DC converter control method, apparatus and device, and storage medium

Abstract

The invention relates to the technical field of power electronics, and discloses a direct-current converter control method, device and equipment and a storage medium, applied to a full-bridge LLC direct-current converter, and the method comprises the following steps: obtaining a closed-loop quantity according to an input current of a direct-current side of a primary side converter and an output voltage of a direct-current side of a secondary side converter; when the closed-loop quantity is smaller than or equal to a preset value and the direct-current converter works in a step-down discharge mode, the time length of a high level input to the secondary side converter is reduced by controlling the switching devices to be simultaneously and alternately conducted in a switching period; and when the closed-loop quantity is greater than a preset value and the direct-current converter works in a boost discharge mode, the resonant circuit performs bidirectional energy storage and energy release through the primary side converter by controlling the switching device to be symmetrically and alternately conducted in the positive and negative half cycles of the resonant current. According to the invention, wide-range boost regulation can be carried out during LLC reverse operation, and good soft switching characteristics can be realized at the same time.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a direct current converter control method, device, equipment and storage medium. Background Art

[0002] With the rapid development of the new energy storage industry, due to the wide voltage range characteristics of lithium batteries, energy storage products have higher and higher requirements for power supply performance to achieve bidirectional buck-boost control. Bidirectional full-bridge LLC converters are widely used because they are easy to implement soft switching and have fewer resonant devices, and have the advantages of high efficiency and high power density. LLC converters work in reverse in LC series resonant mode. The traditional control method uses fixed frequency duty cycle adjustment, fixed frequency phase shift or variable frequency control, and does not have boost capability. In the energy storage system, the LLC low-voltage side is connected to the energy storage battery, and the high-voltage side is connected to the inverter. In the off-grid discharge mode, the bus voltage required by the inverter is relatively fixed, and the LLC reverse operation in the buck mode is sufficient to support the inverter voltage output. In the grid-connected discharge mode, the bus voltage needs to be dynamically adjusted with the grid voltage. Therefore, the traditional control method that only supports the buck mode when working in reverse cannot support the inverter grid-connected operation. Summary of the invention

[0003] Therefore, the technical problem to be solved by the present invention is to solve the problem of limited boost capability of LLC converters in the prior art when working in reverse, thereby providing a DC converter control method, device, equipment and storage medium.

[0004] In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a DC converter control method, which is applied to a full-bridge LLC DC converter, and the method comprises: obtaining an input current of a primary converter DC side and an output voltage of a secondary converter DC side; performing closed-loop control on the input current and the output voltage using a voltage loop and a current loop to obtain a closed-loop quantity; when the closed-loop quantity is less than or equal to a preset value, when the DC converter operates in a step-down discharge mode, the switching devices of each diagonal bridge arm in the primary converter are controlled to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time, thereby reducing the The duration of the high level from the low input to the secondary converter; when the closed-loop quantity is greater than the preset value, the DC converter operates in the boost discharge mode, and the switching devices diagonally opposite to each other in the primary converter are controlled to be alternately turned on at the same time within a switching cycle, and the switching devices on the same side of each bridge arm in the secondary converter are controlled to be symmetrically alternately turned on within the positive and negative half cycles of the resonant current by adjusting the pulse width length, so that the resonant circuit stores energy in both directions through the primary converter, and then the switching devices in the secondary converter are controlled to be turned off, so that the resonant circuit releases energy through the secondary converter.

[0005] The DC converter control method provided by the present invention determines the working state of the full-bridge LLC DC converter by the range of the closed-loop quantity, and the size of the closed-loop quantity determines the buck capability and boost capability of the full-bridge LLC DC converter: when the closed-loop quantity is less than or equal to the preset value, the DC converter operates in the buck discharge mode, at which time the size of the closed-loop quantity determines the phase shift time of the diagonal switch device on the primary side, thereby determining the energy transferred from the low-voltage side to the high-voltage side; when the closed-loop quantity is greater than the preset value, the DC converter operates in the boost discharge mode, at which time the size of the closed-loop quantity determines the pulse width length of the switch device on the same side of the secondary side, thereby adjusting the energy storage of the resonant circuit, and further determining the size of the energy output by the resonant circuit, that is, the boost capability of the DC converter. The DC converter control method provided by the present invention realizes that the DC converter can realize a wide range of boost control and flexibly adjust the boost capability when operating in reverse on the basis of buck output.

