CN112821770B - Duty ratio control method, DCDC converter, vehicle, electronic device, and medium - Google Patents

Duty ratio control method, DCDC converter, vehicle, electronic device, and medium Download PDF

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Publication number
CN112821770B
CN112821770B CN202011640577.0A CN202011640577A CN112821770B CN 112821770 B CN112821770 B CN 112821770B CN 202011640577 A CN202011640577 A CN 202011640577A CN 112821770 B CN112821770 B CN 112821770B
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current
duty ratio
minimum current
voltage
minimum
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CN112821770A (en
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韦彬
黄昊
葛凯
邵南
韩炜
陈锐
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United Automotive Electronic Systems Co Ltd
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United Automotive Electronic Systems 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
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33584—Bidirectional converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer

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

Abstract

The invention provides a duty ratio control method, a DCDC converter, a vehicle, an electronic device and a medium, wherein the duty ratio control method can update the minimum current duty ratio of the previous moment according to a preset minimum current, an output end current preset rule and an update rule on the basis of the existing minimum current loop control, so that the minimum current duty ratio has a preset starting point. Compared with the prior art, the time for waiting for the response of the minimum current loop is saved, the response is quicker, the further reduction of the duty ratio is effectively avoided, the forward output of the DCDC converter with the preset minimum current is maintained, and the fault caused by the overlarge unexpected reverse current can be effectively dealt with.

Description

Duty ratio control method, DCDC converter, vehicle, electronic device, and medium
Technical Field
The present invention relates to the field of electrical technologies, and in particular, to a duty cycle control method, a bidirectional DCDC converter, a vehicle, an electronic device, and a medium.
Background
At present, in a 48V micro-hybrid system of a new energy automobile, a DCDC converter is used as an energy conversion device on a 48V side and a 12V side, and the performance of the DCDC converter plays a crucial role in the normal operation of the whole micro-hybrid system. The bidirectional synchronous rectification DCDC converter is used as a common topological structure in the field of power electronics, is widely applied to the fields of industry, automobiles and the like by virtue of the advantages of low cost and simple control strategy, and therefore becomes an important factor for the layout of the types of automobiles in various automobile factories due to the extremely high cost performance advantage of the bidirectional synchronous rectification DCDC converter.
A DCDC converter refers to a direct current switching power supply (also referred to as DC-DC) that can be used for voltage boosting and/or voltage reduction. The DCDC converter utilizes the energy storage characteristics of a capacitor and an inductor to perform high-frequency switching through a controllable switch (such as a MOSFET, etc.), stores input electric energy in the capacitor (or the inductor), and releases the electric energy to a load to provide energy when the switch is disconnected. The capability of the DCDC output to be power or voltage is related to the duty cycle (the ratio of the switch on time to the period of the entire switch). As shown in fig. 1, fig. 1 is a schematic diagram of a circuit topology of a DCDC converter, and as can be seen from fig. 1, a circuit of a 48V DCDC converter belongs to a parallel synchronous rectification Buck/Boost topology, and an upper tube and a lower tube of a half bridge are complementary in a common control manner; however, since both ends of the on-vehicle DCDC converter are connected to the battery, the output characteristics of the on-vehicle DCDC converter are different depending on the load condition.
When a vehicle is just started, the electric energy of a battery at the 12V side is converted to the 48V side through a Boost mode, a capacitor on a motor controller is charged, and the function of pre-charging is completed. During the running process of the vehicle, the vehicle mainly works in a Buck mode, the battery energy of the 48V side is converted to be used by a load of the 12V side, but the battery energy of the 12V side is also allowed to be converted to be used by the 48V side through a Boost mode under special working conditions.
The 48V DCDC converter adopts a synchronous rectification mode in a Buck mode, namely, upper and lower half-bridge tubes are complementary during working so as to reduce loss during inductive current freewheeling. Referring to fig. 2, fig. 2 is a schematic diagram of a conventional circuit control structure of a DCDC converter. When the DCDC converter works, closed-loop control is adopted, and the command voltage U and the command current I are used as the input of the DCDC converter; the command voltage U is the voltage expected to be output by the DCDC converter, the command current I is the maximum current allowed to be output by the DCDC converter, the two command signals are respectively given as the input of a voltage loop and a current loop, the duty ratio calculated by the voltage loop and the current loop is the minimum value, and the minimum value is used as the actual output duty ratio to control the on-off of the power device and output power. Considering based on cost and result of use, adopting bootstrap drive chip is better selection, but the prerequisite that bootstrap drive can normally work is that the lower tube needs the action when Buck mode, guarantees bootstrap capacitor's charging process, therefore, and when the in-service use, the circumstances that reverse current appears can appear under some special operating mode. Batteries exist on the 48V side and the 12V side, when some special working conditions occur, the duty ratio of an upper tube is reduced, and then the characteristic of Boost is shown in a Buck mode, so that reverse overcurrent on the 12V side or overvoltage fault on the 48V side is caused. The special operating conditions include, but are not limited to, the 12V side load being too light, the command voltage of the DCDC converter being very low, and/or the DCDC pumping the low side while in Buck mode.
