A filter and its parameter design method

Abstract

The present invention provides a filter, a SiC traction converter using the filter, and a parameter design method and device thereof. The filter comprises: a common-mode filter circuit for reducing common-mode interference current and common-mode voltage at the load end of the filter, the input end of the common-mode filter circuit being the input end of the filter; and a differential-mode filter circuit for reducing the voltage change rate and peak voltage amplitude at the load end of the filter, the input end of the differential-mode filter circuit being connected to the output end of the common-mode filter circuit, the output end of the differential-mode filter circuit being the output end of the filter, and the output end of the filter being connected to the load through a connecting line.

Description

Technical Field

[0001] The invention relates to a variable frequency drive system, and in particular to a filter and a parameter design method thereof. Background Art

[0002] With the market application of high-power SiC power devices, the rail transit traction drive system with SiC as the core has been significantly improved in power density and system efficiency, and will definitely become a future development trend.

[0003] Compared with traditional Si-based IGBT converters, the switching frequency and switching speed of SiC converters are significantly improved. On the one hand, the higher switching frequency and voltage change rate will cause strong electromagnetic interference in the traction drive system, and on the other hand, it will cause a large voltage change rate (du / dt) and overvoltage at the traction motor end, which will bring great challenges to the insulation condition of the traction motor and make the bearing voltage of the traction motor too high, bringing serious risk of bearing electrical corrosion.

[0004] For example, when using traditional Si-based IGBTs, since the power cable connecting the inverter module and the traction motor in the rail transit traction drive system is short, a large overvoltage will not be generated at the traction motor end. Correspondingly, after using SiC power devices, since the switching speed of SiC power devices is much greater than the switching speed of Si-based power devices, a large overvoltage will be generated on the shorter power cable. For example, when the switching time of the SiC power device is less than 150ns, as long as the length of the power cable reaches 15m, a peak voltage close to twice the DC voltage on the DC side of the converter will be generated at the traction motor end.

[0005] In order to solve the problem of excessive voltage change rate and peak voltage of a traction converter using SiC power devices, the present invention aims to propose a circuit structure of a filter, a SiC traction converter suitable for the filter, and a parameter design method for the filter and the SiC traction converter. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or critical elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0007] According to one aspect of the present invention, there is provided a filter applicable to a variable frequency drive system, the filter comprising: a common-mode filter circuit for reducing common-mode interference current and common-mode voltage at a load end of the filter, the input end of the common-mode filter circuit being the input end of the filter; and a differential-mode filter circuit for reducing the voltage change rate and peak voltage amplitude at the load end of the filter, the input end of the differential-mode filter circuit being connected to the output end of the common-mode filter circuit, the output end of the differential-mode filter circuit being the output end of the filter, and the output end of the filter being connected to a load via a connecting line.

[0008] Furthermore, the common-mode filter circuit includes: a three-phase common-mode inductor, wherein two ends of the three-phase common-mode inductor are respectively the input end and the output end of the common-mode filter circuit; and the differential-mode filter circuit includes: a three-phase differential-mode inductor, wherein two ends of the three-phase differential-mode inductor are respectively the input end and the output end of the differential-mode filter circuit; and a three-phase RC absorption circuit, wherein one end of the three-phase RC absorption circuit is respectively connected to the three-phase output end of the differential-mode filter circuit, and the other end of the three-phase RC absorption circuit is connected in parallel to form a neutral point, and the neutral point is suspended.

[0009] Furthermore, each RC absorption circuit in the three-phase RC absorption circuit includes: a capacitor and a resistor, one end of the capacitor and one end of the resistor are connected in series, the other end of the capacitor is connected to the output end of the corresponding phase of the differential mode filter circuit, and the other end of the resistor is connected to the neutral point.

[0010] Furthermore, the differential mode filter circuit is a three-phase completely symmetrical circuit.

[0011] According to another aspect of the present invention, a parameter design method for a filter is provided, characterized in that the filter comprises: a common-mode filter circuit and a differential-mode filter circuit, the input end of the common-mode filter circuit is the input end of the filter, the input end of the differential-mode filter circuit is connected to the output end of the common-mode filter circuit, and the output end of the differential-mode filter circuit is the output end of the filter, and the parameter design method comprises: calculating the parameters of the common-mode filter circuit and the differential-mode filter circuit based on basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied.

