Hybrid modular multilevel converter and method for controlling the same

Abstract

The disclosure is a hybrid modular multilevel converter and a control method thereof. A voltage difference is added to an original voltage of each half-bridge sub-module or an original voltage of each full-bridge sub-module to obtain a compensation voltage, the voltage difference has a correlation with a difference between the original voltage of the half-bridge sub-module and the original voltage of the full-bridge sub-module. According to a bridge arm current and a voltage reference value, a signal with the compensation voltage of one sub-module and a signal with the original voltage of another sub-module are sorted to obtain an operation sequence of the half-bridge sub-module and the full-bridge sub-module. According to the original voltage of the half-bridge sub-module and the full-bridge sub-module, the voltage reference value and the operation sequence, an operation mode of the half-bridge sub-module and the full-bridge sub-module is calculated, and a driving signal is output to control the half-bridge and full-bridge sub-modules, so that the voltage difference gradually approaches or equals to 0.

Description

Technical Field

[0001] This disclosure relates to a converter, and more particularly to a hybrid modular multilevel converter and its control method. Background Technology

[0002] In existing technologies, modular converters possess excellent scalability and modularity, and are widely used in medium-voltage and high-voltage power conversion systems, such as static synchronous compensators or high-voltage direct current transmission systems. Modular converters typically consist of multiple submodules (SMs). Furthermore, a spare module can be added to take over operation in case of failure, thereby improving system reliability through redundancy design.

[0003] Traditional modular converters typically employ submodules of a single circuit type, such as half-bridge submodules (HBSM) or full-bridge submodules (FBSM). Half-bridge submodules are simple in structure and highly efficient, and are often used in modular multilevel converters (MMCs). However, half-bridge submodules can only operate in buck AC mode, meaning the output AC voltage amplitude is less than half the DC voltage amplitude, and they lack DC fault blocking capability, requiring a large capacitor to suppress line frequency voltage ripple. Furthermore, while full-bridge submodules possess DC fault blocking and polarity reversal capabilities, they require twice the number of power components, resulting in higher losses.

[0004] To take into account the advantages of both types of sub-modules, the hybrid modular multilevel converter includes a half-bridge sub-module and a full-bridge sub-module. However, in boost AC operation mode, the half-bridge sub-module cannot conduct during the negative arm voltage period, resulting in uneven energy distribution and capacitor voltage ripple differences among the sub-modules, which reduces the overall stability of the hybrid modular multilevel converter.

[0005] Therefore, developing a hybrid modular multilevel converter and its control method that overcomes the above-mentioned shortcomings is an urgent need at present. Summary of the Invention

[0006] The purpose of this disclosure is to provide a hybrid modular multilevel converter and its control method, which has better overall stability.

[0007] To achieve the above objectives, one embodiment of this disclosure provides a hybrid modular multilevel converter, comprising multiple phase bridge arms and a controller. Each phase bridge arm includes an upper bridge arm and a lower bridge arm, which respectively include multiple half-bridge submodules, multiple full-bridge submodules, and an inductor connected in series. The controller is used to control the multiple phase bridge arms and includes a proportional-integral control unit, an adder, a sorting operator, and a synthesizing driver. The proportional-integral control unit is adapted to provide a voltage difference, which is correlated with the difference between the original voltages of the multiple half-bridge submodules and the original voltages of the multiple full-bridge submodules. The adder adds the voltage difference to the original voltage of each half-bridge submodule or each full-bridge submodule to obtain a compensation voltage. The sorting operator sorts the signals having the compensation voltage of one submodule and the signals having the original voltage of another submodule according to the bridge arm current and voltage reference values ​​to obtain the operating sequence of the multiple half-bridge submodules and the multiple full-bridge submodules. The synthesized driver calculates the operating modes of multiple half-bridge submodules and multiple full-bridge submodules based on their original voltages, voltage reference values, and operating sequence. It then outputs corresponding drive signals to control the multiple half-bridge submodules and multiple full-bridge submodules so that the voltage difference gradually approaches or equals 0.

[0008] To achieve the above objectives, another embodiment of this disclosure provides a control method applied to a hybrid modular multilevel converter (HMMDC). The HMMDC includes multiple phase bridge arms, each phase bridge arm comprising an upper bridge arm and a lower bridge arm. The upper and lower bridge arms respectively include multiple half-bridge submodules, multiple full-bridge submodules, and an inductor connected in series. The control method includes the following steps: providing a voltage difference, which is correlated with the difference between the original voltages of the multiple half-bridge submodules and the original voltages of the multiple full-bridge submodules. Adding the voltage difference to the original voltage of each half-bridge submodule or each full-bridge submodule to obtain a compensation voltage. Based on bridge arm current and voltage reference values, sorting signals having the compensation voltage of one submodule and signals having the original voltage of another submodule to obtain the operating sequence of the multiple half-bridge submodules and the multiple full-bridge submodules. Based on the original voltages of multiple half-bridge submodules, the original voltages of multiple full-bridge submodules, voltage reference values, and operating sequence, the operating modes of multiple half-bridge submodules and multiple full-bridge submodules are calculated, and corresponding drive signals are output to control multiple half-bridge submodules and multiple full-bridge submodules so that the voltage difference gradually approaches or equals 0.

[0009] To achieve the above objectives, another embodiment of this disclosure provides a control method applied to a hybrid modular multilevel converter. The hybrid modular multilevel converter includes multiple phase bridge arms, each phase bridge arm including an upper bridge arm and a lower bridge arm. The upper bridge arm and the lower bridge arm respectively include multiple half-bridge sub-modules, multiple full-bridge sub-modules, and an inductor connected in series. The control method includes the following steps: providing a voltage difference, which is correlated with the difference between the original voltages of the multiple half-bridge sub-modules and the original voltages of the multiple full-bridge sub-modules. Outputting real-time half-bridge voltage values ​​and real-time full-bridge voltage values ​​based on the voltage difference, a voltage reference value, and bridge arm currents. Outputting corresponding drive signals to control the multiple full-bridge sub-modules based on the real-time full-bridge voltage value and the original voltages of the multiple full-bridge sub-modules, and outputting corresponding drive signals to control the multiple full-bridge sub-modules and / or the multiple half-bridge sub-modules based on the real-time half-bridge voltage and the original voltages of the multiple half-bridge sub-modules, so that the voltage difference gradually approaches or equals 0. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the circuit structure of the hybrid modular multilevel converter disclosed herein; Figure 2A for Figure 1 A schematic diagram of the circuit structure of a half-bridge submodule of a hybrid modular multilevel converter is shown. Figure 2B for Figure 1 A schematic diagram of the circuit structure of a full-bridge submodule of a hybrid modular multilevel converter shown in the figure. Figure 3 for Figure 1 A detailed circuit diagram of the controller of the first embodiment of the hybrid modular multilevel converter is shown. Figure 4 for Figure 1 The diagram shows the operation steps of the sorting unit in the controller of the hybrid modular multilevel converter. Figure 5 for Figure 1 The diagram shows a result of an embodiment of the hybrid modular multilevel converter utilizing the sorting arithmetic unit of the controller; Figure 6 for Figure 1 The voltage and current waveforms of the internal components of the hybrid modular multilevel converter are shown. Figure 7 for Figure 1 A detailed circuit diagram of the controller of the second embodiment of the hybrid modular multilevel converter shown; Figure 8 for Figure 1A detailed circuit diagram of the controller in the third embodiment of the hybrid modular multilevel converter is shown. Figure 9 for Figure 1 A detailed circuit diagram of the controller in the fourth embodiment of the hybrid modular multilevel converter is shown. Figures 10A to 10C The hybrid modular multilevel converter of this disclosure utilizes... Figure 8 or Figure 9 The diagram shows the parameter waveforms of the controller during three fundamental cycles; and Figures 11A to 11B The hybrid modular multilevel converter of this disclosure utilizes... Figure 8 or Figure 9 The diagram shows parameter waveforms for two other embodiments of the controller being used for control.

