CN116995923B - Control method and control device for direct-current voltage conversion circuit - Google Patents

Control method and control device for direct-current voltage conversion circuit Download PDF

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Publication number
CN116995923B
CN116995923B CN202311237590.5A CN202311237590A CN116995923B CN 116995923 B CN116995923 B CN 116995923B CN 202311237590 A CN202311237590 A CN 202311237590A CN 116995923 B CN116995923 B CN 116995923B
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branch
inductor
duty ratio
switch tube
parallel
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CN116995923A (en
Inventor
李哲峰
舒伟
董汉
陈超
李忠桥
王亚飞
张翠杰
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Suzhou Tsing Standard Automobile Technology Co ltd
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Suzhou Tsing Standard Automobile Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/1566—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
    • 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
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • 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

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

Abstract

The embodiment of the invention relates to the technical field of circuit control, in particular to a control method and a control device of a direct-current voltage conversion circuit. The control method comprises the following steps: after the voltage gain of the direct-current voltage conversion circuit reaches a first gain threshold value smaller than 1, the duty ratio of the first branch circuit is adjusted to be a set value, the set value is smaller than the upper limit value of the duty ratio, and the duty ratio of the second branch circuit is adjusted to be the lower limit value of the duty ratio; controlling the duty ratio of the first branch to be increased, and keeping the duty ratio of the second branch unchanged so as to increase the voltage gain; and after the duty ratio of the first branch is increased to the duty ratio upper limit value, keeping the duty ratio of the first branch unchanged, and controlling the duty ratio of the second branch to be increased so as to enable the voltage gain to be continuously increased until a second gain threshold value larger than 1 is reached. The embodiment of the specification can realize the smooth transition of the direct-current voltage conversion circuit between the step-up mode and the step-down mode.

Description

Control method and control device for direct-current voltage conversion circuit
Technical Field
The present disclosure relates to the field of circuit control technologies, and in particular, to a control method and a control device for a dc voltage conversion circuit.
Background
A dc voltage conversion circuit, also called a DCDC converter, is a device for converting a dc power supply of a certain voltage level into a dc power supply of another voltage level, and is widely used in various fields. For example, in the fields of new energy and energy storage application, there are situations where power supply to a load is required, and there are situations where discharging a battery is required, and thus a dc voltage conversion circuit is required.
The direct-current voltage conversion circuit can realize voltage boosting and voltage reduction. In the existing control method, when the direct-current voltage conversion circuit is controlled to be converted into a buck mode from a boost mode or converted into a boost mode from a buck mode, the voltage gain of the direct-current voltage conversion circuit cannot realize smooth transition due to the limitation of a dead zone of a switching tube, the minimum pulse width and other reasons.
Disclosure of Invention
The embodiment of the specification provides a control method of a direct-current voltage conversion circuit, which is used for enabling the voltage conversion circuit to smoothly transition between a buck mode and a boost mode.
The embodiment of the specification provides a control method of a direct-current voltage conversion circuit, wherein the direct-current voltage conversion circuit comprises a first branch and a second branch which are coupled through an inductor, the first branch comprises a first bridge arm and a second bridge arm which are connected in series, the second branch comprises a third bridge arm and a fourth bridge arm which are connected in series, and the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm comprise switching tubes which are connected in series; the method comprises the following steps:
After the voltage gain of the direct-current voltage conversion circuit reaches a first gain threshold value smaller than 1, the duty ratio of the first branch circuit is adjusted to be a set value, the set value is smaller than the upper limit value of the duty ratio, and the duty ratio of the second branch circuit is adjusted to be the lower limit value of the duty ratio;
Controlling the duty ratio of the first branch to be increased, and keeping the duty ratio of the second branch unchanged so as to increase the voltage gain;
And after the duty ratio of the first branch is increased to the duty ratio upper limit value, keeping the duty ratio of the first branch unchanged, and controlling the duty ratio of the second branch to be increased so as to enable the voltage gain to be continuously increased until a second gain threshold value larger than 1 is reached.
The embodiment of the specification also provides another control method of the direct-current voltage conversion circuit, wherein the direct-current voltage conversion circuit comprises a first branch and a second branch which are coupled through an inductor, the first branch comprises a first bridge arm and a second bridge arm which are connected in series, the second branch comprises a third bridge arm and a fourth bridge arm which are connected in series, and the first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm comprise switching tubes which are connected in series; the method comprises the following steps:
after the voltage gain of the direct-current voltage conversion circuit reaches a second gain threshold value which is larger than 1, the duty ratio of the first branch circuit is adjusted to be the upper limit value of the duty ratio, and the duty ratio of the second branch circuit is adjusted to be a set value which is larger than the lower limit value of the duty ratio;
the duty ratio of the first branch is kept unchanged, and the duty ratio of the second branch is controlled to be reduced so as to reduce the voltage gain;
And after the duty ratio of the second branch is reduced to the duty ratio lower limit value, keeping the duty ratio of the second branch unchanged, and controlling the duty ratio of the first branch to be reduced so as to enable the voltage gain to be continuously reduced until a first gain threshold value smaller than 1 is reached.
The embodiment of the specification provides a control device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the control method when executing the computer program.
In the control method of the embodiment of the present disclosure, after the voltage gain of the dc voltage conversion circuit reaches a first gain threshold value smaller than 1, the duty cycle of the first branch may be adjusted to a set value, and the duty cycle of the second branch may be adjusted to a duty cycle lower limit value; the duty cycle of the first branch can be controlled to be increased, and the duty cycle of the second branch is kept unchanged, so that the voltage gain is increased; after the duty cycle of the first branch is increased to the duty cycle upper limit value, the duty cycle of the first branch can be kept unchanged, and the duty cycle of the second branch is controlled to be increased, so that the voltage gain is continuously increased until a second gain threshold value larger than 1 is reached. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from less than 1 to more than 1, the smooth transition of the direct-current voltage conversion circuit from a voltage reduction mode to a voltage boosting mode is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
In the control method of the embodiment of the present disclosure, after the voltage gain of the dc voltage conversion circuit reaches a second gain threshold greater than 1, the duty cycle of the first branch may be adjusted to an upper limit value of the duty cycle, and the duty cycle of the second branch may be adjusted to a set value; the duty ratio of the first branch circuit can be kept unchanged, and the duty ratio of the second branch circuit is controlled to be reduced so as to reduce the voltage gain; after the duty ratio of the second branch is reduced to the duty ratio lower limit value, the duty ratio of the second branch can be kept unchanged, and the duty ratio of the first branch is controlled to be reduced, so that the voltage gain is continuously reduced until a first gain threshold value smaller than 1 is reached. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from more than 1 to less than 1, the smooth transition from the voltage boosting mode to the voltage reducing mode of the direct-current voltage conversion circuit is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present description or the solutions in the prior art, the drawings that are required for the embodiments or the description of the prior art will be briefly described, the drawings in the following description are only some embodiments described in the present description, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a topology diagram of a dc voltage conversion circuit in an embodiment of the present disclosure;
fig. 2 is a flowchart of a control method of the dc voltage conversion circuit in the present specification;
fig. 3 is a schematic diagram illustrating a control process of the dc voltage conversion circuit in the embodiment of the present disclosure;
FIG. 4a is a timing diagram of control signals in buck mode according to the embodiment of the present disclosure;
FIG. 4b is a timing chart of the control signals in the transition mode according to the embodiment of the present disclosure;
FIG. 4c is a timing chart of the control signals in the boost mode according to the embodiment of the present disclosure;
fig. 5 is a schematic diagram of a control process of the dc voltage conversion circuit in the embodiment of the present disclosure;
FIGS. 6 a-6 d are schematic diagrams illustrating the current flow in the buck mode according to the embodiments of the present disclosure;
FIGS. 7a-7 e are schematic diagrams illustrating the current flow during a first sub-period of a transition mode according to embodiments of the present disclosure;
FIGS. 7 f-7 j are schematic diagrams illustrating the current flow during the second sub-period in the transition mode according to the embodiments of the present disclosure;
FIGS. 8 a-8 d are schematic diagrams illustrating the current flow in the boost mode according to the embodiments of the present disclosure;
Fig. 9 is a flowchart of a control method of the dc voltage conversion circuit in the present specification.