[0012] Furthermore, the common-mode filter circuit includes a three-phase common-mode inductor, and the parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, including: Where, 10kHz≤f≤10MHz, Z cminis the minimum common-mode impedance of the variable frequency drive system; and the saturation current I of the three-phase common-mode inductor Lcm ≥ 1% I base , where I base is the three-phase working current of the load of the variable frequency drive system.

[0013] Furthermore, the differential mode filter circuit includes a three-phase differential mode inductor and a three-phase RC absorption circuit, each RC absorption circuit includes a capacitor and a resistor, and the parameters of the common mode filter circuit and the differential mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, including: the three-phase differential mode inductor Among them, U base is the rated input voltage of the filter input, P base is the rated input power of the filter input, f i is the frequency of the rated input current at the input end of the filter; and the capacitance of the RC absorption circuit Among them, P base is the rated input power of the filter input, f sw is the switching frequency of the variable frequency drive system, V dc is the DC input voltage of the variable frequency drive system.

[0014] Furthermore, the parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, including: based on the requirements of the variable frequency drive system for voltage change rate and maximum overvoltage, the three-phase differential-mode inductance, the capacitance and resistance of the RC absorption circuit are further determined, wherein the voltage change rate The maximum overvoltage V peak =(3l C K / vT r +1)V dc , T r is the required pulse rise time, l C is the length of the connection line, K is the voltage reflection coefficient of the load, v is the transmission speed of the wave in the connection line, L C is the inductance per unit length of the connecting line, C C is the capacitance per unit length of the connecting line, Z L is the impedance of the load, Z0 is the characteristic impedance of the connecting line, R f is the resistance of the RC absorption circuit.

[0015] According to one aspect of the present invention, a SiC traction converter is provided, comprising: an inverter module, wherein the inverter module adopts SiC power devices; and a filter module, wherein an input end of the filter module is connected to an output end of the inverter module, and an output end of the filter module is connected to a traction motor via a power cable, and the filter module comprises a common-mode filter circuit and a differential-mode filter circuit.

[0016] In one embodiment, the inverter module is a three-phase inverter module, and the common-mode filter circuit includes: a three-phase common-mode inductor, which is used to reduce the common-mode interference current and the common-mode voltage at the traction motor end, and one end of the three-phase common-mode inductor is the input end of the filter module; and the differential-mode filter circuit includes: a three-phase differential-mode inductor, which is used to reduce the voltage change rate at the output end of the filter module, and one end of the three-phase differential-mode inductor is respectively connected to the other end of the three-phase common-mode inductor, and the other end of the three-phase differential-mode inductor is the output end of the filter module; and a three-phase RC absorption circuit, which is used to reduce the peak voltage amplitude at the output end of the filter module, and one end of the three-phase RC absorption circuit is respectively connected to the other end of the three-phase differential-mode inductor, and the other end of the three-phase RC absorption circuit is connected in parallel to form a neutral point, and the neutral point is suspended.

[0017] Furthermore, the three-phase common-mode inductance ranges from 50uH to 300uH, and the saturation current of the three-phase common-mode inductance is greater than 5A.

[0018] Furthermore, each RC absorption circuit in the three-phase RC absorption circuit includes: a capacitor and a resistor, one end of the capacitor and one end of the resistor are connected in series, the other end of the capacitor is connected to the other end of a corresponding phase differential mode inductor, and the other end of the resistor is connected to the neutral point.

[0019] Furthermore, the three-phase differential mode inductance ranges from 10uH to 100uH, the capacitance of each RC absorption circuit ranges from 20nF to 470nF, and the resistance of each RC absorption circuit ranges from 10Ω to 100Ω.

[0020] Furthermore, the differential mode filter circuit is a three-phase completely symmetrical circuit.

[0021] According to another aspect of the present invention, a parameter design method for a SiC traction inverter is also provided. The SiC traction inverter includes an inverter module and a filter module. The inverter module adopts a SiC power device. The input end of the filter module is connected to the output end of the inverter module. The output end of the filter module is connected to the traction motor through a power cable. The filter module includes a common-mode filter circuit and a differential-mode filter circuit. The corresponding parameter design method includes: calculating the parameters of the common-mode filter circuit and the differential-mode filter circuit based on the basic electrical parameters, impedance characteristics and insulation requirements of the traction motor of the traction drive system applied to the SiC traction inverter.

