A control method and system of a flying capacitor type three-level boost circuit

Abstract

The application provides a control method and system of a flying capacitor type three-level BOOST circuit, an output voltage and an expected voltage are used to obtain a duty cycle, two cases are set according to the range of the duty cycle, and a difference between a flying capacitor voltage and half of the output voltage is obtained, the difference is compared with a set threshold voltage to obtain three results, six modulation modes are generated by combining the two judgment conditions, drive signals are generated for a first IGBT tube and a second IGBT tube according to the selection results of the modulation modes, and the flying capacitor is charged and discharged to realize the distribution of capacitor energy, so that the capacitor voltage is kept stable and balanced, and the key problems of excessively large or small voltage are effectively and reliably solved, and the application has the advantages of fast response speed, convenient maintenance and simple operation.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, specifically to a control method and system for a flying capacitor type three-level BOOST circuit. Background Technology

[0002] A boost circuit is a voltage converter that increases the output voltage compared to the input voltage. It is widely used in switching power supplies, DC motor drives, photovoltaic power generation systems, and electric vehicle drive control. Boost circuits are further divided into two-level and multi-level circuits. Two-level circuits are mainly used for lower voltage levels, while multi-level boost circuits are primarily used for high-voltage applications, with three-level circuits being the most common. Compared to two-level boost circuits, three-level boost circuits halve the voltage stress on the power devices, allowing for higher voltage outputs with lower voltage rating devices. Furthermore, due to the significantly reduced input current ripple, the size and cost of the inductor can be greatly reduced. Therefore, three-level boost circuits have broad application prospects in high-voltage systems.

[0003] In the control method of the flying capacitor type three-level BOOST circuit, the traditional control method introduces two control loops in the controller, corresponding to the output voltage control loop and the flying capacitor voltage control loop respectively. The two control loops are coupled to each other.

[0004] Selecting the parameters for the flying capacitor voltage control loop is a current technical challenge. If the parameters are set too high, the switching transistor will remain on or off continuously, leading to circuit malfunction. If the parameters are set too low, the flying capacitor voltage will deviate from half the bus voltage, posing a risk of overvoltage damage to the power devices in the circuit. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a control method and system for a flying capacitor type three-level BOOST circuit, which effectively controls the flying capacitor voltage, enabling capacitor voltage equalization in the flying capacitor type three-level BOOST circuit.

[0006] This invention is achieved through the following technical solution:

[0007] A control method for a flying capacitor type three-level BOOST circuit includes:

[0008] The duty cycle is calculated based on the difference between the actual voltage output by the BOOST circuit and the desired voltage.

[0009] Based on the preset duty cycle range, determine the preset range to which the duty cycle belongs;

[0010] The difference is obtained by subtracting half of the voltage across the flying capacitor of the BOOST circuit from half of the output voltage. The difference is then compared with a preset voltage range to obtain the voltage range to which the difference belongs.

[0011] Based on the voltage range and the preset range, as well as the preset modulation mode, the switching mode and switching sequence of the BOOST circuit are determined; the preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching sequence.

[0012] The drive signals for the two IGBT transistors in the BOOST circuit are generated according to the switching mode and switching sequence, and the BOOST circuit is controlled according to the drive signals.

[0013] Furthermore, the voltage range to which the difference belongs is -U th ≤U f -U o / 2≤U th U f -U o / 2<-U th and U f -U o / 2>U th , among which, U f It is the voltage across the capacitor, U o It is the output voltage, U th It is the set threshold voltage.

[0014] Furthermore, the preset duty cycle range is 0≤D<0.5 and 0.5≤D≤1, where D is the duty cycle.

[0015] Furthermore, the basic operating modes include:

[0016] The first mode is M1, which corresponds to both the first IGBT and the second IGBT being turned on.

[0017] The second mode is M2, which corresponds to the first IGBT being turned on and the second IGBT being turned off.

[0018] The third mode is M3, which corresponds to the first IGBT being turned off and the second IGBT being turned on.

[0019] The fourth mode is M4, which corresponds to the first IGBT and the second IGBT being turned off.

