Inverter common-mode voltage suppression method, device, equipment, medium and product

Abstract

The invention relates to the technical field of inverter common-mode voltage suppression, in particular to an inverter common-mode voltage suppression method and device, equipment, a medium and a product, and the method comprises the steps: calculating a half-voltage fluctuation mean value of a current period based on an intermediate DC voltage and a half-intermediate DC voltage; if the half-voltage fluctuation mean value of the current period is greater than the half-voltage fluctuation mean value of the previous period, setting the phase shift angle of the current period according to the phase shift angle of the previous period; performing phase shifting on each inverter according to the phase shifting angle of the current period and the phase shifting direction of each inverter; therefore, offset cancellation of the common-mode voltage of the multiple inverters is realized, so that the adverse effect of the common-mode voltage is reduced.

Description

Technical Field

[0001] This invention relates to the field of inverter common-mode voltage suppression technology, and particularly to an inverter common-mode voltage suppression method, apparatus, equipment, medium, and product. Background Technology

[0002] With the increasing complexity of rail transit vehicle types and the diversification and intelligence of trackside auxiliary and signaling equipment, electromagnetic interference problems have become prominent. This is especially true when high-power new locomotives operate on older lines, where equipment upgrades are slow, leading to interference from vehicle-related electromagnetic signals on trackside equipment. For high-power traction locomotives, the inverters in their traction converters, operating in pulse width modulation (PWM) mode, exhibit zero-sequence components at the motor terminals, inevitably introducing common-mode voltage. A key technical challenge in this field is how to suppress the common-mode voltage in multi-inverter systems. Summary of the Invention

[0003] This invention provides a method, apparatus, device, medium, and product for suppressing common-mode voltage in inverters, solving the technical problem of how to suppress the common-mode voltage of multi-inverter systems.

[0004] In a first aspect, the present invention provides a common-mode voltage suppression method for inverters, the method comprising: calculating the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle, setting the phase shift angle of the current cycle according to the phase shift angle of the previous cycle; and performing phase shifting on each inverter according to the phase shift angle of the current cycle and the phase shift direction of each inverter.

[0005] In some embodiments, after calculating the average half-voltage fluctuation of the current cycle, the method further includes: if the average half-voltage fluctuation of the current cycle is greater than a preset fluctuation threshold, then performing the step of setting the phase shift angle of the current cycle based on the phase shift angle of the previous cycle if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle.

[0006] In some embodiments, the step of calculating the average half-voltage fluctuation of the current period based on the intermediate DC voltage and the half-intermediate DC voltage includes: halving the intermediate DC voltage to obtain a half-voltage reference value; subtracting the half-voltage reference value from the half-intermediate DC voltage to obtain a half-voltage deviation value; and averaging the half-voltage deviation values ​​of the current period to obtain the average half-voltage fluctuation of the current period.

[0007] In some embodiments, the average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period, including: the difference between the average half-voltage fluctuation of the current period and the average half-voltage fluctuation of the previous period is greater than a preset period threshold; or the average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period, and the average half-voltage fluctuation of the previous period is greater than the average half-voltage fluctuation of the period before that.

[0008] In some embodiments, setting the phase shift angle of the current cycle based on the phase shift angle of the previous cycle includes: if the phase shift angle of the previous cycle is not zero, then setting the phase shift angle of the current cycle to the opposite of the phase shift angle of the previous cycle; if the phase shift angle of the previous cycle is zero, then setting the phase shift angle of the current cycle to the phase shift angle of the cycle before that.

[0009] In some embodiments, determining the phase shift direction of each inverter includes: if the total number of inverters is even, then the phase shift directions of inverters with odd numbers are the same; if the total number of inverters is odd, then the phase shift directions of the first 2n inverters with odd numbers are the same, and the last inverter does not shift phase; wherein, the phase shift directions of inverters with even numbers are the same, and the phase shift directions of inverters with even numbers are opposite to the phase shift directions of inverters with odd numbers.

[0010] Secondly, the present invention provides an inverter common-mode voltage suppression device, comprising: an average value determination module, used to calculate the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; a phase shift angle setting module, used to set the phase shift angle of the current cycle according to the phase shift angle of the previous cycle if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle; and a phase shifting module, used to perform phase shifting on each inverter according to the phase shift angle of the current cycle and the phase shifting direction of each inverter.

[0011] Thirdly, the present invention provides a computer device, comprising: a memory and a processor, wherein the memory stores program instructions; when the program instructions are executed by the processor, the processor performs the method as described in any of the above aspects.

[0012] Fourthly, the present invention provides a computer-readable storage medium storing a computer program; when the computer program is run on one or more processors, it performs the method as described in any of the above aspects.

[0013] Fifthly, the present invention provides a computer program product comprising a computer program; wherein, when the computer program is run on a computer, the computer performs the method as described in any of the above aspects.