[0022] Furthermore, the common-mode filter circuit includes a three-phase common-mode inductor. Correspondingly, the parameters of the common-mode filter circuit and the differential-mode filter circuit calculated based on the basic electrical parameters of the application system of the SiC traction converter, the impedance characteristics and the insulation requirements of the traction motor include: Where, 10kHz≤f≤10MHz, Z cmin is the minimum common-mode impedance of the traction drive system; and the saturation current I of the three-phase common-mode inductor Lcm ≥ 1% I base , where I base is the three-phase working current of the traction motor.

[0023] Furthermore, the three-phase common-mode inductance range determined by the parameter design method is 50uH to 300uH, and the saturation current of the three-phase common-mode inductance is greater than 5A.

[0024] Furthermore, the differential mode filter circuit includes a three-phase differential mode inductor and a three-phase RC absorption circuit, each RC absorption circuit includes a capacitor and a resistor. Correspondingly, the parameters of the common mode filter circuit and the differential mode filter circuit calculated based on the basic electrical parameters of the application system of the SiC traction converter, the impedance characteristics and the insulation requirements of the traction motor include: the three-phase differential mode inductor Among them, U base is the rated output voltage of the inverter module, P base is the rated output power of the inverter module, f i The frequency of the rated output current of the inverter module; and the capacitance of the RC absorption circuit Among them, P base is the rated output power of the inverter module, f sw is the switching frequency of the inverter module, V dc is the DC input voltage of the inverter module.

[0025] Furthermore, the parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters of the application system of the SiC traction converter, the impedance characteristics and the insulation requirements of the traction motor, and further include: based on the requirements of the traction motor for the voltage change rate and the maximum overvoltage, the three-phase differential-mode inductance, the capacitance and the resistance of the RC absorption circuit are further determined, wherein the voltage change rate The maximum overvoltage V peak =(3l C K / vT r +1)V dc , T r is the required pulse rise time, l C is the length of the power cable, K is the voltage reflection coefficient of the traction motor, v is the transmission speed of the wave in the power cable, L C is the inductance of the power cable per unit length, C C is the capacitance of the power cable per unit length, Z L is the impedance of the traction motor, Z0 is the characteristic impedance of the power cable, R f is the resistance of the RC absorption circuit.

[0026] Furthermore, the parameters of the common-mode filter circuit and the differential-mode filter circuit calculated based on the basic electrical parameters of the application system of the SiC traction inverter, the impedance characteristics and the insulation requirements of the traction motor also include: the voltage change rate is 1kV / us~3kV / us, the maximum overvoltage is less than 1.5 times the DC input voltage of the inverter module, and the voltage reflection coefficient is 0.8~0.9.

[0027] Furthermore, the three-phase differential mode inductance determined by the parameter design method ranges from 10uH to 100uH, the capacitance of each RC absorption circuit ranges from 20nF to 470nF, and the resistance of each RC absorption circuit ranges from 10Ω to 100Ω.

[0028] According to another aspect of the present invention, there is also provided a parameter design device for a SiC traction converter, comprising a memory, a processor, and a computer program stored on the memory, wherein the processor is used to implement the steps of the parameter design method for the SiC traction converter as described above when executing the computer program stored on the memory.

[0029] According to yet another aspect of the present invention, there is further provided a computer storage medium having a computer program stored thereon, wherein when the computer program is executed, the steps of the parameter design method for the SiC traction converter as described above are implemented.

[0030] The present invention adopts a filter circuit topology structure combining a common-mode filter circuit and a differential-mode filter circuit in the filter, thereby reducing the common-mode interference current and the common-mode voltage at the load end, while reducing the voltage change rate at the output end of the filter and the peak voltage amplitude at the output end of the filter circuit. The circuit topology structure of the filter is simple, which fully limits the volume, weight and loss of the filter, thereby reducing the influence of the filter circuit on the overall efficiency of the variable frequency drive system.

[0031] Furthermore, the present invention also accurately designs the specific parameters of the filter circuit of the SiC traction converter based on the basic electrical parameters, impedance characteristics and insulation requirements of the load of the variable frequency drive system used in the SiC traction converter, which can limit the filter parameters to a smaller range and facilitate the actual material selection. At the same time, the parameter design method comprehensively considers the filter volume, weight and loss indicators, effectively reducing the impact of the filter circuit on the system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above features and advantages of the present invention will be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings.