[0011] Explanation of reference numerals in the attached figures: 1: Hybrid Modular Multilevel Converter 21: First phase electrical energy 22: Second phase electrical energy 23: Third-phase electrical energy 31: First phase bridge arm 311: First upper bridge arm 311a: Half-bridge submodule 311b: Full-bridge submodule La1: First inductor 312: First lower bridge arm Lb1: First inductor 312a: Half-bridge submodule 312b: Full-bridge submodule A: First connection point 32: Second phase bridge arm 321: Second upper bridge arm 321a: Half-bridge submodule 321b: Full-bridge submodule La2: Second upper inductor 322: Second lower bridge arm Lb2: Second inductor 322a: Half-bridge submodule 322b: Full-bridge submodule B: Second connection point 33: Third phase bridge arm 331: Third upper bridge arm 331a: Half-bridge submodule 331b: Full-bridge submodule La3: Third upper inductor 332: Third lower bridge arm Lb3: Third inductor 332a: Half-bridge submodule 332b: Full-bridge submodule C: Third connection point Bridge arm current L1: First main inductor L2: Second main inductor L3: Third main inductor S1, S2: First switches C1: First capacitor Original voltage S3, S4: Second switches S5, S6: Third switches C2: Second capacitor Original voltage 4, 4a, 4b, 4c: Controller 41: First Adder 42: First Filter 43: Second Adder 44: Second Filter 45: Addition and Subtraction Operator 46: Proportional-Integral Control Unit 47: Adder 48: Sorting Operator 49: Synthetic Driver First average voltage Second average voltage Voltage difference Half-bridge compensation voltage Voltage reference value M1-M7: Steps 5: Maintenance Factor Calculator Update voltage 61: Addition and Subtraction Operator 62: Proportional-Integral Control Unit 63: Bridge Arm Voltage Configuration Unit 64: Full-bridge control unit 65: Half-bridge control unit Real-time voltage value of half-bridge Real-time voltage value of the full bridge 661: First Adder 662: First Filter 663: Second Adder 664: Second Filter 631: Sub-configuration unit 632: First Suboperation Unit 633: Second Suboperation Unit 641: The First Divider 642: Third suboperation unit 643: First Sub-Proportional-Integral Control Unit 644: The First Multiplier 645: Fourth Suboperation Unit 646: First Phase Shift Pulse Width Modulation Unit 651: Second Divider 652: Fifth Suboperation Unit 653: Second Sub-Proportional-Integral Control Unit 654: The Second Multiplier 655: Sixth suboperation unit 656: Second Phase Shift Pulse Width Modulation Unit Detailed Implementation

[0012] Some typical embodiments embodying the features and advantages of this disclosure will be described in detail in the following description. It should be understood that this disclosure can have various variations in different forms, all of which do not depart from the scope of this disclosure, and the descriptions and drawings therein are for illustrative purposes only and not for limiting this disclosure.

[0013] Please see Figure 1 , Figure 2A , Figure 2B and Figure 3 ,in Figure 1 This is a schematic diagram of the circuit structure of the hybrid modular multilevel converter disclosed herein. Figure 2A for Figure 1 The circuit diagram shown is a schematic diagram of an embodiment of the half-bridge submodule of the hybrid modular multilevel converter. Figure 2B for Figure 1 The circuit diagram shown is a schematic diagram of an embodiment of the full-bridge submodule of the hybrid modular multilevel converter. Figure 3 for Figure 1The diagram shows a detailed circuit structure of the controller in a first embodiment of the hybrid modular multilevel converter. As shown, the hybrid modular multilevel converter 1 of this disclosure receives three-phase power, which includes a first-phase power 21, a second-phase power 22, and a third-phase power 23. The hybrid modular multilevel converter 1 includes three phase bridge arms (i.e., the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33), three main inductors (i.e., the first main inductor L1, the second main inductor L2, and the third main inductor L3), and a controller 4.

[0014] The first phase bridge arm 31 includes a first upper bridge arm 311 and a first lower bridge arm 312. The first upper bridge arm 311 includes multiple half-bridge sub-modules 311a, multiple full-bridge sub-modules 311b, and a first upper inductor La1 connected in series. The numbers in brackets of the half-bridge (HB) sub-modules 311a represent the serial numbers of the half-bridge sub-modules 311a, and the numbers in brackets of the full-bridge (FB) sub-modules 311b represent the serial numbers of the full-bridge sub-modules 311b. The following sub-modules are also numbered in the same way and will not be described again. The first lower bridge arm 312 includes a first lower inductor Lb1, multiple half-bridge sub-modules 312a, and multiple full-bridge sub-modules 312b connected in series. The connection between the first upper inductor La1 of the first upper bridge arm 311 and the first lower inductor Lb1 of the first lower bridge arm 312 forms a first connection point A. The first main inductor L1 is electrically connected between the first connection point A and the first phase power 21. The second phase bridge arm 32 includes a second upper bridge arm 321 and a second lower bridge arm 322. The second upper bridge arm 321 includes a plurality of half-bridge sub-modules 321a, a plurality of full-bridge sub-modules 321b and a second upper inductor La2 connected in series. The second lower bridge arm 322 includes a second lower inductor Lb2 connected in series, a plurality of half-bridge sub-modules 322a and a plurality of full-bridge sub-modules 322b. The connection between the second upper inductor La2 of the second upper bridge arm 321 and the second lower inductor Lb2 of the second lower bridge arm 322 forms a second connection point B. The second main inductor L2 is electrically connected between the second connection point B and the second phase power 22. The third phase bridge arm 33 includes a third upper bridge arm 331 and a third lower bridge arm 332. The third upper bridge arm 331 includes multiple half-bridge sub-modules 331a and multiple full-bridge sub-modules 331b connected in series, and a third upper inductor La3. The third lower bridge arm 332 includes a third lower inductor Lb3 connected in series, multiple half-bridge sub-modules 332a and multiple full-bridge sub-modules 332b. The connection between the third upper inductor La3 of the third upper bridge arm 331 and the third lower inductor Lb3 of the third lower bridge arm 332 forms a third connection point C. The third main inductor La3 is electrically connected between the third connection point C and the third phase power 23. The first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 all have bridge arm currents. In one embodiment, the number of all full-bridge submodules of the first phase arm 31, the second phase arm 32, and the third phase arm 33 is equal to the number of all half-bridge submodules of the first phase arm 31, the second phase arm 32, and the third phase arm 33, but is not limited thereto.