[0020] Furthermore, the preset modulation modes are modulation mode A, modulation mode B, modulation mode C, modulation mode D, modulation mode E, and modulation mode F;

[0021] The preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching sequence as follows:

[0022] The basic operating modes corresponding to modulation mode A and their switching order are: M3-M4-M2-M4;

[0023] The basic operating modes corresponding to modulation mode B and their switching sequence are: M3-M4-M3-M4;

[0024] The basic operating modes corresponding to modulation mode C and their switching sequence are: M2-M4-M2-M4;

[0025] The basic operating modes corresponding to modulation mode D and their switching order are: M3-M1-M2-M1;

[0026] The basic operating modes corresponding to modulation mode E and their switching sequence are: M3-M1-M3-M1;

[0027] The basic operating modes corresponding to the modulation mode F and their switching order are: M2-M1-M2-M1.

[0028] Furthermore, the mode durations of the modulation mode A are M3:DT S / 2;M4:(1-D)T S / 2; M2: DT S / 2;M4:(1-D)T S / 2;

[0029] The mode durations of the modulation mode B are M3:DT S / 2;M4:(1-D)T S / 2; M3: DTs / 2; M4: (1-D)T S / 2;

[0030] The mode durations of the modulation mode C are M2:DT S / 2;M4:(1-D)T S / 2; M2: DT S / 2;M4:(1-D)T S / 2;

[0031] The mode durations of the modulation mode D are M3: (1-D)T S / 2; M1: DT S / 2;M2:(1-D)T S / 2; M1: DT S / 2;

[0032] The mode durations of the modulation mode E are M3: (1-D)TS / 2; M1: DT S / 2;M3:(1-D)T S / 2; M1: DT S / 2;

[0033] The mode durations of the modulation mode F are M2: (1-D)T S / 2; M1: DT S / 2;M2:(1-D)T S / 2; M1: DT S / 2;

[0034] Among them, T S It is one switching cycle.

[0035] Furthermore, the drive signal controls the BOOST circuit to achieve the following results:

[0036] The voltage across the flying capacitor generated in modulation mode A remains unchanged;

[0037] The voltage rises in the flying capacitor generated in modulation mode B;

[0038] The voltage drop across the flying capacitor generated in modulation mode C;

[0039] The voltage across the flying capacitor generated in modulation mode D remains unchanged;

[0040] The voltage rises in the flying capacitor generated in modulation mode E;

[0041] The voltage drop across the flying capacitor generated in modulation mode F.

[0042] This invention provides a control system for a flying capacitor type three-level BOOST circuit, comprising,

[0043] The duty cycle generation module calculates the duty cycle based on the difference between the actual voltage output by the BOOST circuit and the desired voltage.

[0044] The duty cycle comparison module determines the preset range to which the duty cycle belongs based on the preset duty cycle range;

[0045] The flying capacitor voltage comparison module calculates the difference between the flying capacitor voltage of the BOOST circuit and half of the output voltage, and compares the difference with a preset voltage range to obtain the voltage range to which the difference belongs.

[0046] The modulation mode selection module determines the switching mode and switching sequence of the BOOST circuit based on the voltage range, the preset range, and the preset modulation mode; the preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching sequence.

[0047] The drive circuit module generates drive signals for the two IGBT transistors in the BOOST circuit according to the switching mode and switching sequence, and controls the BOOST circuit according to the drive signals.

[0048] A computer device, comprising:

[0049] Memory, used to store computer programs;

[0050] A processor is used to implement the steps of the control method for a flying capacitor type three-level BOOST circuit when executing the computer program.

[0051] A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the steps of the control method for a flying capacitor type three-level BOOST circuit.

[0052] Compared with the prior art, the present invention has the following beneficial technical effects:

[0053] This invention proposes a control method and system for a flying capacitor type three-level BOOST circuit. The method obtains the duty cycle by comparing the output voltage with the desired voltage, determines the preset range of the duty cycle, and calculates the difference between the capacitor voltage and half the output voltage. This difference is compared with a set threshold voltage to determine the voltage range. Through the filtering and limitation of the above two judgment conditions, the corresponding switching mode and switching sequence are matched in a preset modulation mode. Based on the modulation mode selection result, drive signals are generated for the first and second IGBTs to charge and discharge the flying capacitor, realizing the distribution of capacitor energy and keeping its voltage stable and balanced. This effectively and reliably solves the critical problem of excessively high or low voltage, and has the advantages of fast response speed, convenient maintenance, and simple operation.