[0033] Figure 1 is a module block diagram of a filter in an embodiment according to one aspect of the present invention;

[0034] Figure 2 is a schematic diagram of a topological structure of a filter in an embodiment according to one aspect of the present invention;

[0035] Figure 3 is a module block diagram of a filter parameter design device in an embodiment according to another aspect of the present invention;

[0036] Figure 4 is a module block diagram of a SiC traction converter in an embodiment according to yet another aspect of the present invention;

[0037] Figure 5 is a schematic diagram of a topological structure of a filter module of a SiC traction converter in an embodiment according to one aspect of the present invention;

[0038] Figure 6 is a schematic diagram of a topological structure of a SiC traction converter in an embodiment according to one aspect of the present invention;

[0039] Figure 7 FIG. 4 is a block diagram of a parameter design device for a SiC traction converter in an embodiment according to another aspect of the present invention. DETAILED DESCRIPTION

[0040] The following description is given to enable those skilled in the art to implement and use the invention and incorporate it into a specific application context. Various modifications, as well as various uses in different applications will be readily apparent to those skilled in the art, and the general principles defined herein are applicable to a wide range of embodiments. Thus, the present invention is not limited to the embodiments given herein, but should be granted the broadest scope consistent with the principles and novel features disclosed herein.

[0041] In the following detailed description, many specific details are set forth to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the practice of the present invention need not be limited to these specific details. In other words, known structures and devices are shown in block diagram form without detailed display to avoid obscuring the present invention.

[0042] The reader is reminded of all documents and literature filed simultaneously with this specification and open to public inspection, and the contents of all such documents and literature are incorporated herein by reference. Unless otherwise directly stated, all features disclosed in this specification (including any attached claims, abstracts and drawings) can be replaced by alternative features for achieving the same, equivalent or similar purposes. Therefore, unless otherwise explicitly stated, each feature disclosed is only an example of a group of equivalent or similar features.

[0043] Note that, where used, the symbols left, right, front, back, top, bottom, forward, reverse, clockwise and counterclockwise are used only for convenience and do not imply any specific fixed direction. In fact, they are used to reflect the relative position and / or direction between the various parts of the object. In addition, the terms "first" and "second" are used only for descriptive purposes and should not be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Note that, in the case of use, further, preferably, further and more preferably are simple beginnings for explaining another embodiment based on the previous embodiment, and the content of further, preferably, further or more preferably followed by the above embodiment is combined with the previous embodiment as a complete composition of another embodiment. Several further, preferably, further or more preferably settings followed by the same embodiment can be arbitrarily combined to form another embodiment.

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. Note that the aspects described below in conjunction with the accompanying drawings and specific embodiments are only exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0047] According to one aspect of the present invention, a filter suitable for a variable frequency drive system is provided.

[0048] In one embodiment, if Figure 1 As shown, the filter 100 includes a common mode filter circuit 110 and a differential mode filter circuit 120. The output end of the filter 100 is connected to a load through a connecting line.

[0049] The input end of the common mode filter circuit 110 is used as the input end of the filter 100, and the output end of the common mode filter circuit 110 is connected to the input end of the differential mode filter circuit 120. The common mode filter circuit 110 is used to reduce the common mode interference current and the common mode voltage at the load end of the variable frequency drive system to which the filter is applied.

[0050] The input end of the differential mode filter circuit 120 is connected to the output end of the common mode filter circuit 110, and the output end of the differential mode filter circuit 120 serves as the output end of the filter 100. The differential mode filter circuit 120 is used to reduce the voltage change rate and peak voltage amplitude at the load end.

[0051] Correspondingly, according to another aspect of the present invention, a filter parameter design method is also provided, which is used to implement the design of the device parameters of the filter 110. Therefore, the corresponding parameter design method is comprehensively described in combination with the specific circuit structure of the filter.

[0052] Specifically, the parameter design method of the filter 110 can calculate the parameters of the common mode filter circuit and the differential mode filter circuit based on the basic electrical parameters, impedance characteristics and insulation requirements of the load of the variable frequency drive system to which the filter 110 is applied.

[0053] Furthermore, if Figure 2 As shown, the common-mode filter circuit 110 of the SiC traction converter includes a three-phase common-mode inductor L m , the three-phase common mode inductor L mOne end of is the input end of the common mode filter circuit 110 , and the other end of is the output end of the common mode filter circuit 110 , which is connected to the input end of the differential mode filter circuit 120 .