Detailed Description
The technical solutions of the embodiments of the present specification will be clearly and completely described below with reference to the drawings in the embodiments of the present specification, and it is apparent that the described embodiments are only some embodiments of the present specification, not all embodiments. The specific embodiments described herein are to be considered in an illustrative rather than a restrictive sense. All other embodiments derived by a person of ordinary skill in the art based on the described embodiments of the present disclosure fall within the scope of the present disclosure. In addition, relational terms such as "first" and "second", and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
In addition, in the above-mentioned existing control method, when the direct-current voltage conversion circuit is controlled to be converted from the boost mode to the buck mode or from the buck mode to the boost mode, all switching tubes in the direct-current voltage conversion circuit need to work at a higher switching frequency, so that the loss is larger and the working efficiency is lower.
The embodiment of the specification provides a direct-current voltage conversion circuit.
In some embodiments, the dc voltage conversion circuit, also called DCDC converter, is used to convert a dc power supply of a certain voltage class into a dc power supply of another voltage class. The direct current voltage conversion circuit may include a first branch, a second branch, and an inductor coupling the first branch and the second branch. The first leg may include a first leg and a second leg connected in series. The second leg may include a third leg and a fourth leg connected in series. The first bridge arm, the second bridge arm, the third bridge arm and the fourth bridge arm respectively comprise serially connected switching tubes. The switching tube comprises a controllable switching tube, such as a MOS tube, an IGBT, a triode and the like. The inductor may include a first inductor for storing energy and a second inductor for storing energy. The first inductor may be connected across a midpoint of the first leg and a midpoint of the third leg. The second inductor may be connected across the midpoint of the second leg and the midpoint of the fourth leg. The midpoint may include a connection point of a series-connected switching tube in the bridge arm.
In some embodiments, please refer to fig. 1. The first bridge arm may include a first switching tube Q1P and a second switching tube Q2P connected in series, the second bridge arm may include a third switching tube Q3P and a fourth switching tube Q4P connected in series, the third bridge arm may include a fifth switching tube Q1S and a sixth switching tube Q2S connected in series, and the fourth bridge arm may include a seventh switching tube Q3S and an eighth switching tube Q4S connected in series. The first inductor L1 may be connected across the connection point a and the connection point c, and the second inductor may be connected across the connection point b and the connection point d. The connection point a is a connection point between the first switching tube Q1P and the second switching tube Q2P. The connection point b is a connection point between the third switching tube Q3P and the fourth switching tube Q4P. The connection point c is a connection point between the fifth switching tube Q1S and the sixth switching tube Q2S. The connection point d is a connection point between the seventh switching tube Q3S and the eighth switching tube Q4S.
In some embodiments, switching tubes in the first leg, the second leg, the third leg, and the fourth leg may be connected in parallel with diodes. The diode is used for providing a current reverse flow path. The direct-current voltage conversion circuit can be a bidirectional circuit, and bidirectional flow of current can be realized. It should be noted that the switching tube and the diode connected in parallel may be discrete components. Of course, the switching tube and the diode can also be integrated into one switching device. The switching device may include a switching tube and a diode connected in parallel therewith. So that bidirectional flow of current can be achieved with the diode inside the switching device.
In some embodiments, the first leg may be coupled to a power source (hereinafter referred to as a first power source) and the second leg may be coupled to a power source (hereinafter referred to as a second power source). The direct current voltage conversion circuit may be a bidirectional circuit. The direct-current voltage conversion circuit can be used for charging the second power supply by the first power supply and can also be used for discharging the first power supply by the second power supply.
It is contemplated that the voltage gain of the dc voltage conversion circuit may be greater than 1 or less than 1. The dc voltage conversion circuit may be used to charge the first power supply to the second power supply under buck, the first power supply to the second power supply under boost, the second power supply to the first power supply under boost, or the second power supply to the first power supply under buck.
In some embodiments, the first branch may further include a first capacitor c1p connected in parallel with the first leg, a second capacitor c2p connected in parallel with the second leg, a third capacitor c1s connected in parallel with the third leg, and a fourth capacitor c2s connected in parallel with the fourth leg. The first capacitor c1p and the second capacitor c2p may be connected in series. The third capacitor c1s and the fourth capacitor c2s may be connected in series. The first capacitor c1p, the second capacitor c2p, the third capacitor c1s and the fourth capacitor c2s are used for filtering.
The specification also provides a control method of the direct-current voltage conversion circuit.
Please refer to fig. 2 and fig. 5. The control method provided in the embodiment of the present specification may include the following steps.
Step 11: after the voltage gain of the direct-current voltage conversion circuit reaches a first gain threshold value smaller than 1, the duty ratio of the first branch circuit is adjusted to be a set value, and the duty ratio of the second branch circuit is adjusted to be a duty ratio lower limit value.
Step 12: and controlling the duty ratio of the first branch to be increased, and keeping the duty ratio of the second branch unchanged so as to increase the voltage gain.
Step 13: and after the duty ratio of the first branch is increased to the duty ratio upper limit value, keeping the duty ratio of the first branch unchanged, and controlling the duty ratio of the second branch to be increased so as to enable the voltage gain to be continuously increased until a second gain threshold value larger than 1 is reached.
In some embodiments, a dc voltage conversion circuit may be used to charge a first power source to a second power source. By controlling the direct current voltage conversion circuit, the voltage gain of the direct current voltage conversion circuit can be transited from a first gain threshold value smaller than 1 to a second gain threshold value larger than 1. The direct-current voltage conversion circuit can be smoothly transited from the buck mode to the boost mode.