[0054] Furthermore, by analyzing the switching states of the first and second IGBT transistors, four modes are obtained. Based on different modes and corresponding duty cycles and voltage requirements, corresponding control modes are preset to achieve fine-grained control by category.

[0055] Furthermore, by combining the duty cycle with the mode, it is beneficial to improve the realization process of quantized capacitor voltage equalization, reduce system cost, improve system reliability, and enhance the controllability and stability of capacitor voltage.

[0056] Furthermore, it is determined whether the flying capacitor voltage and the duty cycle meet the preset range, thus dividing the flying capacitor voltage into three cases for analysis. Then, each case is studied and combined with the four modes to obtain the selection conditions for the modulation mode, ensuring that the selection strategy is non-overlapping, non-overlapping, concise and non-redundant.

[0057] Furthermore, a switching period T of the preset modulation mode is set. S The duration within the time frame is determined by the duty cycle, which allows for effective control of the operating time of each mode, thereby avoiding the impact on capacitor voltage caused by prolonged operation in one mode.

[0058] Furthermore, by selecting the modulation mode, the different effects on the voltage of the flying capacitor are obtained, which further simplifies the control method design, greatly improves the reliability of voltage equalization of the capacitor, and significantly reduces the cost of voltage equalization control. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the topology of a flying capacitor type three-level BOOST circuit.

[0060] Figure 2 This is a schematic diagram of the working mode M1.

[0061] Figure 3 This is a schematic diagram of the working mode M2.

[0062] Figure 4 This is a schematic diagram of the working mode M3.

[0063] Figure 5 This is a schematic diagram of the working mode M4.

[0064] Figure 6 This is a schematic diagram of the control method and control loop for a flying capacitor type three-level BOOST circuit.

[0065] Figure 7 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode A.

[0066] Figure 8 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode B.

[0067] Figure 9 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode C.

[0068] Figure 10 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode D.

[0069] Figure 11 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode E.

[0070] Figure 12 This is a schematic diagram of the flying capacitor voltage waveform under modulation mode F. Detailed Implementation

[0071] The present invention will be further described in detail below with reference to specific embodiments. These descriptions are for explanation purposes only and are not intended to limit the scope of the invention.

[0072] This invention provides a control method and system for a flying capacitor-type three-level boost circuit, wherein the topology of the flying capacitor-type three-level boost circuit is as follows: Figure 1 As shown, it includes: a first IGBT S1, a second IGBT S2, a first diode D1, a second diode D2, and a flying capacitor C. f Output capacitor Co, inductor L.

[0073] The on / off states of the first IGBT S1 and the second IGBT S2 divide the operating state of the flying capacitor type three-level BOOST circuit into four basic modes: when the first IGBT S1 is on and the second IGBT S2 is on, it belongs to operating mode M1, such as... Figure 2 As shown, the current path is: input power supply - inductor L - first IGBT S1 - second IGBT S2, flying capacitor C f With the positive terminal floating, its voltage U f The operation remains unchanged; when the first IGBT S1 is turned on and the second IGBT S2 is turned off, it belongs to the working mode M2. Figure 3 As shown, the current path is: input power supply - inductor L - first IGBT S1 - flying capacitor C f -Second diode D2-Output capacitor C o Current flows from across capacitor C f When the negative terminal flows in, its voltage U f The decrease; when the first IGBT S1 is turned off and the second IGBT S2 is turned on, it belongs to the working mode M3, such as... Figure 4 As shown, the current path is: input power supply - inductor L - first diode D1 - flying capacitor C f - The second IGBT transistor S2, current flows from the flying capacitor C f When the positive electrode flows in, its voltage U f Rise; when the first IGBT S1 is turned off and the second IGBT S2 is turned off, it belongs to the working mode M4, such as Figure 5 As shown, the current path is: input power supply - inductor L - first diode D1, second diode D2 - output capacitor Co, and flying capacitor C. f With the negative terminal floating, its voltage U f It remains unchanged.