[0014] In a sixth aspect, the present invention provides a converter including a plurality of inverters and the computer device described above.

[0015] This invention provides a method, apparatus, device, medium, and product for common-mode voltage suppression in inverters. The method includes: calculating the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle, setting the phase shift angle of the current cycle according to the phase shift angle of the previous cycle; performing phase shifting on each inverter according to the phase shift angle of the current cycle and the phase shift direction of each inverter; achieving phase cancellation of common-mode voltage mismatches in multiple inverters, thereby reducing the adverse effects of common-mode voltage. Attached Figure Description

[0016] The invention will now be described in more detail with reference to embodiments and the accompanying drawings:

[0017] Figure 1 This is a schematic flowchart of an inverter common-mode voltage suppression method provided in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of a dynamic carrier phase-shift common-mode voltage suppression device provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of a dynamic carrier phase-shift common-mode voltage suppression control method provided in an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of master-slave control of a multi-inverter control device provided in an embodiment of this application;

[0021] Figure 5 This is a schematic diagram of a dynamic phase shift angle setting provided in an embodiment of this application.

[0022] In the accompanying drawings, the same parts are referred to by the same reference numerals, and the drawings are not drawn to scale. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention and to fully understand and implement the process of how the present invention uses technical means to solve technical problems and achieve corresponding technical effects, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The embodiments of the present invention and the various features therein can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0024] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0025] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0026] With the increasing complexity of rail transit vehicle types and the diversification and intelligence of trackside auxiliary and signaling equipment, electromagnetic interference problems have become prominent. This is especially true when high-power new locomotives operate on older lines, where equipment upgrades are slow, leading to interference from vehicle-related electromagnetic signals on trackside equipment. For high-power traction locomotives, the inverters in their traction converters, operating in pulse width modulation (PWM) mode, exhibit zero-sequence components at the motor terminals, inevitably introducing common-mode voltage. A key technical challenge in this field is how to suppress the common-mode voltage in multi-inverter systems.

[0027] The technical solution of this application will be described below with reference to specific embodiments.

[0028] Example 1

[0029] Figure 1 This is a flowchart illustrating a common-mode voltage suppression method for inverters provided in an embodiment of this application, as shown below. Figure 1 As shown, in the technical solution of this embodiment, a common-mode voltage suppression method for inverters is provided. The method includes: calculating the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle, then setting the phase shift angle of the current cycle according to the phase shift angle of the previous cycle; and performing phase shifting on each inverter according to the phase shift angle of the current cycle and the phase shift direction of each inverter.

[0030] This embodiment addresses the technical problem of suppressing common-mode voltage in multi-inverter systems. Common-mode voltage can have many negative impacts on vehicle equipment and trackside equipment, such as generating high-frequency common-mode leakage current that causes electromagnetic interference, and coupling shaft voltage on the motor shaft that affects the grounding protection judgment of the traction system. This embodiment collects the intermediate DC voltage and half-intermediate DC voltage, calculates the average half-voltage fluctuation, and if the current average is greater than the average of the previous cycle, sets the current phase shift angle according to the phase shift angle of the previous cycle. Finally, phase shifting is performed based on the phase shift angle and the phase shift direction of the inverter. For example, assuming that initially each inverter has no phase shift, as the system operates, the average half-voltage fluctuation increases. Adjustments are made according to the phase shift angle of the previous cycle to dynamically shift the carrier phase of each inverter, achieving phase cancellation of common-mode voltage errors in multi-inverter systems, thereby reducing the adverse effects of common-mode voltage.

[0031] Example 2

[0032] Based on the above embodiments, after calculating the average half-voltage fluctuation of the current cycle, the method further includes: if the average half-voltage fluctuation of the current cycle is greater than a preset fluctuation threshold, then perform the step of setting the phase shift angle of the current cycle according to the phase shift angle of the previous cycle if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle.

[0033] The technical problem to be solved is how to avoid frequent triggering of common-mode rejection (CMRS). There is a need in the art to perform CRS at appropriate times to avoid unnecessary operations. In this embodiment, after calculating the average half-voltage fluctuation of the current cycle, subsequent operations are only performed if the current average value is greater than a preset fluctuation threshold. For example, a fluctuation threshold is set to a certain value. When the half-voltage fluctuation is small, CRS is not triggered. Only when the fluctuation exceeds the threshold are operations such as setting the current phase shift angle based on the phase shift angle of the previous cycle performed. This reduces frequent system adjustments and improves stability. Suppose that during system operation, the half-voltage fluctuation occasionally shows small changes. Without this threshold judgment, CRS operations might be frequently triggered, affecting system efficiency. With this threshold, this situation can be avoided; the corresponding operation is only initiated when the fluctuation is large and CRS is truly needed.

