CN110165903B - Bidirectional DC/DC converter commutation control method and system - Google Patents

Bidirectional DC/DC converter commutation control method and system Download PDF

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CN110165903B
CN110165903B CN201910610600.2A CN201910610600A CN110165903B CN 110165903 B CN110165903 B CN 110165903B CN 201910610600 A CN201910610600 A CN 201910610600A CN 110165903 B CN110165903 B CN 110165903B
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reverse
voltage
preset
working mode
bidirectional
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CN110165903A (en
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陈真
童如德
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Shenzhen Lorentz Technology Co ltd
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Shenzhen Lorentz 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
    • 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
    • H02M3/3353—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 at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
    • 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
    • H02M1/0003—Details of control, feedback or regulation circuits

Abstract

The embodiment of the invention discloses a bidirectional DC/DC converter commutation control method and a system. The bidirectional DC/DC converter is applied to the bidirectional DC/DC converter, the bidirectional DC/DC converter comprises a first end and a second end, the first end is used for being connected with a power supply, the second end is used for being connected with a load, a forward working mode is preset when current flows from the first end to the second end, a reverse working mode is preset when the current flows from the second end to the first end, the reversing control method comprises the steps of obtaining a first voltage of the second end, and if the first voltage reaches a forward preset threshold value, switching to the reverse working mode after processing, and obtaining a second voltage; and if the second voltage reaches the reverse preset threshold value, switching to a forward working mode after processing. Voltage overshoot and current overshoot are reduced, and the stability of system operation is improved.

Description

Bidirectional DC/DC converter commutation control method and system
Technical Field
The invention relates to the technical field of power electronic application, in particular to a bidirectional DC/DC converter commutation control method and system.
Background
The bidirectional DC/DC converter is a DC-DC converter capable of adjusting energy bidirectional transmission according to energy requirements, can be widely applied to the aspects of electric automobiles, distributed power generation systems, intelligent charging and discharging machines and the like, and has wide application prospects. When the isolated bidirectional DC/DC converter performs bidirectional switching control operation, a control circuit which operates in a forward direction or a reverse direction needs to be selected according to the circuit operating point judgment circuit operating direction, and the forward control circuit and the reverse control circuit are switched in a reciprocating manner.
Disclosure of Invention
In view of the above, the present invention provides a bidirectional DC/DC converter commutation control method and system for reducing voltage overshoot and improving system operation reliability, so as to solve the above technical problems.
In a first aspect, the present invention provides a commutation control method for a bidirectional DC/DC converter, the bidirectional DC/DC converter including a first terminal and a second terminal, the first terminal being configured to be connected to a power source, the second terminal being configured to be connected to a load, wherein a forward operation mode is preset for a current flowing from the first terminal to the second terminal, and a reverse operation mode is preset for a current flowing from the second terminal to the first terminal, the commutation control method comprising:
acquiring a first voltage of the second end;
if the first voltage reaches a forward preset threshold value of the forward working mode, switching the bidirectional DC/DC converter to the reverse working mode after processing, and acquiring a second voltage of the second end;
and if the second voltage reaches a reverse preset threshold value of the reverse working mode, switching to the forward working mode after processing.
As a further improvement of the above technical solution, the commutation control method further includes:
the preset forward reference voltage of the forward working mode is smaller than the preset reverse reference voltage of the reverse working mode;
the forward preset threshold is the sum of the preset forward reference voltage and a first preset variation;
the reverse preset threshold is a difference between the preset reverse reference voltage and a second preset variation.
As a further improvement of the above technical solution, the forward preset threshold is smaller than the preset reverse reference voltage, and the reverse preset threshold is larger than the preset forward reference voltage.
As a further improvement of the above technical solution, before switching to the reverse operation mode after the processing, the method further includes:
collecting the forward voltage of the second end for multiple times, judging the times that the collected forward voltage exceeds the forward preset threshold value is greater than a first preset time, and switching the forward working mode into the reverse working mode.
As a further improvement of the above technical solution, before switching to the forward operating mode after the processing, the method further includes:
and collecting the reverse voltage of the second end for multiple times, judging that the collected reverse voltage does not exceed the reverse preset threshold for more than a second preset number of times, and switching the reverse working mode into the forward working mode.