[0054] Correspondingly, the three-phase common mode inductance L m The parameter design steps may include limiting the impedance and saturation current of the three-phase common-mode inductor.

[0055] Specifically, the three-phase common mode inductance L m The impedance should be greater than the minimum common mode impedance Z in the frequency range of 10kHz to 10MHz cmin More than 10 times the three-phase common mode inductance L m Satisfying formula (1):

[0056]

[0057] Where, 10kHz≤f≤10MHz, Z cmin is the minimum common mode impedance of the variable frequency drive system to which the filter 110 is applied.

[0058] Three-phase common mode inductor L m The saturation current should be greater than the three-phase working current I of the load of the variable frequency drive system to which the filter 110 is applied. base 1%, that is, the three-phase common mode inductance L m The saturation current satisfies formula (2):

[0059] I Lcm ≥ 1% I base (2)

[0060] Among them, I Lcm is the three-phase common mode inductance L m The saturation current, I base It is the three-phase working current of the load of the variable frequency drive system.

[0061] Furthermore, if Figure 2 As shown, the differential mode filter circuit 120 of the filter 100 may include a three-phase differential mode inductor L f And three-phase RC absorption circuit.

[0062] Among them, the three-phase differential mode inductance L f The two ends of are respectively the input end and the output end of the differential mode filter circuit 120. The three-phase differential mode inductor can reduce the voltage change rate of the output end of the filter 100.

[0063] One end of the three-phase RC absorption circuit is connected to the three-phase differential mode inductor L fThe output end of the filter 100 is connected, and the other end of the three-phase RC absorption circuit is connected in parallel to form a neutral point N, which is suspended. The three-phase RC absorption circuit can reduce the peak voltage amplitude of the output end of the filter 110.

[0064] More specifically, each RC absorption circuit includes a capacitor C f and a resistor R f , capacitor C f and resistor R f A phase difference mode inductor L connected in series with the RC absorption circuit f and the neutral point N.

[0065] Preferably, the differential mode filter circuit 120 adopts a three-phase completely symmetrical circuit, that is, the differential mode inductance L of each phase is f , capacitor C f and resistor R f Respectively the same.

[0066] Correspondingly, the parameter design of the differential mode filter circuit 120 may include the differential mode inductance L of each phase. f , capacitor C f and resistor R f Parameter restrictions.

[0067] It can be understood by those skilled in the art that the filter needs to reduce the volume, weight and loss of the filter module as much as possible, so as to improve the working efficiency of the variable frequency drive system to which the filter is applied. In order to improve the working efficiency of the variable frequency drive system, it is necessary to adjust the differential mode inductance L in the differential mode filter circuit 120. f and capacitor C f Make restrictions.

[0068] Specifically, the differential mode inductor impedance in each phase differential mode filter circuit should be less than 5% of the load impedance, that is, the differential mode inductor L f Satisfying formula (3):

[0069]

[0070] Among them, U base is the rated input voltage at the input of the filter 100, P base is the rated input power at the input of the filter 100, f i is the frequency of the rated input current at the input end of the filter 100 .

[0071] Specifically, the resistor R in the RC absorption circuit in each phase difference mode filter circuit f The loss and capacitance C f The loss of the filter 100 should be less than 0.5% of the rated input power at its input end. fSatisfying formula (4):

[0072]

[0073] Among them, P base is the rated input power at the input of the filter 100, f sw is the switching frequency of the variable frequency drive system to which the filter 100 is applied, V dc is the DC input voltage of the variable frequency drive system to which the filter 100 is applied.

[0074] The three-phase differential mode inductance L in the differential mode filter circuit can be calculated by equations (3) and (4). f and capacitor C f Constraints can be made, and combined with the load's requirements for voltage change rate and maximum overvoltage, the three-phase differential mode inductance L can be further confirmed. f , the capacitor C of the RC absorption circuit f and resistor R f .