[0034] Example 3

[0035] Based on the above embodiments, the step of calculating the average half-voltage fluctuation of the current period based on the intermediate DC voltage and the half-intermediate DC voltage includes: taking half of the intermediate DC voltage to obtain a half-voltage reference value; subtracting the half-voltage reference value from the half-intermediate DC voltage to obtain a half-voltage deviation value; and averaging the half-voltage deviation values ​​of the current period to obtain the average half-voltage fluctuation of the current period.

[0036] The technical problem addressed in this embodiment is how to calculate the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage. The average half-voltage fluctuation is a key input quantity for carrier phase shift control. This embodiment first takes half of the intermediate DC voltage to obtain a half-voltage reference value, then subtracts this from the half-intermediate DC voltage to obtain a half-voltage deviation value, and finally averages the deviation values ​​to obtain the average half-voltage fluctuation of the current cycle. For example, in a traction system, the intermediate DC voltage changes continuously; this method allows for accurate calculation of the average half-voltage fluctuation. By repeatedly collecting and calculating deviation values ​​within the current cycle and then averaging them to obtain the average half-voltage fluctuation, an accurate basis is provided for subsequent common-mode voltage suppression operations.

[0037] Example 4

[0038] Based on the above embodiments, the average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period, including: the difference between the average half-voltage fluctuation of the current period and the average half-voltage fluctuation of the previous period is greater than a preset period threshold; or the average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period, and the average half-voltage fluctuation of the previous period is greater than the average half-voltage fluctuation of the period before that.

[0039] The technical problem addressed in this embodiment is how to determine whether the average half-voltage fluctuation of the current cycle is greater than that of the previous cycle. Accurately determining the change in the average half-voltage fluctuation is crucial for common-mode voltage suppression. This embodiment uses two methods for determination: first, the difference between the current and previous cycle's average half-voltage fluctuation is greater than a preset cycle threshold; second, the current average is greater than the previous cycle's average, and the previous cycle's average is greater than the cycle before that. For example, setting the cycle threshold to 3V, if the current average half-voltage fluctuation is 11V and the previous cycle's average is 7V, the difference is greater than the threshold, therefore the current average is determined to be greater than the previous cycle. Alternatively, if the current average is 10V, the previous cycle's average is 8V, and the cycle before that is 7V, the current average is also determined to be greater than the previous cycle. This determination method ensures that common-mode voltage suppression is performed at the appropriate time, avoiding misjudgments and unnecessary adjustments, and improving the system's stability and reliability.

[0040] Example 5

[0041] Based on the above embodiments, the phase shift angle of the current cycle is set according to the phase shift angle of the previous cycle, including: if the phase shift angle of the previous cycle is not zero, then the phase shift angle of the current cycle is set to the opposite of the phase shift angle of the previous cycle; if the phase shift angle of the previous cycle is zero, then the phase shift angle of the current cycle is set to the phase shift angle of the cycle before that.

[0042] The technical problem addressed in this embodiment is how to set the phase shift angle of the current cycle based on the phase shift angle of the previous cycle. Dynamically adjusting the phase shift angle is crucial for achieving common-mode voltage suppression. In this embodiment, if the phase shift angle of the previous cycle is not zero, the current phase shift angle is set to the opposite of the phase shift angle of the previous cycle; if the phase shift angle of the previous cycle is zero, it is set to the phase shift angle of the cycle before that. For example, if the phase shift angle of the previous cycle is 30°, the current cycle is set to -30°. If the previous cycle is zero and the cycle before that is 45°, the current cycle is set to 45°. In this way, the phase shift angle can be dynamically adjusted according to the system's operating conditions, achieving effective suppression of common-mode voltage. In multi-inverter systems, this dynamic adjustment can make the carrier phase shift of each inverter more reasonable, better achieve phase cancellation of common-mode voltage, and reduce the adverse effects of common-mode voltage on the system.

[0043] Example 6

[0044] Based on the above embodiments, the phase shift direction of each inverter is determined, including: if the total number of inverters is even, then the phase shift direction of the inverters with odd numbers is the same; if the total number of inverters is odd, then the phase shift direction of the inverters with odd numbers in the first 2n inverters is the same, and the last inverter does not shift phase; wherein, the phase shift direction of the inverters with even numbers is the same, and the phase shift direction of the inverters with even numbers is opposite to the phase shift direction of the inverters with odd numbers.