[0074] like Figure 6As shown, the present invention provides a control method for a flying capacitor type three-level BOOST circuit, comprising:

[0075] The duty cycle is calculated based on the difference between the actual voltage output by the BOOST circuit and the desired voltage.

[0076] Based on the preset duty cycle range, determine the preset range to which the duty cycle belongs;

[0077] The difference is obtained by subtracting half of the voltage across the flying capacitor of the BOOST circuit from half of the output voltage. The difference is then compared with a preset voltage range to obtain the voltage range to which the difference belongs.

[0078] Based on the voltage range and the preset range, as well as the preset modulation mode, the switching mode and switching sequence of the BOOST circuit are determined; the preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching sequence.

[0079] The drive signals for the two IGBT transistors in the BOOST circuit are generated according to the switching mode and switching sequence, and the BOOST circuit is controlled according to the drive signals.

[0080] Specifically, the control method for the flying capacitor type three-level BOOST circuit includes the following steps:

[0081] (1) Duty cycle generation;

[0082] The duty cycle D (0≤D≤1) is calculated based on the difference between the actual output voltage and the desired voltage. The voltage gain of the flying capacitor type three-level BOOST circuit is consistent with the voltage gain formula of the two-level BOOST circuit. The duty cycle can be calculated from this.

[0083] (2) Duty cycle comparison:

[0084] The preset duty cycle range is 0≤D<0.5 and 0.5≤D≤1. Based on the duty cycle result obtained from (1), it is determined whether the duty cycle satisfies 0≤D<0.5 or 0.5≤D≤1, thereby determining the preset range to which the duty cycle belongs.

[0085] When 0≤D<0.5, the operating mode of the flying capacitor type three-level BOOST circuit switches between M2, M3, and M4; when 0.5≤D≤1, the operating mode of the flying capacitor type three-level BOOST circuit switches between M2, M3, and M1.

[0086] (3) Comparison of flying capacitor voltages:

[0087] The difference is obtained by subtracting half of the output voltage from the voltage across the capacitor. The preset voltage range is -U. th ≤U f -U o / 2≤U th or U f -U o / 2<-U th or U f -U o / 2>U th U th For the set 3% U o The difference is compared with a preset voltage range to determine whether the flying capacitor voltage satisfies -U th ≤U f -U o / 2≤U th or U f -U o / 2<-U th or U f -U o / 2>U th The range in the range is used to obtain the voltage range to which the difference belongs.

[0088] (4) Modulation mode selection:

[0089] Based on the duty cycle comparison result obtained in (2), i.e. the preset range to which the duty cycle belongs, and the comparison result of the flying capacitor voltage obtained in (3), i.e. the voltage range to which the difference belongs, a preset modulation mode is selected; based on the actual voltage range and the preset range, the switching mode and switching sequence of the BOOST circuit are obtained.

[0090] Specifically, by combining the above two judgment conditions to generate a pre-modulation mode, since there are two cases for the duty cycle and three cases for the voltage, six combinations are obtained, corresponding to six preset modulation modes. By comparison, the corresponding switching mode and switching sequence are selected.

[0091] The preset modulation modes include modulation mode A, modulation mode B, modulation mode C, modulation mode D, modulation mode E, and modulation mode F;

[0092] When 0 ≤ D < 0.5 and -U th ≤U f -U o / 2≤U th When modulation mode A is selected, the switching modes of the flying capacitor type three-level BOOST circuit are M2, M3, and M4, and the switching sequence is M3-M4-M2-M4;

[0093] When 0 ≤ D < 0.5 and U f -Uo / 2<-U th When modulation mode B is selected, the switching modes of the flying capacitor type three-level BOOST circuit are M3 and M4, and the switching sequence is M3-M4-M3-M4;

[0094] When 0 ≤ D < 0.5 and U f -U o / 2>U th When modulation mode C is selected, the switching modes of the flying capacitor type three-level BOOST circuit are M2 and M4, and the switching sequence is M2-M4-M2-M4;