In a second aspect, the present invention further provides a bidirectional DC/DC converter commutation control system, applied to a bidirectional DC/DC converter, where the bidirectional DC/DC converter includes a first terminal and a second terminal, the first terminal is used for connecting to a power supply, the second terminal is used for connecting to a load, and a forward operation mode is preset for a current flowing from the first terminal to the second terminal, and a reverse operation mode is preset for a current flowing from the second terminal to the first terminal, and the commutation control system includes:
the acquisition module is used for acquiring a first voltage of the second end;
the control module is used for switching the bidirectional DC/DC converter to be in the reverse working mode after processing if the first voltage reaches a forward preset threshold of the forward working mode:
the acquisition module is further used for acquiring a second voltage of the second end;
the control module is further configured to switch to the forward working mode after processing if the second voltage reaches a reverse preset threshold of the reverse working mode.
As a further improvement of the above technical solution, the control module includes a comparing unit and a switching unit;
the acquisition module is also used for acquiring the forward voltage of the second end for multiple times;
the comparison unit is used for judging that the number of times that the collected forward voltage exceeds the forward preset threshold is greater than a first preset number of times, and the switching unit switches the forward working mode into the reverse working mode;
the acquisition module is also used for acquiring reverse voltage of the second end for multiple times;
the comparison unit is also used for enabling the frequency that the collected reverse voltage exceeds the reverse preset threshold value to be larger than a second preset frequency, and the switching unit switches the reverse working mode into the forward working mode.
As a further improvement of the above technical solution, the commutation control system further includes a modulation module, an analog-to-digital conversion module, and a driving module;
the modulation module is used for processing the forward voltage and the reverse voltage and filtering high-frequency clutter;
the analog-to-digital conversion module is used for converting the analog voltage processed by the modulation module into digital voltage;
the control module carries out filtering and operation according to the forward voltage and the reverse voltage processed by the modulation module to obtain a PWM control signal;
the driving module is used for carrying out power amplification on the PWM control signal.
As a further improvement of the above technical solution, the bidirectional DC/DC converter further includes a first switch unit, a transformer, a second switch unit, and a filter unit electrically connected in sequence, wherein the first switch unit is located at the first end, and the filter unit is located at the second end.
As a further improvement of the above scheme, the bidirectional DC/DC converter is an isolated bidirectional DC/DC converter or a non-isolated bidirectional DC/DC converter.
The invention provides a reversing control method and a reversing control system for a bidirectional DC/DC converter, which are characterized in that a forward working mode is preset by flowing current from a first end to a second end of the bidirectional DC/DC converter, a reverse working mode is preset by flowing current from the second end to the second end, a first voltage is obtained at the second end, the bidirectional DC/DC converter is switched to the reverse working mode after being processed and a second voltage of the second end is obtained when the first voltage reaches a forward threshold value of the forward working mode, the second voltage is compared with the reverse preset threshold value and is switched to the forward working mode after being processed. By judging the change of the voltage, the inaccuracy of judgment through the current during light load is avoided. The reverse working voltage of the reverse working mode is set to be larger than the forward working voltage of the forward working mode, and is simultaneously larger than the forward preset threshold value for switching the forward working mode to the reverse working mode, so that the overshoot of voltage and current during switching can be reduced. The working voltage of the forward working mode is set to be smaller than the working voltage of the reverse working mode, and is smaller than a reverse preset threshold value for switching from reverse to forward, so that overshoot of voltage and current can be reduced, the stability of the system during light load is improved, and the running reliability of the system is also improved.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings required to be used in the embodiments will be briefly described below, and it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope of the present invention. Like components are numbered similarly in the various figures.
FIG. 1 shows a flow chart of a bidirectional DC/DC converter commutation control method of an embodiment of the invention;
FIG. 2 shows a block diagram of a bidirectional DC/DC converter commutation control system of an embodiment of the present invention;
FIG. 3 shows a circuit topology schematic of a bidirectional DC/DC converter of an embodiment of the present invention;
FIG. 4 shows a schematic of the driving logic of an embodiment of the present invention.
Description of the main element symbols:
100-a bidirectional DC/DC converter commutation control system; 110-a bidirectional DC/DC converter; 111-a first end; 112-a second end; 120-an acquisition module; 130-a control module; 131-a comparison unit; 132-a switching unit; 140-a first switching unit; 150-a transformer; 160-a second switching unit; 170-a filtering unit; 180-a modulation module; 190-analog-to-digital conversion module; 200-driving module.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Hereinafter, the terms "including", "having", and their derivatives, which may be used in various embodiments of the present invention, are only intended to indicate specific features, numbers, steps, operations, elements, components, or combinations of the foregoing, and should not be construed as first excluding the existence of, or adding to, one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing.
