CN113141115A - Self-adaptive control method and device for dead zone time of LLC resonant circuit - Google Patents

Self-adaptive control method and device for dead zone time of LLC resonant circuit Download PDF

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CN113141115A
CN113141115A CN202010555277.6A CN202010555277A CN113141115A CN 113141115 A CN113141115 A CN 113141115A CN 202010555277 A CN202010555277 A CN 202010555277A CN 113141115 A CN113141115 A CN 113141115A
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primary
current
full
primary side
resonant circuit
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CN113141115B (en
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张小勇
张庆
饶沛南
周峰武
曾明高
曹金洲
罗盼
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Zhuzhou CRRC Times Electric 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
    • 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
    • H02M1/38—Means for preventing simultaneous conduction of switches
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Inverter Devices (AREA)

Abstract

The invention provides a self-adaptive control method and a self-adaptive control device for dead zone time of an LLC (logical Link control) resonant circuit. The self-adaptive control method comprises the following steps: responding to the turn-off of a group of switching tubes of the full-bridge inverter network, and acquiring the primary voltage of the LLC resonant circuit; acquiring a primary side current of the LLC resonant circuit; and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary side voltage and the primary side current. According to the self-adaptive control method and device for the dead time of the LLC resonant circuit, the problem of realization of full-working-condition soft switching of the LLC resonant circuit is solved, and the optimal engineering control of the dead time is realized.

Description

Self-adaptive control method and device for dead zone time of LLC resonant circuit
Technical Field
The invention relates to a current transformation module in the field of electricity, in particular to a self-adaptive control method and a self-adaptive control device for dead zone time of an LLC resonant circuit.
Background
The LLC converter has simple structure, small volume, easy realization of soft switching of a bridge arm switch tube, low switching loss, high conversion efficiency and isolated DC/DC, so the LLC converter has wide application in the field of high-frequency switches.
A common LLC resonant circuit is shown in FIG. 1 and comprises switching tubes Q1-Q4, a transformer T, a resonant capacitor Cr, rectifier diodes D1-D4 and an output capacitor Co. The four switching tubes Q1-Q4 form a full-bridge inverter network, a control mode of fixed frequency and fixed pulse width can be adopted, and a dead zone is arranged between the upper switching tube and the lower switching tube of the same bridge arm. The switch tubes Q1-Q4 are provided with anti-parallel (or body) diodes, and the Cj 1-Cj 4 are junction capacitances of the switch tubes Q1-Q4. The resonant capacitor Cr, the transformer leakage inductance Lr and the excitation inductance Lm jointly form a resonant network. The transformer T may be a high frequency transformer with a transformer transformation ratio of N: 1. the rectifier diodes D1-D4 form a full bridge rectifier circuit on the secondary side.
The main waveforms for a normal operation of an LLC resonant circuit as shown in fig. 1 are shown in fig. 2. According to the characteristics of the LLC circuit, the LLC circuit can work in three regions, wherein the most common working region is region 2, namely the switching frequency is less than the resonance frequency, the converter is inductive, the primary side switching tube Q1-Q4 realizes Zero Voltage switching-on (ZVS, Zero Voltage Switch), the switching-off Current is very small, and the Zero Current switching-off (ZCS, Zero Current Switch) can be approximated; the secondary side rectifier diodes D1-D4 realize natural commutation, namely zero current cut-off. Because the primary side switching tube Q1-Q4 is an approximate zero current turn-off ZCS, the secondary side rectifier diodes D1-D4 are complete zero current turn-off ZCS, the generated switching tube turn-off voltage spike VDM is small, and the rectifier diode reverse recovery voltage spike is zero.
For an LLC resonant circuit as shown in fig. 1, the conditions for achieving soft switching are: 1. dead time (t)d) Is longer than the discharge time (t) of the switch tubef) (ii) a Its 2, dead time (t)d) Less than the zero crossing time (t) of the primary currentg＝tx2-t3)。
The discharge time of the switching tube can be obtained by the following formula (1):
tf＝8*Cj*Lm*fsformula (1)
Wherein
CjThe switch tube junction capacitor is a nonlinear capacitor and changes along with the change of voltage and temperature;
Lm-transformer excitation inductance, fixed value;
fs-switching frequency, constant value.