[0006] In an optional embodiment, the process of using a voltage loop and a current loop to perform closed-loop control on the input current and the output voltage to obtain a closed-loop quantity includes: using the output voltage as the feedback quantity of the voltage loop, comparing it with the voltage loop set value, and then using a PI controller to calculate the current loop set value; using the input current as the feedback quantity of the current loop, comparing it with the current loop set value, and then using a PI controller to calculate the closed-loop quantity.

[0007] In an optional embodiment, one bridge arm of the primary converter includes a first primary power electronic switch and a second primary power electronic switch, and another bridge arm of the primary converter includes a third primary power electronic switch and a fourth primary power electronic switch; one bridge arm of the secondary converter includes a first secondary power electronic switch and a second secondary power electronic switch, and another bridge arm of the secondary converter includes a third secondary power electronic switch and a fourth secondary power electronic switch; the process of controlling the diagonal switching devices of each bridge arm in the primary converter to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time includes In summary: based on the difference between the preset value and the closed-loop quantity, the phase shift time is calculated in combination with the preset switching cycle; in the positive half switching cycle, the first primary power electronic switch is controlled to be turned on, the second primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch are controlled to be turned off, and then the fourth primary power electronic switch is controlled to be turned on after the phase shift time; in the negative half switching cycle, the second primary power electronic switch is controlled to be turned on, the first primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch are controlled to be turned off, and then the third primary power electronic switch is controlled to be turned on after the phase shift time.

[0008] In an optional embodiment, the process of reducing the duration of the high level input to the secondary converter includes: increasing the phase shift time by reducing the closed-loop amount, thereby reducing the common conduction time of the first primary power electronic switch and the fourth primary power electronic switch, and increasing the common conduction time of the first primary power electronic switch and the third primary power electronic switch.

[0009] The DC converter control method provided by the present invention realizes a wide range of voltage reduction adjustment by performing fixed-frequency phase shift control on the primary inverter side, and has high flexibility.

[0010] In an optional embodiment, the process of controlling the switching devices of each diagonal bridge arm in the primary converter to be turned on alternately at the same time within a switching cycle includes: based on the difference between the closed-loop quantity and the preset value, and in combination with the preset switching cycle, calculating and obtaining the pulse width length; in the positive half switching cycle, controlling the first primary power electronic switch and the fourth primary power electronic switch to be turned on, and the second primary power electronic switch and the third primary power electronic switch to be turned off, while controlling the first secondary power electronic switch and the third secondary power electronic switch to be turned on synchronously according to the pulse width length, and the second secondary power electronic switch and the fourth secondary power electronic switch to be turned off; in the negative half switching cycle, controlling the second primary power electronic switch and the third primary power electronic switch to be turned on, and the first primary power electronic switch and the fourth primary power electronic switch to be turned off, while controlling the second secondary power electronic switch and the fourth secondary power electronic switch to be turned on synchronously according to the pulse width length, and the first secondary power electronic switch and the third secondary power electronic switch to be turned off.

[0011] In an optional embodiment, after the resonant circuit performs bidirectional energy storage through the primary converter, the switching devices in the secondary converter are controlled to be turned off, so that the resonant circuit releases energy through the secondary converter, including: in the positive half switching cycle, the resonant circuit performs positive energy storage through the first primary power electronic switch, the fourth primary power electronic switch, the first secondary power electronic switch and the third secondary power electronic switch; in the negative half switching cycle, the resonant circuit performs negative energy storage through the second primary power electronic switch, the third primary power electronic switch, the second secondary power electronic switch and the fourth secondary power electronic switch; when the resonant circuit completes the energy storage process, all the switching devices in the secondary converter are controlled to be turned off for uncontrolled rectification, so that the energy in the resonant circuit is released to the load.

[0012] In an optional implementation, the DC converter control method further includes: increasing the pulse width by increasing the closed-loop quantity, thereby extending the energy storage time of the resonant circuit.

