Converter switch control method of multi-port flexible interconnection equipment and controller

Abstract

The invention relates to the technical field of converter control, in particular to a converter switch control method of multi-port flexible interconnection equipment and a controller, and aims to solve the technical problems of large loss, low stability and the like of a soft switching zero-voltage switching technology in the prior art. In order to achieve the purpose, the carrier signal of the full-bridge circuit of each phase of the converter is judged according to the actual switching frequency and the critical change-over switching frequency of each phase of the converter. And the carrier signal comprises a 180-degree triangular carrier and a phase-shifting special-shaped carrier. The phase-shifting special-shaped carrier wave is a carrier wave obtained by performing phase shifting on a 180-degree triangular carrier wave according to a phase-shifting angle and performing horizontal overturning on the later period in every two switching periods. On-off control is carried out on each phase of the converter according to the carrier signal, the problem that the bridge arm current can generate overlarge current ripples at the zero crossing point is solved, the on-state loss and the switching loss of a switching device are reduced, the converter has a smaller switching frequency fluctuation range, and the stability and the reliability of a system are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter control, in particular to a converter switch control method of a multi-port flexible interconnection device, a controller, a medium and the multi-port flexible interconnection device. BACKGROUND

[0002] With high proportion of distributed energy access to the power grid, the traditional distribution network is insufficient in the accommodation and utilization of distributed power, and the problem of safe and stable operation of the system is highlighted. The multi-port flexible interconnection distribution network converts the traditional single radiation power supply mode into a closed-loop power supply mode, which can flexibly control the power flow and reduce the loss, and has been widely studied in recent years. For the multi-port flexible interconnection device, the ports are connected through flexible converters, so the soft switching technology of the flexible converter is the key to improve the conversion efficiency of the multi-port flexible interconnection device.

[0003] Wide bandgap semiconductor devices have excellent parameter characteristics and are excellent in high-voltage, high-frequency and high-temperature applications, and are widely used in converter power switching devices. For wide bandgap semiconductor devices, the turn-on loss accounts for the main part of the switching loss, so it is necessary to study the soft switching zero voltage switching (ZVS) technology of the multi-port flexible interconnection device converter.

[0004] Soft switching is relative to hard switching. The ideal soft switching process is that the voltage first drops to zero and then the current slowly rises to the conduction value, so that the turn-on loss is approximately zero, and ZVS is achieved. Therefore, the soft switching technology is a key technology to improve the conversion efficiency of the multi-port flexible interconnection device converter. The essential requirement for realizing ZVS is that the polarity of the bridge arm current is reversed in a switching cycle. The existing ZVS schemes are as follows: TCM (Triangle Current Mode, triangular current mode) technology: In order to realize ZVS operation and reduce the switching loss of the converter, the TCM method is widely used in single-phase systems. This method controls the realization of ZVS by increasing the ripple of the inductor current to make the current flow in both directions in each switching cycle. The control principle of this method is simple and has low complexity.

[0005] DPWM (Discontinuous Pulse Width Modulation, discontinuous pulse width modulation technology): The DPWM method decouples the control of any phase, while the other two phases work in TCM mode at the same switching frequency. For the same reference voltage, DPWM only needs to move the switches of two bridge arms, so the switching loss of DPWM will be relatively low[5].

[0006] QCM (Quadrilateral Current Mode) technology: QCM mode adopts traditional 180° interleaved carrier, and a pair of coupled inductors is added between each phase on the basis of three-phase interleaved parallel converter, thereby introducing inter-phase circulating current, and through calculation and selection of switching frequency, the peak-to-peak value of conduction transient ripple is controlled, and ZVS of two switches in each bridge arm is realized in each switching cycle.

[0007] The existing multi-port flexible interconnection device converter ZVS technical solutions all have limitations, and it is difficult to simultaneously consider a narrower switching frequency fluctuation range and a critical current ripple. For example, the TCM method has simple control principle and low complexity, but unlike single-phase systems, the currents in three-phase systems are coupled, so TCM cannot be directly applied to three-phase systems; the DPWM method solves the limitation that TCM cannot be applied to three-phase systems, but due to the changes in inductor current and phase current, the required switching frequency fluctuation range for maintaining ZVS is large, which increases the design complexity of the drive circuit and filter, and is not conducive to system stability; the QCM method has limitations due to the 180° interleaved carrier, and under the condition of consistent three-phase switching frequency, the bridge arm current works in an excessive soft switching mode at the zero-crossing point, which causes the zero-crossing harmonic to be too large, has a great impact on on-state loss and off-state loss, and results in large overall loss.