From the above formula, it can be seen that the non-linear characteristics of the junction capacitances Cj 1-Cj 4 of the switching tubes result in the discharge time t of the switching tubesfIs non-linear.
Zero crossing time t of primary currentgCan be obtained by the following formula (2):
Figure BDA0002543994860000021
wherein
N-transformer transformation ratio, constant value;
Po-output power, varying with load variations;
Vo-output voltage, constant value;
Lm-transformer excitation inductance, fixed value;
fs-switching frequency, fixed value;
fs-resonant frequency, constant value.
From the above equation, it can be seen that the primary zero crossing time varies with the output power.
According to the analysis, it can be known that the dead time is too small, which results in incomplete discharge of the switching tube, and the dead time is too large, which is larger than the primary zero-crossing time, so that the junction capacitance of the switching tube to be switched on is charged, and the ZVS switching-on condition is lost. Since the primary zero crossing time is related to the output power, the greater the power, the shorter this time, and the greater the difficulty in soft switching implementation. It will be appreciated that too much or too little dead time may result in a loss of the soft switching condition.
The traditional dead time control method adopts a fixed dead time method, and the method can well realize soft switching in the engineering application of low power and low voltage. The soft switching implementation condition of the LLC resonant circuit is influenced by both the switch junction capacitance and the load. In high power and high voltage engineering applications, the junction capacitance of the switching tube is not constant, please refer to fig. 3A, fig. 3B and fig. 3C. Fig. 3A, 3B and 3C show the relationship between junction capacitance and voltage, current and junction temperature, respectively, of the switching tube. In fig. 3B and 3C, the magnitude of the junction capacitance is characterized by the voltage settling time t (ns).
That is to say, in the application of high-power high-voltage engineering, under the condition that the junction capacitance of the switching tube changes with the working condition and is not constant, the traditional control method for determining the dead time cannot meet the requirements of soft switching realization of the equipment in the full-power range and the full-temperature range.
In view of this, a control method is needed to solve the problem of soft switching implementation condition change of the LLC resonant circuit due to temperature and load through a simple control logic, and implement full-operating-condition soft disclosure, so as to reduce product cost, improve product environmental adaptability, and improve product competitiveness.
Disclosure of Invention
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
As described above, in order to solve the problem of a soft switching implementation condition change of an LLC resonant circuit due to temperature and load, an aspect of the present invention provides an adaptive control method of a dead time of an LLC resonant circuit, said LLC resonant circuit comprising: the full-bridge inverter network and the resonant network are arranged on the primary side, the transformer is arranged on the primary side, and the full-bridge rectifier circuit is arranged on the secondary side; the self-adaptive control method comprises the following steps:
in response to a set of switching tubes of the full-bridge inverter network being turned off,
acquiring a primary voltage of the LLC resonant circuit;
acquiring a primary side current of the LLC resonant circuit; and
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary side voltage and the primary side current.
In an embodiment of the foregoing adaptive control method, optionally, controlling the conduction of another set of switching tubes of the full-bridge inverter network according to the primary voltage and the primary current further includes:
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network based on the polarity of the primary voltage and the amplitude of the primary current.
In an embodiment of the foregoing adaptive control method, optionally, controlling the conduction of another set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further includes:
in response to detecting that the primary voltage has changed to an opposite polarity, further determining whether the magnitude of the primary current has decreased; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
In an embodiment of the foregoing adaptive control method, optionally, controlling the conduction of another set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further includes:
in response to detecting that the primary voltage changes to an opposite polarity and the magnitude of the primary voltage is within a preset range, further determining whether the magnitude of the primary current decreases; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
In an embodiment of the adaptive control method, optionally, the determining whether the amplitude of the primary current is decreased further includes:
comparing the amplitude of the primary side current with the maximum exciting current of the transformer;
and judging that the amplitude of the primary side current is detected to be reduced in response to the primary side current being smaller than the maximum exciting current.