[0013] The DC converter control method provided by the present invention can achieve a wide range of reverse discharge boost capability by optimizing the driving mode of the secondary rectifier side and adjusting the duty ratio of the switches on the same side at the same time from the perspective of voltage stabilization range.

[0014] In a second aspect, the present invention provides a control device for a DC converter, comprising: an acquisition module for acquiring an input current of a primary converter DC side and an output voltage of a secondary converter DC side; a closed-loop regulation module for performing closed-loop control on the input current and the output voltage using a voltage loop and a current loop to obtain a closed-loop quantity; and a buck control module for controlling the diagonally opposite switching devices of each bridge arm in the primary converter to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time when the closed-loop quantity is less than or equal to a preset value and the DC converter operates in a buck discharge mode, thereby reducing the voltage drop. The duration of the high level from the low input to the secondary converter; a boost control module, which is used to control the switching devices diagonally opposite to each other in the primary converter to be turned on alternately at the same time within a switching cycle when the closed-loop quantity is greater than a preset value and the DC converter operates in a boost discharge mode, and by adjusting the pulse width and controlling the switching devices on the same side of each bridge arm in the secondary converter to be turned on alternately symmetrically within the positive and negative half cycles of the resonant current, so that the resonant circuit stores energy in both directions through the primary converter, and then controls the switching devices in the secondary converter to be turned off, so that the resonant circuit releases energy through the secondary converter.

[0015] In a third aspect, the present invention provides a computer device, comprising: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the control method of the DC converter of the first aspect by executing the computer instructions.

[0016] In a fourth aspect, the present invention provides a computer-readable storage medium having computer instructions stored thereon, the computer instructions being used to enable a computer to execute the control method for a DC converter of the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a specific circuit diagram of a full-bridge LLC DC converter according to an embodiment of the present invention; Figure 2 is a flow chart of a DC converter control method according to an embodiment of the present invention; Figure 3 is a flow chart of another DC converter control method according to an embodiment of the present invention; Figure 4is a schematic diagram of closed-loop control according to an embodiment of the present invention; Figure 5 is a flow chart of another DC converter control method according to an embodiment of the present invention; Figure 6 is a schematic diagram of phase shift control according to an embodiment of the present invention; Figure 7 is a flow chart of another DC converter control method according to an embodiment of the present invention; Figure 8 is a schematic diagram of pulse width control according to an embodiment of the present invention; Fig. 9 is a driving waveform diagram of the primary and secondary sides in a boost mode according to an embodiment of the present invention; Fig.10 is a flow chart of another DC converter control method according to an embodiment of the present invention; Fig.11 is a voltage and current waveform diagram of the primary and secondary sides in a boost mode according to an embodiment of the present invention; Fig.12 is a soft switching waveform diagram of a DC converter according to an embodiment of the present invention; Fig.13 is a schematic diagram of a photovoltaic cleaning robot operating device according to an embodiment of the present invention; Fig.14 It is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] According to an embodiment of the present invention, a DC converter control method embodiment is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0021] This embodiment provides a DC converter control method, which is applied to Figure 1The full-bridge LLC DC converter shown in the figure, wherein one bridge arm of the primary converter 1 of the DC converter includes a first primary power electronic switch P1 and a second primary power electronic switch P2, and another bridge arm of the primary converter 1 includes a third primary power electronic switch P3 and a fourth primary power electronic switch P4; one bridge arm of the secondary converter 2 includes a first secondary power electronic switch S1 and a second secondary power electronic switch S2, and another bridge arm of the secondary converter 2 includes a third secondary power electronic switch S3 and a fourth secondary power electronic switch S4. The primary side of the transformer T is respectively connected to the two bridge arms of the primary converter 1, the secondary side of the transformer T is respectively connected to the two ends of the resonant circuit 3, and the other two ends of the resonant circuit 3 are respectively connected to the two bridge arms of the secondary converter 2. The resonant circuit 3 includes an excitation inductor Lm, a resonant inductor Lr and a resonant capacitor Cr.

[0022] based on Figure 1 The circuit shown, Figure 2 As shown, the DC converter control method includes: Step S1: obtaining the input current of the DC side of the primary converter and the output voltage of the DC side of the secondary converter.