[0015] Each half-bridge submodule 311a, 312a in the first phase bridge arm 31, each half-bridge submodule 321a, 322a in the second phase bridge arm 32, and each half-bridge submodule 331a, 332a in the third phase bridge arm 33 can be derived from... Figure 2A The structure is as follows. As shown in the figure, each half-bridge submodule includes two first switches S1 and S2 and a first capacitor C1. The two first switches S1 and S2 are connected in series, and the first capacitor C1 is connected in parallel with the two first switches S1 and S2. The first capacitor C1 of each half-bridge module has an initial voltage. Each full-bridge submodule 311b, 312b in the first phase arm 31, each full-bridge submodule 321b, 322b in the second phase arm 32, and each full-bridge submodule 331b, 332b in the third phase arm 33 can be derived from... Figure 2B The structure consists of two second switches S3 and S4, two third switches S5 and S6, and a second capacitor C2. The two second switches S3 and S4 are connected in series, the two third switches S5 and S6 are connected in series, and the second capacitor C2 is connected in parallel with the two second switches S3 and S4 and the two third switches S5 and S6. The second capacitor C2 of each full-bridge submodule has an initial voltage. In one embodiment, the capacitance value of the first capacitor C1 may be different from the capacitance value of the second capacitor C2. Of course, in some embodiments, the half-bridge submodule and the full-bridge submodule may be constructed from other structures, and are not limited thereto.

[0016] The controller 4 is connected to the switches of multiple half-bridge submodules and multiple full-bridge submodules within the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33, to control the switches of the multiple half-bridge submodules and multiple full-bridge submodules within the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33. Figure 3 As shown, the controller 4 includes a first adder 41, a first filter 42, a second adder 43, a second filter 44, an addition / subtraction unit 45, a proportional-integral control unit 46, an adder 47, a sorting unit 48, and a synthesis driver 49. The first adder 41 receives the original voltage on the first capacitor C1 corresponding to the multiple half-bridge submodules. and the original voltage on the first capacitor C1 corresponding to multiple half-bridge submodules. The summation is divided by the number of half-bridge sub-modules to obtain the first average voltage. The first filter 42 converts the first average voltage output from the first summer 41 into a single voltage. Filtering is performed to obtain the first DC component. The second adder 43 receives the original voltage on the second capacitor C2 corresponding to multiple full-bridge submodules. And the original voltage on the second capacitor C2 corresponding to multiple full-bridge submodules. The summation is divided by the number of full-bridge submodules to obtain the second average voltage. The second filter 44 converts the second average voltage output from the second summer 43 into a second average voltage. Filtering is performed to obtain the second DC component. The adder / subtractor 45 calculates the first DC component output from the first filter 42 and the second DC component output from the second filter 44 to obtain the component difference. The proportional-integral control unit 46 compensates for the component difference output from the adder / subtractor 45 to output the voltage difference. Adder 47 converts the original voltage of each half-bridge module. Add voltage difference To obtain the half-bridge compensation voltage for each half-bridge submodule The sorting unit 48 has voltage reference values ​​associated with the bridge arm. The sorting unit 48 sorts the voltage reference value. Bridge arm currents on the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 The half-bridge compensation voltage of multiple half-bridge submodules and the original voltage on the second capacitor C2 corresponding to multiple full-bridge submodules. The order of operation of multiple half-bridge submodules and multiple full-bridge submodules is determined by sorting, and the detailed method for determining the order of operation will be explained later. The synthesizer driver 49 operates based on the original voltages of the multiple half-bridge submodules. The original voltage of multiple full-bridge submodules The voltage reference value provided by the sorting unit 48 The system calculates the operating modes of multiple half-bridge submodules and multiple full-bridge submodules according to their operating sequence, and outputs corresponding drive signals to control the multiple half-bridge submodules and multiple full-bridge submodules, so that the voltage difference... The voltage gradually approaches or equals 0; in other words, the DC components of the voltages of multiple half-bridge submodules and multiple full-bridge submodules become nearly identical. In this embodiment, the synthesizer driver 49 can calculate, but is not limited to, four different operating modes. The first operating mode is that the voltage output by the half-bridge submodule (or full-bridge submodule) is the original voltage and it continues to operate, i.e., mode "1". The second operating mode is that the voltage output by the half-bridge submodule (or full-bridge submodule) operates in pulse width modulation (PWM) mode, i.e., mode "PWM". The third operating mode is that the voltage output by the half-bridge submodule (or full-bridge submodule) is 0 and it is bypassed, i.e., mode "0". The fourth operating mode is that the voltage output by the half-bridge submodule (or full-bridge submodule) is the negative original voltage and it continues to operate, i.e., mode "-1".

[0017] As can be seen from the above, the hybrid modular multilevel converter 1 disclosed herein is suitable for providing voltage differential. voltage difference With the original voltage of multiple half-bridge submodules and the original voltage of multiple full-bridge submodules The differences between them are correlated, and the signals with the compensation voltage of one submodule and the original voltage of another submodule are sorted to obtain the operating sequence of multiple half-bridge submodules and multiple full-bridge submodules, thereby controlling the submodules to adjust the voltage difference. The energy gradually approaches or equals 0. Therefore, compared with the uneven energy distribution among the sub-modules of traditional hybrid modular multilevel converters, the energy between the half-bridge sub-modules and full-bridge sub-modules of the hybrid modular multilevel converter 1 disclosed herein gradually approaches uniformity, thereby reducing the ripple difference of capacitor voltage, improving capacitor utilization, and enhancing the overall stability of the hybrid modular multilevel converter 1.

[0018] In another embodiment, adder 47 can perform operations using either a half-bridge submodule or a full-bridge submodule. Adder 47 can convert the original voltage of each full-bridge submodule... Add voltage difference To obtain the full-bridge compensation voltage of each full-bridge submodule. The sorting unit 48 sorts the voltage reference value. Bridge arm currents on the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 The full-bridge compensation voltage of multiple full-bridge submodules and the original voltage on the first capacitor C1 corresponding to each of the multiple half-bridge sub-modules. The modules are sorted to determine the execution order of the multiple half-bridge submodules and multiple full-bridge submodules. The remaining operations are similar to those described above and will not be repeated here. The following example illustrates the operations using adder 47 with a half-bridge submodule.