In an embodiment of the adaptive control method, optionally, the determining whether the amplitude of the primary current is decreased further includes:
and comparing the amplitude of the primary side current at the current moment with the amplitude of the primary side current at the previous moment to judge whether the amplitude of the primary side current is reduced or not.
In another aspect of the present invention, a dead time adaptive LLC resonant circuit is provided, including: set up full-bridge inverter network and resonant network, the transformer on primary and set up the full-bridge rectifier circuit on the secondary, wherein, LLC resonant circuit still includes:
the primary side current sensor is arranged between the full-bridge inverter network and the transformer and used for detecting the primary side current of the LLC resonant circuit; and
and the primary side voltage sensor is arranged at the output end of the full-bridge inverter network and is used for detecting the potential difference between the middle points of two bridge arms in the full-bridge inverter network.
In an embodiment of the LLC resonant circuit, optionally, the primary side current sensor is further configured to detect an amplitude of a primary side current of the LLC resonant circuit; and
the primary side voltage sensor is further used for detecting the polarity of the potential difference between the middle points of the two bridge arms in the full-bridge inverter network.
In an embodiment of the LLC resonant circuit, optionally, the primary side voltage sensor is further configured to detect an amplitude of a potential difference between midpoints of two bridge arms in the full-bridge inverter network.
Another aspect of the present invention further provides an adaptive control apparatus for dead time of an LLC resonant circuit, said LLC resonant circuit comprising: the full-bridge inverter network and the resonant network are arranged on the primary side, the transformer is arranged on the primary side, and the full-bridge rectifier circuit is arranged on the secondary side; the adaptive control means includes:
a memory; and
a processor coupled to the memory, the processor configured to:
in response to a set of switching tubes of the full-bridge inverter network being turned off,
acquiring a primary voltage of the LLC resonant circuit;
acquiring a primary side current of the LLC resonant circuit; and
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary side voltage and the primary side current.
In an embodiment of the foregoing adaptive control device, optionally, the controlling, by the processor, the conduction of another set of switching tubes of the full-bridge inverter network according to the primary voltage and the primary current further includes:
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network based on the polarity of the primary voltage and the amplitude of the primary current.
In an embodiment of the foregoing adaptive control device, optionally, the controlling, by the processor, the conduction of another set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further includes:
in response to detecting that the primary voltage has changed to an opposite polarity, further determining whether the magnitude of the primary current has decreased; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
In an embodiment of the foregoing adaptive control device, optionally, the controlling, by the processor, the conduction of another set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further includes:
in response to detecting that the primary voltage changes to an opposite polarity and the magnitude of the primary voltage is within a preset range, further determining whether the magnitude of the primary current decreases; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
In an embodiment of the foregoing adaptive control device, optionally, the determining, by the processor, whether the amplitude of the primary current decreases further includes:
comparing the amplitude of the primary side current with the maximum exciting current of the transformer;
and judging that the amplitude of the primary side current is detected to be reduced in response to the primary side current being smaller than the maximum exciting current.
In an embodiment of the foregoing adaptive control device, optionally, the determining, by the processor, whether the amplitude of the primary current decreases further includes:
and comparing the amplitude of the primary side current at the current moment with the amplitude of the primary side current at the previous moment to judge whether the amplitude of the primary side current is reduced or not.
Another aspect of the present invention further provides a dead time adaptive LLC resonant circuit system, specifically including the LLC resonant circuit in any one of the embodiments described above; and the adaptive control means in any of the embodiments described above.
Yet another aspect of the present invention provides a computer readable medium having stored thereon computer readable instructions, which, when executed by a processor, implement the steps in any of the embodiments of the adaptive control method as described above.
According to the adaptive control method for the dead time of the LLC resonant circuit, provided by the invention, the optimal dead time can be determined in real time based on the primary current and the primary voltage of the LLC resonant circuit, so that the method is different from the control method for determining the dead time in the prior art. By the self-adaptive control method for the dead zone time of the LLC resonant circuit, the problem of condition change of the soft switch of the LLC resonant circuit caused by temperature and load can be solved through a simple control logic, and soft disclosure under all working conditions is realized, so that the product cost can be reduced, the environmental adaptability of the product is improved, and the product competitiveness is improved.