[0045] This embodiment addresses the technical problem of determining the phase shift direction of each inverter. Clearly defining the phase shift direction is crucial for achieving common-mode voltage phase cancellation in multi-inverter systems. This embodiment determines the phase shift direction based on the parity of the total number of inverters. If the total number is even, inverters with odd-numbered serial numbers have the same phase shift direction; if the total number is odd, the first 2n inverters with odd-numbered serial numbers have the same phase shift direction, the last inverter does not shift phase, and the even-numbered inverters have the opposite phase shift direction to the odd-numbered ones. For example, with four inverters, inverters numbered 1 and 3 have the same phase shift direction, inverters numbered 2 and 4 have the same phase shift direction but opposite to the odd-numbered ones. With five inverters, inverters 1 and 3 have the same phase shift direction, inverters 2 and 4 have the same phase shift direction but opposite to the odd-numbered ones, and inverter 5 does not shift phase. This ensures that the multi-inverter system can effectively achieve common-mode voltage phase cancellation, improving the common-mode voltage suppression effect.

[0046] Example 7

[0047] Figure 2This is a schematic diagram of a dynamic carrier phase-shift common-mode voltage suppression device provided in an embodiment of this application. Based on the above embodiments, this embodiment provides a dynamic carrier phase-shift common-mode voltage suppression device, including: an average value determination module, used to calculate the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; a phase shift angle setting module, used to set the phase shift angle of the current cycle according to the phase shift angle of the previous cycle if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle; and a phase shift module, used to perform phase shifting on each inverter according to the phase shift angle of the current cycle and the phase shift direction of each inverter.

[0048] This embodiment addresses the technical problem of suppressing common-mode voltage in multi-inverter systems. Common-mode voltage can have many negative impacts on vehicle equipment and trackside equipment, such as generating high-frequency common-mode leakage current that causes electromagnetic interference, and coupling shaft voltage on the motor shaft that affects the grounding protection judgment of the traction system. This embodiment collects the intermediate DC voltage and half-intermediate DC voltage, calculates the average half-voltage fluctuation, and if the current average is greater than the average of the previous cycle, sets the current phase shift angle according to the phase shift angle of the previous cycle. Finally, phase shifting is performed based on the phase shift angle and the phase shift direction of the inverter. For example, assuming that initially each inverter has no phase shift, as the system operates, the average half-voltage fluctuation increases. Adjustments are made according to the phase shift angle of the previous cycle to dynamically shift the carrier phase of each inverter, achieving phase cancellation of the common-mode voltage of multiple inverters, thereby reducing the adverse effects of common-mode voltage. Other technical features of this embodiment correspond to those of the above embodiments and will not be repeated here.

[0049] In this embodiment, a computer device is also provided, including a memory and a processor. The memory stores program instructions; when the program instructions are executed by the processor, the processor performs the method as described in any of the above embodiments. The computer device is, for example, a device for controlling an inverter to perform dynamic carrier phase shift common-mode voltage suppression.

[0050] In the technical solution of this embodiment, a computer-readable storage medium is also provided, in which a computer program is stored; when the computer program is run on one or more processors, it performs the method as described in any of the above embodiments.

[0051] In the technical solution of this embodiment, a computer program product is also provided, which includes a computer program or instructions; when the computer program or instructions are run on a computer, the computer performs the method as described in any of the above embodiments.

[0052] In the technical solution of this embodiment, a converter is also provided, including multiple inverters and the aforementioned computer equipment.

[0053] Based on the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory. The processor executes the computer program to implement the steps of the method described in the above embodiments. In some embodiments of this embodiment, a computer-readable storage medium is provided, on which a computer program is stored. The computer program, when executed by a processor, implements the steps of the method described in the above embodiments. In some embodiments of this embodiment, a computer program product is provided, including a computer program / instructions. The computer program, when executed by a processor, implements the steps of the method described in the above embodiments. The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), a Digital Signal Processing Device (DSPD), a Programmable Logic Device (PLD), a Field Programmable Gate Array (FPGA), a controller, a microcontroller, a microprocessor, or other electronic components to execute the methods described in the above embodiments. Computer-readable storage media can be implemented from any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media can include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.). Computer-readable storage media can also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media includes, but is not limited to, volatile memory and / or non-volatile memory. Volatile memory can include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media can include, for example, read-only memory (ROM), hard disks, flash memory, etc. For example, a non-transitory computer-readable storage medium can be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed. In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).The processor can communicate with external devices via a wired or wireless network through an I / O bus. In one embodiment, the at least one computer-executable instruction can also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by the processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0054] Example 8

[0055] Based on the above embodiments, this embodiment provides an application example.

[0056] With the increasing complexity of rail transit vehicle types and the diversification and intelligence of trackside auxiliary and signaling equipment, electromagnetic interference problems have become prominent. This is especially true when high-power new locomotives operate on older lines, where equipment upgrades are slow, leading to interference from vehicle-related electromagnetic signals affecting trackside equipment. For high-power traction locomotives, the inverters in their traction converters, operating in pulse width modulation (PWM) mode, exhibit zero-sequence components at the motor terminals, inevitably introducing common-mode voltage. The field faces the technical challenge of suppressing common-mode voltage in multi-inverter systems, which negatively impacts both the overall vehicle equipment and trackside equipment.