[0019] Please see Figure 4 and cooperate Figures 1 to 3 ,in Figure 4 for Figure 1 The diagram shows the operational steps of the sorting arithmetic unit in the controller of the hybrid modular multilevel converter. First, step M1 is executed, and the sorting arithmetic unit 48 confirms the voltage reference value. Is it greater than 0? The confirmation result in step M1 is yes, meaning the sorting unit 48 confirms the voltage reference value. If the value is greater than 0, execute step M2, and sorting unit 48 confirms the bridge arm current. Is it greater than 0? If the confirmation result of step M2 is yes, then the sorting unit 48 confirms the bridge arm current. When the value is greater than 0, step M3 is executed, and the sorting unit 48 controls the half-bridge compensation voltage of multiple half-bridge submodules. and the original voltage of multiple full-bridge submodules The values ​​are sorted in ascending order to obtain the running sequence. If the confirmation result of step M2 is negative, that is, the sorting operator 48 confirms the bridge arm current. When the value is less than or equal to 0, step M4 is executed, and the sorting unit 48 controls the half-bridge compensation voltage of multiple half-bridge submodules. and the original voltage of multiple full-bridge submodules Sort the values ​​in descending order to obtain the running sequence. If the confirmation result of step M1 is negative, that is, the sorting calculator 48 confirms the voltage reference value. When the current is less than or equal to 0, proceed to step M5, where the sorting unit 48 confirms the bridge arm current. Is it greater than 0? The confirmation result in step M5 is yes, meaning the sorting unit 48 confirms the bridge arm current. When the value is greater than 0, step M6 is executed, and the sorting unit 48 controls the original voltage of multiple full-bridge submodules. The modules are sorted in ascending order of numerical values, and multiple half-bridge submodules are bypassed to obtain the operating sequence. If the confirmation result of step M5 is negative, the sorting arithmetic unit 48 confirms the bridge arm current. When the value is less than or equal to 0, step M7 is executed, and the sorting unit 48 controls the half-bridge compensation voltage of multiple half-bridge submodules. The modules are sorted in descending order of their numerical values, and multiple full-bridge submodules are controlled as bypasses to obtain the running order.

[0020] Please see Figure 5 and cooperate Figures 1 to 4 ,in Figure 5 for Figure 1 The diagram shows a result of an embodiment of the hybrid modular multilevel converter utilizing the sorting operation of the controller. Figure 5The example uses two half-bridge submodules (HB) and three full-bridge submodules (FB), where the two half-bridge submodules each have an initial voltage. and half-bridge compensation voltage The original voltage of the half-bridge submodule is represented by a solid line, and the half-bridge compensation voltage of the half-bridge submodule is represented by a dashed line. The figure shows the half-bridge compensation voltage. , Illustration; and the three full-bridge submodules each have their original voltage. The solid line represents the original voltage in the figure. , , Indication. Figure 5 The arrow at the top center illustrates the half-bridge and full-bridge submodules before they are ordered, showing the half-bridge compensation voltages of the half-bridge modules in sequence. Half-bridge compensation voltage of half-bridge submodule The original voltage of the full-bridge submodule The original voltage of the full-bridge submodule and the original voltage of the full-bridge submodule ; Figure 5 The arrow diagram on the upper left shows the voltage reference value for the half-bridge and full-bridge sub-modules. Greater than 0 and bridge arm current When greater than 0, the half-bridge compensation voltage of the half-bridge submodule and the original voltage of the full-bridge submodule The diagram shows the initial voltages of the full-bridge submodules arranged in ascending order of numerical values. The original voltage of the full-bridge submodule The original voltage of the full-bridge submodule Half-bridge compensation voltage of half-bridge submodule and the half-bridge compensation voltage of the half-bridge submodule ; Figure 5 The arrow diagram on the upper right shows the voltage reference value for the half-bridge and full-bridge sub-modules. Greater than 0 and bridge arm current When less than or equal to 0, the half-bridge compensation voltage of the half-bridge submodule and the original voltage of the full-bridge submodule The diagram shows the half-bridge compensation voltages of the half-bridge submodules arranged in descending order of value. Half-bridge compensation voltage of half-bridge submodule The original voltage of the full-bridge submodule The original voltage of the full-bridge submodule and the original voltage of the full-bridge submodule . Figure 5 The two arrows below illustrate that they respectively represent... Figure 5The two arrows at the top, located on the left and right, are connected in series to form voltage vectors. The upper arrow in the lower two diagrams shows the voltage reference values ​​for the half-bridge and full-bridge submodules. Greater than 0 and bridge arm current When greater than 0, the half-bridge compensation voltage of the half-bridge submodule and the original voltage of the full-bridge submodule When sorted in ascending order of numerical values, the original voltage is present. The full-bridge submodule maintains operation in "1" mode, with the original voltage. The full-bridge submodule maintains operation in "1" mode, with the original voltage. The full-bridge submodule operates in "PWM" mode and features half-bridge compensation voltage. The half-bridge submodule operates in "0" mode as a bypass, and has half-bridge compensation voltage. The half-bridge submodule operates in "0" mode as a bypass. As can be seen from the lower diagram of the two arrows below, the half-bridge and full-bridge submodules operate at the voltage reference value. Greater than 0 and bridge arm current When less than or equal to 0, the half-bridge compensation voltage of the half-bridge submodule and the original voltage of the full-bridge submodule When sorted in descending order of numerical values, it has half-bridge compensation voltage. The half-bridge submodule operates in "1" mode and has half-bridge compensation voltage. The half-bridge submodule maintains operation in "1" mode, with the original voltage. The full-bridge submodule operates in "PWM" mode with the original voltage. The full-bridge submodule operates in "0" mode as a bypass, retaining its original voltage. The full-bridge submodule operates in "0" mode as a bypass. This allows the ripple component of the capacitor voltage to be considered simultaneously during the modulation phase, thereby reducing modulation error and improving output accuracy.

[0021] In one embodiment, Figure 2B When the full-bridge submodule shown is running in "1" mode, the second switch S4 and the third switch S5 are turned on. When it is running in "0" mode as a bypass, the second switch S4 and the third switch S6, or the second switch S3 and the third switch S5, can be turned on, and the operation can be alternated.

[0022] Please see Figure 6 and cooperate Figures 1 to 5 ,in Figure 6 for Figure 1 The diagram shows the voltage and current waveforms of the internal components of the hybrid modular multilevel converter. (See diagram for example.) Figure 6 As shown, the waveforms from top to bottom represent the voltage reference value. and the output voltage of the hybrid modular multilevel converter Bridge arm current Output voltage of half-bridge submodule Output voltage of the full-bridge submodule and the original voltage of any two half-bridge submodules , The original voltage of any two full-bridge submodules , As can be seen from the figure, the capacitance value of the first capacitor C1 in the half-bridge submodule is different from that of the second capacitor C2 in the full-bridge submodule, but their DC components are the same, resulting in the same amplitude of the ripple component.