According to the LLC resonant circuit with the self-adaptive dead time, provided by the invention, only one voltage sensor and one current sensor are required to be added in the realization of the circuit structure, the structure is simple, excessive product cost is not required to be increased, and the LLC resonant circuit can realize soft switching under the full-working-condition environment, so that the dead time optimal engineering control is realized.
Drawings
The above features and advantages of the present disclosure will be better understood upon reading the detailed description of embodiments of the disclosure in conjunction with the following drawings. In the drawings, components are not necessarily drawn to scale, and components having similar relative characteristics or features may have the same or similar reference numerals.
Fig. 1 shows a schematic diagram of a structure of a LLC resonant circuit in the prior art.
Fig. 2 shows the main waveforms in normal operation of the LLC resonant circuit shown in fig. 1.
Fig. 3A shows a relation between a junction capacitance and a voltage of a switching tube in the LLC resonant circuit shown in fig. 1.
Fig. 3B shows a relation between a junction capacitance and a current of a switching tube in the LLC resonant circuit shown in fig. 1.
Fig. 3C shows a relation between junction temperature and junction capacitance of a switching tube in the LLC resonant circuit shown in fig. 1.
Fig. 4 shows a schematic diagram of a dead time adaptive LLC resonant circuit provided by an aspect of the present invention.
Fig. 5 is a flow chart illustrating an embodiment of a method for adaptively controlling a dead time of an LLC resonant circuit according to an aspect of the present invention.
Fig. 6 is a flow chart of another embodiment of the adaptive control method for dead time of the LLC resonant circuit according to an aspect of the present invention.
Fig. 7 illustrates waveforms when the adaptive control of dead time provided according to an aspect of the present invention controls the operation of an LLC resonant circuit.
Fig. 8 shows a schematic diagram of an adaptive control apparatus for dead time of an LLC resonant circuit provided in accordance with an aspect of the present invention.
Reference numerals
Q1-Q4 switch tube
Cj 1-Cj 4 junction capacitor
Cr resonant capacitor
Lr transformer leakage inductance
Lm exciting inductance
T-shaped transformer
D1-D4 rectifier diode
Co output capacitor
SV1 primary side voltage sensor
SC1 primary side current sensor
800 adaptive control device
810 processor
820 memory
Detailed Description
The following description is presented to enable any person skilled in the art to make and use the invention and is incorporated in the context of a particular application. Various modifications, as well as various uses in different applications will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to a wide range of embodiments. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
In the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the practice of the invention may not necessarily be limited to these specific details. In other instances, well-known structures and devices are shown in block diagram form, rather than in detail, in order to avoid obscuring the present invention.
The reader's attention is directed to all papers and documents which are filed concurrently with this specification and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All the features disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
Note that where used, the designations left, right, front, back, top, bottom, positive, negative, clockwise, and counterclockwise are used for convenience only and do not imply any particular fixed orientation. In fact, they are used to reflect the relative position and/or orientation between the various parts of the object. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
It is noted that, where used, further, preferably, still further and more preferably is a brief introduction to the exposition of the alternative embodiment on the basis of the preceding embodiment, the contents of the further, preferably, still further or more preferably back band being combined with the preceding embodiment as a complete constituent of the alternative embodiment. Several further, preferred, still further or more preferred arrangements of the belt after the same embodiment may be combined in any combination to form a further embodiment.
The invention is described in detail below with reference to the figures and specific embodiments. It is noted that the aspects described below in connection with the figures and the specific embodiments are only exemplary and should not be construed as imposing any limitation on the scope of the present invention.