[0023] Step S2: Use the voltage loop and the current loop to perform closed-loop control on the input current and the output voltage to obtain closed-loop quantities.

[0024] Specifically, refer to Figure 1 , obtain the input current of the DC side of the primary converter 1, obtain the output voltage of the DC side of the secondary converter 2, and set the voltage loop set value and the current loop limit value, and then use the output voltage outer loop and the input current inner loop for closed-loop control.

[0025] Alternatively, if Figure 3 As shown, the process of using the voltage loop and the current loop to perform closed-loop control on the input current and the output voltage to obtain the closed-loop quantity includes: Step S21: The output voltage is used as the feedback of the voltage loop, and after comparing it with the voltage loop set value, the current loop set value is calculated using the PI controller.

[0026] Step S22: The input current is used as the feedback quantity of the current loop, and after comparing it with the current loop set value, the closed-loop quantity is calculated using the PI controller.

[0027] Specifically, refer to Figure 4 , obtain the input current i of the DC side of the primary converter 1 in , (i.e., the discharge current of the battery on the DC side of the primary converter 1), and obtain the output voltage u on the DC side of the secondary converter 2 o (i.e., the voltage across the output load R), set the voltage loop given value u ref After that, u oAs the feedback of the voltage loop and the voltage loop given value u ref The current loop given value i is calculated by the PI controller. ref , change i in As the feedback of the current loop and the current loop given value i ref The final closed-loop value is calculated by the PI controller after comparison, and the range of the closed-loop value is limited to 0~1.

[0028] Optionally, different PWM drive modes are switched according to the range of the closed-loop quantity to achieve the buck function or boost function of the DC converter: (1) When the closed-loop value is in the range of 0~0.5, the DC converter operates in the step-down discharge mode.

[0029] (2) When the closed-loop value is in the range of 0.5~1, the DC converter operates in the boost discharge mode.

[0030] Step S3: When the closed-loop quantity is less than or equal to the preset value, when the DC converter operates in the step-down discharge mode, the switching devices of each diagonal bridge arm in the primary converter are controlled to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time, thereby reducing the duration of the high level input to the secondary converter.

[0031] Alternatively, if Figure 5 As shown, the process of controlling the switching devices of each diagonally opposite bridge arm in the primary converter to be turned on alternately at the same time in one switching cycle by adjusting the phase shift time includes: Step S31: Calculate the phase shift time based on the difference between the preset value and the closed-loop value and in combination with the preset switching cycle.

[0032] Specifically, refer to Figure 1 and Figure 6 , set the preset value to 0.5. When the closed-loop quantity is less than or equal to the preset value 0.5, the primary converter 1 adopts phase shift control and calculates the phase shift time t0 = phase shift ratio × switching period 1 / Ts, where the phase shift ratio = 0.5-closed-loop quantity.

[0033] Step S32: in the positive half switching cycle, the first primary power electronic switch is controlled to be turned on, the second primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch are controlled to be turned off, and then the fourth primary power electronic switch is controlled to be turned on after the phase shift time.

[0034] Step S33: in the negative half switching cycle, the second primary power electronic switch is controlled to be turned on, the first primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch are turned off, and then the third primary power electronic switch is controlled to be turned on after the phase shift time.

[0035] Specifically, refer to Figure 1 and Figure 6 , the duty cycle of each power electronic switch of the primary converter 1 is 50%, and the upper and lower switches of each bridge arm are turned on complementary. Two groups of diagonal power electronic switches are turned on alternately in a switching cycle, for example: P1 and P4 are turned on in the positive half cycle of the resonance cycle, and P2 and P3 are turned on in the negative half cycle. According to the closed-loop quantity, the two diagonal switch tubes of each group are controlled according to the calculated phase shift time t0, and P4 is turned on after P1 according to the phase shift time, and P3 is turned on after P2 according to the phase shift time.

[0036] Step S34: increasing the phase shift time by reducing the closed-loop amount, thereby reducing the common conduction time of the first primary power electronic switch and the fourth primary power electronic switch, and increasing the common conduction time of the first primary power electronic switch and the third primary power electronic switch.