[0023] In one embodiment, to reduce the switching frequency of the hybrid modular multilevel converter, the hybrid modular multilevel converter may further include a sustain factor operator. See also... Figure 7 , it is Figure 1 A detailed circuit diagram of the controller of the second embodiment of the hybrid modular multilevel converter is shown. As shown in the figure, compared to... Figure 3 The controller 4 shown in this embodiment further includes a sustaining factor calculator 5. The sustaining factor calculator 5 includes a preset sustaining factor, an upper voltage limit, and a lower voltage limit, wherein the sustaining factor is less than 1. The sustaining factor calculator 5 calculates the sustaining factor based on the bridge arm current on the bridge arm. Upper voltage limit, lower voltage limit, and half-bridge compensation voltage for multiple half-bridge submodules. and the original voltage of multiple full-bridge submodules The update voltages of the full-bridge submodules and the half-bridge submodules are obtained. Figure 7 The updated full-bridge update voltage and half-bridge update voltage are as follows: This indicates that the sorting unit 48 is based on the voltage reference value. Bridge arm currents on the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 Full-bridge update voltage and half-bridge update voltage Sort the modules to obtain the running order of multiple half-bridge submodules and multiple full-bridge submodules.

[0024] The following will further explain the operation of the sustain factor operator 5. In the first case, the sustain factor operator 5 is based on the bridge arm current. A value greater than 0 indicates that the corresponding half-bridge submodule or the corresponding full-bridge submodule was in operation during the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule is... Or the original voltage of the corresponding full-bridge submodule When the voltage is less than the upper voltage limit, control the corresponding half-bridge submodule to update the half-bridge update voltage. For half-bridge compensation voltage Multiply by the maintenance factor, or control the full-bridge update voltage after the corresponding full-bridge submodule update. Original voltage Multiply by the maintenance factor. Since the maintenance factor is less than 0, the updated full-bridge update voltage or full-bridge update voltage... The reduction allows the corresponding submodule to potentially run again within the same cycle. In the second case, the maintenance factor operator 5 maintains the bridge arm current. The value is greater than 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was bypassed in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge module is greater than 0. Or the original voltage of the corresponding full-bridge submodule When the voltage exceeds the lower limit, control the corresponding half-bridge submodule to update the half-bridge update voltage. For half-bridge compensation voltage Divide by the maintenance factor, or control the full-bridge update voltage after the corresponding full-bridge submodule update. Original voltage Divide by the maintenance factor. Since the maintenance factor is less than 0, the updated full-bridge update voltage or full-bridge update voltage... The rise causes the corresponding submodule to remain bypassed within the same cycle. In the third case, the maintenance factor operator 5 maintains the bridge arm current. The voltage is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge module is... Or the original voltage of the corresponding full-bridge submodule When the voltage exceeds the lower limit, control the corresponding half-bridge submodule to update the half-bridge update voltage. For half-bridge compensation voltage Divide by the maintenance factor, or control the full-bridge update voltage after the corresponding full-bridge submodule update. Original voltage Divide by the maintenance factor. Since the maintenance factor is less than 0, the updated full-bridge update voltage or full-bridge update voltage... This reduces the current, allowing the corresponding submodule to potentially run again within the same cycle. In the fourth case, the maintenance factor operator 5 maintains the bridge arm current. The voltage is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was bypassed in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge module is... Or the original voltage of the corresponding full-bridge submodule When the voltage exceeds the lower limit, control the corresponding half-bridge submodule to update the half-bridge update voltage. For half-bridge compensation voltage Multiply by the maintenance factor, or control the full-bridge update voltage after the corresponding full-bridge submodule update. Original voltage Multiply by the maintenance factor. Since the maintenance factor is less than 0, the updated full-bridge update voltage or full-bridge update voltage... The frequency increases, causing the corresponding submodule to remain bypassed within the same cycle. As can be seen from the above, based on the maintenance factor within maintenance factor operator 5, the submodule's likelihood of maintaining its original operating state is increased, thereby reducing the overall switching frequency.

[0025] Please see Figure 8 , it is Figure 1 The diagram shows a detailed circuit structure of the controller in the third embodiment of the hybrid modular multilevel converter. As shown, the controller 4b in this embodiment implements carrier modulation control, and includes an adder / subtractor 61, a proportional-integral control unit 62, a bridge arm voltage configuration unit 63, a full-bridge control unit 64, and a half-bridge control unit 65. The adder / subtractor 61 is similar to... Figure 3 The addition and subtraction unit 45, based on the first average voltage and the second average voltage This outputs the component difference. The proportional-integral control unit 62 is similar to... Figure 3 The proportional-integral control unit 46 compensates for the component differences output by the adder / subtractor 61, and outputs the voltage difference. The bridge arm voltage configuration unit 63 configures the voltage based on the voltage difference. Voltage reference value Bridge arm currents on the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 To output the real-time voltage value of the half-bridge and real-time voltage value of the full bridge The real-time half-bridge voltage value output by the bridge arm voltage configuration unit 63 and real-time voltage value of the full bridge It conforms to the following expression, The number of half-bridge sub-modules, The number of full-bridge submodules, For the corresponding module voltage (i.e., the half-bridge compensation voltage of the corresponding half-bridge sub-module) Or the original voltage of the corresponding full-bridge submodule The full-bridge control unit 64 calculates the real-time voltage value of the full bridge. The half-bridge control unit 65 outputs a corresponding drive signal to control the full-bridge submodule based on the original voltage of the full-bridge submodule. The half-bridge control unit 65 outputs a corresponding drive signal based on the real-time voltage of the half-bridge. The controller 4b outputs a corresponding drive signal to control the half-bridge submodule based on its original voltage, so that the voltage difference gradually approaches or equals 0. In this embodiment, the controller 4b uses the above control method to reduce the ripple of the capacitor voltage of the corresponding bridge arm and balance the energy between the full-bridge submodule and the half-bridge submodule.

[0026] Please see Figure 9 , it is Figure 1 The diagram shows a detailed circuit structure of the controller in the fourth embodiment of the hybrid modular multilevel converter. Compared to... Figure 8 The controller 4b, in this embodiment, further includes a first adder 661, a first filter 662, a second adder 663, and a second filter 664, wherein the first adder 661, the first filter 662, the second adder 663, and the second filter 664 are similar to... Figure 3 The first aggregator 41, first filter 42, second aggregator 43, and second filter 44 are described in detail here. The bridge arm voltage configuration unit 63 includes a sub-configuration unit 631, a first sub-operation unit 632, and a second sub-operation unit 633. The sub-configuration unit 631 configures the voltage difference... Voltage reference value Bridge arm currents on the first phase bridge arm 31, the second phase bridge arm 32, and the third phase bridge arm 33 Based on the output voltage reference difference The first sub-operation unit 632 will use 0.5 times the voltage reference value. Difference from voltage reference Sum them to get the real-time output half-bridge voltage value. The second sub-operation unit 633 will use 0.5 times the voltage reference value. Difference from voltage reference Subtract to get the real-time voltage value of the full bridge. .