In order to solve the problem of the change of the soft switching implementation condition of the LLC resonant circuit due to temperature and load, an aspect of the present invention provides a dead time adaptive LLC resonant circuit, and fig. 4 shows a schematic structural diagram of the LLC resonant circuit provided by an aspect of the present invention. As shown in fig. 4, an aspect of the present invention provides an LLC resonant circuit that adds a primary current sensor SC1 and a primary voltage sensor SV1 to the existing structure. And the primary side current sensor SC1 is arranged between the full-bridge inverter network and the transformer T and is used for detecting the primary side current of the LLC resonant circuit. The primary side voltage sensor SV1 is arranged at the output end of the full-bridge inverter network and is used for detecting the potential difference between the middle points A, B of two bridge arms in the full-bridge inverter network.
Further, it will be appreciated that the primary side current sensor SC1 described above may also be used to achieve primary side overcurrent protection. Alternatively, the primary current of the LLC resonant circuit can be detected by a prior art current sensor for primary overcurrent protection. That is, the dead time adaptive LLC resonant circuit provided in one aspect of the present invention adds only one voltage sensor, so that the dead time adaptation can be achieved by the adaptive control method provided in another aspect of the present invention. According to the dead time self-adaptive LLC resonant circuit, a complex structure is not additionally added, so that the product cost can be controlled, the problem of soft switch realization condition change caused by temperature and load of the LLC resonant circuit is solved, the environmental adaptability of a product is improved, and the product competitiveness is improved.
Referring to fig. 5-7, an adaptive control method of dead time according to another aspect of the present invention will be described in detail with reference to the circuit configuration shown in fig. 4. First, referring to fig. 5, as shown in fig. 5, the dead time adaptive control method provided by the present invention includes step S100: turning off a group of switching tubes in the full-bridge inverter network; step S200: acquiring a primary voltage of an LLC resonant circuit; step S300: acquiring a primary side current of the LLC resonant circuit; and step S400: and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary voltage and the primary current.
Referring to fig. 4, taking the switching tubes Q1 and Q4 in fig. 4 as an example of a set of switching tubes, the pair of switching tubes Q1 and Q4 are Q2 and Q3, the switching tubes Q1 and Q4 can be selectively turned off in step S100, and correspondingly, the switching tubes Q2 and Q3 are turned on in step S400.
In the step S200, the primary voltage of the LLC resonant circuit can be obtained by the newly added primary voltage sensor SV1, and it can be understood that the primary voltage of the LLC resonant circuit is the potential difference U between the midpoint A, B of the two bridge arms in the full-bridge inverter networkAB。
In the above step S300, the primary side current of the LLC resonant circuit can be obtained by the newly added primary side current sensor SC1, and it can be understood that the primary side current of the LLC resonant circuit can be regarded as the current i on the leakage inductance Lr of the transformerLrBefore the switched-off switching tube discharges, the primary current is the same as the maximum excitation current Im of the transformer T.
In the step S400, controlling the conduction of another set of switching tubes of the full-bridge inverter network according to the primary voltage and the primary current further includes: and controlling the conduction of the other group of switching tubes of the full-bridge inverter network based on the polarity of the primary voltage and the amplitude of the primary current. It will be appreciated that the primary voltage sensor SV1 shown in fig. 4 is also used to obtain the polarity of the primary voltage, and the primary current sensor SC1 is also used to obtain the magnitude of the primary current.
In another embodiment, as shown in fig. 6, in response to a set of switching tubes in the full-bridge inverter network being turned off, the dead time adaptive method provided by the present invention executes step S410 after acquiring the primary voltage in step S200: determining whether the primary voltage has changed to an opposite polarity, and in response to the primary voltage not changing to the opposite polarity, continuing to acquire the primary voltage until the primary voltage changes to the opposite polarity.
In response to the determination in step S410 that the primary voltage has changed to the opposite polarity, in a preferred embodiment, the dead time adaptive control method provided by the present invention further comprises executing step S420: judging primary side electricityWhether the magnitude of the pressure is within a preset range. It can be understood that the primary voltage U is obtained after the group of switching tubes Q1, Q4 is turned offABContinuously decrease, not only experience UABIn reverse direction, will eventually equal-VAB. That is, the turned-off set of switching tubes Q1, Q4 has been completely discharged, and the first condition of soft switching is satisfied. By setting the preset range to be less than VABIn the small section of the interval, the moment when the switching tubes Q1 and Q4 are completely discharged can be ensured to be detected, so that preparation is made for conducting the pair tubes Q2 and Q3 after the initial point current is detected subsequently.