Furthermore, the terms "first," "second," "third," and the like are used solely to distinguish one from another and are not to be construed as indicating or implying relative importance.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of the present invention belong. The terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning that is consistent with their contextual meaning in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in various embodiments of the present invention.
Referring to fig. 1, in a first aspect, the present invention provides a commutation control method for a bidirectional DC/DC converter, the bidirectional DC/DC converter including a first terminal and a second terminal, the first terminal being configured to be connected to a power source, the second terminal being configured to be connected to a load, wherein a forward operation mode is preset for a current flowing from the first terminal to the second terminal, and a reverse operation mode is preset for a current flowing from the second terminal to the first terminal, the commutation control method including:
step S1: acquiring a first voltage of the second end;
step S2: if the first voltage reaches a forward preset threshold value of the forward working mode, switching the bidirectional DC/DC converter to the reverse working mode after processing, and acquiring a second voltage of the second end;
step S3: and if the second voltage reaches a reverse preset threshold value of the reverse working mode, switching to the forward working mode after processing.
In this embodiment, the bidirectional DC/DC converter includes a first end and a second end, and the bidirectional DC/DC converter is connected to the circuit, where the first end is used to connect to a power supply and is a high-voltage side, and the second end is used to connect to a load and is a low-voltage side, and a forward operation mode is preset when a current flows from the first end to the second end, and a reverse operation mode is preset when a current flows from the second end to the first end. It should be noted that the preset forward reference voltage in the forward working mode is smaller than the preset reverse reference voltage in the reverse working mode, and the reference voltage is a voltage standard in the electronic circuit and is a basis for measuring and calibrating other voltages in the circuit. For example, an analog-to-digital converter (A/D) and a direct current stabilized power supply have to have reference voltage so as to accurately measure unknown voltage and output standard voltage.
The reference voltage of the forward working mode is preset to be smaller than the reference voltage of the reverse working mode, the forward preset threshold is the sum of the preset forward reference voltage and a first preset variation of voltage rise, and the reverse preset threshold is the difference between the preset reverse reference voltage and a second preset variation of voltage drop. In other words, the forward preset threshold is an upper limit value of the voltage of the bidirectional DC/DC converter switched from the forward operation mode to the reverse operation mode, and the reverse preset threshold is a lower limit value of the voltage of the bidirectional DC/DC converter switched from the reverse operation mode to the forward operation mode. Voltage sampling at the second terminal may determine the operating mode of the bi-directional DC/DC converter and whether switching is required. The specific judgment process is as follows: when the first voltage is larger than the forward preset threshold value, switching the bidirectional DC/DC converter to the reverse working mode; when the second voltage in the reverse working mode approaches the reverse preset threshold, that is, the second voltage is smaller than the reverse preset threshold, switching the bidirectional DC/DC converter to the forward working mode; when the second voltage in the reverse working mode is greater than the reverse preset threshold, the forward working mode needs to be switched to.
It should be noted that, first preset variation, second preset variation all by preset forward reference voltage with preset reverse reference voltage decides, first preset variation with second preset variation can be the same, also can be different, comes the nimble selection of suitable according to actual conditions first preset variation with second preset variation, and this place no longer restricts. The forward preset threshold is smaller than the preset reverse reference voltage, the reverse preset threshold is larger than the preset forward reference voltage, and final system operation tends to be stable through continuous judgment and cyclic switching of the voltages in the forward working mode and the reverse working mode.
Specifically, for convenience of understanding, assuming that the preset forward reference voltage is 12V and the preset reverse reference voltage is 13V as an example, assuming that the forward preset threshold value for switching the forward operating mode to the reverse operating mode is 12.7V and the reverse preset threshold value for switching the reverse operating mode to the forward operating mode is 12.3V, when the collected voltage of the second end is 11V, it may be determined that the bidirectional DC/DC converter is in the forward operating mode at this time and does not need to be switched to the reverse operating mode; when the collected voltage of the second end is 12.8V, and the 12.8V is just greater than the forward preset threshold, switching the working mode of the bidirectional DC/DC converter to the reverse working mode; when the acquired voltage of the second end is 12.6V, and the 12.6V is just between the reverse preset threshold and the preset reverse reference voltage, the working mode of the bidirectional DC/DC converter does not need to be switched at this time, that is, the current bidirectional DC/DC converter is in the reverse working mode; when the voltage of the second terminal acquired at a certain time in the reverse operation mode reaches 12.3V, for example, the reverse voltage is 12.29V, the reverse operation mode needs to be switched to the forward operation mode after processing, that is, the bidirectional DC/DC converter enters the forward operation mode, so as to reduce the frequency of voltage overshoot.