[0027] The full-bridge control unit 64 includes a first divider 641, a third sub-operational unit 642, a first sub-proportional-integral control unit 643, a first multiplier 644, a fourth sub-operational unit 645, and a first phase-shift pulse width modulation unit 646. The first divider 641 divides the real-time voltage value of the full bridge... Divide by the number of full-bridge sub-modules and the corresponding module voltages to output the first signal. The third sub-operation unit 642 calculates the second average voltage. Subtract the original voltage on the second capacitor C2 corresponding to multiple full-bridge submodules The first sub-proportional-integral control unit 643 will convert the second average voltage... Subtract the original voltage on the second capacitor C2 corresponding to multiple full-bridge submodules The result is then subjected to proportional-integral (PI) calculation. The first multiplier 644 multiplies the PI result with the bridge arm current. The first signal is multiplied by the second signal output by the first divider 641 to output the second signal output by the first multiplier 644, and the second signal output by the first multiplier 644 is added to output the third signal. The first phase-shift pulse width modulation unit 646 pulse-width modulates the third signal to output the corresponding drive signal to control the multiple full-bridge sub-modules.

[0028] The half-bridge control unit 65 includes a second divider 651, a fifth sub-operational unit 652, a second sub-proportional-integral control unit 653, a second multiplier 654, a sixth sub-operational unit 655, and a second phase-shift pulse width modulation unit 656. The second divider 651 divides the real-time voltage value of the half-bridge... Divide by the number of half-bridge sub-modules and the corresponding module voltage to output the first signal. The fifth sub-operation unit 652 calculates the first average voltage. Subtract the original voltage on the first capacitor C1 corresponding to each of the multiple half-bridge sub-modules The second sub-proportional-integral control unit 653 will convert the first average voltage... Subtract the original voltage on the first capacitor C1 corresponding to each of the multiple half-bridge sub-modules The result is then subjected to proportional-integral (PI) calculation. The second multiplier 654 multiplies the PI result with the bridge arm current. The first signal is multiplied by the second signal to output the second signal. The sixth sub-operation unit 655 adds the first signal output by the second divider 651 to the second signal output by the second multiplier 654 to output the third signal. The second phase-shift pulse width modulation unit 656 pulse-width modulates the third signal to output the corresponding drive signal to control the multiple half-bridge sub-modules.

[0029] In one embodiment, the sorting arithmetic unit 48 and the synthesis driver 49 may be implemented using a digital signal processor (DSP), microcontroller unit (MCU), or other controller to execute firmware stored in non-volatile memory. The sorting program uses a fast sorting algorithm to compare all half-bridge compensation voltages. and original voltage The synthesizer uses a voltage reference value. and bridge arm current The sort index is mapped to one of four operating modes ("1", "PWM", "0", "-1"), as defined in Table 1 below.

[0030]

[0031] The maintenance factor operator 5 is implemented as a state machine and has a temporary storage register to store the previous submodule state and thresholds (V_upper, V_lower). The maintenance factor α is a preset constant, 0.1 ≤ α < 1.0, and is stored in EEPROM.

[0032] Please see Figures 10A to 10C The hybrid modular multilevel converter disclosed herein utilizes... Figure 8 or Figure 9 The diagram shows the parameter waveforms of the controller during the three fundamental cycles. Figures 10A to 10C The waveform diagrams are shown for the first, second, and third fundamental frequency cycles, respectively. Figures 10A to 10C In the diagram, the first waveform represents the voltage reference value. Real-time voltage value of the full bridge and real-time voltage value of half bridge The waveform diagram for the first fundamental cycle, and the second waveform diagram for the bridge arm current. The first waveform diagram shows the energy waveforms of the half-bridge and full-bridge submodules. The third waveform diagram shows the energy waveforms of the half-bridge and full-bridge submodules. Figure 10A The first waveform shows that between time t1 and time t2 of the first fundamental period, i.e., the voltage difference... The real-time voltage value of the full bridge within the corresponding time interval Lowering means reducing the number of operating full-bridge submodules to lower the voltage reference value. The required voltage is allocated to the half-bridge submodules, meaning the number of operating half-bridge submodules is increased. The second waveform shows that, between time t1 and time t2, the bridge arm current... The third waveform shows the bridge arm current during the charging state, between time t1 and time t2. Increase the energy of the half-bridge submodule, making its energy approach that of the full-bridge submodule. Figure 10B The first waveform shows that the time interval between time t1 and time t2 in the second fundamental period is lengthened, i.e., the voltage difference is increased. The corresponding time interval is lengthened, and by Figure 10B In the third waveform, the energy of the half-bridge submodule is closer to the energy of the full-bridge submodule compared to the energy of the half-bridge submodule in the first fundamental cycle. Figure 10C The first waveform shows that the time interval between time t1 and time t2 in the third fundamental period is further lengthened, i.e., the voltage difference is greater. The corresponding time interval is longer, and by Figure 10CIn the third waveform, the energy of the half-bridge submodule is closer to the energy of the full-bridge submodule than the energy of the half-bridge submodule in the second fundamental cycle. In other words, the voltage difference between the half-bridge submodule and the full-bridge submodule is close to or equal to 0.

[0033] Please see Figures 11A to 11B The hybrid modular multilevel converter disclosed herein utilizes... Figure 8 or Figure 9 The diagram shows parameter waveforms for two other embodiments of the controller during operation. Compared to... Figures 10A to 10C , Figure 11A and Figure 11B voltage difference The corresponding time interval is longer, but it can still achieve the above-mentioned technical effect, that is, the voltage difference between the half-bridge submodule and the full-bridge submodule approaches or equals 0.

[0034] In some embodiments, the hybrid modular multilevel converter is adapted to provide a voltage difference that is correlated with the difference between the original voltages of all half-bridge submodules and all full-bridge submodules. Signals with compensation voltages and signals with the original voltages of another submodule are sorted to obtain the operating sequence of all half-bridge and full-bridge submodules, thereby controlling the submodules to gradually bring the voltage difference closer to or equal to 0. Alternatively, the hybrid modular multilevel converter implements carrier modulation control, controlling the half-bridge and full-bridge submodules based on the real-time voltage values ​​of the half-bridge and full-bridge submodules to gradually bring the voltage difference closer to or equal to 0. Therefore, in this embodiment, the energy between the half-bridge and full-bridge submodules of the hybrid modular multilevel converter gradually becomes more consistent, thereby reducing capacitor voltage ripple differences, improving capacitor utilization, and enhancing the overall stability of the hybrid modular multilevel converter.