Taking the command voltage of the DCDC to be lower as an example, when the command voltage U is much smaller than the output-side battery voltage U, referring to fig. 3, fig. 3 is a control block diagram of a reverse Boost occurring during voltage closed-loop calculation based on the conventional band control structure of fig. 2, it can be seen from fig. 3 that an Error between a command and feedback is a negative value, after being input to the PI controller, an upper-tube Duty ratio output by the PI controller is gradually decreased, and a corresponding lower-tube Duty ratio is gradually increased. The output-side cell voltage U varies by a small amount due to the presence of the secondary battery, which causes the upper tube Duty to continuously decrease. The characteristic of the reverse Boost becomes strong to a certain extent by accumulation. Referring to fig. 4, fig. 4 is a schematic diagram illustrating waveforms of inductor currents when a reverse Boost occurs in the DCDC converter, and it can be seen from fig. 4 that the reverse currents become larger and larger, so that a reverse overcurrent fault is caused. Referring to fig. 1, Top On in fig. 4 is to turn On the MOS transistor M1, and Top Off is to turn Off the MOS transistor M1. In Buck mode, MOS transistor M1 (Top ) is used.
In the prior art, a 'minimum current loop' control is usually introduced in a control link to perform reverse current suppression of a synchronous rectification topology. The basic idea of "minimum current loop" control is: when unexpected reverse current occurs, the closed loop control will work on the current loop to maintain the constant normal current output of the DCDC. The method adopts closed-loop control to maintain the direction of the output current of the DCDC, and has the advantages of better stability, but the scheme has the following defects: the response speed is limited, and under the condition that the reverse overcurrent protection threshold value is low, a larger reverse current can still occur and cause a reverse OCP fault because the minimum current loop cannot timely generate the effect.
Therefore, how to provide a duty ratio control method to overcome the above-mentioned deficiencies in the prior art is becoming one of the technical problems to be solved by those skilled in the art.
It is noted that the information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The present invention is directed to provide a duty cycle control method, a DCDC converter, a vehicle, an electronic device and a medium for quickly and effectively suppressing an unexpected reverse overcurrent fault caused by various operating conditions of a bidirectional synchronous rectification DCDC converter, in order to overcome the above-mentioned drawbacks of the prior art.
In order to achieve the purpose, the invention is realized by the following technical scheme: a duty cycle control method for controlling the duty cycle of a bidirectional synchronous rectification DCDC converter comprises the following steps:
s1: acquiring a voltage duty ratio according to the instruction voltage and the output end voltage of the bidirectional synchronous rectification DCDC converter; acquiring a current duty ratio according to the instruction current and the current at the output end of the bidirectional synchronous rectification DCDC converter;
s2: the voltage duty ratio and the current duty ratio are minimum, and a first output duty ratio is obtained;
s3: obtaining the minimum current duty ratio at the current moment: judging whether the preset minimum current and the output end current meet a preset rule, if so, updating the minimum current duty ratio at the previous moment according to an updating rule, and executing the step S4; otherwise, go to step S4;
s4: acquiring the minimum current duty ratio of the current moment according to the preset minimum current, the current of the output end and the minimum current duty ratio of the previous moment;
s5: and obtaining a second output duty ratio by taking the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment, and taking the second output duty ratio as the duty ratio of the bidirectional synchronous rectification DCDC converter.
Optionally, before step S1, the method further includes the following steps:
determining an operating mode of the rectifying DCDC converter, wherein the operating mode comprises a Buck mode and a Boost mode;
and executing steps S1-S5 when the working mode of the bidirectional synchronous rectification DCDC converter is determined to be a Boost mode.
Optionally, in step S1, the method for obtaining the voltage duty ratio according to the command voltage and the output terminal voltage of the bidirectional synchronous rectification DCDC converter includes:
subtracting the instruction voltage and the output end voltage to obtain a first subtraction output result;
and obtaining the voltage duty ratio by adopting a first PID algorithm according to the first subtraction output result.
Optionally, in step S1, the method for obtaining the current duty ratio according to the command current and the output current of the bidirectional synchronous rectification DCDC converter includes:
subtracting the instruction current and the output end current to obtain a second subtraction output result;
and obtaining the current duty ratio by adopting a second PID algorithm according to the second subtraction output result.
Optionally, in step S3, the determining step determines whether the preset minimum current and the output-end current satisfy a preset rule, and if so, updates the minimum current duty ratio of the previous moment according to an update rule, and then executes step S4; otherwise, step S4 is executed, including:
judging whether the current of the output end is smaller than a preset minimum current, if so, using the voltage duty ratio or the current duty ratio as the minimum current duty ratio of the previous moment; step S4 is executed; otherwise, step S4 is executed.
Optionally, the method for obtaining the minimum current duty ratio according to the preset minimum current, the output end current, and the minimum current duty ratio at the previous time includes:
subtracting the preset minimum current and the output end current to obtain a third subtraction output result;
and obtaining the minimum current duty ratio by adopting a third PID algorithm according to the third subtraction output result and the minimum current duty ratio at the previous moment.
Optionally, the initial value of the minimum current duty cycle at the previous time is 0.