[0037] Specifically, refer to Figure 1 and Figure 6 The conduction order of the power electronic switches of the primary converter 1 is P1, P4, P2, and P3. According to the calculation method of the phase shift time t0, the smaller the closed-loop amount, the longer the phase shift time, the shorter the common conduction time of the diagonally opposite power electronic switches P1 and P4 of the primary converter 1, and the longer the common conduction time of the power electronic switches P1 and P3 on the same side, that is, the shorter the time when the bridge arm output voltage is at a high level and the longer the time when it is at a zero level, the less energy is transferred to the load and the lower the output voltage.

[0038] Step S4: When the closed-loop quantity is greater than the preset value, when the DC converter operates in the boost discharge mode, the switching devices diagonally opposite each bridge arm in the primary converter are controlled to be alternately turned on simultaneously within a switching cycle, and the pulse width is adjusted and the switching devices on the same side of each bridge arm in the secondary converter are controlled to be symmetrically alternately turned on within the positive and negative half cycles of the resonant current, so that the resonant circuit stores energy in both directions through the primary converter, and then the switching devices in the secondary converter are controlled to be turned off, so that the resonant circuit releases energy through the secondary converter.

[0039] Alternatively, if Figure 7 As shown, the process of controlling the diagonally opposite switching devices of each bridge arm in the primary converter to be simultaneously and alternately turned on in one switching cycle includes: Step S41: Calculate the pulse width based on the difference between the closed-loop value and the preset value and in combination with the preset switching period.

[0040] Specifically, refer to Figure 1 and Figure 8 , set the preset value to 0.5. When the closed-loop value is greater than the preset value 0.5, the primary converter 1 adopts a fixed switching frequency and a phase shift angle of 0, and the secondary converter 2 adopts pulse width control. The calculated pulse width length = (closed-loop value - 0.5) × switching period 1 / Ts.

[0041] Step S42: In the positive half switching cycle, the first primary power electronic switch and the fourth primary power electronic switch are controlled to be turned on, and the second primary power electronic switch and the third primary power electronic switch are controlled to be turned off. At the same time, the first secondary power electronic switch and the third secondary power electronic switch are controlled to be turned on synchronously according to the pulse width length, and the second secondary power electronic switch and the fourth secondary power electronic switch are controlled to be turned off.

[0042] Step S43: In the negative half switching cycle, the second primary power electronic switch and the third primary power electronic switch are controlled to be turned on, and the first primary power electronic switch and the fourth primary power electronic switch are controlled to be turned off. At the same time, the second secondary power electronic switch and the fourth secondary power electronic switch are controlled to be turned on synchronously according to the pulse width length, and the first secondary power electronic switch and the third secondary power electronic switch are controlled to be turned off.

[0043] Specifically, refer to Figure 1 and Figure 8 , the two groups of power electronic switches on the same side of the secondary converter 2 are in the resonant current i r The two upper power electronic switches S1 and S3 of the secondary converter 2 are symmetrically turned on alternately in the positive and negative half cycles. For example, the positive half cycle controls the rising edge of a group of diagonal power electronic switches P1 and P4 of the primary converter 1 to be consistent, and keeps S1 and S3 turned on synchronously according to the calculated pulse width length; the negative half cycle controls the two lower power electronic switches S2 and S4 of the secondary converter 2 to be consistent with the rising edge of another group of diagonal power electronic switches P2 and P3 of the primary converter 1, and keeps S2 and S4 turned on synchronously according to the calculated pulse width length.

[0044] Specifically, Fig. 9 : This is the driving waveform diagram of the primary converter 1 and the secondary converter 2 in the boost mode. The duty cycle of the power electronic switch of the primary converter 1 is 50%, the shift phase is 0, the secondary sides S1 and S3 are synchronously turned on for a certain time in the positive half cycle and the rising edge follows P1 and P4, and S2 and S4 are synchronously turned on for a certain time in the negative half cycle and the rising edge follows P2 and P3.