[0035] In summary, the hybrid modular multilevel converter disclosed herein is suitable for providing a voltage difference that is correlated with the difference between the original voltages of multiple half-bridge submodules and multiple full-bridge submodules. It sorts signals containing compensation voltages of one submodule and signals containing the original voltages of another submodule to obtain the operating sequence of the multiple half-bridge and full-bridge submodules, thereby controlling the submodules to gradually bring the voltage difference closer to or equal to 0. Alternatively, the hybrid modular multilevel converter implements carrier modulation control, controlling the half-bridge and full-bridge submodules based on the real-time voltage values ​​of the half-bridge and full-bridge submodules to gradually bring the voltage difference closer to or equal to 0. Therefore, the energy of the half-bridge and full-bridge submodules of the hybrid modular multilevel converter disclosed herein gradually becomes more consistent, thereby reducing capacitor voltage ripple differences, improving capacitor utilization, and enhancing the overall stability of the hybrid modular multilevel converter.

Claims

1. A hybrid modular multilevel converter, comprising: Multiple phase bridge arms, each phase bridge arm comprising an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm respectively comprising multiple half-bridge sub-modules, multiple full-bridge modules and an inductor connected in series; and A controller for controlling the plurality of phase bridge arms, and comprising: A proportional-integral control unit is adapted to provide a voltage difference, wherein the voltage difference is correlated with the difference between an original voltage of the plurality of half-bridge submodules and an original voltage of the plurality of full-bridge submodules; An adder adds the voltage difference to the original voltage of each half-bridge submodule or the original voltage of each full-bridge submodule to obtain a compensation voltage. A sorting unit sorts the signals of the compensated voltage of one submodule and the original voltage of another submodule according to a bridge arm current and a voltage reference value, to obtain an operating sequence of the plurality of half-bridge submodules and the plurality of full-bridge submodules; and A composite driver calculates the operating modes of the plurality of half-bridge submodules and the plurality of full-bridge submodules based on the original voltages of the plurality of half-bridge submodules, the original voltages of the plurality of full-bridge submodules, the voltage reference value, and the operating sequence, and outputs corresponding drive signals to control the plurality of half-bridge submodules and the plurality of full-bridge submodules so that the voltage difference gradually approaches or equals 0.

2. The hybrid modular multilevel converter as claimed in claim 1, wherein the controller further comprises: A first summator adds the original voltages of the plurality of half-bridge submodules and divides the sum by the number of the plurality of half-bridge submodules to obtain a first average voltage. A first filter is used to filter the first average voltage to obtain a first DC component; A second summator adds the original voltages of the plurality of full-bridge submodules and divides the sum by the number of the plurality of full-bridge submodules to obtain a second average voltage. A second filter is used to filter the second average voltage to obtain a second DC component; as well as An adder / subtractor calculates the first DC component and the second DC component to obtain a component difference value, wherein the proportional-integral control unit compensates for the component difference value to output the voltage difference value.

3. The hybrid modular multilevel converter as described in claim 1, wherein when the voltage reference value is greater than 0 and the bridge arm current is greater than 0, the sorting unit controls the half-bridge compensation voltage of the plurality of half-bridge submodules and the original voltage of the plurality of full-bridge submodules to be sorted in ascending order to obtain the operating sequence; when the voltage reference value is greater than 0 and the bridge arm current is less than or equal to 0, the sorting unit controls the half-bridge compensation voltage of the plurality of half-bridge submodules and the original voltage of the plurality of full-bridge submodules to be sorted in descending order to obtain the operating sequence; when the voltage reference value is less than or equal to 0 and the bridge arm current is greater than 0, the sorting unit controls the original voltage of the plurality of full-bridge submodules to be sorted in ascending order and controls the plurality of half-bridge submodules to be bypassed to obtain the operating sequence; when the voltage reference value is less than or equal to 0 and the bridge arm current is less than or equal to 0, the sorting unit controls the half-bridge compensation voltage of the plurality of half-bridge submodules to be sorted in descending order and controls the plurality of full-bridge submodules to be bypassed to obtain the operating sequence.

4. The hybrid modular multilevel converter as described in claim 1, wherein the controller includes a sustain factor operator, the sustain factor operator including a sustain factor, an upper voltage limit and a lower voltage limit, the sustain factor operator obtaining an updated full-bridge voltage and an updated half-bridge voltage of the plurality of full-bridge submodules based on the bridge arm current, the upper voltage limit, the lower voltage limit, the half-bridge compensation voltage of the plurality of half-bridge submodules and the original voltage of the plurality of full-bridge submodules, wherein the sorting operator sorts the plurality of half-bridge submodules and the half-bridge update voltage, the bridge arm current and the voltage reference value to obtain the operating order of the plurality of half-bridge submodules and the plurality of full-bridge submodules, wherein the sustain factor is less than 0.

5. The hybrid modular multilevel converter as described in claim 4, wherein when the arm current is greater than 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in maintenance operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is less than the upper voltage limit, the maintenance factor operator controls the updated half-bridge voltage of the corresponding half-bridge submodule to be the half-bridge compensation voltage multiplied by the maintenance factor, or controls the updated full-bridge voltage of the corresponding full-bridge submodule to be the original voltage multiplied by the maintenance factor; when the arm current is greater than 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in bypass operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the maintenance factor operator controls the updated half-bridge voltage of the corresponding half-bridge submodule to be the half-bridge compensation voltage divided by the maintenance factor, or controls the updated full-bridge voltage of the corresponding full-bridge submodule to be the original voltage multiplied by the maintenance factor. The initial voltage is divided by the maintenance factor. When the arm current is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in maintenance operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the maintenance factor operator controls the updated half-bridge voltage of the corresponding half-bridge submodule to be the half-bridge compensation voltage divided by the maintenance factor, or controls the updated full-bridge voltage of the corresponding full-bridge submodule to be the original voltage divided by the maintenance factor. When the arm current is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in bypass operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the maintenance factor operator controls the updated half-bridge voltage of the corresponding half-bridge submodule to be the half-bridge compensation voltage multiplied by the maintenance factor, or controls the updated full-bridge voltage of the corresponding full-bridge submodule to be the original voltage multiplied by the maintenance factor.

6. The hybrid modular multilevel converter as described in claim 1, wherein each half-bridge submodule includes two first switches and a first capacitor, the two first switches being connected in series and the first capacitor being connected in parallel with the two first switches; each full-bridge submodule includes two second switches, two third switches and a second capacitor, the two second switches being connected in series and the two third switches being connected in series, and the second capacitor being connected in parallel with the two second switches and the two third switches.

7. The hybrid modular multilevel converter as claimed in claim 6, wherein the capacitance value of the first capacitor is different from the capacitance value of the second capacitor.

8. The hybrid modular multilevel converter as claimed in claim 1, wherein the number of the plurality of full-bridge submodules is equal to the number of the plurality of half-bridge submodules.