At the same time, although the input voltage VABIs a constant value, it being understood that setting less than VABCan also exclude the input voltage V within a small preset rangeABIn an unstable state, the timing at which the switching tubes Q1 and Q4 are completely discharged can be accurately detected.
In response to the primary voltage having been detected to have changed to the opposite polarity in step S410 of one embodiment or the primary voltage having been detected to have a magnitude within a preset range in step S420 of another preferred embodiment, step S300 is performed to obtain the primary current, and then step S430 is performed: and judging whether the amplitude of the primary side current is reduced or not.
It is understood that, since the primary current does not decrease until the switching tubes Q1, Q4 are fully discharged, when the primary current begins to decrease, it is considered that the switching tubes Q1, Q4 are fully discharged again. At this time, step S440 may be performed: the pair transistors Q2 and Q3 of the switching transistors Q1 and Q4 are turned on, so that the dead time t can be ensureddAs much as possible with the discharge time t of the switching tubes Q1, Q4fApproach so that the dead time t can be secureddNot more than the primary zero crossing time tg.
In another embodiment, the primary current can be obtained in real time after the switching tubes Q1 and Q4, and whether the amplitude of the primary current starts to decrease is judged, so that the problem that in an embodiment that whether the amplitude of the primary voltage needs to be judged in a preset range is avoided, because the input voltage is too low, the switching tubes Q1 and Q4 are mistaken to be that the power is not completely discharged all the time, the primary zero-crossing time is reached, and the second condition of the soft switch is met is missed.
Meanwhile, the dead time self-adaptive method provided by the invention also comprises the step of detecting the primary voltage, so that the amplitude reduction caused by abnormal fluctuation of the primary current can be avoided, the switching tubes Q1 and Q4 are mistakenly completely discharged, the dead time is ended before the discharge time, and the problem that the first condition of the soft switch is met is missed.
In the above embodiment, determining whether the amplitude of the primary current becomes smaller further includes: the magnitude of the primary current is compared to the maximum excitation current of the transformer. And judging that the amplitude of the detected primary side current is reduced in response to the fact that the primary side current is smaller than the maximum exciting current. As described above, the primary current is equal to the maximum exciting current of the transformer before the switching tube is completely discharged, and therefore, whether the amplitude of the primary current is reduced or not can be determined by comparing the obtained primary current with the maximum exciting current, that is, a signal that the primary current starts to decrease is obtained.
In another embodiment, the processor determining whether the magnitude of the primary current has decreased further comprises: and comparing the amplitude of the primary side current at the current moment with the amplitude of the primary side current at the previous moment to judge whether the amplitude of the primary side current is reduced or not. By detecting the amplitude of the primary current in real time, a signal that the primary current starts to decrease can be intuitively obtained.
According to the dead time self-adaptive control method provided by the invention, the dead time t can be ensureddGreater than the turn-off time t of the switching tubefAnd meanwhile, the dead zone time is less than the primary zero-crossing time tg, so that dead zone optimal engineering control can be realized. FIG. 7 illustrates the waveform of the operation of the LLC resonant circuit as shown in FIG. 4 controlled by the dead time adaptive control method provided by the invention, it can be seen from FIG. 4 that the dead time satisfies tf＜td＜tgThereby, soft switching of the LLC resonant circuit can be ensured.
It will be appreciated that, since the LLC resonant circuit and its control are symmetrical, the implementation of the other half-cycle, i.e. turning off the switching transistors Q2, Q3, and the time scheme for turning on the switching transistors Q1, Q4 after the adaptive dead time is similar to that described above.