In some embodiments, the duty cycle of the first leg may include a duty cycle of a switching tube in the first leg that is not directly coupled to the second leg. For example, the duty cycle of the first branch may be the duty cycle of the first switching tube Q1P or the duty cycle of the fourth switching tube Q4P. In some scene examples, the duty cycles of the first switching tube Q1P and the fourth switching tube Q4P may be the same, and the phases may be 180 ° out of phase. The duty ratios of the second switching transistor Q2P and the third switching transistor Q3P may be the same, and the phases may be 180 ° out of phase. The duty cycle of the first switching tube Q1P and the second switching tube Q2P may be complementary. The duty cycle of the third switching tube Q3P and the fourth switching tube Q4P are complementary. Where the duty cycle complementation is understood to mean that the sum of the duty cycles is equal to 1. Specifically, for example, the sum of the duty ratios of the first switching transistor Q1P and the second switching transistor Q2P may be equal to 1. Thus, when the first switching tube Q1P is turned on, the second switching tube Q2P is turned off; when the first switching tube Q1P is turned off, the second switching tube Q2P is turned on. The sum of the duty ratios of the third switching tube Q3P and the fourth switching tube Q4P may be equal to 1. Thus, when the third switching tube Q3P is turned on, the fourth switching tube Q4P is turned off; when the third switching tube Q3P is turned off, the fourth switching tube Q4P is turned on.
In some embodiments, the duty cycle of the second leg may include a duty cycle of a switching tube in the third leg directly coupled to the fourth leg. For example, the duty cycle of the second branch may be the duty cycle of the sixth switching tube Q2S or the duty cycle of the seventh switching tube Q3S. In some scene examples, the duty cycles of the fifth and eighth switching transistors Q1S and Q4S may be the same, and the phases may be 180 ° out of phase. The duty ratios of the sixth switching tube Q2S and the seventh switching tube Q3S may be the same, and the phases may be 180 ° out of phase. The duty ratios of the fifth switching tube Q1S and the sixth switching tube Q2S may be complementary. The duty ratios of the seventh switching tube Q3S and the eighth switching tube Q4S are complementary. Where the duty cycle complementation is understood to mean that the sum of the duty cycles is equal to 1. Specifically, for example, the sum of the duty ratios of the fifth switching tube Q1S and the sixth switching tube Q2S may be equal to 1. Thus, when the fifth switching tube Q1S is turned on, the sixth switching tube Q2S is turned off; when the fifth switching tube Q1S is turned off, the sixth switching tube Q2S is turned on. The sum of the duty ratios of the seventh switching tube Q3S and the eighth switching tube Q4S may be equal to 1. Thus, when the seventh switching tube Q3S is turned on, the eighth switching tube Q4S is turned off; when the seventh switching tube Q3S is turned off, the eighth switching tube Q4S is turned on.
In some embodiments, the duty cycles of the first and second legs may satisfy the following formula: ; where G represents the voltage gain of the dc voltage conversion circuit, D1 represents the duty cycle of the first branch, and D2 represents the duty cycle of the second branch.
The voltage gain of the dc voltage conversion circuit may comprise a ratio of voltages between the second branch and the first branch. For example, the voltage gain of the DC voltage conversion circuit may be expressed as. U1 is the voltage across the first branch, and U2 is the voltage across the second branch. Please refer to fig. 1. Voltage U ab=D1×U1 between points a and b. The duty ratio of the first switching tube Q1P is complementary with that of the second switching tube Q2P, and the duty ratio of the third switching tube Q3P and the fourth switching tube Q4P is complementary. The voltage U cd=（1-D2）×U2 between points c and d can be derived. Considering the volt-second balance relation of the inductance under the steady state condition, the method can obtain。
In some embodiments, due to the limitation of the dead zone of the switching tube, the minimum pulse width, and other reasons, the duty ratio of the first branch (or the second branch) cannot continue to increase continuously after reaching the upper limit value; the decrease in the continuity cannot be continued even after the duty cycle of the first branch (or the second branch) reaches the lower limit value. The upper limit value of the duty cycle may be denoted Dmax. The lower limit value of the duty cycle may be denoted Dmin, and the duty cycle of the first branch (or the second branch) may be 0, or may be 1, or may also be any value between [ Dmin, dmax ]. For example, dmax=0.95, dmin=0.05.
The duty cycle upper limit values of the first branch and the second branch may be equal. The duty cycle lower limit values of the first branch and the second branch may also be equal. The voltage gain when the duty ratio of the first branch is the upper limit value and the duty ratio of the second branch is 0 may be set as the first gain threshold of the dc voltage conversion circuit. In particular, the method comprises the steps of,. G1 represents a first gain threshold. /(I)Representing the upper limit value of the duty cycle of the first branch. The voltage gain when the duty ratio of the first branch is 1 and the duty ratio of the second branch is the lower limit value may be used as the second gain threshold of the dc voltage conversion circuit. Specifically,/>. G2 represents a second gain threshold. /(I)Representing the lower limit value of the duty cycle of the second branch.
In some embodiments, please refer to fig. 3. The current loop can be constructed by an inductor, and the voltage gain of the direct-current voltage conversion circuit can be determined by the current loop of the inductor. Specifically, the actual inductor current of the first inductor or the second inductor may be sampled; the voltage gain of the direct current voltage conversion circuit can be determined according to the actual inductor current. For example, the current loop of the inductor may be a negative feedback current loop, such that the voltage gain may be determined from the difference between the actual inductor current and the reference inductor current. Specifically, for example, the difference value may be input to a controller (e.g., PID controller) to obtain the voltage gain.
The reference inductor current may be obtained in any manner. For example, a current loop may be constructed by the second power supply, and the reference inductor current may be determined by the current loop of the second power supply. Specifically, the actual supply current of the second power supply may be sampled; the reference inductor current may be determined from the actual supply current and the reference supply current. For example, the current loop of the second power supply may be a negative feedback current loop, such that the reference inductor current may be determined from the difference between the actual power supply current and the reference power supply current. For example, the difference may be input to a controller (e.g., a PID controller) to obtain a reference inductor current.
The voltage gain of the dc voltage conversion circuit may be used to control the switching states of the switching tubes in the first and second branches. The first branch may correspond to a first modulation module. The voltage gain may be input to a first modulation module. The first modulation module may generate a modulation signal according to the voltage gain, and the modulation signal may include a direct current signal. The modulation signal may be compared with a triangular carrier signal to obtain a control signal for a switching tube in the first branch, where the control signal may include a PWM (Pulse Width Modulation ) control signal. For example, the control signal of the switching tube in the first branch may include g1p, g2p, g3p, g4p, etc. The control signals g1p, g2p, g3p and g4p are respectively used for controlling the switching states of the first switching tube, the second switching tube, the third switching tube and the fourth switching tube. g1p and g2p are complementary control signals, whose corresponding triangular carrier signals are in phase. g3p and g4p are complementary control signals, whose corresponding triangular carrier signals are in phase. g1p and g4p are 180 degrees apart and g2p and g3p are 180 degrees apart. In addition, the voltage gain may also be input to the second modulation module. The second modulation module may generate a modulation signal according to the voltage gain, which may include a direct current signal. The modulation signal may be compared with a triangular carrier signal to obtain a control signal of the switching tube in the second branch, where the control signal may include a PWM control signal. For example, the control signal of the switching tube in the second branch may comprise g1s, g2s, g3s, g4s, etc. The control signals g1s, g2s, g3s and g4s are respectively used for controlling the switching states of the fifth switching tube, the sixth switching tube, the seventh switching tube and the eighth switching tube. g1s and g2s are complementary control signals, and the corresponding triangular carrier signals are in phase. g3s and g4s are complementary control signals, and the corresponding triangular carrier signals are in phase. g1s and g4s are 180 degrees apart, and g2s and g3s are 180 degrees apart. The triangular carrier signal of g1p, the triangular carrier signal of g2p, the triangular carrier signal of g3s, and the triangular carrier signal of g4s may be in phase. The triangular carrier signal g3p, the triangular carrier signal g4p, the triangular carrier signal g1s, and the triangular carrier signal g2s may be in phase.