[0008] Correspondingly, there is a need for a new converter switching control scheme to solve the above problems. SUMMARY

[0009] In order to overcome the above defects, the present application is proposed to solve or at least partially solve the technical problems of large loss and low stability of the soft switching zero voltage turn-on technology in the prior art.

[0010] In a first aspect, a multi-port flexible interconnection device converter switching control method is provided, the converter including interleaved three-phase parallel; each phase includes two parallel full-bridge circuits, the bridge arm midpoint of each full-bridge circuit is connected with the first end of an auxiliary inductor, and the second ends of the two full-bridge circuits are connected with a transformer substation after being connected with each other; the first end and the second end of the converter are connected with the positive and negative poles of a DC bus respectively; the method comprises: For each phase of the converter, the actual switching frequency of the converter and the critical switching frequency of each phase are obtained; According to the actual switching frequency and the critical switching frequency, carrier signals of two full-bridge circuits in a current switching period of each phase are obtained; the carrier signals include 180° triangular carrier signals and phase-shifted special-shaped carrier signals; the phase-shifted special-shaped carrier signals are obtained by phase-shifting the 180° triangular carrier signals according to a phase-shift angle and horizontally flipping a latter one of every two switching periods; the phase-shift angle is determined according to the actual switching frequency of the converter and the actual switching frequency of each phase; and a phase difference between the phase-shifted special-shaped carrier signals of the two full-bridge circuits is determined by the phase-shift angle. According to the carrier signals, each phase of the converter is controlled.

[0011] In one of the above technical solutions of the converter switching control method, the step of obtaining the carrier signals of the two full-bridge circuits in the current switching period of each phase according to the actual switching frequency and the critical switching frequency includes: If the actual switching frequency and the critical switching frequency are the same, the carrier signals are determined as the 180° triangular carrier signals. If the actual switching frequency and the critical switching frequency are different, the carrier signals are determined as the phase-shifted special-shaped carrier signals.

[0012] In one of the above technical solutions of the converter switching control method, the method further includes obtaining the phase-shift angle of each phase according to the following steps: The actual switching frequency of the converter, the actual switching frequency of each phase and a reference voltage are obtained; wherein the actual switching frequency of the converter is the minimum value of the actual switching frequencies of the three phases. According to the actual switching frequency of the converter, the actual switching frequency of each phase and the reference voltage, the phase-shift angle of each phase is obtained.

[0013] In one of the above technical solutions of the converter switching control method, the step of obtaining the phase-shift angle of each phase according to the actual switching frequency of the converter, the actual switching frequency of each phase and the reference voltage includes obtaining the phase-shift angle according to the following formula: wherein, is a phase-shift angle of an xth phase of an nth converter, is the actual switching frequency of the nth converter, is the actual switching frequency of the xth phase of the nth converter, is a reference voltage of the xth phase of the nth converter.

[0014] In one of the technical solutions of the above-mentioned converter switch control method, the phase-shifted special-shaped carrier includes a first special-shaped carrier and a second special-shaped carrier; the method includes obtaining the first special-shaped carrier and the second special-shaped carrier according to the following steps: According to the phase-shifted angle and the reference voltage of each phase, a first initial value of the first special-shaped carrier and a second initial value of the second special-shaped carrier are obtained; According to the first initial value, the 180° triangular carrier is phase-shifted, and the last period in every two switching periods is horizontally flipped to obtain the first special-shaped carrier; According to the second initial value, the 180° triangular carrier is phase-shifted, and the last period in every two switching periods is horizontally flipped to obtain the second special-shaped carrier.

[0015] In one of the technical solutions of the above-mentioned converter switch control method, the first initial value of the first special-shaped carrier and the second initial value of the second special-shaped carrier are obtained according to the phase-shifted angle and the reference voltage of each phase, including obtaining the first initial value and the second initial value according to the following formula: Wherein, is the first initial value; is the second initial value, is the reference voltage; is the phase-shifted angle.