In order to achieve the above object, the present invention further provides a bidirectional synchronous rectification DCDC converter, wherein a duty cycle control circuit is used to control a duty cycle, and the duty cycle control circuit includes:
a voltage single loop configured to obtain a voltage duty cycle from a command voltage and an output terminal voltage of the bidirectional synchronous rectification DCDC converter;
a current single loop configured to obtain a current duty cycle from a command current and an output current of the bidirectional synchronous rectification DCDC converter;
a minimum value taking module configured to take a minimum value for the voltage duty cycle and the current duty cycle to obtain a first output duty cycle;
a minimum current loop configured to obtain a minimum current duty cycle at a current time by: if the preset minimum current and the output end current meet the preset rule, updating the minimum current duty ratio at the previous moment according to the updating rule, and acquiring the minimum current duty ratio at the current moment by adopting a minimum current duty ratio calculation method; otherwise, directly adopting the minimum current duty ratio calculation method to obtain the minimum current duty ratio at the current moment; the minimum current duty ratio calculation method comprises the following steps: acquiring the minimum current duty ratio of the current moment according to the preset minimum current, the current of the output end and the minimum current duty ratio of the previous moment;
and the maximum value module is configured to obtain a second output duty ratio by taking the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment, and the second output duty ratio is used as the duty ratio of the bidirectional synchronous rectification DCDC converter.
Optionally, the voltage single loop comprises:
the first subtractor is configured to subtract the instruction voltage and the output end voltage to obtain a first subtraction output result;
a first PID controller configured to receive the first subtraction output result and obtain the voltage duty ratio according to the first subtraction output result;
and/or
The current single loop comprises:
the second subtracter is configured to subtract the instruction current and the output end current to obtain a second subtraction output result;
a second PID controller configured to receive the second subtraction output result and obtain the current duty ratio according to the second subtraction output result;
and/or
The minimum current loop comprises:
the judging module is configured to update the minimum current duty ratio of the previous moment according to an updating rule if the preset minimum current and the output end current are judged to meet the preset rule;
the third subtracter is configured to subtract the preset minimum current and the output end current to obtain a third subtraction output result;
and the third PID controller is configured to receive the third subtraction output result and acquire the minimum current duty ratio according to the third subtraction output result and the minimum current duty ratio at the previous moment.
Optionally, the determining module is configured to update the minimum current duty ratio of the previous moment according to an update rule if it is determined that the preset minimum current and the output end current satisfy a preset rule, and includes:
and if the current of the output end is judged to be smaller than the preset minimum current, using the voltage duty ratio or the current duty ratio as the minimum current duty ratio at the previous moment.
In order to achieve the above object, the present invention also provides a vehicle including the DCDC converter of any one of the above;
or
The vehicle comprises a bidirectional synchronous rectification DCDC converter, and the duty ratio of the bidirectional synchronous rectification DCDC converter is controlled by adopting any one of the duty ratio control methods.
In order to achieve the above object, the present invention further provides an electronic apparatus, which includes a processor and a storage device, wherein the processor is adapted to implement instructions, and the storage device is adapted to store a plurality of instructions, and the instructions are adapted to be loaded by the processor and to execute the steps of the duty cycle control method according to any one of the above.
To achieve the above object, the present invention also provides a computer-readable storage medium having stored thereon computer-executable instructions that, when executed, implement the duty cycle control method of any one of the above.
Compared with the prior art, the duty ratio control method provided by the invention has the following beneficial effects:
the duty ratio control method provided by the invention comprises the following steps: s1: acquiring a voltage duty ratio according to the instruction voltage and the output end voltage of the bidirectional synchronous rectification DCDC converter; acquiring a current duty ratio according to the instruction current and the output end current of the bidirectional synchronous rectification DCDC converter; s2: the voltage duty ratio and the current duty ratio are minimum, and a first output duty ratio is obtained; s3: obtaining the minimum current duty ratio at the current moment: judging whether the preset minimum current and the output end current meet a preset rule, if so, updating the minimum current duty ratio at the previous moment according to an updating rule, and executing the step S4; otherwise, go to step S4; s4: acquiring the minimum current duty ratio of the current moment according to the preset minimum current, the current of the output end and the minimum current duty ratio of the previous moment; s5: and obtaining a second output duty ratio by taking the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment, and taking the second output duty ratio as the duty ratio of the bidirectional synchronous rectification DCDC converter. Therefore, when the current of the output end is smaller than the preset minimum current, the actual voltage duty ratio or the actual current duty ratio is used for updating the calculation result of the minimum current duty ratio at the previous moment. After the minimum current duty ratio has a preset 'starting point', the minimum current duty ratio is used as the actual output duty ratio. Therefore, compared with the existing duty ratio control method, the duty ratio control method provided by the invention can change the minimum current duty ratio into the duty ratio at the current moment immediately after the reverse current appears when the output voltage instruction of the bidirectional synchronous rectification DCDC converter is low and the pump power or the input voltage of the DCDC converter is powered off, and then the voltage loop duty ratio continuously drops, so that the current can be quickly adjusted to recover the normal state. Therefore, the time for waiting the response of the minimum current loop is saved, the response is quicker, the further reduction of the duty ratio is effectively avoided, the forward output of the DCDC converter at the preset minimum current is maintained, and the fault caused by the overlarge unexpected reverse current can be effectively dealt with.
Furthermore, the duty ratio control circuit of the bidirectional synchronous rectification DCDC converter provided by the invention has a simple structure, is little or even not required to be changed in the conventional circuit structure, and is easy to implement; and the required components are easy to obtain and low in cost. The bidirectional synchronous sorting DCDC converter can quickly and effectively inhibit unexpected reverse overcurrent faults of the bidirectional DCDC caused by various working conditions, so that preset small current forward output can be maintained, and various application scenes with low OCP threshold values can be met.
Because the bidirectional DCDC converter, the vehicle, the electronic device and the medium provided by the invention belong to the same inventive concept as the duty ratio control method provided by the invention, the bidirectional DCDC converter, the vehicle, the electronic device and the medium at least have the same beneficial effects as the duty ratio control method, and are not repeated.