In some embodiments, the control process of the direct current voltage conversion circuit may include the following 3 stages.
Stage (1): the voltage gain of the direct current voltage conversion circuit is smaller than a first gain threshold value.
Under the condition that the voltage gain of the direct-current voltage conversion circuit is smaller than a first gain threshold, the voltage U1 of the first branch is higher than the voltage U2 at two ends of the second branch, and the direct-current voltage conversion circuit works in a step-down mode and can be used for charging the second power supply by the first power supply. The voltage of the second power supply can be increased continuously along with charging, so that the voltage gain of the direct-current voltage conversion circuit is increased continuously. In the buck mode, the duty cycle of the first branch may be controlled to increase, and the duty cycle of the second branch may be maintained at 0. The duty ratio of the second branch is 0, that is, the fifth switching tube Q1S and the eighth switching tube Q4S are in an on state, and the sixth switching tube Q2S and the seventh switching tube Q3S are in an off state. According to the formulaIt is known that the duty ratio of the first branch is increased, and the duty ratio of the second branch is 0, so that the voltage gain of the dc voltage conversion circuit can be increased. Thus, in the buck mode, the switching tube in the first branch is operated in the PWM state, and the switching state of the switching tube in the second branch is kept unchanged. All switching tubes in the direct-current voltage conversion circuit are prevented from working at a higher switching frequency, loss is reduced, and working efficiency is improved.
Please refer to fig. 4a. In the buck mode, T s represents a control period of the dc voltage conversion circuit.. F s may be the switching frequency of the switching tube. g1P is the PWM control signal of the first switching transistor Q1P. g1P is obtained by comparing the modulated signal of the first switching tube Q1P with the triangular carrier signal of the first switching tube Q1P. g4P is the PWM control signal of the fourth switching tube Q4P. g4P is obtained by comparing the modulated signal of the fourth switching tube Q4P with the triangular carrier signal of the fourth switching tube Q4P. g2S is the PWM control signal of the sixth switching tube Q2S. g2S is obtained by comparing the modulated signal of the sixth switching tube Q2S with the triangular carrier signal of the sixth switching tube Q2S. g3S is the PWM control signal of the seventh switching tube Q3S. g3S is obtained by comparing the modulated signal of the seventh switching tube Q3S with the triangular carrier signal of the seventh switching tube Q3S. The duty cycle of g2s and g3s is 0.IL is inductor current. According to the PWM control signal shown in fig. 4a, the current flow diagram of the dc voltage conversion circuit can be shown in fig. 6 a-6 d in one control period.
In fig. 6a, the current path may include: the first switch tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switch tube Q1S, the diode connected in parallel with the second power supply and the eighth switch tube Q4S, the second inductor L2, the diode connected in parallel with the third switch tube Q3P and the first capacitor C1P. Next in fig. 6b, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 6c, the current path may include: the diode, the first inductor L1, the diode, the second power supply and the diode, the second inductor L2, the fourth switch tube Q4P and the second capacitor C2P are connected in parallel, wherein the diode, the first inductor L1 and the diode, the second power supply and the diode, the second inductor L2, the fourth switch tube Q4P and the second capacitor C2P are connected in parallel. Next in fig. 6d, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P.
Stage (2): the voltage gain of the direct current voltage conversion circuit is larger than the first gain threshold value and smaller than the second gain threshold value.
After the voltage gain of the direct-current voltage conversion circuit is increased to a first gain threshold value, the direct-current voltage conversion circuit enters a transition mode. As described above, the voltage gain when the duty ratio of the first branch is the upper limit value and the duty ratio of the second branch is 0 may be used as the first gain threshold value. Therefore, after the voltage gain of the direct-current voltage conversion circuit is increased to the first gain threshold value, the duty ratio of the first branch is increased to the duty ratio upper limit value. In order to smoothly increase the voltage gain of the dc voltage conversion circuit, the duty ratio of the first branch may be adjusted from the upper limit value to a set value (hereinafter, referred to as a first set value), and the duty ratio of the second branch may be adjusted from 0 to the lower limit value. Wherein the first set value is smaller than the upper limit value of the duty ratio according to the following specific conditionsAnd (5) calculating to obtain the product. G1 represents a first gain threshold. D1 max denotes the upper limit value of the duty cycle of the first branch. D2 min denotes a duty cycle lower limit value of the second branch. D1 s denotes a first set value.
The duty cycle of the first leg may be controlled to increase, leaving the duty cycle of the second leg unchanged (i.e., keeping the duty cycle of the second leg at D2 min). According to the formulaIt can be seen that the duty ratio of the first branch is increased, and the duty ratio of the second branch is D2 min, so that the voltage gain of the dc voltage conversion circuit can be increased. After the duty cycle of the first leg is increased to the upper limit value, the duty cycle of the first leg may be kept unchanged (i.e., the duty cycle of the first leg is kept at D1 max), and the duty cycle of the second leg is controlled to be increased. According to the formula/>It can be seen that the duty ratio of the first branch is D1 max, and the duty ratio of the second branch is increased, so that the voltage gain of the dc voltage conversion circuit can be increased until the voltage gain reaches the second gain threshold greater than 1. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from less than 1 to more than 1, the smooth transition of the direct-current voltage conversion circuit from a voltage reduction mode to a voltage boosting mode is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
In the transition mode, the control period of the direct current voltage conversion circuit may include a first sub-period and a second sub-period. The duration of the first sub-period and the second sub-period may be the same or different. In the first sub-period of the control period, the switching tube in the first branch circuit can be enabled to work in a PWM state, and the switching state of the switching tube in the second branch circuit can be kept unchanged. In the second sub-period of the control period, the switching state of the switching tube in the first branch circuit can be kept unchanged, and the switching tube in the second branch circuit can be enabled to work in a PWM state. In this way, in the whole control period of the direct-current voltage conversion circuit, the first sub-period is similar to the step-down mode, the switching tube in the first branch works in a PWM state, and the switching state of the switching tube in the second branch is kept unchanged; the second sub-period is similar to the subsequent boost mode, the switching state of the switching tubes in the first branch remains unchanged, and the switching tubes in the second branch operate in PWM state. That is, in each sub-period, the number of switching tubes operating in the PWM state is consistent with that of the buck mode (or boost mode), so that all switching tubes in the dc voltage conversion circuit are prevented from operating at a higher switching frequency, loss in the transient process is reduced, and the working efficiency is improved.