[0016] In one of the technical solutions of the above-mentioned converter switch control method, the switch control of each phase of the converter according to the carrier signal includes: Comparing the carrier signal with the reference voltage of the current phase to obtain a pulse width modulation signal; According to the pulse width modulation signal, the switch control of each phase of the converter is performed.

[0017] In a second aspect, a controller is provided, including at least one processor; and a memory connected in communication with the at least one processor; wherein the memory stores a computer program, and the computer program is executed by the at least one processor to implement the method of any one of the technical solutions of the above-mentioned multi-port flexible interconnection device converter switch control method.

[0018] In a third aspect, a computer-readable storage medium is provided, wherein a plurality of program codes are stored in the computer-readable storage medium, the program codes being adapted to be loaded and run by a processor to perform the method of any one of the technical solutions of the converter switch control method of the multi-port flexible interconnection device.

[0019] In a fourth aspect, a multi-port flexible interconnection device is provided, the device comprising a plurality of converters and the controller of claim 8; the converter comprising three phases in interleaved parallel connection; each phase comprising two full-bridge circuits in parallel connection, the bridge arm midpoint of each full-bridge circuit being connected with a first end of an auxiliary inductor, the second ends of the two full-bridge circuits being connected with each other and then connected with a transformer substation; the first end and the second end of the converter being connected with the positive pole and the negative pole of a DC bus respectively.

[0020] The one or more technical solutions of the above application have at least one or more of the following beneficial effects: In the implementation of the technical solution of the converter switch control method of the multi-port flexible interconnection device provided by the application, the carrier signals of the full-bridge circuits in the current switching period of each phase of the converter are determined according to the actual switching frequency and the critical switching frequency of each phase. The carrier signals include a 180° triangular carrier and a phase-shifted special-shaped carrier. The phase-shifted special-shaped carrier is obtained by phase-shifting the 180° triangular carrier according to a phase-shift angle and horizontally flipping the carrier in the latter one of every two switching periods. Each phase of the converter is controlled according to the carrier signals. Through the above configuration, the selection of the carrier signals can be realized based on the actual switching frequency and the critical switching frequency of each phase, and the zero-voltage turn-on of the converter can be realized by combining the 80° triangular carrier and the phase-shifted special-shaped carrier. The problem of excessive current ripple of the bridge arm current at the zero-crossing point in the prior art is solved, and the on-state loss and switching loss of the switching device are effectively reduced. At the same time, the converter of the application has a smaller switching frequency fluctuation range, which improves the system stability and reliability. Moreover, the switching process of the zero-voltage turn-on of the application is simple, and the control process is easier to implement. BRIEF DESCRIPTION OF DRAWINGS

[0021] The disclosure of the application will become more apparent with reference to the drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes, and are not intended to limit the scope of protection of the application. Among them: Figure 1 is a main step flow diagram of the converter switch control method of the multi-port flexible interconnection device according to an embodiment of the application; Figure 2 is a main component structure diagram of the multi-port flexible interconnection device according to an embodiment of the application; Figure 3 is a schematic diagram of a phase-shifted special-shaped carrier modulation process according to an embodiment of the present application; Figure 4 is a schematic diagram of the relationship among the critical switching frequency, the actual switching frequency and the critical switching frequency according to an embodiment of the present application; Figure 5 is a main control process block diagram of a converter switching control method according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] Some embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art will understand that the embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0023] In the description of the present application, "module" and "processor" can include hardware, software or a combination of both. A module can include hardware circuit, various suitable sensors, communication port, memory, and can also include software part such as program code, and can be a combination of software and hardware. The term "A and / or B" means all possible combinations of A and B, such as only A, only B, or A and B. The term "at least one of A or B" or "at least one of A and B" has similar meaning as "A and / or B", and can include only A, only B, or A and B. The singular form of the term "one", "this" can also include plural forms.

[0024] First, some terms are explained: Zero-Voltage Switching (ZVS); Quadrilateral Current Mode (QCM); Triangle Current Mode (TCM); Trapezoidal current mode (TZM).