Drawings
FIG. 1 is a schematic diagram of one of the circuit topologies of a DCDC converter;
FIG. 2 is a schematic diagram of a conventional circuit control structure of a DCDC converter;
fig. 3 is a control block diagram of a dc-dc converter using the conventional circuit control structure of fig. 2, in which a reverse Boost occurs during voltage closed-loop calculation;
fig. 4 is a schematic diagram of a waveform of an inductor current of the DCDC converter when a reverse Boost occurs;
FIG. 5 is a schematic diagram of a prior art minimum current loop controlled duty cycle control circuit;
FIG. 6 is a schematic diagram of current and duty cycle of a DCDC converter controlled by a minimum current loop when the OCP is a first threshold;
FIG. 7 is a schematic diagram of current and duty cycle of a DCDC converter controlled by a minimum current loop when the OCP has a second threshold;
fig. 8 is a flowchart illustrating a duty cycle control method according to an embodiment of the present invention;
FIG. 9 is a schematic diagram of current and duty cycle using the duty cycle control method provided by the present invention;
fig. 10 is a schematic structural diagram of a duty cycle control circuit according to an embodiment of the present invention;
wherein the reference numerals are as follows:
100-voltage single ring, 110-first subtracter, 120-first PID controller, 200-current single ring, 210-second subtracter, 220-second PID controller, 300-minimum current ring, 310-third subtracter, 320-third PID controller, 330-judgment module, 400-minimum value module and 500-maximum value module.
Detailed Description
To make the objects, advantages and features of the present invention more apparent, the duty cycle control method, the bidirectional DCDC converter, the vehicle, the electronic device and the medium according to the present invention will be described in further detail with reference to the accompanying drawings. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. It should be understood that the drawings are not necessarily to scale, showing the particular construction of the invention, and that illustrative features in the drawings, which are used to illustrate certain principles of the invention, may also be somewhat simplified. Specific design features of the invention disclosed herein, including, for example, specific dimensions, orientations, locations, and configurations, will be determined in part by the particular intended application and use environment. In the embodiments described below, the same reference numerals are used in common between different drawings to denote the same portions or portions having the same functions, and a repetitive description thereof will be omitted. In this specification, like reference numerals and letters are used to designate like items, and therefore, once an item is defined in one drawing, further discussion thereof is not required in subsequent drawings.
These terms, as used herein, are interchangeable where appropriate. Similarly, if the method described herein comprises a series of steps, the order in which these steps are presented herein is not necessarily the only order in which these steps may be performed, and some of the described steps may be omitted and/or some other steps not described herein may be added to the method.
Before specifically describing a duty cycle control method proposed by the present invention, a basic principle of the duty cycle control method proposed by the present invention is explained as follows.
Referring to fig. 5, fig. 5 is a schematic diagram of a structure of a duty cycle control circuit controlled by a minimum current loop in the prior art, and it can be seen from fig. 5 that, in order to suppress a DCDC reverse current of a synchronous rectification topology, a strategy of a "minimum current loop" is adopted to suppress the reverse current. In closed loop control, a current loop is constructed, a minimum forward current Imin is preset, and Imin is used as a command of the current loop. The minimum current loop also participates in closed loop calculation in real time, and the calculation result of the minimum current loop and the calculation result of the voltage loop/current loop take a larger value. When a reverse Boost is generated, a smaller Top-tube (Top) duty cycle must accompany it. At the moment, the duty ratio of the upper tube is regulated through a minimum current loop, so that the current of the low-voltage side is stabilized at a minimum current threshold value. However, in practical applications, different OCP thresholds, especially where the tolerance to reverse current is low, sometimes trigger an OCP fault, causing the DCDC to enter a fault state, which is obviously not a desirable result. However, it is generally considered by those skilled in the art that the OCP threshold setting is not only a reasonable result, but usually solves the problem of the DCDC entering a fault state due to the addition of the minimum current loop strategy by continuously adjusting the OCP threshold.
The inventor of the present invention finds that, for achieving a better reverse current suppression effect and avoiding an OCP fault, and increasing the application range of the bidirectional synchronous rectification DCDC converter, it is necessary to increase the response speed of a strategy for suppressing a reverse current, by comparing and analyzing waveforms of the current and the duty ratio of the DCDC converter controlled by the minimum current loop, especially under the condition of different OCP thresholds. Specifically, referring to fig. 6 and 7, fig. 6 and 7 are schematic diagrams illustrating the current and the duty ratio of the DCDC converter controlled by the minimum current loop when the OCP takes the first threshold and the OCP takes the second threshold, respectively, where the OCP threshold in fig. 7 is smaller than the OCP threshold in fig. 6. Specifically, the meanings of the respective times in fig. 6 are as follows: t 1: the command voltage suddenly decreases in the Buck mode; t 2: the output current is 0, and the duty ratio of the minimum current loop begins to increase at the moment; t 3: at the boundary of the voltage loop duty ratio and the minimum current loop duty ratio, the minimum current loop begins to take the dominant role at the moment; t 4: the minimum current loop of the DCDC completes regulation and enters a steady state. The meanings of the moments in fig. 7 are as follows: t 1: the command voltage suddenly decreases in the Buck mode; t 2: the output current is 0, and the duty ratio of the minimum current loop begins to increase at the moment; t 3: due to the triggering of the OCP fault, the DCDC enters a fault state and no longer outputs a duty cycle.