It should be noted that both the first voltage and the second voltage are voltage values acquired at the second end at a certain time, that is, the sampled voltage is an instantaneous voltage. Sampling a voltage at the second end to obtain the first voltage, comparing the first voltage with the forward preset threshold or comparing the first voltage with the reverse preset threshold according to the first voltage, the forward preset threshold and the reverse preset threshold, and determining whether the bidirectional DC/DC converter needs to switch the current working mode, wherein the switching of the working mode of the bidirectional DC/DC converter can be switched from the forward working mode to the reverse working mode, or from the reverse working mode to the forward working mode. The first voltage may be a voltage at which the bidirectional DC/DC converter is in the forward operation mode, and the second voltage may be a voltage at which the bidirectional DC/DC converter is in the reverse operation mode.
Further, before switching to the reverse operation mode after the processing, the method further includes:
collecting the forward voltage of the second end for multiple times, judging the times that the collected forward voltage exceeds the forward preset threshold value is greater than a first preset time, and switching the forward working mode into the reverse working mode.
In this embodiment, the second end performs multiple voltage sampling, and determines the number of times that the collected forward voltage is greater than the forward preset threshold value according to the voltage obtained at a certain time within a first preset time. For example, the first preset number of times is 5, and the total number of times that the collected voltages are all greater than the forward preset threshold value is just more than 5 times, the forward operation mode is switched to the reverse operation mode, so that overshoot of the voltage for switching the forward operation mode to the reverse operation mode can be reduced, and the operation reliability of the bidirectional DC/DC converter is improved.
Further, before switching to the forward operating mode after the processing, the method further includes:
and collecting the reverse voltage of the second end for multiple times, judging that the collected reverse voltage does not exceed the reverse preset threshold for more than a second preset number of times, and switching the reverse working mode into the forward working mode.
In this embodiment, the second end is subjected to multiple voltage sampling, the collected voltage is compared with the reverse preset threshold, and the number of times that the collected voltage is smaller than the reverse preset threshold is counted. For example, the second preset number of times is 5, the total number of times that the voltages acquired within the second preset time are all smaller than the reverse preset threshold value is just over 5, and the reverse operation mode is switched to the forward operation mode, so that voltage overshoot can be reduced, and the operation stability of the bidirectional DC/DC converter is improved. It should be noted that the first preset number of times and the second preset number of times may be the same or different, for convenience of implementation and convenience of judgment, it is preferable that the time intervals of the collected voltages are the same, and the first preset number of times and the second preset number of times are the same, so that the accuracy of judging the voltage change is improved.
Referring to fig. 2, in a second aspect, the present invention further provides a bidirectional DC/DC converter commutation control system 100, applied to a bidirectional DC/DC converter 110, where the bidirectional DC/DC converter 110 includes a first end 111 and a second end 112, the first end 111 is used for connecting to a power source, the second end 112 is used for connecting to a load, and a forward operation mode is preset when a current flows from the first end 111 to the second end 112, and a reverse operation mode is preset when a current flows from the second end 112 to the first end 111, and the commutation control system includes:
an acquisition module 120, configured to acquire a first voltage of the second end 112;
a control module 130, configured to switch the bidirectional DC/DC converter 110 to the reverse operating mode after processing if the first voltage reaches a forward preset threshold of the forward operating mode:
the collecting module 120 is further configured to obtain a second voltage of the second end 112;
the control module 130 is further configured to switch to the forward working mode after processing if the second voltage reaches a reverse preset threshold of the reverse working mode.