[0075] Among them, the voltage change rate du / dt of the load of the variable frequency drive system satisfies formula (5):

[0076]

[0077] Maximum overvoltage V of the load of the variable frequency drive system peak Satisfying formula (6):

[0078] V peak =(3l C K / vT r +1)V dc (6)

[0079] The resistance R of the RC absorption circuit f Satisfying formula (7):

[0080]

[0081] in, T r is the pulse rise time required by the load, l C is the length of the connection line between the filter and the load, K is the voltage reflection coefficient of the load, v is the transmission speed of the wave in the connection line, L C is the inductance per unit length of the connecting line, C C is the capacitance per unit length of the connecting line, Z L is the impedance of the load, and Z0 is the characteristic impedance of the connection line. The connection line can be a power cable or a copper busbar.

[0082] According to another aspect of the present invention, a filter parameter design device is also provided. Figure 3 As shown, it includes a memory 310 and a processor 320 .

[0083] The memory 310 is used to store computer programs.

[0084] The processor 320 is connected to the memory 310 and is used to execute the computer program in the memory 310. When the computer program is executed, the steps of the parameter design method of the filter 100 are implemented.

[0085] According to yet another aspect of the present invention, there is further provided a computer storage medium on which a computer program is stored. When the computer program is executed, the steps of the parameter design method of the filter 100 described above are implemented.

[0086] According to yet another aspect of the present invention, a SiC traction converter is provided, which is applicable to a traction drive system of a rail transit system.

[0087] In one embodiment, if Figure 4 As shown, the SiC traction converter 400 includes an inverter module 410 and a filter module 420 .

[0088] The input terminal of the inverter module 410 is a DC input voltage V dc The output end of the inverter module 410 outputs a three-phase voltage for powering the traction motor.

[0089] The input end of the filter module 420 is connected to the output end of the inverter module 410, and the output end of the filter module 420 is connected to the traction motor through a power cable. The filter module 420 includes a common mode filter circuit 421 and a differential mode filter circuit 422. Among them, the common mode filter circuit 421 is used to reduce the common mode interference current and the common mode voltage at the traction motor end; the differential mode filter circuit 422 is used to reduce the voltage change rate and peak voltage amplitude at the traction motor end.

[0090] Correspondingly, according to another aspect of the present invention, a parameter design method for a SiC traction converter is also provided, which is used to implement the design of device parameters in the filter module in the above-mentioned SiC traction converter. Therefore, the corresponding parameter design method is comprehensively described in combination with the specific circuit structure of the SiC traction converter.

[0091] Specifically, the parameter design method can calculate the parameters of the common-mode filter circuit and the differential-mode filter circuit based on the basic electrical parameters, impedance characteristics and insulation requirements of the traction drive system applied to the SiC traction converter.

[0092] Furthermore, if Figure 5 As shown, the common-mode filter circuit 421 of the SiC traction converter includes a three-phase common-mode inductor L m , the three-phase common mode inductor L mOne end of each of the three-phase common-mode inductors L is connected to the three-phase output end of the inverter module 410. m The other end is connected to the differential mode filter circuit.

[0093] Correspondingly, the three-phase common mode inductance L m The parameter design steps may include limiting the three-phase common-mode inductor impedance and saturation current.

[0094] Specifically, the three-phase common mode inductance L m The impedance should be greater than the minimum common mode impedance Z of the traction drive system in the frequency range of 10kHz to 10MHz cmin More than 10 times the three-phase common mode inductance L m Satisfying formula (1):

[0095]

[0096] Where, 10kHz≤f≤10MHz, Z cmin The minimum common-mode impedance of the traction drive system for which the SiC traction converter is applicable.

[0097] Three-phase common mode inductor L m The saturation current should be greater than the three-phase working current I of the traction motor. base 1%, that is, the three-phase common mode inductance L m The saturation current satisfies formula (2):

[0098] I Lcm ≥ 1% I base (2)

[0099] Among them, I Lcm is the three-phase common mode inductance L m The saturation current, I base is the three-phase working current of the traction motor.

[0100] Specifically, based on the minimum common-mode impedance range of the commonly used traction drive system and the three-phase operating current range of the saturated traction motor, the above equations (1) and (2) can be combined to determine: Figure 7 The three-phase common-mode inductor L in the common-mode filter circuit shown m The inductance range is 50uH ~ 400uH, and the saturation current of the three-phase common-mode inductor is greater than 5A.

[0101] Furthermore, if Figure 5 As shown, the differential mode filter circuit 422 of the SiC traction converter may include a three-phase differential mode inductor L f And three-phase RC absorption circuit.