[0095] When 0.5≤D≤1 and -U th ≤U f -U o / 2≤U th When modulation mode D is selected, the switching modes of the flying capacitor type three-level BOOST circuit are M1, M3, and M4, and the switching sequence is M3-M1-M2-M4. 1；

[0096] When 0.5≤D≤1 and U f -U o / 2<-U th When modulation mode E is selected, the switching modes of the flying capacitor type three-level BOOST circuit are M1 and M3, and the switching sequence is M3-M1-M3-M1;

[0097] When 0.5≤D≤1 and U f -U o / 2>U th When modulation mode F is selected, the switching modes M1 and M2 of the flying capacitor type three-level BOOST circuit are switched in the order of M2-M1-M2-M1.

[0098] In the switching modes and switching sequence of the BOOST circuit described above, the basic operating mode of each switching mode is also set to switch in the switching sequence and continue for a certain period of time. This allows for effective control of the operating time of each mode, thereby avoiding the impact on the capacitor voltage caused by prolonged operation in one mode. In other words, the operating mode duration of the flying capacitor type three-level BOOST circuit within one switching cycle Ts under different modulation modes satisfies the following:

[0099] The mode durations of modulation mode A are M3: DTs / 2; M4: (1-D)Ts / 2; M2: DTs / 2; M4: (1-D)Ts / 2;

[0100] The mode durations of modulation mode B are M3: DTs / 2; M4: (1-D)Ts / 2; M3: DTs / 2; M4: (1-D)Ts / 2;

[0101] The mode durations of modulation mode C are M2: DTs / 2; M4: (1-D)Ts / 2; M2: DTs / 2; M4: (1-D)Ts / 2;

[0102] The mode durations of modulation mode D are M3: (1-D)Ts / 2; M1: DTs / 2; M2: (1-D)Ts / 2; M1: DTs / 2;

[0103] The mode durations of modulation mode E are M3: (1-D)Ts / 2; M1: DTs / 2; M3: (1-D)Ts / 2; M1: DTs / 2;

[0104] The mode durations of modulation mode F are M2: (1-D)Ts / 2; M1: DTs / 2; M2: (1-D)Ts / 2; M1: DTs / 2.

[0105] (5) Generation of driving signals:

[0106] Based on the result of the modulation mode selection in (4), the existing drive circuit located between the main circuit and the control circuit generates drive signals for the first IGBT S1 and the second IGBT S2. The generated drive signals control the flying capacitor type three-level BOOST circuit to charge and discharge the flying capacitor.

[0107] In this process, the six different pre-modulation modes will affect the flying capacitor C. f voltage U f Different effects will occur, distributing the energy of the capacitor and keeping its voltage balanced, resulting in the following outcomes:

[0108] like Figure 7 As shown, in modulation mode A, the flying capacitor C f Voltage U during M3 mode f The voltage rises, decreases during the M2 mode, and decreases during the M4 mode. f Since the duration of mode M3 is equal to the duration of mode M2, overall, when the flying capacitor type three-level BOOST operates in modulation mode A, the flying capacitor C remains unchanged. f voltage U f constant.

[0109] like Figure 8 As shown, in modulation mode B, the flying capacitor C f Voltage U during M3 modef The voltage U rises during the M4 mode. f Unchanged overall, when the flying capacitor type three-level BOOST operates in modulation mode B, the flying capacitor C f voltage U f rise.

[0110] like Figure 9 As shown, in modulation mode C, the flying capacitor C f Voltage U during M2 mode f The voltage U decreases during the M4 mode. f Unchanged overall, when the flying capacitor type three-level BOOST operates in modulation mode C, the flying capacitor C f voltage U f decline.

[0111] like Figure 10 As shown, in modulation mode D, the flying capacitor C f Voltage U during M3 mode f The voltage rises, decreases during the M2 mode, and decreases during the M1 mode. f Since the duration of mode M3 is equal to the duration of mode M2, overall, when the flying capacitor type three-level BOOST operates in modulation mode D, the flying capacitor C remains unchanged. f voltage U f constant.

[0112] like Figure 11 As shown, in modulation mode E, the flying capacitor C f Voltage U during M3 mode f The voltage U rises during the M1 mode. f The overall value remains unchanged when the flying capacitor type three-level BOOST operates in modulation mode E. f voltage U f rise.