[0057] On the one hand, the common-mode voltage generates high-frequency common-mode leakage current under the effect of parasitic coupling capacitance between the stator and the grounded chassis, causing electromagnetic interference. Electromagnetic interference is divided into radiated interference and conducted interference. It can interfere with the power supply side through the power line, and can also flow into the trackside signaling equipment through the rail, which can easily cause malfunctions of protection relays and signaling equipment.

[0058] On the other hand, high-frequency common-mode voltage acting on the motor will couple to generate shaft voltage on the motor shaft, affecting the grounding protection judgment of the traction system and easily causing protection malfunctions, thus affecting vehicle operation. In addition, if the motor has no grounding wire or poor grounding, it will cause electric shock accidents. Moreover, when the common-mode voltage is too high, it will threaten the motor insulation, causing it to age prematurely. The shaft current generated will also increase the wear of the motor and reduce the service life of the motor equipment.

[0059] Therefore, researching and developing technical solutions such as common-mode voltage suppression algorithms for traction systems to mitigate or eliminate the hazards caused by common-mode voltage can bring about multifaceted improvements in the product capabilities of rail transit vehicles. Firstly, it can improve vehicle reliability and utilization, avoiding issues such as track aging, axle current mechanical corrosion, and increasingly frequent false grounding faults caused by long-term common-mode voltage. Secondly, it helps improve driving safety and the vehicle's adaptability to various tracks, reducing common-mode voltage interference, preventing interference between vehicle electromagnetic signals and track signals and other trackside equipment, avoiding malfunctions, and enabling vehicles to meet the application requirements of older tracks and the stringent electromagnetic standards required by the market.

[0060] The purpose of this invention is to propose an adaptive common-mode voltage suppression control method and device based on the common intermediate DC bus main circuit of multiple traction converters. By real-time acquisition and calculation of the fluctuation information of the half-intermediate voltage of the intermediate DC circuit, the carrier of each inverter is dynamically phase-shifted to achieve phase cancellation of the common-mode voltage of multiple inverters. This can significantly reduce the inherent common-mode voltage interference of the converter caused by pulse width modulation control, greatly reduce the impact of common-mode voltage on rail vehicles and trackside equipment, improve vehicle performance, and ensure the reliability of vehicle operation and driving safety.

[0061] The flow principle of the common-mode voltage suppression control method and device based on carrier dynamic adaptive phase misalignment is shown in the figure below. Figure 3 Schematic block diagram of dynamic carrier phase-shift common-mode voltage suppression control method. Figure 4 This diagram illustrates the master-slave control of a multi-inverter control system. Each inverter is controlled by an independent controller, and the controllers can exchange data through internal or external communication. By customizing the default master-slave controller settings, the dynamic phase shift angle calculated and output by the master controller module is transmitted to other slave controllers, thereby achieving master-slave dynamic carrier phase shift control of the multi-inverter system and ultimately eliminating phase misalignment of the common-mode voltage.

[0062] The specific control of carrier dynamic phase shift is as follows.

[0063] The first step is to operate the traction converter, collect the intermediate DC voltage and half-intermediate DC voltage of the DC bus, and set a certain sampling calculation period according to the converter's operating switching frequency. The average fluctuation value of the half-intermediate DC voltage (half-voltage) within each sampling calculation period is calculated and used as the input quantity for the carrier phase shift control of each inverter. The common-mode voltage suppression mechanism is as follows: through the phase cancellation of the carriers of each inverter, the suppression effect can be directly reflected in the fluctuation degree of the half-intermediate DC voltage (half-intermediate voltage). The control effect of carrier phase shift corresponds to the fluctuation degree of the half-voltage. Therefore, accurate acquisition and processing of the half-voltage fluctuation value is the key to carrier phase shift control, providing a basis for judging the suppression of common-mode voltage.

[0064] The second step is to set a half-intermediate DC voltage fluctuation threshold (fluctuation threshold). Its initial value is set to 0, and it is dynamically adjusted according to the average value of the half-voltage fluctuation average value of multiple sampling calculation cycles, so that the threshold value (fluctuation threshold) gradually approaches the half-voltage fluctuation average value, which serves as a reference value for phase shift control.