[0102] Among them, the three-phase differential mode inductance L f One end of each is connected to the three-phase common-mode inductor and the three-phase differential-mode inductor Lf The other end is the output end of the filter module 420, that is, the three-phase differential mode inductor L f The other end of the three-phase inductor is connected to the three-phase power supply end of the traction motor through a power cable. The three-phase differential mode inductor can reduce the voltage change rate of the output end of the filter module 420.

[0103] One end of the three-phase RC absorption circuit is connected to the three-phase differential mode inductor L f The other end of is connected to the output end of the filter module 420, and the other end of the three-phase RC absorption circuit is connected in parallel to form a neutral point N, which is suspended. The three-phase RC absorption circuit can reduce the peak voltage amplitude of the output end of the filter module 420.

[0104] Specifically, each RC absorption circuit includes a capacitor C f and a resistor R f , capacitor C f and resistor R f A phase difference mode inductor L connected in series with the RC absorption circuit f and the neutral point N.

[0105] Preferably, the differential mode filter circuit 422 adopts a three-phase completely symmetrical circuit, that is, the differential mode inductance L of each phase is f , capacitor C f and resistor R f Respectively the same.

[0106] Correspondingly, the parameter design of the differential mode filter circuit 422 may include the differential mode inductance L of each phase. f , capacitor C f and resistor R f Parameter restrictions.

[0107] It can be understood by those skilled in the art that the filter module of the SiC traction converter applicable to the rail transit traction drive system needs to reduce the volume, weight and loss of the filter module as much as possible, so as to improve the working efficiency of the traction drive system. In order to improve the working efficiency of the traction drive system, it is necessary to adjust the differential mode inductance L in the differential mode filter circuit 422. f and capacitor C f Make restrictions.

[0108] Specifically, the differential mode inductor impedance in each phase differential mode filter circuit should be less than 5% of the load impedance, that is, the differential mode inductor L f Satisfying formula (3):

[0109]

[0110] Among them, U base is the rated output voltage of the inverter module 410, P base is the rated output power of the inverter module 410, fi The frequency of the rated output current of the inverter module 410 .

[0111] Specifically, the resistor R in the RC absorption circuit in each phase difference mode filter circuit f The loss and capacitance C f The loss of the filter module 420 should be less than 0.5% of the rated output power of the inverter module. f Satisfying formula (4):

[0112]

[0113] Among them, P base is the rated output power of the inverter module 410, f sw is the switching frequency of the inverter module 410, V dc is the DC input voltage of the inverter module 410 .

[0114] The three-phase differential mode inductance L in the differential mode filter circuit can be calculated by equations (3) and (4). f and capacitor C f Constraints can be made, and combined with the requirements of the traction motor on the voltage change rate and the maximum overvoltage, the three-phase differential mode inductance L can be further confirmed. f , the capacitor C of the RC absorption circuit f and resistor R f .

[0115] Among them, the voltage change rate du / dt of the traction motor satisfies formula (5):

[0116]

[0117] Maximum overvoltage of traction motor V peak Satisfying formula (6):

[0118] V peak =(3l C K / vT r +1)V dc (6)

[0119] The resistance R of the RC absorption circuit f Satisfying formula (7):

[0120]

[0121] in, T r is the pulse rise time required by the traction motor, l C is the length of the power cable, K is the voltage reflection coefficient of the traction motor, v is the transmission speed of the wave in the power cable, L C is the inductance of the power cable per unit length, CC is the capacitance of the power cable per unit length, Z L is the impedance of the traction motor, and Z0 is the characteristic impedance of the power cable.

[0122] In order to make the SiC traction converter compatible with the existing traction drive system, while considering the volume, weight and loss of the filter module, the target range of the voltage change rate du / dt on the traction motor side is 1kV / us~3kV / us, and the maximum overvoltage V peak Less than 1.5 times of the DC input voltage of the inverter module 410 . The voltage reflection coefficient of a commonly used high-power traction motor is in the range of 0.8 to 0.9.

[0123] Specifically, based on the voltage change rate of the traction motor side of the above-mentioned commonly used traction drive system, the maximum overvoltage of the traction motor, and the parameter range of the voltage reflection coefficient of the high-power traction motor, combined with the above-mentioned formulas (3) to (7), it can be determined as follows: Figure 7 The three-phase differential mode inductor L in the common mode filter circuit shown f The range is 10uH~100uH, and the capacitance C of each RC absorption circuit f The range is 20nF~470nF; the resistance R of each RC absorption circuit f The range is 10Ω~100Ω.

