Bidirectional boost MMC circuit and flexible direct current engineering electronic equipment

Abstract

The invention discloses a bidirectional boost MMC circuit and flexible DC engineering electronic equipment, and is applied to the technical field of flexible DC power transmission. According to the bidirectional boost type MMC circuit, a first inductor, a second inductor and a first power semiconductor switch assembly are additionally arranged in a conventional half-bridge type MMC circuit. When a DC energy storage capacitor is in a discharge state due to on-off of a second power semiconductor switch assembly and a third power semiconductor switch assembly in a half-bridge MMC circuit, two inductors can absorb part of electric energy, so that voltage at two ends of the second power semiconductor switch assembly is effectively reduced, and the service life of the power semiconductor switch assemblies is prolonged. Meanwhile, when the withstand voltage of the power semiconductor switch assemblies is limited and the direct-current energy storage capacitor is in a charging state, the first power semiconductor switch assembly is controlled to adjust the electric energy transmission characteristic through a pulse modulation signal determined by the driving adjustment module based on the bridge arm current, a higher voltage level is output, and the voltage utilization rate is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flexible direct current transmission, in particular to a bidirectional boost MMC circuit and a flexible direct current engineering electronic device. BACKGROUND

[0002] As a new transmission technology in recent years, compared with the conventional direct current transmission technology, the flexible direct current transmission technology has many significant advantages. The conventional direct current transmission relies on grid voltage commutation, has inherent risk of commutation failure, and needs to absorb a large amount of reactive power and configure a large filter device. The flexible direct current transmission adopts all-controllable devices and voltage source converters, has independent and fast active and reactive power control capability, which not only fundamentally eliminates the commutation failure problem, enables it to be connected to even support the passive weak alternating current system, and significantly simplifies the station equipment, realizes the black start and other grid recovery functions. Therefore, the flexible direct current technology has a broader application prospect and irreplaceable strategic value than the conventional direct current technology in improving the flexibility, reliability and adaptability of renewable energy dispersed access of modern power system requirements.

[0003] At present, most of the flexible direct current projects adopt half-bridge MMC (Modular Multilevel Converter, modular multilevel converter) structure as the basic unit of the converter valve part. Because the number of sub-modules in the MMC is large, a large number of sub-modules need to be connected in series to form the converter valve bridge arm in the actual project. For the valve control system, it needs to complete the switching sequence, capacitor voltage balancing and fault diagnosis of thousands of sub-modules within microseconds, which has high requirements for communication synchronization and computing power, and the utilization rate of the direct current voltage in the system is insufficient. And a large number of sub-modules are prone to faults and black module events in actual engineering operation, which is not conducive to the safe and stable operation of the power grid.

[0004] In view of the above-mentioned technology, seeking a bidirectional boost MMC circuit to improve the utilization rate of voltage is a problem to be solved by those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a bidirectional boost MMC circuit and a flexible direct current engineering electronic device. The problem of insufficient utilization rate of direct current voltage and the problem of not conducive to the safe and stable operation of the power grid caused by the half-bridge MMC structure of the existing technology can be solved.

[0006] To solve the above technical problems, the present application provides a bidirectional boost MMC circuit, comprising: a half-bridge MMC circuit, a first inductor, a second inductor and a first power semiconductor switch component.

[0007] The first end of the first inductor is connected with the first electrode of the second power semiconductor switch component in the half-bridge MMC circuit.

[0008] a second end of the first inductor is connected with a first end of the second inductor and a first electrode of the first power semiconductor switching component;

[0009] a second end of the second inductor is connected with a first end of a direct current energy storage capacitor in the half-bridge MMC circuit;

[0010] a second electrode of the first power semiconductor switching component is connected with a first electrode of a third power semiconductor switching component, a second end of the direct current energy storage capacitor and a negative electrode of a direct current bus in the half-bridge MMC circuit;

[0011] a control electrode of the first power semiconductor switching component is connected with the drive adjustment module, for receiving a pulse modulation signal determined by the drive adjustment module based on a bridge arm current, and periodically switching between an on state and an off state based on the pulse modulation signal, to adjust the electric energy transmission characteristic; wherein the bridge arm current is a current on a connection line connected with the second electrode of the second power semiconductor switching component, the second electrode of the third power semiconductor switching component and the positive electrode of the direct current bus.

