention, a new group of Boost circuits and switched capacitor modules are introduced, so that the voltage gain of the converter is increased, and the voltage stress borne by a switching device is reduced.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The above-described preferred features may be used in any combination without conflict with each other.

Claims (10)

1. A Boost cascade and switched capacitor bidirectional DC-DC converter is characterized by comprising three groups of cascade Boost circuits and switched capacitor modules connected with the Boost circuits, wherein the switched capacitor modules are positioned on a high-voltage side; the three cascaded sets of Boost circuits are located on a low-voltage side, wherein:
the three groups of cascaded Boost circuits enable the converter to have large voltage gain in a cascaded mode, and meanwhile, current is divided into three branches on the low-voltage side, so that current stress borne by the inductor is reduced.
2. The Boost cascaded and switched capacitor bidirectional DC-DC converter of claim 1, wherein the three sets of cascaded Boost circuits, wherein:
the first group of Boost circuits is composed of a capacitor CL、C1Inductance L3Switching device Q1、Q2Composition of wherein CLA low-side capacitor;
second groupBoost circuit is by electric capacity C2Inductance L2Switching device Q3、Q4Composition is carried out;
the third group of Boost circuits is composed of a capacitor C4Inductance L1Switching device Q5、Q6Composition is carried out;
capacitor CLThe negative electrode of the capacitor C is connected with the negative electrode of the power supplyLIs connected with the positive pole of the voltage side power supply and the inductor L3One terminal of (1), inductance L3The other end of the capacitor C is connected with a capacitor C1Positive electrode of (2), Q2Source electrode of (2) is connected to Q3Source electrode of (1), capacitor C1Is connected to Q2Source and Q of3Between the source electrodes of, Q2The drain electrode of the power supply is connected with the negative electrode of a voltage side power supply; q1Source electrode of (2) is connected with a capacitor CLNegative electrode of (1), Q2Drain electrode, Q4Drain electrode of (1), capacitor C4Is connected to the cathode, the drain is connected to the inductor L3Capacitor C1To (c) to (d); inductor L2One end is connected with a capacitor CLThe anode of the voltage side power supply and the other end of the voltage side power supply are connected with a capacitor C2Positive electrode of (2), Q3Is connected to the inductor L2And a capacitor C2Between, capacitance C2Is connected to Q4、Q5Q of4Source and Q of5Drain electrode connection of, Q4Is connected to the negative pole of the voltage side power supply; inductor L1One end of which is connected with a capacitor CLThe positive pole of the voltage side power supply, and the other end of the voltage side power supply is connected with Q6Source electrode of, Q5Is connected to the inductance L1、Q6And connected to the switched capacitor module; q6Is connected to the switched capacitor module and the capacitor C4Between the positive electrodes of (1), a capacitance C4Is connected to the negative pole of the voltage side power supply.
3. The Boost cascade and switched capacitor bidirectional DC-DC converter according to claim 2, wherein the switching device Q1、Q2、Q3、Q4、Q5、Q6Corresponding drive signal is S1、S2、S3、S4、S5、S6In a switching period TSInternal, driving signal S1、S3And S5Same and duty ratio of d, S2、S4And S6Is the same as S1、S3And S5Complementary, duty cycle 1-d, switching frequency fS＝1/TS。
4. The Boost cascade and switched capacitor bidirectional DC-DC converter of claim 3, wherein the switched capacitor module is composed of a capacitor C3And CHSwitching device Q7And Q8Composition, capacitance C3The negative electrode of the three-group cascade Boost circuit is connected with the Q of the three-group cascade Boost circuit5Drain electrode, Q6Source and inductor L1One terminal of (C), a capacitor3Positive electrode of (2) is connected with Q7Drain electrode of (1) and Q8Source electrode of, Q7Source electrode of (2) is connected to Q6Drain electrode of (1), capacitor C4Positive electrode of (2), Q8The drain of the second transistor is connected with the anode of the high-voltage side power supply.
5. The Boost cascade and switched capacitor bidirectional DC-DC converter according to claim 4, wherein the switching device Q7And Q8Has a drive signal of S7And S8，S7And S1、S3And S5Same, S8And S2、S4And S6The same is true.
6. A control method of a Boost cascade and switched capacitor bidirectional DC-DC converter according to any one of claims 1 to 5, characterized in that the converter is in a Boost working mode, energy flows from a low-voltage side to a high-voltage side, a circuit realizes Boost operation, and R isHThe Boost mode is divided into a mode 1 and a mode 2 for a high-voltage side load resistor according to the difference of the conduction sequence and the current path of a switching device,
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Forward conduction, Q7Conducting reversely; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Charging and storing energy; capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; high-voltage side load RHFrom CHSupplying power;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting reversely; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; high-voltage side load RHFrom C3And (5) supplying power.
7. A control method of a Boost cascade and switched capacitor bidirectional DC-DC converter as claimed in any one of claims 1-5, characterized in that the converter is in Buck operation mode, energy flows from high voltage side to low voltage side, the circuit realizes step-down operation, R is RLFor the low-voltage side load resistor, the Buck mode is divided into a mode 1 mode and a mode 2 mode according to the conduction sequence of the switching devices and the difference of current paths:
mode 1: when the time is more than or equal to 0 and less than or equal to t and less than or equal to dTSTime of day, drive signal S of switching device1S2S3S4＝1010,S5S6S7S8＝1010；Q1、Q3And Q5Reverse conduction, Q7Conducting in the forward direction; q2、Q4、Q6And Q8Turning off; inductor L1、L2And L3Discharging and releasing energy; capacitor C1、C2、C4And CHCharging, capacitance C3Discharging; low side load RLConsuming energy;
mode 2: when the time is at dTS≤t≤TSTime of day, drive signal S of switching device1S2S3S4＝0101,S5S6S7S8＝0101；Q1、Q3、Q5And Q7Turning off; q2、Q4、Q6And Q8Conducting in the forward direction; inductor L1、L2And L3Charging and storing energy; capacitor C1、C2、C4And CHDischarge, capacitance C3Charging; low side load RLConsuming energy.
8. A method for controlling a Boost cascade and switched capacitor bidirectional DC-DC converter according to claim 6 or 7, characterized in that in one switching period TSInternal, driving signal S1、S3And S5Same and duty ratio of d, S2、S4And S6Is the same as S1、S3And S5Complementary, duty cycle 1-d, switching frequency fS＝1/TS；
When the bidirectional DC-DC converter works, different voltage gains can be realized by controlling the duty ratio d to be one variable.
9. An electronic terminal comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor is configured to execute the method for controlling a Boost cascade and switched capacitor bidirectional DC-DC converter according to any one of claims 6 to 8 when executing the program.
10. A computer readable storage medium having stored thereon a computer program, characterized in that the program, when being executed by a processor, is adapted to perform the method of Boost cascade and switched capacitor bidirectional DC-DC converter according to any of the claims 6-8.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140043010A1 (en) * 2012-08-12 2014-02-13 Loai Galal Bahgat Salem Recursive dc-dc converter
CN112511003A (en) * 2020-11-24 2021-03-16 上海交通大学 Bidirectional DC/DC converter and control method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20140043010A1 (en) * 2012-08-12 2014-02-13 Loai Galal Bahgat Salem Recursive dc-dc converter
CN112511003A (en) * 2020-11-24 2021-03-16 上海交通大学 Bidirectional DC/DC converter and control method thereof

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