In this embodiment, the collecting module 120 mainly samples the low voltage at the second end 112 in real time, the bidirectional DC/DC converter commutation control system 100 further includes a storage module (not shown), the storage module can pre-store data information such as the preset forward reference voltage, the preset reverse reference voltage, the first preset variation and the second preset variation, and the control module 130 analyzes and determines according to the real-time voltage collected by the collecting module 120. Voltage overshoot broadly refers to the fact that the actual voltage exceeds the normal operating voltage of the circuit or device, and is often of short duration, also referred to as transient overshoot voltage. For example, in the access circuit of the bidirectional DC/DC converter 110, usually, the preset forward reference voltage of the forward working mode is smaller than the preset reverse reference voltage of the reverse working mode, the voltage sampling is performed on the second end 112 connected to the load, when the sampling voltage of the second end 112 is larger than the forward preset threshold, it may be determined that the bidirectional DC/DC converter 110 is in the forward working mode, it is determined that there is a voltage overshoot at this time, and the forward working mode needs to be switched to the reverse working mode; when the sampling voltage of the second terminal 112 is less than the reverse preset threshold, it is determined that the bidirectional DC/DC converter 110 is in the reverse operation mode, and the reverse operation mode needs to be switched to the forward operation mode. The acquisition module 120 samples the voltage of the second terminal 112 every 1ms, and samples the second terminal 112 (low voltage side), so that the operating mode and voltage variation of the bidirectional DC/DC converter can be accurately determined, the bidirectional DC/DC converter 110 is switched between the forward operating mode and the reverse operating mode, the frequency of voltage overshoot and current overshoot is effectively reduced, and the operating stability of the bidirectional DC/DC converter 110 under light load is improved to a certain extent.
Further, the control module 130 includes a comparing unit 131 and a switching unit 132;
the collecting module 120 is further configured to collect the forward voltage of the second end 112 multiple times;
the comparing unit 131 is configured to determine that the number of times that the collected forward voltage exceeds the forward preset threshold is greater than a first preset number of times, and the switching unit 132 switches the forward working mode to the reverse working mode;
the collecting module 120 is further configured to collect the reverse voltage of the second end 112 for multiple times;
the comparing unit 131 is further configured to determine that the number of times that the acquired reverse voltage does not exceed the reverse preset threshold is greater than a second preset number of times, and the switching unit 132 switches the reverse working mode to the forward working mode.
In this embodiment, the collecting module 120 samples the voltage of the second end 112 multiple times and stores the collected voltage in a storage module (not shown) when the bidirectional DC/DC converter 110 is in the forward operating mode or the reverse operating mode. The comparing unit 131 compares the forward voltage with the forward preset threshold within a first preset time, and counts the number of times that the forward voltage exceeds the forward preset threshold, and when the counted number of times is greater than the first preset number of times, the switching unit 132 switches the bidirectional DC/DC converter 110 from the forward operating mode to the reverse operating mode, that is, the bidirectional DC/DC converter 110 enters the reverse operating mode, at this time, the reference voltage of the bidirectional DC/DC converter is a preset reverse reference voltage, and the preset reverse reference voltage is greater than the preset forward reference voltage; when the bidirectional DC/DC converter 110 is in the reverse working mode, the comparing unit 131 compares the reverse voltage with the reverse preset threshold, and counts the number of times that the reverse voltage does not exceed the reverse preset threshold, that is, the number of times that the reverse voltage is smaller than the reverse preset threshold, and when the counted total number of times is greater than the second preset number of times, the switching unit 132 switches the bidirectional DC/DC converter 110 from the reverse working mode to the forward working mode. It should be noted that the first preset number and the second preset number may be the same or different, and in this embodiment, it is preferable that the first preset number and the second preset number are the same, and voltage delay determination is required when the operating mode of the bidirectional DC/DC converter 110 is switched, so that the operating reliability of the bidirectional DC/DC converter 110 is improved.
Further, the bidirectional DC/DC converter commutation control system 100 further includes a modulation module 180, an analog-to-digital conversion module 190, and a driving module 200;
the modulation module 180 is configured to process the forward voltage and the reverse voltage, and filter out high-frequency noise;
the analog-to-digital conversion module 190 is configured to convert the analog voltage processed by the modulation module 180 into a digital voltage;
the control module 130 performs filtering and operation according to the forward voltage and the reverse voltage processed by the modulation module 180 to obtain a PWM control signal;
the driving module 200 is configured to perform power amplification on the PWM control signal.