[0012] Preferably, further comprising: a diode;

[0013] wherein an anode of the diode is connected with the second end of the first inductor, the first end of the second inductor and the first electrode of the first power semiconductor switching component;

[0014] a cathode of the diode is connected with the first end of the second inductor and the first end of the direct current energy storage capacitor.

[0015] Preferably, the drive adjustment module comprises: a current acquisition unit and a PI control unit;

[0016] wherein an input end of the current acquisition unit is connected with the second electrode of the second power semiconductor switching component and the second electrode of the third power semiconductor switching component as an input end of the drive adjustment module;

[0017] an output end of the current acquisition unit is connected with an input end of the PI control unit;

[0018] an output end of the PI control unit is connected with the control electrode of the first power semiconductor switching component as an output end of the drive adjustment module.

[0019] Preferably, the first power semiconductor switching component is a first IGBT component;

[0020] wherein a collector of the first IGBT component is connected with the second end of the first inductor and the first end of the second inductor as the first electrode of the first power semiconductor switching component;

[0021] The emitter of the first IGBT component is connected with the second electrode of the first power semiconductor switching component, the first electrode of the third power semiconductor switching component, the second end of the direct current energy storage capacitor and the negative pole of the direct current bus as the second electrode of the first power semiconductor switching component;

[0022] The gate of the first IGBT component is connected with the driving and adjusting module as the control electrode of the first power semiconductor switching component.

[0023] Preferably, the second power semiconductor switching component is a second IGBT component, and the third power semiconductor switching component is a third IGBT component.

[0024] The collector of the second IGBT component is connected with the first end of the first inductor as the first electrode of the second power semiconductor switching component.

[0025] The emitter of the second IGBT component is connected with the collector of the third IGBT as the second electrode of the second power semiconductor switching component and the second electrode of the third power semiconductor switching component, and is connected with the positive pole of the direct current bus together.

[0026] The emitter of the third IGBT is connected with the second electrode of the first power semiconductor switching component, the second end of the direct current energy storage capacitor and the negative pole of the direct current bus as the first electrode of the third power semiconductor switching component.

[0027] The gate of the second IGBT component is connected with the first switch control circuit as the control electrode of the second power semiconductor switching component.

[0028] The gate of the third IGBT component is connected with the second switch control circuit as the control electrode of the third power semiconductor switching component.

[0029] In another aspect, the application also provides a flexible direct current engineering electronic device, comprising: a plurality of bidirectional boost type MMC circuits.

[0030] Preferably, the number of bidirectional boost type MMC circuits put into the upper bridge arm in the flexible direct current engineering electronic device is ;

[0031] The formula of the number of bidirectional boost type MMC circuits put into the upper bridge arm is:

[0032] ;

[0033] Wherein, is the total number of bidirectional boost type MMC circuits in the flexible direct current engineering electronic device; is the target output voltage; is the capacitor voltage corresponding to the direct current energy storage capacitor in the bidirectional boost type MMC circuit; is the rounding function.

[0034] Preferably, the number of bidirectional boost-type MMC circuits incorporated in the lower bridge arm of the flexible DC engineering electronic device is: ;

[0035] The formula for determining the number of bidirectional boost-type MMC circuits incorporated in the lower bridge arm is as follows:

[0036] ;

[0037] in, This represents the total number of bidirectional boost-type MMC circuits in flexible DC engineering electronic equipment. The target output voltage; This refers to the capacitor voltage corresponding to the DC energy storage capacitor in a bidirectional boost MMC circuit. This is the floor function.

[0038] Preferably, when the bridge arm current is greater than zero, the bidirectional boost MMC circuit with a smaller capacitor voltage is given priority for activation.

[0039] Preferably, when the bridge arm current is less than zero, the bidirectional boost MMC circuit with a large capacitor voltage is given priority.

[0040] The bidirectional boost MMC circuit provided in this application adds a first inductor, a second inductor, and a first power semiconductor switching component to a conventional half-bridge MMC circuit. In the half-bridge MMC circuit, when the DC energy storage capacitor is in a discharging state due to the switching of the second and third power semiconductor switching components, the first and second inductors can absorb some electrical energy, thereby effectively reducing the voltage across the second power semiconductor switching component and extending its service life. Simultaneously, when the power semiconductor switching component has limited voltage tolerance and the DC energy storage capacitor is in a charging state, the first power semiconductor switching component is controlled by a pulse modulation signal determined based on the bridge arm current by a drive regulation module to adjust its power transfer characteristics, outputting a higher voltage level, thereby improving voltage utilization and operational safety. Attached Figure Description