Please refer to fig. 4b. In the transition mode, the control period of the DC voltage conversion circuit may be. The first sub-period is the first T s in the control period and the second sub-period is the second T s in the control period. In the first sub-period, the duty cycle of g2s and g3s is 0. In the second sub-period, the duty cycle of g1g and g4p is 1. g1P is the PWM control signal of the first switching transistor Q1P. g1P is obtained by comparing the modulated signal of the first switching tube Q1P with the triangular carrier signal of the first switching tube Q1P. g4P is the PWM control signal of the fourth switching tube Q4P. g4P is obtained by comparing the modulated signal of the fourth switching tube Q4P with the triangular carrier signal of the fourth switching tube Q4P. g2S is the PWM control signal of the sixth switching tube Q2S. g2S is obtained by comparing the modulated signal of the sixth switching tube Q2S with the triangular carrier signal of the sixth switching tube Q2S. g3S is the PWM control signal of the seventh switching tube Q3S. g3S is obtained by comparing the modulated signal of the seventh switching tube Q3S with the triangular carrier signal of the seventh switching tube Q3S. IL is inductor current. According to the PWM control signal shown in fig. 4b, the current flow diagram of the dc voltage conversion circuit can be shown in fig. 7 a-7 j in one control period. Fig. 7a to fig. 7e are schematic diagrams of current flow in the first sub-period, and fig. 7f to fig. 7j are schematic diagrams of current flow in the second sub-period.
In fig. 7a, the current path may include: the first switch tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switch tube Q1S, the diode connected in parallel with the second power supply and the eighth switch tube Q4S, the second inductor L2, the diode connected in parallel with the third switch tube Q3P and the first capacitor C1P. Next in fig. 7b, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 7c, the current path may include: the diode, the first inductor L1, the diode, the second power supply and the diode, the second inductor L2, the fourth switch tube Q4P and the second capacitor C2P are connected in parallel, wherein the diode, the first inductor L1 and the diode, the second power supply and the diode, the second inductor L2, the fourth switch tube Q4P and the second capacitor C2P are connected in parallel. Next in fig. 7d, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 7e, the current path may include: the first switch tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switch tube Q1S, the diode connected in parallel with the second power supply and the eighth switch tube Q4S, the second inductor L2, the diode connected in parallel with the third switch tube Q3P and the first capacitor C1P.
In fig. 7f, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the third capacitor C1S, the seventh switching tube Q3S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 7g, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 7h, the current path may include: the first switch tube Q1P, the first inductor L1, the sixth switch tube Q2S, the fourth capacitor C2S and the diode, the second inductor L2 and the fourth switch tube Q4P which are connected in parallel with the eighth switch tube Q4S. Next in fig. 7i, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 7j, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the third capacitor C1S, the seventh switching tube Q3S, the second inductor L2 and the fourth switching tube Q4P.
Stage (3). The voltage gain of the direct current voltage conversion circuit is larger than a second gain threshold value.
After the voltage gain of the direct-current voltage conversion circuit is increased to the second gain threshold value, the direct-current voltage conversion circuit enters a boost mode. As described above, the voltage gain when the duty ratio of the first branch is 1 and the duty ratio of the second branch is the lower limit value may be used as the second gain threshold. Therefore, after the voltage gain of the dc voltage conversion circuit increases to the second gain threshold, the duty cycle of the second branch is increased to a set value (hereinafter referred to as a second set value). Wherein the second set value may be greater than the duty cycle lower limit value, specifically according toAnd (5) calculating to obtain the product. G2 represents a second gain threshold. D2 min denotes a duty cycle lower limit value of the second branch. D1 max denotes the upper limit value of the duty cycle of the first branch. D2 s denotes a second set value. In order to enable the voltage gain of the direct-current voltage conversion circuit to continue to smoothly increase, the duty ratio of the first branch circuit may be adjusted to be 1, and the duty ratio of the second branch circuit may be adjusted to be a duty ratio lower limit value; the duty cycle of the first branch may be kept unchanged (i.e., the duty cycle of the first branch may be kept at 1), and the duty cycle of the second branch may be controlled to increase. The duty ratio of the first branch is 1, that is, the first switching tube Q1P and the fourth switching tube Q4P are in an on state, and the second switching tube Q2P and the third switching tube Q3P are in an off state. According to the formula/>It is known that the duty ratio of the first branch is 1, and the duty ratio of the second branch is increased, so that the voltage gain of the dc voltage conversion circuit can be increased. Thus, the direct-current voltage conversion circuit works in a boost mode and can be used for the first power supply to charge the second power supply. In addition, in the boost mode, the switching state of the switching tube in the first branch is kept unchanged, and the switching tube in the second branch works in the PWM state. Therefore, all switching tubes in the direct-current voltage conversion circuit are prevented from working at a higher switching frequency, loss is reduced, and working efficiency is improved.
Please refer to fig. 4c. In the buck mode, T s represents a control period of the dc voltage conversion circuit.. F s may be the switching frequency of the switching tube. g1P is the PWM control signal of the first switching transistor Q1P. g1P is obtained by comparing the modulated signal of the first switching tube Q1P with the triangular carrier signal of the first switching tube Q1P. g4P is the PWM control signal of the fourth switching tube Q4P. g4P is obtained by comparing the modulated signal of the fourth switching tube Q4P with the triangular carrier signal of the fourth switching tube Q4P. g2S is the PWM control signal of the sixth switching tube Q2S. g2S is obtained by comparing the modulated signal of the sixth switching tube Q2S with the triangular carrier signal of the sixth switching tube Q2S. g3S is the PWM control signal of the seventh switching tube Q3S. g3S is obtained by comparing the modulated signal of the seventh switching tube Q3S with the triangular carrier signal of the seventh switching tube Q3S. The duty cycle of g1p and g4p is 1.IL is inductor current. According to the PWM control signal shown in fig. 4c, the current flow diagram of the dc voltage conversion circuit can be shown in fig. 8 a-8 d in one control period.
In fig. 8a, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the third capacitor C1S, the seventh switching tube Q3S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 8b, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P. Next in fig. 8c, the current path may include: the first switch tube Q1P, the first inductor L1, the sixth switch tube Q2S, the fourth capacitor C2S and the diode, the second inductor L2 and the fourth switch tube Q4P which are connected in parallel with the eighth switch tube Q4S. Next in fig. 8d, the current path may include: the first switching tube Q1P, the first inductor L1, the diode connected in parallel with the fifth switching tube Q1S, the second power supply, the diode connected in parallel with the eighth switching tube Q4S, the second inductor L2 and the fourth switching tube Q4P.
In the control method of the embodiment of the present disclosure, after the voltage gain of the dc voltage conversion circuit reaches a first gain threshold value smaller than 1, the duty cycle of the first branch may be adjusted to a set value, and the duty cycle of the second branch may be adjusted to a duty cycle lower limit value; the duty cycle of the first branch can be controlled to be increased, and the duty cycle of the second branch is kept unchanged, so that the voltage gain is increased; after the duty cycle of the first branch is increased to the duty cycle upper limit value, the duty cycle of the first branch can be kept unchanged, and the duty cycle of the second branch is controlled to be increased, so that the voltage gain is continuously increased until a second gain threshold value larger than 1 is reached. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from less than 1 to more than 1, the smooth transition of the direct-current voltage conversion circuit from a voltage reduction mode to a voltage boosting mode is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
The specification also provides a control method of the direct-current voltage conversion circuit.