9. A control method applied to a hybrid modular multilevel converter, the hybrid modular multilevel converter comprising multiple phase bridge arms, each phase bridge arm comprising an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm respectively comprising multiple half-bridge sub-modules, multiple full-bridge sub-modules and an inductor connected in series, wherein the control method comprises: (a) Provide a voltage difference, wherein the voltage difference is correlated with the difference between an original voltage of the plurality of half-bridge submodules and an original voltage of the plurality of full-bridge submodules; (b) Add the voltage difference to the original voltage of each half-bridge submodule or the original voltage of each full-bridge submodule to obtain a compensation voltage. (c) Based on a bridge arm current and a voltage reference value, the signal of the compensation voltage of one submodule and the signal of the original voltage of another submodule are sorted to obtain an operating sequence of the plurality of half-bridge submodules and the plurality of full-bridge submodules. as well as (d) Based on the original voltage of the plurality of half-bridge submodules, the original voltage of the plurality of full-bridge submodules, the voltage reference value and the operating sequence, calculate the operating mode of the plurality of half-bridge submodules and the plurality of full-bridge submodules, and output the corresponding drive signal to control the plurality of half-bridge submodules and the plurality of full-bridge submodules so that the voltage difference gradually approaches or equals 0.

10. The control method of claim 9, wherein in step (c), when the voltage reference value is greater than 0 and the bridge arm current is greater than 0, the half-bridge compensation voltages of the plurality of half-bridge submodules and the original voltages of the plurality of full-bridge submodules are controlled to be ordered in ascending order to obtain the operating sequence; when the voltage reference value is greater than 0 and the bridge arm current is less than or equal to 0, the half-bridge compensation voltages of the plurality of half-bridge submodules and the original voltages of the plurality of full-bridge submodules are controlled to be ordered in descending order to obtain the operating sequence; when the voltage reference value is less than or equal to 0 and the bridge arm current is greater than 0, the original voltages of the plurality of full-bridge submodules are controlled to be ordered in ascending order, and the plurality of half-bridge submodules are controlled to be bypassed to obtain the operating sequence; when the voltage reference value is less than or equal to 0 and the bridge arm current is less than or equal to 0, the half-bridge compensation voltages of the plurality of half-bridge submodules are controlled to be ordered in descending order, and the plurality of full-bridge submodules are controlled to be bypassed to obtain the operating sequence.

11. The control method of claim 9, wherein step (c) further comprises: (e) Based on the arm current, an upper voltage limit, a lower voltage limit, the half-bridge compensation voltage of the plurality of half-bridge submodules and the original voltage of the plurality of full-bridge submodules, obtain the updated full-bridge voltage of the plurality of full-bridge submodules and the updated half-bridge voltage of the plurality of half-bridge submodules. (f) When the arm current is greater than 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in maintenance operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is less than the upper voltage limit, the updated half-bridge voltage of the corresponding half-bridge submodule is controlled to be the half-bridge compensation voltage multiplied by the maintenance factor, or the updated full-bridge voltage of the corresponding full-bridge submodule is controlled to be the original voltage multiplied by the maintenance factor; when the arm current is greater than 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in bypass operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the updated half-bridge voltage of the corresponding half-bridge submodule is controlled to be the half-bridge compensation voltage divided by the maintenance factor, or the updated full-bridge voltage of the corresponding full-bridge submodule is controlled to be the original voltage divided by the maintenance factor; when the When the arm current is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in maintenance operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the updated half-bridge voltage of the corresponding half-bridge submodule is controlled to be the half-bridge compensation voltage divided by the maintenance factor, or the updated full-bridge voltage of the corresponding full-bridge submodule is controlled to be the original voltage divided by the maintenance factor; when the arm current is less than or equal to 0, the corresponding half-bridge submodule or the corresponding full-bridge submodule was in bypass operation in the previous cycle, and the half-bridge compensation voltage of the corresponding half-bridge submodule or the original voltage of the corresponding full-bridge submodule is greater than the lower voltage limit, the updated half-bridge voltage of the corresponding half-bridge submodule is controlled to be the half-bridge compensation voltage multiplied by the maintenance factor, or the updated full-bridge voltage of the corresponding full-bridge submodule is controlled to be the original voltage multiplied by the maintenance factor.

12. A control method applied to a hybrid modular multilevel converter, the hybrid modular multilevel converter comprising multiple phase bridge arms, each phase bridge arm comprising an upper bridge arm and a lower bridge arm, the upper bridge arm and the lower bridge arm respectively comprising multiple half-bridge submodules, multiple full-bridge submodules and an inductor connected in series, wherein the control method comprises: (a) Provide a voltage difference, wherein the voltage difference is correlated with the difference between an original voltage of the plurality of half-bridge submodules and an original voltage of the plurality of full-bridge submodules; (b) Based on the voltage difference, a voltage reference value, and a bridge arm current, output the real-time voltage values ​​of the half-bridge and the full-bridge; and (c) Based on the real-time voltage value of the full bridge and the original voltage of the plurality of full bridge sub-modules, output a corresponding drive signal to control the plurality of full bridge sub-modules, and based on the real-time voltage of the half bridge and the original voltage of the plurality of half bridge sub-modules, output a corresponding drive signal to control the plurality of half bridge sub-modules, so that the voltage difference gradually approaches or equals 0.

13. The control method of claim 12, wherein in step (b), the real-time voltage values ​​of the half-bridge and the real-time voltage values ​​of the full-bridge conform to the following expressions: in, This is the reference value for the voltage. This is the real-time voltage value of the half-bridge. This is the real-time voltage value of the full bridge. This refers to the number of these multiple half-bridge submodules. The number of these multiple full-bridge submodules, This corresponds to the module voltage.

14. The control method of claim 12, wherein step (b) further comprises: (d) Output a voltage reference difference based on the voltage difference, the voltage reference value, and the bridge arm current; (e) Add 0.5 times the voltage reference value to the voltage reference difference to output the real-time voltage value of the half-bridge; and (f) Subtract 0.5 times the voltage reference value from the voltage reference difference to output the real-time voltage value of the full bridge.

15. The control method of claim 14, wherein step (c) further comprises: (g) Divide the real-time voltage value of the full bridge by the number of the multiple full bridge sub-modules and the corresponding module voltage to output a first signal; (h) Subtract the original voltage of the plurality of full-bridge submodules from a second average voltage, perform proportional-integral calculation, and multiply it by the bridge arm current to output a second signal; (i) Add the first signal to the second signal to output a third signal; (j) The third signal is pulse-width modulated to output the corresponding drive signal to control the plurality of full-bridge submodules; (k) Divide the real-time voltage value of the half-bridge by the number of the multiple half-bridge sub-modules and the corresponding voltage of the module to output a fourth signal; (l) Subtract the original voltage of the plurality of half-bridge submodules from a first average voltage, perform proportional-integral calculation, and multiply it by the bridge arm current to output a fifth signal; (m) Add the fourth signal to the fifth signal to output a sixth signal; as well as (n) The sixth signal is pulse-width modulated to output the corresponding drive signal to control the multiple half-bridge sub-modules.

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