In this embodiment, the forward voltage is the voltage of the second terminal in the forward operating mode of the bidirectional DC/DC converter 110, the reverse voltage is the voltage of the second terminal in the reverse operating mode of the bidirectional DC/DC converter 110, the forward voltage and the reverse voltage include a plurality of voltage values, the modulation module 180 may play a role of filtering out high-frequency noise when the voltage delay is determined, and the analog-to-digital conversion module 190 may convert an analog voltage into a digital voltage, so as to sample and determine the voltage. The control module 130 may adopt a controller including a PID algorithm, the PID algorithm is composed of three parts of proportion, differentiation and integration, when a control object and an output to be controlled reach a set value, open-loop or closed-loop control is usually used, if the response of the control object is stable and not affected by other links, open-loop control may be used, otherwise, if the controlled object is affected by a set value, a load or a source end to generate fluctuation, closed-loop control should be used, so that voltage ripple may be reduced. The driving module 200 may perform power amplification on the PWM control signal, and enhancing the PWM control model may improve the operating performance of the bidirectional DC/DC converter 110.
Referring to fig. 3, the bidirectional DC/DC converter 110 further includes a first switch unit 140, a transformer 150, a second switch unit 160, and a filter unit 170 electrically connected in sequence, wherein the first switch unit 140 is located at the first end 111, and the filter unit 170 is located at the second end 112.
For convenience of understanding, the bidirectional DC/DC converter 110 is preferably an isolated bidirectional DC/DC converter, the first end 111 is connected to a high-voltage side, the second end 112 is connected to a low-voltage side, a capacitor C1 is connected between the first end 111 and a voltage source v1 in parallel, the first switching unit 140 includes a first power switching tube Q1, a second power switching tube Q2, a third power switching tube Q3 and a fourth power switching tube Q4, the second switching unit 160 includes a fifth power switching tube Q5 and a sixth power switching tube Q6, and the filtering unit 170 includes an inductor L1 and a capacitor C2.
When the bidirectional DC/DC converter 110 is in the forward operating mode, the specific working process is as follows: when the first power switch Q1 and the fourth power switch Q4 are turned on, the sixth power switch Q6 is also turned on at the same time, the first power switch Q1 and the fourth power switch Q4 are used as high-frequency switches, and the sixth power switch Q6 is used as a synchronous rectifier; when the second power switch Q2 and the third power switch Q3 are turned on, the power switch Q5 is also turned on simultaneously, the second power switch Q2 and the third power switch Q3 are used as high frequency switches, and the fifth power switch Q5 is used as a synchronous rectifier; when the first power switch Q1, the second power switch Q2, the third power switch Q3 and the fourth power switch Q4 are turned off, the fifth power switch Q5 and the sixth power switch Q6 are both turned on, the transformer does not transfer power, the fifth power switch Q5 and the sixth power switch Q6 provide a channel for current follow current on the low-voltage side of the bidirectional DC/DC converter, and the filtering unit provides low-voltage load energy. In the whole forward operating mode, the first power switch tube Q1, the fourth power switch tube Q4, the second power switch tube Q2, and the third power switch tube are used as high-frequency switch tubes, the direct current on the high-voltage bus source is inverted into square-wave alternating current, the square-wave alternating current is transmitted to the low-voltage side through the transformer 150, the alternating current is rectified into low-voltage direct current by the fifth power switch tube Q5 and the sixth power switch tube Q6, and the inductor L1 is used for filtering out switching ripples to obtain stable low-voltage direct current, so that the low-voltage load is powered.
When the bidirectional DC/DC converter 110 is in the reverse operation mode, the specific operation process is as follows: the fifth power switch Q5 and the sixth power switch Q6 are turned on simultaneously, the first power switch Q1, the second power switch Q2, the third power switch Q3 and the fourth power switch Q4 are turned off, the stored energy in the inductor L1 is increased, and the transformer 150 and the first switch unit 140 do not transfer power; when only one of the fifth power switch Q5 and the sixth power switch Q6 is turned on, the synchronous rectifier is used when the first power switch Q1 and the fourth power switch Q4 in the first switch unit 140 are turned on simultaneously or the second power switch Q2 and the third power switch Q3 are turned on simultaneously, the inductor L1 stores less energy, and the low-voltage side transmits power to the high-voltage side. In the whole reverse operation mode, the fifth power switch Q5 and the sixth power switch Q6 are used as high-frequency switches to convert the low-voltage dc power at the low-voltage side into high-frequency square-wave ac dc power for transmission to the high-voltage side, and the first power switch Q1, the fourth power switch Q4, the second power switch Q2 and the third power switch Q3 are used as synchronous rectifiers to rectify the high-frequency square-wave ac power into high-voltage dc power to supply energy to a high-voltage bus source.