[0065] The third step is to determine whether phase-shift control should be performed and to set the phase-shift angle value. This is based on the average half-voltage fluctuation and dynamic threshold value obtained in the first and second steps for each calculation cycle. The determination is made to determine whether phase-shift control is needed in the next cycle and to set the phase-shift angle. If the current average half-voltage fluctuation is greater than the average half-voltage fluctuation or threshold value of the previous cycle by a cycle threshold value x (where x is the set deviation value), phase-shift control is performed. Otherwise, the deviation value of the average half-voltage in the last three cycles is assessed. If the average value of the (n-1)th cycle is greater than that of the (n-2)th cycle, and the average value of the nth cycle is greater than that of the (n-1)th cycle, phase-shift control is performed; otherwise, it is not performed. The execution criteria can be adaptively adjusted according to the phase-shift precision. When the current average half-voltage fluctuation is much greater than the threshold value, rapid phase-shift control is performed, with the phase-shift angle set to kθ (k≥2). When the two are close, fine phase-shift control is performed, with the phase-shift angle set to θ. Subsequently, based on the direction and magnitude of the phase shift angle in the previous calculation cycle and the current calculation cycle, the direction and magnitude of the phase shift angle in the next calculation cycle are set, where the phase shift angle value is negative when shifting to the left and positive when shifting to the right.

[0066] The fourth step involves allocating the master-slave relationship of the inverters according to the main circuit structure, performing carrier phase shift control on each inverter, adjusting the carrier period of each inverter, matching the set phase shift angle, gradually realizing phase misalignment control, and dynamically adjusting in real time according to the magnitude of the average half-intermediate voltage fluctuation, thereby achieving dynamic phase misalignment suppression of the common-mode voltage.

[0067] The following sections will introduce each module step by step. It is worth noting that the following solution is only a preferred solution, and other solutions that utilize the technical concept of this application should also fall within the protection scope of this application.

[0068] Regarding the acquisition and processing of the average half-voltage fluctuation.

[0069] For the main circuit of the traction system, electrical energy is supplied to the voltage-source PWM inverter through the intermediate DC circuit. During the switching operation of the inverter, common-mode interference is generated, forming loop interference currents at the input and output terminals of the inverter. The impact of common-mode interference voltage can be directly reflected in the fluctuation of the half-intermediate DC voltage (also referred to as the half-voltage in this field). Therefore, the fluctuation component of the half-intermediate voltage is extracted as the input parameter for dynamic carrier phase-shift common-mode voltage suppression. The traction converter includes an intermediate DC voltage sensor and a half-intermediate voltage sensor to acquire the intermediate DC voltage and the half-intermediate DC voltage in real time. The intermediate DC voltage is low-pass filtered to obtain a stable voltage value, and half of it is taken as the reference value of the half-intermediate voltage.

[0070] To ensure stable extraction of the common-mode voltage, a time Ts longer than the inverter switching cycle is set as the calculation period Ts for the half-voltage fluctuation component. The instantaneous half-voltage value detected by the half-intermediate voltage sensor is compared with the reference voltage value of the half-intermediate voltage to obtain the absolute value of the half-intermediate voltage deviation. The average of the absolute values ​​of the deviation is then used to calculate the average half-voltage fluctuation within the current period. Simultaneously, the deviation of the average half-voltage fluctuation over the past three calculation periods is calculated as a parameter for the trend change of the half-voltage fluctuation.

[0071] Regarding the half-voltage fluctuation threshold reference setting.

[0072] To achieve dynamic suppression and control of common-mode voltage and adapt to locomotives and rolling stock with variable intermediate DC voltage systems, a half-voltage fluctuation threshold reference value is set as the benchmark threshold for dynamic phase-shift control. The initial value of the half-intermediate DC voltage fluctuation threshold (initial fluctuation threshold value) is set to 0, and the fluctuation threshold is dynamically adjusted based on the average value of the half-voltage fluctuation over the past three sampling calculation periods. When the deviation between the average value of the half-voltage fluctuation and the fluctuation threshold is large, the threshold (fluctuation threshold) is adjusted rapidly; when the deviation is small, the threshold is adjusted slowly, so that the threshold value gradually approaches and follows the current half-voltage fluctuation average value, and serves as the dynamic adjustment reference value for phase-shift control.

[0073] Regarding the setting of the dynamic phase shift angle.

[0074] Dynamic phase shift angle is crucial for carrier phase shift suppression common-mode voltage control. It determines the phase shift angle setting for the next calculation cycle based on the change in the average fluctuation of the half-voltage in the preceding and following calculation cycles, as well as the phase shift angle settings in the preceding and following cycles. The specific setting decision is as follows: Figure 5 As shown. If the average value of the current half-intermediate voltage fluctuation is greater than the average value of the half-intermediate voltage fluctuation in the previous calculation cycle and the difference exceeds the cycle threshold x (set according to the system situation), then further phase shift value selection judgment is performed. Otherwise, if the average value of the half-intermediate voltage fluctuation increases for two or more consecutive cycles, then further phase shift value selection judgment is performed. Otherwise, no phase shift control is required, and the phase shift angle is set to 0.