[0025] Referring to the drawings Figure 1 , Figure 1 is a main step flow schematic diagram of a converter switching control method of a multi-port flexible interconnection device according to an embodiment of the present application. As shown in Figure 1As shown, the multi-port flexible interconnection device in the embodiment of the application includes a plurality of interleaved parallel converters, the converter including interleaved parallel three-phase; each phase includes two parallel full-bridge circuits, the bridge arm midpoint of each full-bridge circuit is connected with the first end of an auxiliary inductor, the second ends of the two full-bridge circuits are connected with each other and then connected with the distribution area; the first end and the second end of the converter are connected with the positive and negative poles of the DC bus respectively. The converter switching control method in the embodiment of the application mainly includes the following steps S101 to S103.

[0026] Step S101: for each phase of the converter, the actual switching frequency of the converter and the critical switching switching frequency of each phase are obtained.

[0027] In the embodiment, the plurality of interleaved parallel converters, i.e. converter #1, converter #2, …, converter #N, are shown in FIG. 1. Figure 2 , Figure 2 Each converter includes interleaved parallel three-phase, i.e. a phase, b phase and c phase. Each phase includes two parallel full-bridge circuits, the full-bridge circuit is composed of two switching devices, i.e. (S xn1 -S ’ xn1 ) and (S xn2 -S ’ xn2 ). The bridge arm midpoint is connected with the first end of an auxiliary inductor L xm , and the auxiliary inductor is used to realize soft switching function, and the inductance thereof is far less than the output filter inductor L0. Figure 2 In FIG. 1, x respectively corresponds to a, b, c three-phase, n=1, 2, …, N, corresponding to the nth power distribution port. In which, the auxiliary inductance L xm1 -L xm2 The inductance values are equal, and a coupled inductor or a differential mode inductor can be selected. In which, V dc is the DC bus voltage, i xn is the phase current, V xn1 and V xn2 are the output voltages of the bridge arm midpoint, i xn1 and i xn2 are the bridge arm currents.

[0028] Step S102: according to the actual switching frequency and the critical switching frequency, the carrier signals of the two full-bridge circuits in the current switching period of each phase are obtained; the carrier signal includes a 180° triangular carrier and a phase-shifted special-shaped carrier; the phase-shifted special-shaped carrier is obtained by phase-shifting the 180° triangular carrier according to the phase-shift angle and horizontally flipping the latter one of each two switching periods; the phase-shift angle is determined according to the actual switching frequency of the converter and the actual switching frequency of each phase; the phase difference of the phase-shifted special-shaped carrier signals of the two full-bridge circuits is determined through the phase-shift angle.

[0029] In the embodiment, step S102 can further include the following step S1021 and step S1022: Step S1021: if the actual switching frequency is the same as the critical switching frequency, it is determined that the carrier signal is a 180° triangular carrier; Step S1022: if the actual switching frequency is different from the critical switching frequency, it is determined that the carrier signal is a phase-shifted special-shaped carrier.

[0030] In the embodiment, since the 180° triangular carrier is used for modulation when the actual switching frequency is different from the critical switching frequency, an excessive ripple will be generated. Therefore, the phase-shifted special-shaped carrier can be applied to eliminate the current ripple by phase shift.

[0031] In one embodiment, the phase shift angle can be obtained according to the following step S201 and step S202: Step S201: obtaining the actual switching frequency of the converter, the actual switching frequency of each phase and the reference voltage; wherein the actual switching frequency of the converter is the minimum value of the actual switching frequencies of the three phases; Step S202: obtaining the phase shift angle of each phase according to the actual switching frequency of the converter, the actual switching frequency of each phase and the reference voltage.

[0032] In one embodiment, the phase-shifted special-shaped carrier can include a first special-shaped carrier and a second special-shaped carrier. The first special-shaped carrier and the second special-shaped carrier can be obtained according to the following steps S301 to S303: Step S301: obtaining the first initial value of the first special-shaped carrier and the second initial value of the second special-shaped carrier according to the phase shift angle and the reference voltage of each phase; Step S302: obtaining the first special-shaped carrier by phase-shifting the 180° triangular carrier and horizontally flipping the latter one of each two switching periods; Step S303: obtaining the second special-shaped carrier by phase-shifting the 180° triangular carrier and horizontally flipping the latter one of each two switching periods.