[0045] Alternatively, if Fig.10 As shown, after the resonant circuit stores energy bidirectionally through the primary converter, the switching device in the secondary converter is controlled to be turned off so that the resonant circuit releases energy through the secondary converter, including: Step S44: In the positive half switching cycle, the resonant circuit performs forward energy storage via the first primary power electronic switch, the fourth primary power electronic switch, the first secondary power electronic switch and the third secondary power electronic switch.

[0046] Step S45: In the negative half switching cycle, the resonant circuit performs negative energy storage via the second primary power electronic switch, the third primary power electronic switch, the second secondary power electronic switch and the fourth secondary power electronic switch.

[0047] Step S46: When the resonant circuit finishes the energy storage process, all the switch devices in the secondary converter are controlled to be turned off to perform uncontrolled rectification, so that the energy in the resonant circuit is released to the load.

[0048] Specifically, refer to Figure 1 and Figure 8 During the period when S1 and S3 of the secondary converter 2 are synchronously turned on, the bridge arm output voltage of the secondary converter 2 is 0, and the bridge arm voltage of the primary converter 1 is u in During this period, the resonant circuit 3 only stores energy in the forward direction and does not transfer energy. The load current is provided by the filter capacitor Co. During the period when S2 and S4 of the secondary converter 2 are synchronously turned on, the bridge arm voltage of the secondary converter 2 is 0, and the bridge arm voltage of the primary converter 1 is -u in During this period, the resonant circuit 3 performs negative energy storage. After the energy storage stage is completed, all drivers of the secondary converter 2 are turned off and uncontrolled rectification is started, and the energy of the resonant circuit 3 is transferred to the load R.

[0049] Alternatively, if Fig.10 As shown, the DC converter control method also includes: Step S47: increasing the pulse width by increasing the closed loop quantity, thereby extending the energy storage time of the resonant circuit.

[0050] Specifically, refer to Figure 1 According to the calculation method of pulse width, the larger the closed-loop quantity, the larger the pulse width of the two upper power electronic switches on the same side of the secondary converter 2 is synchronously turned on, so that the resonant circuit 3 stores more energy, the more energy is transferred to the load in the uncontrolled rectification stage, and the output voltage is higher.

[0051] For example, Fig.11 The voltage and current waveforms of the primary converter 1 and the secondary converter 2 in the boost mode, the input voltage u in =40V, output voltage u o =280V, achieving reverse boost control; reference Figure 1 During the period when the two upper power electronic switches on the same side of the secondary converter 2 are turned on together, the primary energy is completely transferred to the resonant circuit 3, and the resonant current i r Approximately linear rise; after the secondary converter 2 is driven off, the energy of the primary converter 1 is transferred to the load R, and the resonant current i rIt changes approximately sinusoidally until it drops to 0 and enters the DCM discontinuous mode, so the power electronic switch of the secondary converter 2 can naturally achieve ZCS zero current switching. During the discontinuous period of the secondary converter 2, the excitation current is converted to the primary converter 1, which is just the discharge of the parasitic capacitance of the power electronic switch of the primary converter 1 that is about to be turned on.

[0052] For example, Fig.12 As shown in the figure, the drain-source voltage has dropped to 0 before the drive of P1 arrives, that is, the primary side can achieve ZVS zero voltage turn-on. At the same time, the turn-off current of S2 is also the value converted from the excitation current of the secondary converter 2 when it is intermittent, which can be ignored compared with the resonant current. Therefore, it can be approximately considered that the primary side ZCS zero current turn-off.

[0053] In the present embodiment, a control device for a DC converter is also provided, which is used to implement the above-mentioned embodiments and preferred implementation modes, and the descriptions that have been made will not be repeated. As used below, the term "module" can implement a combination of software and / or hardware of a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0054] This embodiment provides a control device for a DC converter, such as Fig.13 As shown, the device comprises: The acquisition module 1301 is used to acquire the input current of the DC side of the primary converter and the output voltage of the DC side of the secondary converter.

[0055] The closed-loop regulation module 1302 is used to perform closed-loop control on the input current and the output voltage using the voltage loop and the current loop to obtain closed-loop quantities.

[0056] The buck control module 1303 is used to control the switching devices of each diagonal bridge arm in the primary converter to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time when the closed-loop quantity is less than or equal to the preset value and the DC converter operates in the buck discharge mode, thereby reducing the duration of the high level input to the secondary converter.