[0041] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A circuit diagram of a bidirectional boost MMC circuit provided in an embodiment of this application;

[0043] Figure 2A circuit diagram of the first topology operation mode provided in the embodiments of this application;

[0044] Figure 3 This is a circuit diagram of the second topology operation mode provided in the embodiments of this application;

[0045] Figure 4 A circuit diagram of the third topology operation mode provided in the embodiments of this application;

[0046] Figure 5 A circuit diagram of the fourth topology operation mode provided in the embodiments of this application;

[0047] Figure 6 The control flowchart for nearest-level approximation modulation provided in the embodiments of this application is shown. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0049] The core of this application is to provide a bidirectional boost-type MMC circuit and a flexible DC engineering electronic device.

[0050] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0051] Figure 1 A circuit diagram of a bidirectional boost MMC circuit provided for embodiments of this application is shown below. Figure 1 As shown, it includes: a half-bridge MMC circuit, a first inductor L1, a second inductor L2, and a first power semiconductor switching component S1. The half-bridge MMC circuit includes: a second power semiconductor switching component S2, a third power semiconductor switching component S3, and a DC energy storage capacitor C0. In addition, Figure 1 The bidirectional boost MMC circuit shown also includes: diode D1, drive adjustment module 1, first switch control circuit 2, and second switch control circuit 3.

[0052] In this design, the first power semiconductor switching component S1 can be a first IGBT component; the second power semiconductor switching component S2 can be a second IGBT component; and the third power semiconductor switching component S3 can be a third IGBT component.

[0053] The connection relationship of its bidirectional boost-type MMC circuit is as follows: the first terminal of the first inductor L1 is connected to the first electrode (collector of the second IGBT component) of the second power semiconductor switching component S2; the second terminal of the first inductor L1 is connected to the first terminal of the second inductor L2, the anode of the diode D1, and the first electrode (collector of the first IGBT component) of the first power semiconductor switching component S1; the second terminal of the second inductor L2 is connected to the first terminal of the DC energy storage capacitor C0 and the cathode of the diode D1; the second electrode (emitter of the first IGBT component) of the first power semiconductor switching component S1 is connected to the first electrode (emitter of the third IGBT component) of the third power semiconductor switching component S3, the second terminal of the DC energy storage capacitor C0, and the negative terminal of the DC bus; the control electrode (gate of the first IGBT component) of the first power semiconductor switching component S1 is connected to the drive adjustment module 1 for receiving data from the drive adjustment module 1 based on the bridge arm current. A defined pulse modulation signal is used, and the power transfer characteristics are adjusted based on the periodic switching of the pulse modulation signal between the on and off states; among which, the bridge arm current... The current is on the connection line connecting the second electrode (emitter of the second IGBT component) of the second power semiconductor switching component S2, the second electrode (collector of the third IGBT component) of the third power semiconductor switching component S3, and the positive terminal of the DC bus; the control electrode (gate of the second IGBT component) of the second power semiconductor switching component S2 is connected to the first switch control circuit 2; the control electrode (gate of the third IGBT component) of the third power semiconductor switching component S3 is connected to the second switch control circuit 3.

[0054] In specific embodiments, the bidirectional boost MMC circuit provided in this application includes four topology operation modes, the first of which is as follows: Figure 2 As shown, its second power semiconductor switch component S2 is turned off, the third power semiconductor switch component S3 is turned off, and the bridge arm current... When the current direction is positive (default is left to right), the sub-modules (first inductor L1, second inductor L2, diode D1, first power semiconductor switch assembly S1, and DC energy storage capacitor C0) are in the active state, charging the DC energy storage capacitor C0. At this time, the first power semiconductor switch assembly S1 is turned on, and the first inductor L1 and second inductor L2 convert electrical energy into magnetic energy for storage. Simultaneously, together with the first inductor L1 and diode D1, a BOOST circuit (boost chopper circuit) is formed, which can effectively increase the capacitor voltage across the DC energy storage capacitor C0. Among them, the bridge arm current The current is on the connection line connecting the second electrode of the second power semiconductor switch assembly S2, the second electrode of the third power semiconductor switch assembly S3, and the positive terminal of the DC bus.