Referring to fig. 4, the acquisition module 120 samples the low-voltage side to obtain a voltage V0, performs operation filtering processing on the voltage V0, filters high-frequency noise, and then transmits the voltage V0 to the control module 130, the control module 130 performs analog-to-digital conversion on the voltage V0 to obtain a digital voltage Vd, the filtering unit 170 performs operation processing on the voltage Vd, filters interference data to obtain the voltage Vd, and the control module 130 performs control operation to obtain a voltage control signal Ve. The control module 130 further includes a modulation unit and a driving unit (not shown), the modulation unit modulates the voltage control signal Ve to obtain a PWM signal, and finally the driving unit amplifies the power of the PWM signal generated by the modulation unit to obtain driving PWM signals, VgsQ1, VgsQ4, VgsQ2, VgsQ3, VgsQ5 and VgsQ6, which can be directly used by the power switching tube. Wherein VgsQ1 and VgsQ4 are driving PWM signals of the first power switch Q1 and the fourth power switch Q4, and indicate that the driving PWM signals for turning on the first power switch Q1 and the fourth power switch Q4 are sent out from T1 to Ts/2 within a switching period Ts; VgsQ2 and VgsQ3 are driving PWM signals of the second power switch Q2 and the third power switch Q3, and indicate that during a switching period Ts, a driving PWM signal for turning on the second power switch Q2 and the third power switch Q3 is sent from Ton (Ton ═ T1+ Ts/2) to Ts; VgsQ5 is the driving PWM signal of the fifth power switch Q5, and indicates that the driving PWM signal for turning on the fifth power switch Q5 will be sent from 0 to Ton in two switching periods Ts; VgsQ6 is the driving PWM signal of the sixth power switch Q6, and indicates that the driving PWM signal for turning on the sixth power switch Q6 will be sent from 0 to T1 and Ts/2 to Ts in two switching periods Ts.
The operation of the bi-directional DC/DC converter 110 is described in conjunction with the following example. The preset forward reference voltage is set to Vref 1-13V, the preset reverse reference voltage is set to Vref 2-14V, the forward preset threshold for determining the switch from the forward operation mode to the reverse operation mode is 13V +/Δ V1, the value of Δ V1 (the first preset variation) is a value within 14V-13V-1V, and the value of Δ V1 may be set to (Vref2-Vref1) × K, where K is 0.5-0.9, in consideration that the voltage at the second end 112 is 13V and may have ripple or dynamic fluctuation. Assuming that 0.7 is taken now, the final result is that Vref1 +. DELTA.V 1 is 13.7V, the forward operating voltage is Vref1 is 13V, the output voltage in the forward operating mode is greater than 13.7V, and the reverse operating mode is entered by performing a delay determination. The delay judgment is equivalent to filtering and interference is eliminated. The reverse operating voltage is Vref2 equal to 14V, the same logic (Vref2-Vref1) × K, where K is 0.7, and Δ V2 (second preset variation) equal to 0.7V can be obtained. That is to say, when the working voltage of the reverse working mode is lower than 13.3V, a delay judgment is performed to enter the forward working mode, it should be noted that the forward preset threshold is 13.7V, and the reverse preset threshold is 13.3V, where the delay judgment is respectively the same as the above-mentioned process of performing the voltage delay judgment on the second end 112, and is not described herein again.
The invention provides a bidirectional DC/DC converter commutation control method and a system, which presets a forward working mode by flowing current from a first end 111 to a second end 112 of a bidirectional DC/DC converter 110, presets a reverse working mode by flowing current from the second end 112 to the first end 111, acquires a first voltage at the second end, switches to the reverse working mode after processing according to the fact that the first voltage reaches a forward threshold value of the forward working mode, acquires a second voltage at the second end 112, compares the second voltage with the reverse preset threshold value, and switches to the forward working mode after processing. By judging the change of the voltage, the problem of inaccurate judgment through current in light load is avoided. The reverse working voltage of the reverse working mode is set to be larger than the forward working voltage of the forward working mode, and is simultaneously larger than the forward preset threshold value for switching the forward working mode to the reverse working mode, so that the overshoot of voltage and current during switching can be reduced. By setting the working voltage of the forward working mode to be smaller than the working voltage of the reverse working mode and simultaneously smaller than a reverse preset threshold value for switching from the reverse mode to the forward mode, overshoot of voltage and current can be reduced, so that the stability of the system during light load is improved, and the running reliability of the system is also improved.