It can be seen that the minimum current loop depends largely on the magnitude of the reverse OCP threshold setting. Therefore, in some cases where the tolerance to reverse current is low, the scheme using the minimum current loop cannot suppress the reverse current. In fig. 6, the transition time from t2 to t3 is a time when the reverse current increases. During the period, the duty ratio of the minimum current loop is cumulatively increased from 0, and simultaneously, the duty ratio calculated by the voltage loop is gradually decreased until the time t3, the duty ratios of the minimum current loop and the voltage loop are equal, referring to fig. 5, the duty ratio of the minimum current loop is started at the time t3 as the actual output duty ratio, the closed loop enters the minimum current loop to be adjusted, and the output current is given I by the set minimum currentminTo control the target, the current is gradually restored to the forward direction during the regulation. The inventor has found through research that the actual output duty ratio is decreasing from t2 to t3, and a reverse current already occurs during this time, but due to the limitation of the current loop bandwidth, the current loop response speed is affected, and the DCDC fault state problem in fig. 7 is prone to occur when the OCP threshold is small. I.e. when stableEnsuring that the DCDC continuously outputs forward current; but the Duty ratio Top Duty3 is only when the current is less than IminThe time is increased, so that a transition time exists before the minimum current loop plays a leading role, and in the transition time, the DCDC converter still shows reverse Boost characteristics outwards. When the reverse OCP threshold value is larger, the Buck state without reverse current can be finally transited back by adopting a minimum current loop strategy; when the reverse OCP threshold is small, it is likely that an OCP fault will be triggered without transitioning back to the Buck state.
Based on the above research, the inventor of the present invention proposes a duty cycle control method for controlling the duty cycle of a bidirectional synchronous rectification DCDC converter, so as to save the time waiting for the minimum current loop response from t2 to t3, and effectively cope with the fault caused by the unexpected excessive reverse current.
Referring to fig. 8, fig. 8 is a schematic flowchart of a duty cycle control method according to an embodiment of the present invention, and as can be seen from fig. 8, the duty cycle control method according to the present invention includes the following steps:
s1: acquiring a voltage duty ratio according to the instruction voltage and the output end voltage of the bidirectional synchronous rectification DCDC converter; and acquiring the current duty ratio according to the instruction current and the current at the output end of the bidirectional synchronous rectification DCDC converter.
S2: and taking the minimum value of the voltage duty ratio and the current duty ratio to obtain a first output duty ratio.
S3: obtaining the minimum current duty ratio at the current moment: judging whether the preset minimum current and the output end current meet a preset rule, if so, updating the minimum current duty ratio at the previous moment according to an updating rule, and executing the step S4; otherwise, step S4 is executed.
S4: and acquiring the minimum current duty ratio at the current moment according to the preset minimum current, the current at the output end and the minimum current duty ratio at the previous moment.
S5: and obtaining a second output duty ratio by taking the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment, and taking the second output duty ratio as the duty ratio of the bidirectional synchronous rectification DCDC converter.
It can be understood that the above steps are executed at a certain moment when controlling the duty ratio of the bidirectional synchronous rectification DCDC converter, and the obtained voltage duty ratio, the obtained current duty ratio and the obtained minimum current duty ratio are values at the same moment, and the obtaining order is not sequential, for example, taking the obtaining of the voltage duty ratio and the current duty ratio in step S1 as an example, the obtaining order of the voltage duty ratio and the obtaining of the current duty ratio may be changed arbitrarily. Other steps without mutual dependency relationship are similar and are not described in detail.
Referring to fig. 9, fig. 9 is a schematic diagram of current and duty ratio by using the duty ratio control method provided by the present invention, and it can be seen from fig. 9 that, when the current at the output end is smaller than the preset minimum current, the actual current duty ratio or the actual voltage duty ratio is used to update the calculation result of the minimum current duty ratio at the previous moment. So configured, the minimum current loop control can be immediately transitioned when the current reverses, thereby speeding up the regulation process. Comparing fig. 8 and fig. 9, it can be seen that, after the reverse current appears, the duty ratio of the minimum current loop is immediately changed to the duty ratio of the current time, then the duty ratio of the voltage loop continuously decreases, and after the duty ratio of the minimum current loop has a preset "starting point", the duty ratio of the minimum current loop is used as the duty ratio of the actual output, and the current is rapidly adjusted to return to the normal state. Compared with the existing duty ratio control method, the duty ratio control method provided by the invention can save the time waiting for minimum current loop response from t2 to t3 when the output voltage instruction of the DCDC converter is low and the pump power is supplied or the input voltage of the DCDC converter is powered off, has quicker response, and effectively avoids the further reduction of the duty ratio, thereby maintaining the DCDC converter to output in the forward direction with the preset minimum current and effectively coping with the fault caused by the excessive unexpected reverse current.
Preferably, in one exemplary embodiment, before step S1, the method further includes the following steps:
determining an operating mode of the rectifying DCDC converter, wherein the operating mode comprises a Buck mode and a Boost mode; and executing steps S1-S5 when the working mode of the bidirectional synchronous rectification DCDC converter is determined to be a Boost mode.
Preferably, in one exemplary embodiment, in step S1, the method for obtaining the voltage duty ratio according to the command voltage and the output voltage of the bidirectional synchronous rectification DCDC converter includes:
subtracting the instruction voltage and the output end voltage to obtain a first subtraction output result; and obtaining the voltage duty ratio by adopting a first PID algorithm according to the first subtraction output result.