According to the adaptive control method for the dead time of the LLC resonant circuit, provided by the invention, the optimal dead time can be determined in real time based on the primary current and the primary voltage of the LLC resonant circuit, so that the method is different from the control method for determining the dead time in the prior art. By the self-adaptive control method for the dead zone time of the LLC resonant circuit, the problem of condition change of the soft switch of the LLC resonant circuit caused by temperature and load can be solved through a simple control logic, and soft disclosure under all working conditions is realized, so that the product cost can be reduced, the environmental adaptability of the product is improved, and the product competitiveness is improved.
The present invention further provides an adaptive control apparatus for dead time of an LLC resonant circuit, please refer to fig. 8, and fig. 8 shows a schematic diagram of the adaptive control apparatus. As shown in fig. 8, the adaptive control apparatus 800 includes a processor 810 and a memory 820. The processor 810 of the adaptive control apparatus 800 can implement the adaptive control method described above when executing the computer program stored in the memory 820, and please refer to the description of the adaptive control method, which is not repeated herein.
The invention also provides a dead time adaptive LLC resonant circuit system, comprising the LLC resonant circuit in any one of the embodiments described above; and the adaptive control means in any of the embodiments described above. For the dead time adaptive LLC resonant circuit system, please refer to the above description of the adaptive control method and apparatus, and will not be described herein again.
So far, the adaptive control method and device provided by the invention have been described. The present invention also provides a computer storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the adaptive control method as described above. For details, please refer to the above description of the adaptive control method, which is not repeated herein.
According to the adaptive control method for the dead time of the LLC resonant circuit, provided by the invention, the optimal dead time can be determined in real time based on the primary current and the primary voltage of the LLC resonant circuit, so that the method is different from the control method for determining the dead time in the prior art. By the self-adaptive control method for the dead zone time of the LLC resonant circuit, the problem of condition change of the soft switch of the LLC resonant circuit caused by temperature and load can be solved through a simple control logic, and soft disclosure under all working conditions is realized, so that the product cost can be reduced, the environmental adaptability of the product is improved, and the product competitiveness is improved.
According to the LLC resonant circuit with the self-adaptive dead time, provided by the invention, only one voltage sensor and one current sensor are required to be added in the realization of the circuit structure, the structure is simple, excessive product cost is not required to be increased, and the LLC resonant circuit can realize soft switching under the full-working-condition environment, so that the dead time optimal engineering control is realized.
The various illustrative logical modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web site, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, Digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. It is to be understood that the scope of the invention is to be defined by the appended claims and not by the specific constructions and components of the embodiments illustrated above. Those skilled in the art can make various changes and modifications to the embodiments within the spirit and scope of the present invention, and these changes and modifications also fall within the scope of the present invention.

Claims (17)

1. An adaptive control method of dead time of an LLC resonant circuit, said LLC resonant circuit comprising: the full-bridge inverter network and the resonant network are arranged on the primary side, the transformer is arranged on the primary side, and the full-bridge rectifier circuit is arranged on the secondary side; the self-adaptive control method is characterized by comprising the following steps:
in response to a set of switching tubes of the full-bridge inverter network being turned off,
acquiring a primary voltage of the LLC resonant circuit;
acquiring a primary side current of the LLC resonant circuit; and
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary side voltage and the primary side current.
2. The adaptive control method of claim 1, wherein controlling the other set of switching tubes of the full-bridge inverter network to conduct according to the primary voltage and the primary current further comprises:
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network based on the polarity of the primary voltage and the amplitude of the primary current.
3. The adaptive control method of claim 2, wherein controlling the conduction of the other set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further comprises:
in response to detecting that the primary voltage has changed to an opposite polarity, further determining whether the magnitude of the primary current has decreased; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
4. The adaptive control method of claim 2, wherein controlling the conduction of the other set of switching tubes of the full-bridge inverter network based on the polarity direction of the primary voltage and the magnitude of the primary current further comprises:
in response to detecting that the primary voltage changes to an opposite polarity and the magnitude of the primary voltage is within a preset range, further determining whether the magnitude of the primary current decreases; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
5. The adaptive control method of claim 3 or 4, wherein determining whether the magnitude of the primary current has decreased further comprises:
comparing the amplitude of the primary side current with the maximum exciting current of the transformer;
and judging that the amplitude of the primary side current is detected to be reduced in response to the primary side current being smaller than the maximum exciting current.