In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other ways. The apparatus embodiments described above are merely illustrative and, for example, the flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
In addition, each functional module or unit in each embodiment of the present invention may be integrated together to form an independent part, or each module may exist separately, or two or more modules may be integrated to form an independent part.
The functions, if implemented in the form of software functional modules and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention or a part of the technical solution that contributes to the prior art in essence can be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a smart phone, a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention.

Claims (6)

1. A bidirectional DC/DC converter commutation control method is characterized in that the bidirectional DC/DC converter commutation control method is applied to a bidirectional DC/DC converter, the bidirectional DC/DC converter comprises a first end and a second end, the first end is used for connecting a power supply, the second end is used for connecting a load, wherein, a forward working mode is preset when current flows from the first end to the second end, a reverse working mode is preset when current flows from the second end to the first end, and a preset forward reference voltage of the forward working mode is smaller than a preset reverse reference voltage of the reverse working mode; the commutation control method comprises the following steps:
when the device is in the forward working mode, collecting forward voltage of the second end for multiple times;
if the collected forward voltage exceeds the forward preset threshold of the forward working mode for more than a first preset number of times, switching the bidirectional DC/DC converter to the reverse working mode;
when the second end is in the reverse working mode, collecting reverse voltage of the second end for multiple times;
if the collected reverse voltage does not exceed the reverse preset threshold of the reverse working mode for more than a second preset number of times, switching to the forward working mode, wherein the forward preset threshold is smaller than the preset reverse reference voltage, and the reverse preset threshold is larger than the preset forward reference voltage.
2. The commutation control method of claim 1, wherein the forward preset threshold is a sum of the preset forward reference voltage and a first preset variation; the reverse preset threshold is a difference between the preset reverse reference voltage and a second preset variation.
3. A bidirectional DC/DC converter commutation control system is characterized in that the bidirectional DC/DC converter commutation control system is applied to a bidirectional DC/DC converter, the bidirectional DC/DC converter comprises a first end and a second end, the first end is used for connecting a power supply, the second end is used for connecting a load, wherein, a forward working mode is preset when current flows from the first end to the second end, a reverse working mode is preset when current flows from the second end to the first end, and a preset forward reference voltage of the forward working mode is smaller than a preset reverse reference voltage of the reverse working mode; the commutation control system comprises:
the acquisition module is used for acquiring the forward voltage of the second end for multiple times when the device is in the forward working mode;
the control module is used for switching the bidirectional DC/DC converter to be in the reverse working mode if the number of times that the collected forward voltage exceeds the forward preset threshold of the forward working mode is greater than a first preset number of times:
the acquisition module is further used for acquiring reverse voltage of the second end for multiple times when the acquisition module is in the reverse working mode;
the control module is further configured to switch to the forward working mode if the number of times that the acquired reverse voltage does not exceed the reverse preset threshold of the reverse working mode is greater than a second preset number of times, where the forward preset threshold is smaller than the preset reverse reference voltage, and the reverse preset threshold is greater than the preset forward reference voltage.
4. The commutation control system of claim 3, further comprising a modulation module, an analog-to-digital conversion module, and a drive module;
the modulation module is used for processing the forward voltage and the reverse voltage and filtering high-frequency clutter;
the analog-to-digital conversion module is used for converting the analog voltage processed by the modulation module into digital voltage;
the control module carries out filtering and operation according to the forward voltage and the reverse voltage processed by the modulation module to obtain a PWM control signal;
the driving module is used for carrying out power amplification on the PWM control signal.
5. The commutation control system of claim 3, wherein the bidirectional DC/DC converter further comprises a first switch unit, a transformer, a second switch unit, and a filter unit electrically connected in sequence, the first switch unit is located at the first end, and the filter unit is located at the second end.
6. The commutation control system of claim 5, wherein the bidirectional DC/DC converter is an isolated bidirectional DC/DC converter or a non-isolated bidirectional DC/DC converter.
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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108574411A (en) * 2018-05-22 2018-09-25 安徽工业大学 Two-way DC/DC power inverters dual-port stable control method and its control circuit

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108574411A (en) * 2018-05-22 2018-09-25 安徽工业大学 Two-way DC/DC power inverters dual-port stable control method and its control circuit

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