[0057] The boost control module 1304 is used to control the switching devices diagonally opposite to each other in each bridge arm in the primary converter to be turned on alternately at the same time within a switching cycle when the closed-loop quantity is greater than a preset value and the DC converter operates in a boost discharge mode. By adjusting the pulse width length and controlling the switching devices on the same side of each bridge arm in the secondary converter to be turned on alternately symmetrically within the positive and negative half cycles of the resonant current, the resonant circuit stores energy bidirectionally through the primary converter, and then controls the switching devices in the secondary converter to be turned off, so that the resonant circuit releases energy through the secondary converter.

[0058] The control device of the DC converter in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC circuit, a processor and a memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0059] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0060] An embodiment of the present invention further provides a computer device having the control device of the DC converter.

[0061] See also Fig.14 , Fig.14 is a schematic diagram of the structure of a computer device provided by an optional embodiment of the present invention, such as Fig.14 As shown, the computer device includes: one or more processors 10, a memory 20, and interfaces for connecting various components, including high-speed interfaces and low-speed interfaces. Various components are connected to each other using different buses for communication, and can be installed on a common mainboard or installed in other ways as needed. The processor can process the instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as, a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Fig.14 A processor 10 is taken as an example.

[0062] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0063] The memory 20 stores instructions executable by at least one processor 10, so that at least one processor 10 executes the method shown in the above embodiment.

[0064] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created by the use of a computer device based on the presentation of a small program landing page, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0065] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0066] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0067] The embodiment of the present invention also provides a computer-readable storage medium. The method according to the embodiment of the present invention can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0068] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A DC converter control method, characterized in that: Applied to a full-bridge LLC DC converter, the method comprises: Obtaining the input current of the DC side of the primary converter and the output voltage of the DC side of the secondary converter; Performing closed-loop control on the input current and the output voltage using a voltage loop and a current loop to obtain a closed-loop quantity; When the closed-loop quantity is less than or equal to the preset value, when the DC converter operates in the step-down discharge mode, the switching devices of each diagonally opposite bridge arm in the primary converter are controlled to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time, thereby reducing the duration of the high level input to the secondary converter; When the closed-loop quantity is greater than a preset value, when the DC converter operates in a boost discharge mode, the switching devices diagonally opposite each bridge arm in the primary converter are controlled to be alternately turned on simultaneously within a switching cycle, and the pulse width is adjusted and the switching devices on the same side of each bridge arm in the secondary converter are controlled to be symmetrically alternately turned on within the positive and negative half cycles of the resonant current, so that the resonant circuit stores energy bidirectionally through the primary converter, and then the switching devices in the secondary converter are controlled to be turned off, so that the resonant circuit releases energy through the secondary converter.

2. The control method according to claim 1, characterized in that: The process of using the voltage loop and the current loop to perform closed-loop control on the input current and the output voltage to obtain closed-loop quantities includes: The output voltage is used as the feedback of the voltage loop, and after comparing it with the voltage loop set value, the current loop set value is calculated by using the PI controller; The input current is used as the feedback quantity of the current loop, and after being compared with the current loop set value, a closed-loop quantity is obtained by calculating using a PI controller.

3. The control method according to claim 2, characterized in that: One bridge arm of the primary converter includes a first primary power electronic switch and a second primary power electronic switch, and another bridge arm of the primary converter includes a third primary power electronic switch and a fourth primary power electronic switch; one bridge arm of the secondary converter includes a first secondary power electronic switch and a second secondary power electronic switch, and another bridge arm of the secondary converter includes a third secondary power electronic switch and a fourth secondary power electronic switch; The process of controlling the diagonally opposite switching devices of each bridge arm in the primary converter to be turned on alternately at the same time in one switching cycle by adjusting the phase shift time includes: Based on the difference between the preset value and the closed-loop value, and in combination with the preset switching cycle, the phase shift time is calculated; In the positive half switching cycle, after controlling the first primary power electronic switch to be turned on, the second primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch to be turned off, the fourth primary power electronic switch is controlled to be turned on after the phase shift time; In the negative half switching cycle, the second primary power electronic switch is controlled to be turned on, the first primary power electronic switch, the third primary power electronic switch and the fourth primary power electronic switch are turned off, and then the third primary power electronic switch is controlled to be turned on after the phase shift time.