[0055] The second operating mode is as follows: Figure 3 As shown, when the second power semiconductor switch component S2 is turned on and the third power semiconductor switch component S3 is turned off, the bridge arm current... When the submodule is in the active state, it discharges the DC energy storage capacitor C0. At this time, the first power semiconductor switching component S1 is turned off. Since the first inductor L1 and the second inductor L2 themselves store some energy, the output voltage is... At this time, the first inductor L1, the second inductor L2, and the second power semiconductor switch assembly S2 are connected in series to divide the voltage, which can effectively reduce the voltage across the second power semiconductor switch assembly S2. Among these, This is the inductance voltage corresponding to the first inductor L1; This is the inductance voltage corresponding to the second inductor L2.

[0056] The third operating mode is as follows: Figure 4 As shown, the second power semiconductor switch component S2 is turned off, and the third power semiconductor switch component S3 is turned on, and the bridge arm current... When the submodule is in the disconnected state, the current does not pass through the subsequent circuit.

[0057] The fourth operating mode is as follows: Figure 5 As shown, when the second power semiconductor switch component S2 is turned off and the third power semiconductor switch component S3 is turned off, the bridge arm current... At this time, the current flows through diode D1 to form a loop and does not pass through the subsequent circuit.

[0058] In these four operating modes, the switching on and off of the second power semiconductor switch assembly S2 is controlled by the first switch control circuit 2, while the switching on and off of the third power semiconductor switch assembly S3 is controlled by the second switch control circuit 3.

[0059] The drive regulation module 1 connected to the first power semiconductor switching component S1 includes a current acquisition unit and a PI control unit; wherein, the input terminal of the current acquisition unit serves as the input terminal of the drive regulation module 1 and is connected to the second electrode of the second power semiconductor switching component S2 and the second electrode of the third power semiconductor switching component S3; the output terminal of the current acquisition unit is connected to the input terminal of the PI control unit; and the output terminal of the PI control unit serves as the output terminal of the drive regulation module 1 and is connected to the control electrode of the first power semiconductor switching component S1.

[0060] Based on this, the principle by which the drive adjustment module 1 controls the first power semiconductor switching component S1 is as follows: the current acquisition unit acquires the selected bridge arm current. This is used as the control variable, employing a PI control strategy; the PI (Proportional-Integral Control) control unit uses the current reference value... And measuring the actual bridge arm current Take the difference to get the difference value. Then based on the difference Adjust the proportional coefficient of the current loop using a PI controller. and integral coefficient Finally, based on the proportional coefficient and integral coefficient The corresponding pulse modulation signal is determined and sent to the first power semiconductor switching component S1, so that the first power semiconductor switching component S1 periodically switches between the on and off states based on the pulse modulation signal to adjust the power transmission characteristics.

[0061] It is based on the difference Adjust the proportional coefficient of the current loop using a PI controller. and integral coefficient The specific adjustment principle is: when When, the proportionality coefficient Adjusted from 1 to 1.5, integral coefficient Keep it unchanged at 0.01, and adjust the proportional coefficient. Accelerate system response speed; when When, the proportionality coefficient according to Each decrease The proportion decreases by 0.1, and the proportionality coefficient... The minimum value is 0.5; when proportionality coefficient The integral coefficient is 1. The value is 0.015, reducing the overall output error of the system. The output is transmitted through the PI control unit (which can also be understood as a PI controller), and the modulation input is sent to the first power semiconductor switching component S1 to realize the operation of the topology within the power frequency cycle.

[0062] In other words, the bidirectional boost-type MMC circuit provided in this application adds a first inductor, a second inductor, and a first power semiconductor switching component to the conventional half-bridge MMC circuit. In the half-bridge MMC circuit, when the DC energy storage capacitor is in a discharging state due to the switching of the second and third power semiconductor switching components, the first and second inductors can absorb some electrical energy, thereby effectively reducing the voltage across the second power semiconductor switching component and extending its service life. Simultaneously, when the power semiconductor switching component has limited voltage tolerance and the DC energy storage capacitor is in a charging state, the first power semiconductor switching component is controlled by the drive regulation module based on a pulse modulation signal determined by the bridge arm current to adjust its power transfer characteristics, outputting a higher voltage level, thereby improving voltage utilization and operational safety.

[0063] On the other hand, this application also provides a flexible DC engineering electronic device, which is composed of a plurality of the aforementioned bidirectional boost-type MMC circuits. The plurality of bidirectional boost-type MMC circuits constitute the upper arm of the flexible DC engineering electronic device; the plurality of bidirectional boost-type MMC circuits constitute the lower arm of the flexible DC engineering electronic device.