Please refer to fig. 5 and 9. The control method provided in the embodiment of the present specification may include the following steps.
Step 21: after the voltage gain of the direct-current voltage conversion circuit reaches a second gain threshold value larger than 1, the duty ratio of the first branch circuit is adjusted to be the upper limit value of the duty ratio, and the duty ratio of the second branch circuit is adjusted to be a set value.
Step 22: the duty cycle of the first branch is kept unchanged, and the duty cycle of the second branch is controlled to be reduced so that the voltage gain is reduced.
Step 23: and after the duty ratio of the second branch is reduced to the duty ratio lower limit value, keeping the duty ratio of the second branch unchanged, and controlling the duty ratio of the first branch to be reduced so as to enable the voltage gain to be continuously reduced until a first gain threshold value smaller than 1 is reached.
In some embodiments, the dc voltage conversion circuit may be used for discharging the first power supply from the second power supply. By controlling the direct current voltage conversion circuit, the voltage gain of the direct current voltage conversion circuit can be transited from a second gain threshold value larger than 1 to a first gain threshold value smaller than 1. The direct-current voltage conversion circuit can be smoothly transited from the step-up mode to the step-down mode.
In some embodiments, the first gain threshold, the second gain threshold, the upper duty cycle limit, the lower duty cycle limit may be referred to the previous embodiments. As the setting value of step 21, reference may be made to the second setting value in the foregoing embodiment.
In some embodiments, the control process of the direct current voltage conversion circuit may include the following 3 stages.
Stage (4). The voltage gain of the direct current voltage conversion circuit is larger than a second gain threshold value.
Please refer to fig. 4c. Under the condition that the voltage gain of the direct-current voltage conversion circuit is larger than a second gain threshold, the voltage U1 of the first branch is lower than the voltage U2 at two ends of the second branch, and the direct-current voltage conversion circuit works in a boosting mode and is used for discharging the first power supply by the second power supply. The voltage of the second power supply can be reduced along with the discharge, so that the voltage gain of the direct-current voltage conversion circuit is reduced continuously. In the boost mode, the duty cycle of the first branch may be kept at 1, and the duty cycle of the second branch is controlled to be reduced. The duty ratio of the first branch is 1, that is, the first switching tube Q1P and the fourth switching tube Q4P are in an on state, and the second switching tube Q2P and the third switching tube Q3P are in an off state. According to the formulaIt is known that the duty ratio of the first branch is 1, and the duty ratio of the second branch is reduced, so that the voltage gain of the dc voltage conversion circuit can be reduced. In this way, in boost mode, the switching state of the switching tube in the first branch remains unchanged, and the switching tube in the second branch operates in PWM state. All switching tubes in the direct-current voltage conversion circuit are prevented from working at a higher switching frequency, loss is reduced, and working efficiency is improved.
Stage (5). The voltage gain of the direct current voltage conversion circuit is smaller than the second gain threshold value and larger than the first gain threshold value.
Please refer to fig. 4b. After the voltage gain of the direct-current voltage conversion circuit is reduced to a second gain threshold value, the direct-current voltage conversion circuit enters a transition mode. As described above, the voltage gain when the duty ratio of the first branch is 1 and the duty ratio of the second branch is the lower limit value may be used as the second gain threshold. Therefore, after the voltage gain of the direct-current voltage conversion circuit is reduced to the second gain threshold value, the duty ratio of the second branch circuit is reduced to the duty ratio lower limit value. In order to enable the voltage gain of the dc voltage conversion circuit to continue to be smoothly reduced, the duty cycle of the first branch may be adjusted from 1 to the duty cycle upper limit value, and the duty cycle of the second branch may be adjusted from the duty cycle lower limit value to the second set value. The second set value may be greater than the duty cycle lower limit value.
The duty cycle of the first leg may be kept unchanged (i.e., the duty cycle of the first leg may be kept at D1 max), and the duty cycle of the second leg may be controlled to decrease. According to the formulaIt can be seen that the duty ratio of the first branch is D1 max, and the duty ratio of the second branch is reduced, so that the voltage gain of the dc voltage conversion circuit can be reduced. After the duty cycle of the second leg is reduced to the duty cycle lower limit value, the duty cycle of the second leg may be kept unchanged (i.e., the duty cycle of the second leg is kept to be D2 min), and the duty cycle of the first leg is controlled to be reduced. According to the formula/>As can be seen, the duty ratio of the first branch is reduced, and the duty ratio of the second branch is D2 min, so that the voltage gain of the dc voltage conversion circuit can be continuously reduced until the first gain threshold value smaller than 1 is reached. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from more than 1 to less than 1, the smooth transition from the voltage boosting mode to the voltage reducing mode of the direct-current voltage conversion circuit is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
In the transition mode, the control period of the direct current voltage conversion circuit may include a first sub-period and a second sub-period. The duration of the first sub-period and the second sub-period may be the same or different. In the first sub-period of the control period, the switching tube in the first branch circuit can be enabled to work in a PWM state, and the switching state of the switching tube in the second branch circuit can be kept unchanged. In the second sub-period of the control period, the switching state of the switching tube in the first branch circuit can be kept unchanged, and the switching tube in the second branch circuit can be enabled to work in a PWM state. In this way, in the whole control period of the direct-current voltage conversion circuit, the first sub-period is similar to the step-down mode, the switching tube in the first branch works in a PWM state, and the switching state of the switching tube in the second branch is kept unchanged; the second sub-period is similar to the subsequent boost mode, the switching state of the switching tubes in the first branch remains unchanged, and the switching tubes in the second branch operate in PWM state. That is, in each sub-period, the number of switching tubes operating in the PWM state is consistent with that of the buck mode (or boost mode), so that all switching tubes in the dc voltage conversion circuit are prevented from operating at a higher switching frequency, loss in the transient process is reduced, and the working efficiency is improved.
For example, the control period of the DC voltage conversion circuit may be. F s may be the switching frequency of the switching tube. The third time period is the first T s in the control period and the fourth time period is the second T s in the control period.
Stage (6). The voltage gain of the direct current voltage conversion circuit is smaller than a first gain threshold value.