Preferably, in an exemplary embodiment, in step S1, the method for obtaining a current duty ratio according to a command current and an output current of the bidirectional synchronous rectification DCDC converter includes:
subtracting the instruction current and the output end current to obtain a second subtraction output result; and obtaining the current duty ratio by adopting a second PID algorithm according to the second subtraction output result.
Preferably, in one exemplary embodiment, in step S3, when the minimum current duty ratio at the current time is obtained, the determining step determines whether the preset minimum current and the output-end current satisfy a preset rule, and if so, updates the minimum current duty ratio at the previous time according to an update rule, and executes step S4; otherwise, step S4 is executed, including:
judging whether the current of the output end is smaller than a preset minimum current, if so, using the voltage duty ratio or the current duty ratio as the minimum current duty ratio of the previous moment; step S4 is executed; otherwise, step S4 is executed.
Preferably, in one exemplary embodiment, the method for obtaining the minimum current duty ratio according to the preset minimum current, the output end current and the minimum current duty ratio at the previous moment includes:
and subtracting the preset minimum current and the output end current to obtain a third subtraction output result. And obtaining the minimum current duty ratio by adopting a third PID algorithm according to the third subtraction output result and the minimum current duty ratio at the previous moment.
Preferably, the first PID algorithm, the second PID algorithm, and the third PID algorithm include, but are not limited to, a proportional control algorithm, an integral control algorithm, a derivative control algorithm, and the like. For ease of understanding, the first PID algorithm, the second PID algorithm, and the third PID algorithm are illustrated as incremental (step-wise) algorithms. The duty ratio is calculated iteratively in a way as shown in the following formula:
Err(n)＝Ref_temp-Out(n)
Duty(n)＝Duty(n-1)+Kp*[Error(n)-Err(n-1)]+Ki*Error(n)+
Kd*[Error(n-2)+Error(n)-2*Error(n-1)]
Err(n-2)＝Error(n-1)
Err(n-1)＝Error(n)
Duty(n-1)＝Duty(n)
Duty(0)＝Dinit
error (n) represents a difference between the reference value and the output value after the current operation, Ref _ temp represents a command value, out (n) represents an output value after the current operation, duty (n) represents a duty ratio obtained by the current operation (at the current time), n represents the current operation, Kp represents a proportionality coefficient, Ki represents an integral coefficient, and Kd represents a differential coefficient.
Referring to fig. 10, the Error1, Error2, and Error3 in fig. 10 should be represented as Error1(n), Error2(n), and Error3(n) in the incremental PIDs, and the expression of PIDs is not only incremental, so the Error1(n), Error2(n), and Error3(n) are not used in fig. 10. Similarly, Ref _ temp represents the command voltage U when the voltage duty cycle is obtaineddesDuty (n) is Top Duty1 (n); ref _ temp represents the command current I when the current duty cycle is obtaineddesDuty (n) is Top Duty2 (n); when the minimum current duty ratio is obtained, Ref _ temp presets the minimum current IminDuty (n) is TopDaty 3 (n).
Particularly, when the minimum current duty ratio at the current moment is calculated, if the output end current I is smaller than the preset minimum current IminThen the voltage Duty cycle Top Duty1(n) is usedOr the current Duty ratio Top Duty2(n) as the minimum current Duty ratio Top Duty3(n-1) at its previous instant. If the output end current I is not less than the preset minimum current IminThen, the minimum current Duty Top Duty3(n-1) at the previous time is substituted into the calculation formula of the current minimum current Duty3 (n).
Preferably, in one exemplary embodiment, the initial value Dinit of the voltage Duty ratio Top Duty1 is 1, the initial value Dinit of the current Duty ratio Top Duty2 is any value between 0 and 1, and the initial value Dinit of the minimum current Duty ratio is 0; the preset minimum current is the maximum reverse current allowed by the safe and stable operation of the bidirectional synchronous rectification DCDC converter in the buck mode, and can be set according to the actual working condition. The invention is not limited in this regard.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
Still another embodiment of the present invention provides a bidirectional synchronous rectification DCDC converter, which uses a duty cycle control circuit to control the duty cycle. Referring to fig. 10, fig. 10 is a schematic structural diagram of a duty cycle control circuit provided in this embodiment, and as can be seen from fig. 10, the duty cycle control circuit includes: a voltage single loop 100, a current single loop 200, a minimum current loop 300, a minimum module 400, and a maximum module 500.
In particular, the voltage single loop 100 is configured to operate according to a command voltage UdesAnd the output end voltage U of the bidirectional synchronous rectification DCDC converter acquires the voltage Duty ratio Top Duty 1. The current single loop 200 configured to operate according to a command current IdesAnd the output end current I of the bidirectional synchronous rectification DCDC converter, and acquiring a current Duty ratio Top Duty 2. The minimum value taking module 400 is configured to take a minimum value for the voltage Duty ratio Top Duty3 and the current Duty ratio Top Duty2 to obtain a first output Duty ratio. The minimum current loop 300 is configured to obtain the minimum current Duty ratio Top Duty3 at the current moment by: if the predetermined maximum is judgedLow current IminIf the current I at the output end meets a preset rule, updating the minimum current duty ratio at the previous moment according to an updating rule, and acquiring the minimum current duty ratio at the current moment by adopting a minimum current duty ratio calculation method; otherwise, the minimum current duty ratio at the current moment is obtained by directly adopting the minimum current duty ratio calculation method. The minimum current duty ratio calculation method comprises the following steps: according to the preset minimum current IminThe output end current I and the minimum current Duty ratio at the previous moment, and obtaining the minimum current Duty ratio Top Duty 3. Specifically, the minimum current duty ratio calculation method PID algorithm includes, but is not limited to, a proportional control algorithm, an integral control algorithm, a derivative control algorithm, and the like. The maximum module 500 is configured to obtain a second Output Duty ratio Top Duty Output by taking a maximum value of the first Output Duty ratio and the minimum current Duty ratio Top Duty3 at the current moment, and use the second Output Duty ratio Top Duty Output as the Duty ratio of the bidirectional synchronous rectification DCDC converter.