[0064] In actual engineering operation, the number of bidirectional boost-type MMC circuits in the upper and lower bridge arms is huge. The essence of the closest level approximation modulation method is that the square wave formed by the bidirectional boost-type MMC circuit at any time is as close as possible to the modulated wave.

[0065] The implementation method of the level approximation modulation strategy controlling the MMC submodule is as follows: the number of bidirectional boost-type MMC circuits in the upper bridge arm is... The number of bidirectional boost-type MMC circuits incorporated in the lower bridge arm is .

[0066] The formula for the number of bidirectional boost-type MMC circuits incorporated in its upper bridge arm is:

[0067] ;

[0068] The formula for the number of bidirectional boost-type MMC circuits incorporated in the lower bridge arm is:

[0069] ;

[0070] in, This represents the total number of bidirectional boost-type MMC circuits in flexible DC engineering electronic equipment. The target output voltage; This refers to the capacitor voltage corresponding to the DC energy storage capacitor in a bidirectional boost MMC circuit. This is the floor function.

[0071] The entire modulation process of the closest level approximation is as follows: Figure 6 As shown, it shifts the modulated wave up by one modulation wave amplitude value and then directly uses... The function is rounded down to obtain the number of bidirectional boost MMC circuits that should be connected in each bridge arm; then the capacitor voltage in each bidirectional boost MMC circuit is calculated. Sort the data, then sort it according to the bridge arm current. The magnitude of the current determines the direction of current flow, thereby determining the switching state of each bidirectional boost-type MMC circuit, and thus obtaining the corresponding modulation signal, which can also be understood as a trigger pulse.

[0072] When using the nearest-level modulation method, because of the rounding function Since the rounding is approximate, the input modulation signal must be processed to ensure that the result of the rounding function is not less than zero. Additionally, the capacitor voltage of each bidirectional boost MMC circuit must be monitored in real time. Regarding capacitor voltage The sizes are sorted, and then the bidirectional boost-type MMC circuit is added or removed according to the following logic:

[0073] 1) When the bidirectional boost MMC circuits in the upper and lower bridge arms remain unchanged, the switching state of each bidirectional boost MMC circuit remains unchanged.

[0074] 2) When the bidirectional boost MMC circuit in the upper and lower bridge arms changes, its activation state is determined by the bridge arm current. According to the sorted capacitor voltage The smaller bidirectional boost MMC circuit is put into operation first; when the bridge arm current... The sorted capacitor voltages Larger bidirectional boost MMC circuits will be implemented first.

[0075] Therefore, the bidirectional boost MMC circuit and the flexible DC engineering electronic device composed of the bidirectional boost MMC circuit provided in this application have the following advantages:

[0076] 1. When the power semiconductor switching component has limited voltage tolerance and the DC energy storage capacitor is in a charging state, the first power semiconductor switching component is controlled by the drive regulation module based on the pulse modulation signal determined by the bridge arm current to adjust the power transmission characteristics, output a higher voltage level, and thus improve the voltage utilization rate.

[0077] 2. Each bridge arm of the converter valve in the converter station requires a large number of bidirectional boost-type MMC circuits. By controlling the boost circuit with the first power semiconductor switching component, fewer bidirectional boost-type MMC circuits can be used to achieve the ideal voltage level.

[0078] 3. In a half-bridge MMC circuit, when the DC energy storage capacitor is in a discharging state due to the switching of the second and third power semiconductor switching components, the first and second inductors can absorb some electrical energy, thereby effectively reducing the voltage across the second power semiconductor switching component and extending the service life of the power semiconductor switching component.

[0079] The bidirectional boost-type MMC circuit and flexible DC engineering electronic device provided in this application have been described in detail above. The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to in the method section. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

[0080] It should also be noted that, in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A bidirectional boost MMC circuit, characterized in that, include: A half-bridge MMC circuit, a first inductor, a second inductor, and a first power semiconductor switching assembly; Wherein, the first end of the first inductor is connected to the first electrode of the second power semiconductor switching component in the half-bridge MMC circuit; The second end of the first inductor is connected to the first end of the second inductor and the first electrode of the first power semiconductor switching assembly; The second terminal of the second inductor is connected to the first terminal of the DC energy storage capacitor in the half-bridge MMC circuit; The second electrode of the first power semiconductor switching component is connected to the first electrode of the third power semiconductor switching component in the half-bridge MMC circuit, the second terminal of the DC energy storage capacitor, and the negative terminal of the DC bus. The control electrode of the first power semiconductor switch assembly is connected to the drive adjustment module, and is used to receive the pulse modulation signal determined by the drive adjustment module based on the bridge arm current, and to periodically switch between the on and off states based on the pulse modulation signal to adjust the power transmission characteristics; wherein, the bridge arm current is the current on the connection line connecting the second electrode of the second power semiconductor switch assembly, the second electrode of the third power semiconductor switch assembly, and the positive terminal of the DC bus.