[0113] like Figure 12 As shown, in modulation mode F, the flying capacitor C f Voltage U during M2 mode f The voltage U decreases during the M1 mode. f The overall value remains unchanged when the flying capacitor type three-level BOOST operates in modulation mode F, with the flying capacitor C... f voltage U f decline.

[0114] This invention also provides a control system for a flying capacitor type three-level BOOST circuit, which can implement the control method for the flying capacitor type three-level BOOST circuit described above, and provides corresponding hardware, including:

[0115] The duty cycle generation module calculates the duty cycle based on the difference between the actual voltage output by the BOOST circuit and the desired voltage.

[0116] The duty cycle comparison module determines the preset range to which the duty cycle belongs based on the preset duty cycle range;

[0117] The flying capacitor voltage comparison module calculates the difference between the flying capacitor voltage of the BOOST circuit and half of the output voltage, and compares the difference with a preset voltage range to obtain the voltage range to which the difference belongs.

[0118] The modulation mode selection module determines the switching mode and switching sequence of the BOOST circuit based on the voltage range, the preset range, and the preset modulation mode; the preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching sequence.

[0119] The drive circuit module generates drive signals for the two IGBT transistors in the BOOST circuit according to the switching mode and switching sequence, and controls the BOOST circuit according to the drive signals.

[0120] The present invention also provides a computer device, comprising:

[0121] Memory, used to store computer programs;

[0122] The steps of a processor for implementing a control method for a flying capacitor type three-level BOOST circuit when executing the computer program.

[0123] The present invention also provides a computer-readable storage medium storing a computer program, wherein the computer program, when executed by a processor, implements the steps of the control method for a flying capacitor type three-level BOOST circuit.

[0124] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0125] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0126] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0127] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A control method for a flying capacitor type three-level BOOST circuit, characterized in that, include: The duty cycle is calculated based on the difference between the actual voltage output by the BOOST circuit and the desired voltage. Based on the preset duty cycle range, determine the preset range to which the duty cycle belongs; The difference is obtained by subtracting half of the voltage across the flying capacitor of the BOOST circuit from half of the output voltage. The difference is then compared with a preset voltage range to obtain the voltage range to which the difference belongs. Based on the voltage range and the preset range, as well as the preset modulation mode, determine the switching mode and switching sequence of the BOOST circuit; The preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic working mode and its switching mode; The drive signals for the two IGBT transistors in the BOOST circuit are generated according to the switching mode and switching sequence, and the BOOST circuit is controlled according to the drive signals. The topology of the flying capacitor type three-level BOOST circuit includes: a first IGBT transistor. Second IGBT tube First diode Second diode Flying capacitor Output capacitor Co, inductor L; The positive terminal of the input power supply is connected in series with an inductor L and a first diode. Second diode Connect the positive terminal of the output voltage; connect the negative terminal of the input power supply to the negative terminal of the output voltage. First IGBT tube Second IGBT tube Series connection; first IGBT tube The collector is connected to the series inductor L and the first diode. Between the anodes, the first IGBT tube The emitter is connected to the second IGBT. The collector of the second IGBT transistor The emitter is connected to the negative terminal of the input power supply; Flying capacitor One end is connected to the first diode Cathode and Second Diode Between the anodes; the other end is connected to the first IGBT transistor. The emitter; The two ends of the output capacitor Co are connected to the positive and negative terminals of the output voltage, respectively.

2. The control method for a flying capacitor type three-level BOOST circuit according to claim 1, characterized in that, The voltage range to which the difference belongs is , and ,in, It is the voltage across the capacitor. It is the output voltage. It is the set threshold voltage.

3. The control method for a flying capacitor type three-level BOOST circuit according to claim 2, characterized in that, The preset duty cycle range is 0≤D<0.5 and 0.5≤D≤1, where D is the duty cycle.

4. The control method for a flying capacitor type three-level BOOST circuit according to claim 3, characterized in that, The basic operating modes include: The first mode is Both the first and second IGBTs are turned on. The second mode is This corresponds to the first IGBT being turned on and the second IGBT being turned off. The third mode is This corresponds to the first IGBT being turned off and the second IGBT being turned on. The fourth mode is This corresponds to both the first and second IGBT transistors being turned off.