[0033] Step S103: switching control is performed on each phase of the converter according to the carrier signal.

[0034] In the embodiment, step S103 can further include the following step S1031 and step S1032: Step S1031: comparing the carrier signal with the reference voltage of the current phase to obtain a pulse width modulation signal; Step S1032: switching control is performed on each phase of the converter according to the pulse width modulation signal.

[0035] In this embodiment, the carrier signal and the reference voltage can be compared to obtain a pulse width modulation (PWM) signal, and the switching control of each phase of the converter can be performed based on the PWM signal.

[0036] Based on the methods described in steps S101 to S103 above, this embodiment of the application determines the carrier signal of the full-bridge circuit for each phase of the converter according to the actual switching frequency and critical switching frequency of each phase. The carrier signal includes a 180° triangular carrier and a phase-shifted irregular carrier. The phase-shifted irregular carrier is obtained by phase-shifting the 180° triangular carrier according to the phase shift angle and then horizontally flipping it in the latter of every two switching cycles. Switching control of each phase of the converter is performed according to the carrier signal. Through the above configuration, this embodiment of the application can achieve carrier signal selection based on the actual switching frequency and critical switching frequency of each phase, and can achieve zero-voltage turn-on of the converter by combining the 80° triangular carrier and the phase-shifted irregular carrier. This solves the problem of excessive current ripple generated when the bridge arm current crosses zero in the prior art, effectively reducing the conduction loss and switching loss of the switching devices. At the same time, it also makes the converter of this application have a smaller switching frequency fluctuation range, improving system stability and reliability. Furthermore, the switching process for achieving zero-voltage turn-on in this application is simple, and the control process is easier to implement.

[0037] The following is combined with Figures 2 to 5 The converter switching control method of the multi-port flexible interconnect device according to the embodiments of this application will be further described.

[0038] In existing technologies, if only a 180° triangular carrier wave is used, the following limitations exist: Considering the three-phase symmetry and the consistency of the multi-port structure, with Figure 2 Taking any phase of any converter in the circuit as an example, L xm Assisting in the implementation of ZVS (Zero-Voltage Switching), phase current i xn It is the current i in both bridge arms xn1 i xn2 The sum of these can be expressed by the following formula (1): (1) Where t is time, i cir_xn For interphase circulation, V xn1 and V xn2 This is the output voltage at the midpoint of the bridge arm.

[0039] Therefore, the bridge arm voltage difference V xn12 =Vxn1 -V xn2 Inducing interphase circulation between the two bridge arms cir_xn V can be used xn12 with i cir_xn The linear relationship controls the peak value of the interphase circulation, making i xn1 i xn2 The polarity of the switch reverses within one switching cycle, achieving full-range ZVS.

[0040] During 180° triangular carrier modulation, since the phase current remains essentially constant within one switching cycle and the carrier signal phase shift is fixed at 180°, the interphase circulating current amplitude can only be controlled by actively adjusting the switching frequency. The peak value of the interphase circulating current is ∆I. cir_xn With the critical switching frequency f s_xn The relationship between them can be expressed by the following formula (2): (2)

[0041] Because the actual switching frequency f of the converter sn To ensure three-phase consistency and balanced switching frequencies, the actual switching frequencies f of the three phases will be used. s_x The minimum switching frequency is determined to be the actual switching frequency f of the converter. sn As shown in the following formula (3): (3)

[0042] However, the selected three-phase consistent switching frequency can only guarantee that the switching frequency of one phase of the converter meets the critical switching frequency f in formula (2). s_xn Therefore, the traditional 180° carrier wave is limited by phase control limitations, and in any phase f s_xn ≠f sn The region cannot meet the conditions for critical soft switching, which manifests as excessive current ripple near the zero-crossing point of the inductor current, causing the switching device to operate in the excessive ZVS region. This application's embodiment is based on the 180° triangular carrier modulation principle, switching the carrier signal in the excessive ZVS region from a 180° triangular carrier to a phase-shifted irregular carrier with an adjustable phase angle, thereby achieving critical ZVS for the switching device through carrier phase shifting.

[0043] The process of obtaining phase-shifted, irregularly shaped carrier waves is explained below.