Preferably, the voltage single loop 100 includes a first subtractor 110 and a first PID controller 120. Wherein the first subtractor 110 is configured to the command voltage UdesAnd subtracting the output end voltage U to obtain a first subtraction output result Error 1. The first PID controller 120 is configured to receive the first subtraction output result Error1 and obtain the voltage Duty ratio Top Duty1 according to the first subtraction output result Error 1.
Preferably, the current single loop 200 includes a second subtractor 210 and a second PID controller 220. Wherein the second subtractor 210 is configured to the command current IdesSubtracting the output end current I to obtain a second subtraction output result Error 2; the second PID controller 220 is configured to receive the second subtraction output result Error2 and obtain the current Duty ratio Top Duty2 according to the second subtraction output result Error 2.
Preferably, the minimum current loop 300 includes a third subtractor 310, a third PID controller 320, and a judgment module 330. In particular toThe determining module 330 is configured to determine the preset minimum current I if determining the preset minimum current IminIf the current I at the output end meets a preset rule, updating the minimum current duty ratio of the previous moment according to an updating rule; the third subtractor 320 is configured to subtract the preset minimum current IminSubtracting the output end current I to obtain a third subtraction output result Error 3; the third PID controller 320 is configured to receive the third subtraction output result Error3, and obtain the minimum current Duty ratio Top Duty3 according to the third subtraction output result Error3 and the minimum current Duty ratio at the previous time.
Preferably, in one exemplary embodiment, the determining module 330 is configured to determine the preset minimum current I if determining the preset minimum current IminAnd if the output end current I meets a preset rule, updating the minimum current duty ratio of the previous moment according to an updating rule, wherein the updating rule comprises the following steps: if the current I of the output end is judged to be smaller than the preset minimum current IminThen the voltage Duty cycle Top Duty1 or the current Duty cycle Top Duty1 is used as the minimum current Duty cycle of the previous time instant.
The bidirectional synchronous rectification DCDC converter provided by the invention adopts the duty ratio control circuit to control the duty ratio. The duty ratio control circuit and the duty ratio control method provided in the foregoing embodiments belong to the same inventive concept, and therefore, the duty ratio control circuit has at least the same effect as the duty ratio control circuit, and please refer to the beneficial effect of the duty ratio control method, which is not described in detail herein.
Furthermore, the duty ratio control circuit of the bidirectional synchronous rectification DCDC converter provided by the invention has a simple structure, is little or even not required to be changed in the conventional circuit structure, and is easy to implement; and the required components are easy to obtain and low in price. The bidirectional synchronous sorting DCDC converter can quickly and effectively inhibit unexpected reverse overcurrent faults of the bidirectional DCDC caused by various working conditions, so that preset small current forward output can be maintained, and various application scenes with low OCP threshold values can be met.
Another embodiment of the present invention provides a vehicle, in one of the embodiments, the vehicle includes the DCDC converter of any of the above embodiments; in yet another embodiment, or
The vehicle comprises a bidirectional synchronous rectification DCDC converter, and the duty ratio of the bidirectional synchronous rectification DCDC converter is controlled by adopting any one of the duty ratio control methods.
Yet another embodiment of the present invention provides an electronic apparatus, which includes a processor and a storage device, wherein the processor is adapted to implement instructions, and the storage device is adapted to store a plurality of instructions, and the instructions are adapted to be loaded by the processor and to execute the steps of the duty cycle control method according to any of the above embodiments. For specific steps, please refer to each embodiment of the duty ratio control method, which is not described in detail herein.
Yet another embodiment of the present invention provides a computer-readable storage medium, which stores computer-executable instructions, and when the computer-executable instructions are executed, the duty cycle control method according to any one of the above embodiments is implemented. For specific steps, please refer to each embodiment of the duty ratio control method, which is not described in detail herein.
Since the bidirectional DCDC converter, the vehicle, the electronic device and the medium provided by the invention belong to the same inventive concept as the duty ratio control method provided by the invention, the bidirectional DCDC converter, the vehicle, the electronic device and the medium at least have the same beneficial effects as the duty ratio control method, and are not repeated herein.
From the above description of embodiments, it should be apparent to those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects, with the understanding that aspects of the present invention that are believed to be within the scope of the present invention will be embodied in the form of a computer software product stored on a computer-readable storage medium including, but not limited to, disk storage, CD-ROM, optical storage, and the like.
The present invention is described in terms of flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
In summary, the above embodiments have been described in detail on different configurations of the duty cycle control method, the bidirectional DCDC converter, the vehicle, the electronic device and the medium, and it is understood that the above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way.