[0075] When phase shifting is required, if the current phase shift angle is θ (i.e., the phase shift angle determined in period N-1 is θ), then the phase shift angle for the next period (i.e., period N) is set to -θ; if the current phase shift angle is -θ, then the phase shift angle for the next period is set to θ; otherwise, if the current phase shift angle is 0, then it is necessary to determine the phase shift angle based on the previous period (i.e., period N-2). If the phase shift angle of the previous calculation period is θ, then the phase shift angle for the next period is set to θ; otherwise, the phase shift angle is set to -θ. Here, θ is an angle value greater than zero.

[0076] Regarding carrier phase shift master-slave allocation execution.

[0077] Considering two cases where the number of converters sharing a common intermediate DC bus is 2n and 2n+1 (n = 1, 3, 5, ...), with both odd and even numbers, the first converter (1) is considered the master control converter and the other converters are slave control converters. When the number of converters is even (2n), based on the phase shift angle calculated by the master control converter, the n converters numbered 1, 3, ..., 2n-1 (odd numbers) on the common bus are shifted by a phase shift angle θ in the same direction, while the remaining n even-numbered converters are shifted by a phase shift angle θ in the opposite direction. When the number of converters is odd (2n+1), based on the phase shift angle calculated by the master control converter, the n converters numbered 1, 3, ..., 2n-1 (odd numbers) on the common bus are shifted by a phase shift angle θ in the same direction, while the n even-numbered converters numbered 2, 4, ..., 2n are shifted by a phase shift angle θ in the opposite direction. The (2n+1)th converter serves as a reference converter and does not undergo phase shifting. Furthermore, if the first converter 1 fails, the second converter 2 will be set as the main control converter in sequence. Other converter failures will be handled in a similar manner. At the same time, the phase shift control principle will be adjusted accordingly based on the number of converters operating normally on the bus, according to the odd and even conditions.

[0078] For traction converters in rail vehicles, the main inverter configuration with a common DC bus in the main circuit is typically a two-inverter parallel or a three-inverter parallel architecture. Phase-shift control uses the average half-intermediate voltage fluctuation as the step size, and performs a carrier phase shift once within this time period according to the controller cycle to ensure stable phase-shift control. When the main circuit structure is a two-inverter DC bus main circuit, the first inverter 1 is set as the master inverter and the second inverter 2 as the slave inverter. According to the phase misalignment requirement, only the master inverter 1 needs to be phase-shifted. When the main circuit structure is a three-inverter DC bus main circuit, the inverter 1 is set as the master, the inverter 2 as the slave, and the inverter 3 as the reference. According to the phase misalignment requirement, the phase shifting control of the inverter 1 and the inverter 2 is performed, and the phase shifting directions of the two inverters are opposite. The phase shifting angle is calculated by the controller of the inverter 1 and transmitted to the controller of the inverter 2 through the existing data communication network. Simultaneous phase shifting control is achieved within the half-voltage fluctuation average calculation period, thereby realizing dynamic phase misalignment adjustment between different inverters, and thus achieving the purpose of common-mode voltage phase misalignment cancellation.

[0079] The innovation of this invention lies in:

[0080] 1) A common-mode voltage regulation evaluation mechanism based on a dynamic threshold constructed from a semi-intermediate voltage is proposed.

[0081] To address the issue of lacking a controllable reference value for common-mode voltage suppression control, this application proposes a dynamic parameter adjustment threshold scheme for common-mode voltage suppression control based on the intermediate DC voltage and half-intermediate DC voltage collected by the system. This scheme utilizes the fluctuation component of the half-intermediate DC voltage to construct the threshold value. The threshold value can be adaptively adjusted according to the current common-mode voltage state of the system, so that the common-mode voltage suppression control of the system tends to the optimal value.

[0082] 2) A common-mode voltage suppression method based on carrier phase shifting was constructed.

[0083] To address the serious impact of common-mode voltage when multiple inverters operate on a common DC bus, this application's technical solution creatively proposes a common-mode voltage suppression strategy based on dynamic phase shifting of the carrier of each inverter. This strategy adjusts the magnitude and direction of the phase shift angle of the carrier of each inverter in real time based on the change of the average value of the current half-intermediate voltage fluctuation and the constructed dynamic threshold, thereby achieving phase cancellation of common-mode voltage among multiple inverters, significantly reducing the effective value of the common-mode voltage, and reducing the impact of common-mode voltage on the system.

[0084] 3) A highly adaptable multi-inverter common-mode voltage suppression system solution

[0085] Without adding hardware, it can be applied to two-inverter, three-inverter, and multi-inverter DC bus operating systems based on existing systems, and can be extended to traction and auxiliary inverter systems. At the same time, combined with master-slave settings, it provides high redundancy in the event of partial inverter failures, and can achieve good overall control and suppression of common-mode voltage in multi-inverter systems.