4. The control method according to claim 3, characterized in that: The process of reducing the duration of the high level input to the secondary converter includes: The phase shift time is increased by reducing the closed-loop amount, thereby reducing the common conduction time of the first primary power electronic switch and the fourth primary power electronic switch, and increasing the common conduction time of the first primary power electronic switch and the third primary power electronic switch.

5. The control method according to claim 3, characterized in that: The process of controlling the diagonally opposite switching devices of each bridge arm in the primary converter to be simultaneously and alternately turned on in one switching cycle includes: Based on the difference between the closed-loop quantity and the preset value, and in combination with the preset switching cycle, the pulse width length is calculated; In the positive half switching cycle, the first primary power electronic switch and the fourth primary power electronic switch are controlled to be turned on, and the second primary power electronic switch and the third primary power electronic switch are controlled to be turned off, while the first secondary power electronic switch and the third secondary power electronic switch are controlled to be turned on synchronously according to the pulse width length, and the second secondary power electronic switch and the fourth secondary power electronic switch are controlled to be turned off; In the negative half switching cycle, the second primary power electronic switch and the third primary power electronic switch are controlled to be turned on, and the first primary power electronic switch and the fourth primary power electronic switch are controlled to be turned off. At the same time, the second secondary power electronic switch and the fourth secondary power electronic switch are controlled to be turned on synchronously according to the pulse width length, and the first secondary power electronic switch and the third secondary power electronic switch are controlled to be turned off.

6. The control method according to claim 3, characterized in that: After the resonant circuit stores energy bidirectionally through the primary converter, the switching device in the secondary converter is controlled to be turned off so that the resonant circuit releases energy through the secondary converter, including: In the positive half switching cycle, the resonant circuit stores forward energy through the first primary power electronic switch, the fourth primary power electronic switch, the first secondary power electronic switch and the third secondary power electronic switch; In the negative half switching cycle, the resonant circuit stores negative energy through the second primary power electronic switch, the third primary power electronic switch, the second secondary power electronic switch and the fourth secondary power electronic switch; When the resonant circuit finishes the energy storage process, all the switch devices in the secondary converter are controlled to be turned off to perform uncontrolled rectification, so that the energy in the resonant circuit is released to the load.

7. The control method according to claim 2, characterized in that: Also includes: The pulse width is increased by increasing the closed-loop quantity, thereby extending the energy storage time of the resonant circuit.

8. A control device for a DC converter, characterized in that: include: An acquisition module is used to acquire the input current of the DC side of the primary converter and the output voltage of the DC side of the secondary converter; A closed-loop regulation module, used to perform closed-loop control on the input current and the output voltage using a voltage loop and a current loop to obtain a closed-loop quantity; A buck control module, used for, when the closed-loop quantity is less than or equal to a preset value, when the DC converter operates in a buck discharge mode, controlling the diagonally opposite switching devices of each bridge arm in the primary converter to be alternately turned on simultaneously within a switching cycle by adjusting the phase shift time, thereby reducing the duration of the high level input to the secondary converter; A boost control module is used to control the switch devices diagonally opposite to each other in each bridge arm in the primary converter to be turned on alternately at the same time within a switching cycle when the closed-loop quantity is greater than a preset value and the DC converter operates in a boost discharge mode, and to control the switch devices on the diagonal sides of each bridge arm in the secondary converter to be turned on alternately and symmetrically within the positive and negative half-cycles of the resonant current by adjusting the pulse width and controlling the switch devices on the same side of each bridge arm in the secondary converter to be turned on alternately and symmetrically within the positive and negative half-cycles of the resonant current, so that the resonant circuit stores energy bidirectionally through the primary converter, and then controls the switch devices in the secondary converter to be turned off, so that the resonant circuit releases energy through the secondary converter.

9. A computer device, characterized in that: include: A memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the control method of the DC converter according to any one of claims 1 to 7 by executing the computer instructions.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a computer to execute the control method of the DC converter according to any one of claims 1 to 7.

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