[0044] like Figure 3 As shown, with Figure 2 Taking any phase of any converter in the present application as an example, the phase-shifted irregular carrier involved in the embodiments of this application is... Figure 2 C in rxn1 and C rxn2 C rxn1 and C rxn2Corresponding to switch pairs (S) xn1 , S' xn1 ) 、(S xn2 ,S' xn2 ). Figure 2 I in bs For the critical bias current, φ xn This is the phase shift angle. Simultaneously, to ensure interphase circulation i... cir_xn Amplitude-second balance to prevent bridge arm current i from being affected by error factors. xn1 i xn2 The phase shift is achieved by horizontally flipping the carrier wave in the latter cycle between two adjacent switching cycles, resulting in the following: Figure 3 The phase-shifted irregular carrier shown can be represented by the initial value in each switching cycle as shown in formula (4): (4) Among them, C rxn1 C is the first initial value of the first irregular carrier wave. rxn2 The second initial value for the second irregular carrier wave. This is the reference voltage for the x-th phase of the nth converter.

[0045] Specifically, to ensure i xn1 i xn2 Polarity reversal achieves ZVS, such as Figure 3 As shown, the bridge arm current must satisfy the condition shown in the following formula (5): (5)

[0046] The peak value of the interphase circulating current of the phase-shifted irregular carrier can be obtained according to the following formula (6): (6) Among them, V dc This is the DC bus voltage.

[0047] Combining the above formulas (2) and (6), the expression for the phase shift angle of the phase-shifted irregular carrier under critical conditions can be obtained, as shown in the following formula (7): (7) in, Let x be the phase shift angle of the x-th phase of the n-th converter. The actual switching frequency of the nth converter Let x be the actual switching frequency of the x-th phase of the nth converter. This is the reference voltage for the x-th phase of the nth converter.

[0048] The shape and initial value of the shaped carrier and the calculation of the phase shift angle are integrated, and the required phase shift shaped carrier is obtained. The phase shift shaped carrier adjusts the variable frequency modulation of the converter to the critical soft switching by adjusting the phase shift angle in each switching period in real time.

[0049] Since f s_xn ≠ f sn The carrier frequency of the region phase cannot meet the critical condition, causing the current ripple of the region phase to be too large, and the switching device to work in the over-ZVS region. Therefore, in the embodiments of the present application, the carrier in this region is switched from the 180° triangular carrier to the phase shift shaped carrier obtained by the foregoing method. Therefore, the critical switching frequency f xn of the carrier needs to be determined, which can be obtained by combining formulas (2) and (5), and the critical switching frequency f xn of the carrier is as shown in formula (8): (8) Wherein, the critical switching frequency f s_xn , the actual switching frequency f sn and the relationship between the critical switching frequency f xn are as shown in Figure 4 From Figure 4 , it can be seen that f s_xn is consistent in three phases and has a small fluctuation range, f xn is located at the critical intersection of f s_xn ≠ f sn and f s_xn =f sn . Therefore, in the embodiments of the present application, the carrier signal in the region f s_xn =f sn can remain 180° triangular carrier, and the carrier signal in the region f s_xn ≠ f sn is switched from the 180° triangular carrier to the foregoing phase shift shaped carrier.

[0050] In one embodiment of the embodiments of the present application, reference can be made to the accompanying drawings Figure 5 , as shown in Figure 5 , for a plurality of converters as shown in Figure 2 , a multi-port flexible interconnection device is staggered and connected in parallel, and for example, any one phase of any one converter can be used. The foregoing formula (7) is used to calculate the phase shift angle according to the reference voltage ; the actual switching frequency f dc is calculated according to the foregoing formula (3) according to the DC bus voltage V xn and the phase current i sn ; and the critical switching frequency f xnThe obtained actual switching frequency f sn is compared with the critical switching frequency f xn , and it is determined whether the actual switching frequency f sn is the same as the critical switching frequency f xn . If they are the same, it is determined that the carrier signal is a 180° triangular carrier; if they are different, it is determined that the carrier signal is a phase-shifted special carrier. According to the determined carrier signal, the reference voltage is compared to obtain a PWM signal, so as to realize switching control of the converter (i.e., (S xn1 -S ’ xn1 ) and (S xn2 -S ’ xn2 ).