5. The control method for a flying capacitor type three-level BOOST circuit according to claim 4, characterized in that, The preset modulation modes are modulation mode A, modulation mode B, modulation mode C, modulation mode D, modulation mode E, and modulation mode F; The preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching mode as follows: The basic operating mode and its switching mode corresponding to modulation mode A are as follows: - - - ; The basic operating mode and its switching mode corresponding to modulation mode B are as follows: - - - ; The basic operating mode and its switching mode corresponding to the modulation mode C are as follows: - - - ; The basic operating mode and its switching mode corresponding to the modulation mode D are as follows: - - - ; The basic operating mode and its switching mode corresponding to the modulation mode E are as follows: - - - ; The basic operating mode and its switching mode corresponding to the modulation mode F are as follows: - - - .

6. The control method for a flying capacitor type three-level BOOST circuit according to claim 5, characterized in that, The mode durations of the modulation mode A are respectively : ; : ; : ; : ; The mode durations of the modulation mode B are respectively : ; : ; DTs / 2; : ; The mode durations of the modulation mode C are respectively : ; : ; : ; : ; The mode durations of the modulation mode D are respectively : ; : ; : ; : ; The mode durations of the modulation mode E are respectively : ; : ; : ; : ; The mode durations of the modulation mode F are respectively : ; : ; : ; : ; in, It is one switching cycle.

7. The control method for a flying capacitor type three-level BOOST circuit according to claim 5, characterized in that, The drive signal controls the BOOST circuit to obtain the following results: The voltage across the flying capacitor generated in modulation mode A remains unchanged; The voltage rises in the flying capacitor generated in modulation mode B; The voltage drop across the flying capacitor generated in modulation mode C; The voltage across the flying capacitor generated in modulation mode D remains unchanged; The voltage rises in the flying capacitor generated in modulation mode E; The voltage drop across the flying capacitor generated in modulation mode F.

8. A control system for a flying capacitor type three-level BOOST circuit, characterized in that, include, The duty cycle generation module calculates the duty cycle based on the difference between the actual voltage output by the BOOST circuit and the desired voltage. The duty cycle comparison module determines the preset range to which the duty cycle belongs based on the preset duty cycle range; The flying capacitor voltage comparison module calculates the difference between the flying capacitor voltage of the BOOST circuit and half of the output voltage, and compares the difference with a preset voltage range to obtain the voltage range to which the difference belongs. The modulation mode selection module determines the switching mode and switching sequence of the BOOST circuit based on the voltage range, the preset range, and the preset modulation mode; the preset modulation mode is obtained by combining the preset range and the voltage range to obtain the corresponding basic operating mode and its switching mode. The drive circuit module generates drive signals for the two IGBT transistors in the BOOST circuit according to the switching mode and switching sequence, and controls the BOOST circuit according to the drive signals. The topology of the flying capacitor type three-level BOOST circuit includes: a first IGBT transistor. Second IGBT tube First diode Second diode Flying capacitor Output capacitor Co, inductor L; The positive terminal of the input power supply is connected in series with an inductor L and a first diode. Second diode Connect the positive terminal of the output voltage; connect the negative terminal of the input power supply to the negative terminal of the output voltage. First IGBT tube Second IGBT tube Series connection; first IGBT tube The collector is connected to the series inductor L and the first diode. Between the anodes, the first IGBT tube The emitter is connected to the second IGBT. The collector of the second IGBT transistor The emitter is connected to the negative terminal of the input power supply; Flying capacitor One end is connected to the first diode Cathode and Second Diode Between the anodes; the other end is connected to the first IGBT transistor. The emitter; The two ends of the output capacitor Co are connected to the positive and negative terminals of the output voltage, respectively.

9. A computer device, characterized in that, include: Memory, used to store computer programs; A processor, configured to implement the steps of a control method for a flying capacitor type three-level BOOST circuit as described in any one of claims 1 to 7 when executing the computer program.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of a control method for a flying capacitor type three-level BOOST circuit as described in any one of claims 1 to 7.

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