[0086] Compared with other technologies, the present invention has the following beneficial effects:

[0087] ① No additional hardware equipment is required. The technical solution of this application can reduce the effective value of the common mode voltage of a multi-inverter common intermediate DC bus system by more than 70%, thereby significantly reducing the common mode voltage. This can greatly reduce the adverse effects of common mode voltage on vehicle insulation aging and axle corrosion, and at the same time avoid false grounding faults.

[0088] ② It can significantly reduce the amplitude of common-mode voltage, achieving the same suppression effect as the common-mode voltage filter capacitor of the vehicle equipment. It can realize the replacement of hardware equipment by software control scheme, which is conducive to cost reduction of converter equipment.

[0089] ③ Significantly reduces the impact of electromagnetic noise and track interference current caused by common-mode voltage, avoiding malfunctions of trackside and signaling equipment, improving the technical specifications and competitiveness of converter products, and enhancing the universality of vehicles on application lines, vehicle reliability and driving safety, as well as the market expansion capabilities of converter products. The impact and promotion value are significant.

[0090] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0091] It should be noted that, in this invention, 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 limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0092] While the embodiments disclosed in this invention are as described above, the above content is merely for the purpose of facilitating understanding of this invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope disclosed in this invention; however, the scope of patent protection of this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A common-mode voltage suppression method for an inverter, characterized in that, The method includes: Calculate the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage; If the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle, then the phase shift angle of the current cycle is set according to the phase shift angle of the previous cycle. Based on the phase shift angle of the current cycle and the phase shift direction of each inverter, phase shift is performed on each inverter.

2. The inverter common-mode voltage suppression method according to claim 1, characterized in that, After the step of calculating the average half-voltage fluctuation of the current period, the method further includes: If the average half-voltage fluctuation of the current cycle is greater than the preset fluctuation threshold, then the step of setting the phase shift angle of the current cycle according to the phase shift angle of the previous cycle is executed if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle.

3. The inverter common-mode voltage suppression method according to claim 1, characterized in that, The step of calculating the average half-voltage fluctuation of the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage includes: The intermediate DC voltage is halved to obtain a half-voltage reference value; The half-voltage reference value is subtracted from the half-intermediate DC voltage to obtain the half-voltage deviation value; The average half-voltage deviation value of the current cycle is averaged to obtain the average half-voltage fluctuation value of the current cycle.

4. The inverter common-mode voltage suppression method according to claim 1, characterized in that, The fact that the average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period includes: The difference between the average half-voltage fluctuation of the current period and the average half-voltage fluctuation of the previous period is greater than the preset period threshold; or The average half-voltage fluctuation of the current period is greater than the average half-voltage fluctuation of the previous period, and the average half-voltage fluctuation of the previous period is greater than the average half-voltage fluctuation of the period before that.

5. The inverter common-mode voltage suppression method according to claim 1 or 4, characterized in that, The step of setting the phase shift angle of the current cycle based on the phase shift angle of the previous cycle includes: If the phase shift angle of the previous cycle is not zero, then the phase shift angle of the current cycle is set to the opposite of the phase shift angle of the previous cycle. If the phase shift angle of the previous cycle is zero, then the phase shift angle of the current cycle is set as the phase shift angle of the cycle before that.

6. The inverter common-mode voltage suppression method according to claim 1, characterized in that, Determining the phase shift direction of each inverter includes: If the total number of inverters is even, then the inverters with odd serial numbers have the same phase shift direction; If the total number of inverters is odd, then the inverters with odd serial numbers in the first 2n inverters have the same phase shift direction, and the last inverter does not shift phase. Among them, the inverters with even serial numbers have the same phase shift direction, and the phase shift direction of the inverters with even serial numbers is opposite to that of the inverters with odd serial numbers.

7. An inverter common-mode voltage suppression device, characterized in that, The device includes: The mean value determination module is used to calculate the mean of half-voltage fluctuation in the current cycle based on the intermediate DC voltage and the half-intermediate DC voltage. The phase shift angle setting module is used to set the phase shift angle of the current cycle based on the phase shift angle of the previous cycle if the average half-voltage fluctuation of the current cycle is greater than the average half-voltage fluctuation of the previous cycle. The phase-shifting module is used to shift the phase of each inverter according to the phase-shifting angle of the current cycle and the phase-shifting direction of each inverter.

8. A computer device, characterized in that, include: A memory and a processor, wherein the memory stores program instructions; when the program instructions are executed by the processor, the processor performs the inverter common-mode voltage suppression method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program; when the computer program is run on one or more processors, it performs the inverter common-mode voltage suppression method as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, The computer program product includes a computer program; when the computer program is run on a computer, it causes the computer to perform the inverter common-mode voltage suppression method as described in any one of claims 1 to 6.

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