[0051] The switching control method of the converter of the multi-port flexible interconnection device according to the embodiments of the present application does not need to add or change additional hardware circuits to the converter, improves the power density of the multi-port flexible interconnection device, and reduces the cost; the switching period fluctuation range of the switching control method of the converter according to the embodiments of the present application is narrow, which improves the system stability and reliability of the multi-port flexible interconnection device; the phase-shifted special carrier solves the problem of excessive zero-crossing point ripple of the 180° triangular carrier, reduces the on-state loss and switching loss of the switching device; at the same time, the construction process of the phase-shifted special carrier only needs to introduce real-time phase-shift calculation, and the carrier switching mode is simple, and the control is easy to realize; and all switching devices can work in the critical ZVS condition, keep the critical current ripple, and maximize the conversion efficiency of the multi-port flexible interconnection device.

[0052] It should be noted that, although the steps in the above embodiments are described in a specific order, those skilled in the art can understand that, in order to achieve the effects of the present application, the different steps do not necessarily have to be executed in such an order, and they can be executed simultaneously (in parallel) or in other orders, and these adjusted schemes and the technical schemes described in the present application belong to equivalent technical schemes, and thus will also fall within the protection scope of the present application.

[0053] Those skilled in the art can understand that all or part of the processes in the method of the embodiment described above can also be completed by a computer program instructing related hardware, and the computer program can be stored in a computer readable storage medium. When the computer program is executed by a processor, the steps of the various method embodiments described above can be implemented. The computer program includes computer program code, which can be in the form of source code, object code, executable files or some intermediate forms, etc. The computer readable storage medium can include any entity or device, medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code.

[0054] Another aspect of the present application also provides a computer readable storage medium.

[0055] In an embodiment of the computer readable storage medium according to the present application, the computer readable storage medium can be configured to store a program for implementing the converter switch control method of the multi-port flexible interconnection device described above, which can be loaded and run by the processor to implement the converter switch control method described above. For the convenience of description, only the parts related to the embodiments of the present application are shown, and the specific technical details not disclosed are referred to the method part of the embodiments of the present application. The computer readable storage medium can be a storage device formed by various electronic devices, such as magnetic disk, hard disk, optical disk, flash memory, read-only memory, random access memory, etc. Optionally, the computer readable storage medium in the embodiments of the present application is a non-transitory computer readable storage medium.

[0056] Another aspect of the present application also provides a controller.

[0057] In an embodiment of the controller according to the present application, the controller can include at least one processor; and a memory connected in communication with the at least one processor; wherein the memory has stored therein a computer program, which, when executed by the at least one processor, implements the method described in any of the converter switch control method embodiments of the multi-port flexible interconnection device.

[0058] Further, the present application also provides a multi-port flexible interconnection device.

[0059] In one multi-port flexible interconnection device embodiment according to the present application, the multi-port flexible interconnection device comprises a plurality of interleaved parallel converters and the controller described in the above controller embodiment. The converter can comprise three phases interleaved in parallel; each phase can comprise two parallel full-bridge circuits, the midpoint of the bridge arm of each full-bridge circuit is connected with the first end of an auxiliary inductor, the second ends of the two full-bridge circuits are connected with each other and then connected with the distribution area; the first end and the second end of the converter are connected with the positive pole and the negative pole of the DC bus respectively.

[0060] So far, the technical solution of the present application has been described in combination with one embodiment shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will fall within the protection scope of the present application.

Claims

1. A converter switching control method for a multi-port flexible interconnection device, characterized in that, The equipment includes multiple alternating parallel converters; each converter includes three phases connected in alternating parallel; each phase includes two parallel full-bridge circuits, the midpoint of the bridge arm of each full-bridge circuit is connected to the first terminal of an auxiliary inductor, and the second terminals of the auxiliary inductors of the two full-bridge circuits are interconnected and then connected to the transformer substation; the first and second terminals of the converters are respectively connected to the positive and negative terminals of the DC bus; the method includes: For each phase of the converter, obtain the actual switching frequency of the converter and the critical switching frequency of each phase; Based on the actual switching frequency and the critical switching frequency, carrier signals for the two full-bridge circuits in each corresponding previous switching cycle are obtained; the carrier signals include a 180° triangular carrier and a phase-shifted irregular carrier; the phase-shifted irregular carrier is obtained by phase-shifting the 180° triangular carrier according to the phase shift angle, and then horizontally flipping it in the latter cycle of every two switching cycles; the phase shift angle is determined according to the actual switching frequency of the converter and the actual switching frequency of each phase; the phase difference between the phase-shifted irregular carrier signals of the two full-bridge circuits is determined by the phase shift angle; Based on the carrier signal, each phase of the converter is switched on and off.