Please refer to fig. 4a. After the voltage gain of the direct-current voltage conversion circuit is reduced to a first gain threshold value, the direct-current voltage conversion circuit enters a step-down mode. As described above, the voltage gain when the duty ratio of the first branch is the upper limit value and the duty ratio of the second branch is 0 may be used as the first gain threshold value. Therefore, after the voltage gain of the direct-current voltage conversion circuit is reduced to the first gain threshold value, the duty ratio of the first branch circuit is reduced to the first set value. In order to enable the voltage gain of the direct-current voltage conversion circuit to continue to be reduced smoothly, the duty ratio of the first branch circuit may be adjusted to be the duty ratio upper limit value, and the duty ratio of the second branch circuit may be adjusted to be 0; the duty cycle of the first branch may be controlled to decrease and the duty cycle of the second branch may be kept unchanged (i.e., the duty cycle of the second branch is kept at 0). The duty ratio of the second branch is 0, that is, the fifth switching tube Q1S and the eighth switching tube Q4S are in an on state, and the sixth switching tube Q2S and the seventh switching tube Q3S are in an off state. According to the formulaThe duty ratio of the first branch is reduced, and the duty ratio of the second branch is 0, so that the voltage gain of the direct-current voltage conversion circuit can be reduced. Thus, the direct-current voltage conversion circuit works in a step-down mode and can be used for discharging the first power supply by the second power supply. In buck mode, the switching tubes in the first branch operate in PWM state, and the switching states of the switching tubes in the second branch remain unchanged. All switching tubes in the direct-current voltage conversion circuit are prevented from working at a higher switching frequency, loss is reduced, and working efficiency is improved.
In the control method of the embodiment of the present disclosure, after the voltage gain of the dc voltage conversion circuit reaches a second gain threshold greater than 1, the duty cycle of the first branch may be adjusted to an upper limit value of the duty cycle, and the duty cycle of the second branch may be adjusted to a set value; the duty ratio of the first branch circuit can be kept unchanged, and the duty ratio of the second branch circuit is controlled to be reduced so as to reduce the voltage gain; after the duty ratio of the second branch is reduced to the duty ratio lower limit value, the duty ratio of the second branch can be kept unchanged, and the duty ratio of the first branch is controlled to be reduced, so that the voltage gain is continuously reduced until a first gain threshold value smaller than 1 is reached. Therefore, the voltage gain of the direct-current voltage conversion circuit can be smoothly transited from more than 1 to less than 1, the smooth transition from the voltage boosting mode to the voltage reducing mode of the direct-current voltage conversion circuit is realized, and the stable operation of the direct-current voltage conversion circuit in the transition process is ensured.
The embodiment of the specification also provides a control device, which comprises a memory, a processor and a computer program stored on the memory and capable of running on the processor, wherein the processor realizes the control method when executing the computer program. The control means may comprise a computer device, a controller or the like.
The present specification embodiment also provides a computer-readable storage medium storing a computer program which, when executed by a processor, implements the above-described control method.
The present description also provides a computer program product comprising a computer program which, when executed by a processor, implements the control method described above.
The description has been described with reference to flowchart illustrations and/or block diagrams of methods according to embodiments of the description. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. The computer may be a personal computer, a laptop computer, a cellular telephone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.
Those skilled in the art will appreciate that the descriptions of various embodiments are provided herein with respect to each of the embodiments, and that reference may be made to the relevant descriptions of other embodiments for parts of one embodiment that are not described in detail. In addition, it will be appreciated that those skilled in the art, upon reading the present specification, may conceive of any combination of some or all of the embodiments set forth herein without any inventive effort, and that such combination is within the scope of the disclosure and protection of the present specification.
Although the present specification is depicted by way of example, it will be appreciated by those skilled in the art that the above examples are merely intended to aid in understanding the core ideas of the present specification. Those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover such modifications and variations as fall within the true spirit of this present description.

Claims (7)

1. The control method of the direct-current voltage conversion circuit is characterized in that the direct-current voltage conversion circuit comprises a first branch and a second branch which are coupled through a first inductor and a second inductor, the first branch is coupled with a first power supply in parallel, the first branch comprises a first bridge arm and a second bridge arm which are connected in series, a first capacitor and a second capacitor which are respectively connected with the first bridge arm and the second bridge arm in parallel, the second branch is coupled with the second power supply in parallel, the second branch comprises a third bridge arm and a fourth bridge arm which are connected in series, a third capacitor and a fourth capacitor which are respectively connected with the third bridge arm and the fourth bridge arm in parallel, the first bridge arm comprises a first switching tube and a second switching tube which are connected in series, the second bridge arm comprises a fifth switching tube and a sixth switching tube which are connected in series, the fourth bridge comprises a seventh switching tube and an eighth switching tube which are connected in series, the first inductor is connected with a connecting point of the second switching tube and a connecting point of the fifth switching tube which is connected with the fourth switching tube in parallel, and a connecting point of the fourth switching tube which is connected with the fourth switching tube in series; the method is used for controlling a first power supply to charge a second power supply, and comprises the following steps:
When the voltage gain of the direct-current voltage conversion circuit is smaller than a first gain threshold value, the first gain threshold value is smaller than 1, the duty ratio of the first branch circuit is controlled to be increased, and the duty ratio of the second branch circuit is kept to be 0, so that the voltage gain is increased; the control period of the direct-current voltage conversion circuit is made to be T s, F s denotes the switching frequency of the switching transistor operating in PWM state;
After the voltage gain reaches a first gain threshold, the duty ratio of the first branch is adjusted to a first set value, the first set value is smaller than the duty ratio upper limit value, the duty ratio of the second branch is adjusted to a duty ratio lower limit value, the duty ratio upper limit value is smaller than 1, and the duty ratio lower limit value is larger than 0; controlling the duty ratio of the first branch to be increased, and keeping the duty ratio of the second branch unchanged so as to increase the voltage gain; after the duty ratio of the first branch circuit is increased to the upper limit value of the duty ratio, keeping the duty ratio of the first branch circuit unchanged, and controlling the duty ratio of the second branch circuit to be increased so as to enable the voltage gain to be continuously increased until a second gain threshold value larger than 1 is reached; when the voltage gain is greater than the first gain threshold and less than the second gain threshold, the control period of the direct current voltage conversion circuit is set to be 2T s, the control period 2T s is composed of a first sub-period T s and a second sub-period T s, the first sub-period is composed of 5 stages, and the current path of the first stage includes: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor, the diode connected in parallel with the third switch tube and the first capacitor; the current path of the second phase comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the third phase comprises: the diode connected in parallel with the second switching tube, the first inductor, the diode connected in parallel with the fifth switching tube, the second power supply, the diode connected in parallel with the eighth switching tube, the second inductor, the fourth switching tube and the second capacitor; the current path of the fourth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the fifth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor, the diode connected in parallel with the third switch tube and the first capacitor;
The second sub-period is made up of 5 phases, the current path of the first phase comprising: the diode, the third capacitor, the seventh switching tube, the second inductor and the fourth switching tube which are connected in parallel with the first switching tube, the first inductor and the fifth switching tube, and the current path of the second stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the third phase comprises: the first switch tube, the first inductor, the sixth switch tube, the fourth capacitor and the diode, the second inductor and the fourth switch tube which are connected in parallel with the eighth switch tube; the current path of the fourth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the fifth stage comprises: the first switch tube, the first inductor, the diode, the third capacitor, the seventh switch tube, the second inductor and the fourth switch tube are connected in parallel with the fifth switch tube;
After the voltage gain reaches a second gain threshold, the duty ratio of the first branch is adjusted to be 1, and the duty ratio of the second branch is adjusted to be a duty ratio lower limit value; the duty ratio of the first branch is kept unchanged, and the duty ratio of the second branch is controlled to be increased so that the voltage gain is continuously increased; the control period of the DC voltage conversion circuit is set to be T s.