Claims (11)

1. A duty cycle control method for controlling the duty cycle of a bidirectional synchronous rectification (DCDC) converter is characterized by comprising the following steps:
s1: acquiring a voltage duty ratio according to the instruction voltage and the output end voltage of the bidirectional synchronous rectification DCDC converter; acquiring a current duty ratio according to the instruction current and the output end current of the bidirectional synchronous rectification DCDC converter;
s2: the voltage duty ratio and the current duty ratio are minimum, and a first output duty ratio is obtained;
s3: obtaining the minimum current duty ratio at the current moment: judging whether the current of the output end is smaller than a preset minimum current, if so, using the voltage duty ratio or the current duty ratio as the minimum current duty ratio of the previous moment, and executing a step S4; otherwise, go to step S4;
s4: acquiring the minimum current duty ratio of the current moment according to the preset minimum current, the current of the output end and the minimum current duty ratio of the previous moment;
s5: and obtaining a second output duty ratio by taking the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment, and taking the second output duty ratio as the duty ratio of the bidirectional synchronous rectification DCDC converter.
2. The duty ratio control method according to claim 1, characterized by, before step S1, further comprising the steps of:
determining an operating mode of the rectifying DCDC converter, wherein the operating mode comprises a Buck mode and a Boost mode;
and when the working mode of the bidirectional synchronous rectification DCDC converter is determined to be the Boost mode, executing steps S1-S5.
3. The duty cycle control method according to claim 1, wherein in step S1, the method for obtaining the voltage duty cycle according to the command voltage and the output voltage of the bidirectional synchronous rectification DCDC converter comprises:
subtracting the command voltage and the output end voltage to obtain a first subtraction output result;
and obtaining the voltage duty ratio by adopting a first PID algorithm according to the first subtraction output result.
4. The method according to claim 1, wherein in step S1, the method for obtaining the current duty ratio according to the command current and the output current of the bidirectional synchronous rectification DCDC converter comprises:
subtracting the instruction current and the output end current to obtain a second subtraction output result;
and obtaining the current duty ratio by adopting a second PID algorithm according to the second subtraction output result.
5. The duty cycle control method according to claim 1, wherein the method for obtaining the minimum current duty cycle according to the preset minimum current, the output end current and the minimum current duty cycle at the previous time comprises:
subtracting the preset minimum current and the output end current to obtain a third subtraction output result;
and obtaining the minimum current duty ratio by adopting a third PID algorithm according to the third subtraction output result and the minimum current duty ratio at the previous moment.
6. The duty ratio control method according to claim 1, wherein an initial value of the minimum current duty ratio at the previous time is 0.
7. A bidirectional synchronous rectification DCDC converter is characterized in that a duty ratio control circuit is adopted to control the duty ratio, and the duty ratio control circuit comprises:
a voltage single loop configured to obtain a voltage duty cycle from a command voltage and an output terminal voltage of the bidirectional synchronous rectification DCDC converter;
a current single loop configured to obtain a current duty cycle from a command current and an output current of the bidirectional synchronous rectification DCDC converter;
a minimum value taking module configured to take a minimum value for the voltage duty cycle and the current duty cycle to obtain a first output duty cycle;
a minimum current loop configured to obtain a minimum current duty cycle at a current time by: if the current of the output end is judged to be smaller than the preset minimum current, the voltage duty ratio or the current duty ratio is used as the minimum current duty ratio of the previous moment, and the minimum current duty ratio of the current moment is obtained by adopting a minimum current duty ratio calculation method; otherwise, directly adopting the minimum current duty ratio calculation method to obtain the minimum current duty ratio at the current moment; the minimum current duty ratio calculation method comprises the following steps: acquiring the minimum current duty ratio of the current moment according to the preset minimum current, the current of the output end and the minimum current duty ratio of the previous moment;
and the maximum value taking module is configured to take the maximum value of the first output duty ratio and the minimum current duty ratio at the current moment to obtain a second output duty ratio, and the second output duty ratio is used as the duty ratio of the bidirectional synchronous rectification DCDC converter.
8. The bi-directional synchronous rectified DCDC converter of claim 7, wherein said voltage single loop comprises:
a first subtractor configured to subtract the command voltage and the output end voltage to obtain a first subtraction output result;
a first PID controller configured to receive the first subtraction output result and obtain the voltage duty ratio according to the first subtraction output result;
and/or
The current single loop comprises:
the second subtracter is configured to subtract the instruction current and the output end current to obtain a second subtraction output result;
a second PID controller configured to receive the second subtraction output result and obtain the current duty ratio according to the second subtraction output result;
and/or
The minimum current loop comprises:
the judging module is configured to update the minimum current duty ratio of the previous moment according to an updating rule if the preset minimum current and the output end current are judged to meet the preset rule;
the third subtracter is configured to subtract the preset minimum current and the output end current to obtain a third subtraction output result;
a third PID controller configured to receive the third subtraction output result and obtain the minimum current duty ratio according to the third subtraction output result and the minimum current duty ratio at the previous time.
9. A vehicle characterized by comprising the DCDC converter of any one of claims 7 to 8;
or
The vehicle includes a bidirectional synchronous rectification DCDC converter whose duty cycle is controlled using the duty cycle control method of any one of claims 1-6.
10. An electronic apparatus, comprising a processor adapted to implement instructions and a storage device adapted to store a plurality of instructions, the instructions being adapted to be loaded by the processor and to perform the steps of the duty cycle control method of any of claims 1 to 6.
11. A computer-readable storage medium having computer-executable instructions stored thereon, wherein the computer-executable instructions, when executed, implement the duty cycle control method of any one of claims 1 to 6.
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