2. The converter switching control method according to claim 1, characterized in that, The step of obtaining the carrier signals of the two full-bridge circuits for each corresponding previous switching cycle based on the actual switching frequency and the critical switching frequency includes: If the actual switching frequency and the critical switching frequency are the same, then the carrier signal is determined to be a 180° triangular carrier. If the actual switching frequency is different from the critical switching frequency, then the carrier signal is determined to be a phase-shifted irregular carrier.

3. The converter switching control method according to claim 1 or 2, characterized in that, The method further includes obtaining the phase shift angle of each phase according to the following steps: Obtain the actual switching frequency of the converter, the actual switching frequency of each phase, and the reference voltage; wherein, the actual switching frequency of the converter is the minimum value of the actual switching frequencies of the three phases; The phase shift angle of each phase is obtained based on the actual switching frequency of the converter, the actual switching frequency of each phase, and the reference voltage.

4. The converter switching control method according to claim 3, characterized in that, The step of obtaining the phase shift angle of each phase based on the actual switching frequency of the converter, the actual switching frequency of each phase, and the reference voltage includes obtaining the phase shift angle according to the following formula: in, Let x be the phase shift angle of the x-th phase of the n-th converter. The actual switching frequency of the nth converter Let x be the actual switching frequency of the x-th phase of the nth converter. This is the reference voltage for the x-th phase of the nth converter.

5. The converter switching control method according to claim 1 or 2, characterized in that, The phase-shifted irregular carrier includes a first irregular carrier and a second irregular carrier; the method includes obtaining the first irregular carrier and the second irregular carrier according to the following steps: Based on the phase shift angle and the reference voltage of each phase, obtain the first initial value of the first irregular carrier and the second initial value of the second irregular carrier; Based on the first initial value, the 180° triangular carrier is phase-shifted, and then horizontally flipped in the second cycle of every two switching cycles to obtain the first irregular carrier. Based on the second initial value, the 180° triangular carrier is phase-shifted, and then horizontally flipped in the second cycle of every two switching cycles to obtain the second irregular carrier.

6. The converter switching control method according to claim 5, characterized in that, The step of obtaining the first initial value of the first irregular carrier and the second initial value of the second irregular carrier based on the phase shift angle and the reference voltage of each phase includes obtaining the first initial value and the second initial value according to the following formula: in, Use the first initial value; As the second initial value, Reference voltage; This is the phase shift angle.

7. The converter switching control method according to claim 1, characterized in that, The step of controlling the switching of each phase of the converter according to the carrier signal includes: The carrier signal is compared with the reference voltage of the current phase to obtain the pulse width modulation signal; The switching control of each phase of the converter is performed according to the pulse width modulation signal.

8. A controller, characterized in that, include: At least one processor; And, a memory communicatively connected to the at least one processor; The memory stores a computer program, which, when executed by the at least one processor, implements the converter switching control method for the multi-port flexible interconnect device according to any one of claims 1 to 7.

9. A computer-readable storage medium storing a plurality of program codes, characterized in that, The program code is adapted to be loaded and run by a processor to perform the converter switching control method for the multi-port flexible interconnect device according to any one of claims 1 to 7.

10. A multi-port flexible interconnect device, characterized in that, The device includes multiple alternating parallel converters and the controller as described in claim 8; the converters include three phases in alternating parallel connection; each phase includes two parallel full-bridge circuits, the midpoint of the bridge arm of each full-bridge circuit is connected to the first end of an auxiliary inductor, and the second ends of the auxiliary inductors of the two full-bridge circuits are connected to each other and then connected to the transformer substation; the first and second ends of the converters are respectively connected to the positive and negative terminals of the DC bus.

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