6. The adaptive control method of claim 3 or 4, wherein determining whether the magnitude of the primary current has decreased further comprises:
and comparing the amplitude of the primary side current at the current moment with the amplitude of the primary side current at the previous moment to judge whether the amplitude of the primary side current is reduced or not.
7. A dead time adaptive LLC resonant circuit, comprising: set up full-bridge inverter network and resonant network, the transformer on primary and set up the full-bridge rectifier circuit on the secondary, its characterized in that, LLC resonant circuit still includes:
the primary side current sensor is arranged between the full-bridge inverter network and the transformer and used for detecting the primary side current of the LLC resonant circuit; and
and the primary side voltage sensor is arranged at the output end of the full-bridge inverter network and is used for detecting the potential difference between the middle points of two bridge arms in the full-bridge inverter network.
8. The LLC resonant circuit of claim 7, wherein said primary current sensor is further configured to detect an amplitude of a primary current of the LLC resonant circuit; and
the primary side voltage sensor is further used for detecting the polarity of the potential difference between the middle points of the two bridge arms in the full-bridge inverter network.
9. The LLC resonant circuit of claim 8, wherein said primary voltage sensor is further configured to detect a magnitude of a potential difference between midpoints of two legs in said full-bridge inverter network.
10. An adaptive control apparatus for dead time of an LLC resonant circuit, said LLC resonant circuit comprising: the full-bridge inverter network and the resonant network are arranged on the primary side, the transformer is arranged on the primary side, and the full-bridge rectifier circuit is arranged on the secondary side; wherein the adaptive control means comprises:
a memory; and
a processor coupled to the memory, the processor configured to:
in response to a set of switching tubes of the full-bridge inverter network being turned off,
acquiring a primary voltage of the LLC resonant circuit;
acquiring a primary side current of the LLC resonant circuit; and
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network according to the primary side voltage and the primary side current.
11. The adaptive control apparatus according to claim 10, wherein the processor controlling the other set of switching tubes of the full-bridge inverter network to be conductive based on the primary voltage and the primary current further comprises:
and controlling the conduction of the other group of switching tubes of the full-bridge inverter network based on the polarity of the primary voltage and the amplitude of the primary current.
12. The adaptive control apparatus according to claim 11, wherein the processor controlling the other set of switching tubes of the full-bridge inverter network to be turned on based on the polarity direction of the primary voltage and the magnitude of the primary current further comprises:
in response to detecting that the primary voltage has changed to an opposite polarity, further determining whether the magnitude of the primary current has decreased; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
13. The adaptive control apparatus according to claim 11, wherein the processor controlling the other set of switching tubes of the full-bridge inverter network to be turned on based on the polarity direction of the primary voltage and the magnitude of the primary current further comprises:
in response to detecting that the primary voltage changes to an opposite polarity and the magnitude of the primary voltage is within a preset range, further determining whether the magnitude of the primary current decreases; and
and controlling the other group of switching tubes of the full-bridge inverter network to be conducted in response to the detection that the amplitude of the primary side current becomes smaller.
14. The adaptive control apparatus of claim 12 or 13, wherein the processor determining whether the magnitude of the primary current has decreased further comprises:
comparing the amplitude of the primary side current with the maximum exciting current of the transformer;
and judging that the amplitude of the primary side current is detected to be reduced in response to the primary side current being smaller than the maximum exciting current.
15. The adaptive control apparatus of claim 12 or 13, wherein the processor determining whether the magnitude of the primary current has decreased further comprises:
and comparing the amplitude of the primary side current at the current moment with the amplitude of the primary side current at the previous moment to judge whether the amplitude of the primary side current is reduced or not.
16. A dead time adaptive LLC resonant circuit system, characterized in that it comprises an LLC resonant circuit as claimed in any one of claims 7-9; and
the adaptive control apparatus of any one of claims 10-15.
17. A computer readable medium having stored thereon computer readable instructions which, when executed by a processor, carry out the steps of the adaptive control method according to any one of claims 1-6.
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