2. The method of claim 1, wherein the duty cycle of the first leg and the duty cycle of the second leg satisfy the following formulas: ; where G represents the voltage gain of the dc voltage conversion circuit, D1 represents the duty cycle of the first branch, and D2 represents the duty cycle of the second branch.
3. The method according to claim 1, wherein the method further comprises:
sampling an actual power supply current coupled to the second branch;
Determining a reference inductor current according to the actual power supply current and the reference power supply current;
Sampling the actual inductance current of the first inductor or the second inductor;
And determining the voltage gain of the direct-current voltage conversion circuit according to the actual inductance current and the reference inductance current.
4. The control method of the direct-current voltage conversion circuit is characterized in that the direct-current voltage conversion circuit comprises a first branch and a second branch which are coupled through a first inductor and a second inductor, the first branch is coupled with a first power supply in parallel, the first branch comprises a first bridge arm and a second bridge arm which are connected in series, a first capacitor and a second capacitor which are respectively connected with the first bridge arm and the second bridge arm in parallel, the second branch is coupled with the second power supply in parallel, the second branch comprises a third bridge arm and a fourth bridge arm which are connected in series, a third capacitor and a fourth capacitor which are respectively connected with the third bridge arm and the fourth bridge arm in parallel, the first bridge arm comprises a first switching tube and a second switching tube which are connected in series, the second bridge arm comprises a fifth switching tube and a sixth switching tube which are connected in series, the fourth bridge comprises a seventh switching tube and an eighth switching tube which are connected in series, the first inductor is connected with a connecting point of the second switching tube and a connecting point of the fifth switching tube which is connected with the fourth switching tube in parallel, and a connecting point of the fourth switching tube which is connected with the fourth switching tube in series; the method is used for controlling the second power supply to charge the first power supply, and comprises the following steps:
When the voltage gain of the direct current voltage conversion circuit is larger than a second gain threshold value, the second gain threshold value is larger than 1, the duty ratio of the first branch circuit is adjusted to be 1, the duty ratio of the second branch circuit is adjusted to be a set value, the set value is larger than the lower limit value of the duty ratio, the lower limit value of the duty ratio is larger than 0, the upper limit value of the duty ratio is smaller than 1, the duty ratio of the first branch circuit is kept unchanged, and the duty ratio of the second branch circuit is controlled to be reduced so that the voltage gain is reduced; the control period of the direct-current voltage conversion circuit is made to be T s, F s denotes the switching frequency of the switching transistor operating in PWM state;
After the voltage gain reaches a second gain threshold, the duty ratio of the first branch is adjusted to be the upper limit value of the duty ratio, and the duty ratio of the second branch is adjusted to be a second set value, wherein the second set value is larger than the lower limit value of the duty ratio; the duty ratio of the first branch is kept unchanged, and the duty ratio of the second branch is controlled to be reduced so as to reduce the voltage gain; after the duty ratio of the second branch is reduced to the lower limit value of the duty ratio, keeping the duty ratio of the second branch unchanged, and controlling the duty ratio of the first branch to be reduced so as to enable the voltage gain to be continuously reduced until a first gain threshold value smaller than 1 is reached; when the voltage gain is greater than the first gain threshold and less than the second gain threshold, the control period of the direct current voltage conversion circuit is set to be 2T s, the control period 2T s is composed of a first sub-period T s and a second sub-period T s, the first sub-period is composed of 5 stages, and the current path of the first stage includes: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor, the diode connected in parallel with the third switch tube and the first capacitor; the current path of the second phase comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the third phase comprises: the diode connected in parallel with the second switching tube, the first inductor, the diode connected in parallel with the fifth switching tube, the second power supply, the diode connected in parallel with the eighth switching tube, the second inductor, the fourth switching tube and the second capacitor; the current path of the fourth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the fifth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor, the diode connected in parallel with the third switch tube and the first capacitor;
The second sub-period is made up of 5 phases, the current path of the first phase comprising: the diode, the third capacitor, the seventh switching tube, the second inductor and the fourth switching tube which are connected in parallel with the first switching tube, the first inductor and the fifth switching tube, and the current path of the second stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the third phase comprises: the first switch tube, the first inductor, the sixth switch tube, the fourth capacitor and the diode, the second inductor and the fourth switch tube which are connected in parallel with the eighth switch tube; the current path of the fourth stage comprises: the first switch tube, the first inductor, the diode connected in parallel with the fifth switch tube, the second power supply, the diode connected in parallel with the eighth switch tube, the second inductor and the fourth switch tube; the current path of the fifth stage comprises: the first switch tube, the first inductor, the diode, the third capacitor, the seventh switch tube, the second inductor and the fourth switch tube are connected in parallel with the fifth switch tube;
After the voltage gain reaches a first gain threshold, the duty ratio of the first branch is adjusted to be the upper limit value of the duty ratio, and the duty ratio of the second branch is adjusted to be 0; controlling the duty ratio of the first branch to be reduced, and keeping the duty ratio of the second branch unchanged so as to enable the voltage gain to be continuously reduced; the control period of the DC voltage conversion circuit is set to be T s.
5. The method of claim 4, wherein the duty cycle of the first leg and the duty cycle of the second leg satisfy the following formulas: ; where G represents the voltage gain of the dc voltage conversion circuit, D1 represents the duty cycle of the first branch, and D2 represents the duty cycle of the second branch.
6. The method according to claim 4, wherein the method further comprises:
sampling an actual power supply current coupled to the second branch;
Determining a reference inductor current according to the actual power supply current and the reference power supply current;
Sampling the actual inductance current of the first inductor or the second inductor;
And determining the voltage gain of the direct-current voltage conversion circuit according to the actual inductance current and the reference inductance current.
7. A control apparatus, characterized by comprising:
a processor; a memory for storing processor-executable instructions;
the processor implements the control method of any one of claims 1-6 by executing the instructions.
CN202311237590.5A 2023-09-25 2023-09-25 Control method and control device for direct-current voltage conversion circuit Active CN116995923B (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN209823644U (en) * 2019-04-16 2019-12-20 科华恒盛股份有限公司 DCDC bidirectional conversion circuit and converter
CN113328626A (en) * 2021-04-29 2021-08-31 武汉麦格米特电气有限公司 Control method and controller of four-switch Buck-Boost converter and power supply equipment
CN114400894A (en) * 2022-01-19 2022-04-26 燕山大学 Bidirectional DCDC conversion circuit and control method
CN114598151A (en) * 2022-04-07 2022-06-07 南京航空航天大学 Modulation method of four-tube Buck-Boost converter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN209823644U (en) * 2019-04-16 2019-12-20 科华恒盛股份有限公司 DCDC bidirectional conversion circuit and converter
CN113328626A (en) * 2021-04-29 2021-08-31 武汉麦格米特电气有限公司 Control method and controller of four-switch Buck-Boost converter and power supply equipment
CN114400894A (en) * 2022-01-19 2022-04-26 燕山大学 Bidirectional DCDC conversion circuit and control method
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