2. The bidirectional boost MMC circuit according to claim 1, characterized in that, Also includes: diode; Wherein, the anode of the diode is connected to the second terminal of the first inductor, the first terminal of the second inductor, and the first electrode of the first power semiconductor switching assembly; The cathode of the diode is connected to the first terminal of the second inductor and the first terminal of the DC energy storage capacitor.

3. The bidirectional boost MMC circuit according to claim 1, characterized in that, The drive adjustment module includes: a current acquisition unit and a PI control unit; The input terminal of the current acquisition unit serves as the input terminal of the drive adjustment module and is connected to the second electrode of the second power semiconductor switch assembly and the second electrode of the third power semiconductor switch assembly. The output terminal of the current acquisition unit is connected to the input terminal of the PI control unit; The output terminal of the PI control unit is connected to the control electrode of the first power semiconductor switching assembly as the output terminal of the drive adjustment module.

4. The bidirectional boost MMC circuit according to claim 1, characterized in that, The first power semiconductor switching component is a first IGBT component; Wherein, the collector of the first IGBT component serves as the first electrode of the first power semiconductor switch component and is connected to the second terminal of the first inductor and the first terminal of the second inductor; The emitter of the first IGBT component serves as the second electrode of the first power semiconductor switch component and is connected to the first electrode of the third power semiconductor switch component, the second terminal of the DC energy storage capacitor, and the negative terminal of the DC bus. The gate of the first IGBT component is connected to the drive regulation module as the control electrode of the first power semiconductor switch component.

5. The bidirectional boost MMC circuit according to claim 1, characterized in that, The second power semiconductor switching component is a second IGBT component, and the third power semiconductor switching component is a third IGBT component; Wherein, the collector of the second IGBT component is connected to the first terminal of the first inductor as the first electrode of the second power semiconductor switch component; The emitter of the second IGBT component is connected as the second electrode of the second power semiconductor switch component and the collector of the third IGBT, which is the second electrode of the third power semiconductor switch component, and both are connected to the positive terminal of the DC bus. The emitter of the third IGBT serves as the first electrode of the third power semiconductor switching assembly and is connected to the second electrode of the first power semiconductor switching assembly, the second terminal of the DC energy storage capacitor, and the negative terminal of the DC bus. The gate of the second IGBT component is connected to the first switch control circuit as the control electrode of the second power semiconductor switch component. The gate of the third IGBT component is connected to the second switch control circuit as the control electrode of the third power semiconductor switch component.

6. A flexible DC engineering electronic device, characterized in that, include: The bidirectional boost MMC circuit according to any one of claims 1-5.

7. The flexible DC engineering electronic device according to claim 6, characterized in that, The number of bidirectional boost-type MMC circuits deployed in the upper bridge arm of the flexible DC engineering electronic device is: ; The formula for the number of bidirectional boost-type MMC circuits inserted in the upper bridge arm is as follows: ； in, The total number of bidirectional boost-type MMC circuits in the flexible DC engineering electronic equipment; The target output voltage; This refers to the capacitor voltage corresponding to the DC energy storage capacitor in the bidirectional boost MMC circuit. This is the floor function.

8. The flexible DC engineering electronic device according to claim 6, characterized in that, The number of bidirectional boost-type MMC circuits deployed in the lower bridge arm of the flexible DC engineering electronic device is: ; The formula for the number of bidirectional boost-type MMC circuits incorporated in the lower bridge arm is as follows: ； in, The total number of bidirectional boost-type MMC circuits in the flexible DC engineering electronic equipment; The target output voltage; This refers to the capacitor voltage corresponding to the DC energy storage capacitor in the bidirectional boost MMC circuit. This is the floor function.

9. The flexible DC engineering electronic device according to claim 7, characterized in that, When the bridge arm current is greater than zero, the bidirectional boost MMC circuit with the smaller capacitor voltage is given priority for activation.

10. The flexible DC engineering electronic device according to claim 9, characterized in that, When the bridge arm current is less than zero, the bidirectional boost MMC circuit with the larger capacitor voltage is given priority for activation.

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