[0124] Furthermore, those skilled in the art will appreciate that the inverter module 410 may be implemented using a commonly used inverter circuit topology, such as Figure 6 The three-phase full-bridge inverter circuit shown in FIG. Further, the input end of the inverter module 410 may also be provided with other adaptable devices, such as Figure 6 The inductor L and capacitor C are shown.

[0125] In an embodiment of an urban rail transit system, the DC power supply voltage is 1.5 kV. Figure 5 After the topological structure of the filter module 420 of the SiC traction inverter is shown and the parameters of the filter module 420 are designed using the above parameter design method, the high-frequency interference of the SiC traction inverter is reduced by 30dB at most after the filter module is adopted, the maximum overvoltage on the traction motor side is reduced from 2.8kV to 1.7kV, and the voltage change rate is reduced from 10kV / us to 2kV / us.

[0126] According to another aspect of the present invention, a parameter design device is also provided. Figure 7 As shown, it includes a memory 710 and a processor 720 .

[0127] The memory 710 is used to store computer programs.

[0128] The processor 720 is connected to the memory 710 and is used to execute a computer program on the memory 710 . When the computer program is executed, the steps of the parameter design method of the SiC traction converter are implemented.

[0129] According to yet another aspect of the present invention, there is further provided a computer storage medium having a computer program stored thereon, wherein when the computer program is executed, the steps of the parameter design method for the SiC traction converter as described above are implemented.

[0130] Those skilled in the art will appreciate that information, signals, and data may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips cited throughout the above description may be represented by voltage, current, electromagnetic waves, magnetic fields or magnetic particles, optical fields or optical particles, or any combination thereof.

[0131] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0132] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0133] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0134] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, a server, or other remote source using a coaxial cable, a fiber optic cable, a twisted pair, a digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0135] The foregoing description is provided to enable any person skilled in the art to practice the various aspects described herein. However, it should be understood that the scope of protection of the present invention shall be subject to the appended claims and shall not be limited to the specific structures and components of the above-described embodiments. Those skilled in the art may make various changes and modifications to the embodiments within the spirit and scope of the present invention, and these changes and modifications also fall within the scope of protection of the present invention.

Claims

1. A filter, suitable for a variable frequency drive system, comprising: A common-mode filter circuit is used to reduce the common-mode interference current and the common-mode voltage at the load end of the filter, the input end of the common-mode filter circuit is the input end of the filter, wherein the common-mode filter circuit includes: a three-phase common-mode inductor, and the three-phase common-mode inductor ,in, , is the minimum common-mode impedance of the variable frequency drive system; and the saturation current of the three-phase common-mode inductor ,in, is the three-phase operating current of the load of the variable frequency drive system; and A differential mode filter circuit is used to reduce the voltage change rate and peak voltage amplitude at the load end of the filter, the input end of the differential mode filter circuit is connected to the output end of the common mode filter circuit, the output end of the differential mode filter circuit is the output end of the filter, and the output end of the filter is connected to the load through a connecting line.

2. The filter according to claim 1, characterized in that The two ends of the three-phase common-mode inductor are respectively the input end and the output end of the common-mode filter circuit; as well as The differential mode filtering circuit comprises: A three-phase differential mode inductor, wherein two ends of the three-phase differential mode inductor are respectively an input end and an output end of the differential mode filter circuit; as well as A three-phase RC absorption circuit, one end of which is respectively connected to the three-phase output ends of the differential mode filter circuit, and the other end of which is connected in parallel to form a neutral point, and the neutral point is suspended.

3. The filter according to claim 2, characterized in that Each of the three-phase RC absorption circuits comprises: A capacitor and a resistor, one end of the capacitor and one end of the resistor are connected in series, the other end of the capacitor is connected to the output end of the corresponding phase of the differential mode filter circuit, and the other end of the resistor is connected to the neutral point.

4. The filter according to any one of claims 1 to 3, characterized in that The differential mode filter circuit is a three-phase completely symmetrical circuit.

5. A filter parameter design method, characterized in that: The filter comprises: a common mode filter circuit and a differential mode filter circuit, the input end of the common mode filter circuit is the input end of the filter, wherein the common mode filter circuit comprises a three-phase common mode inductor, the input end of the differential mode filter circuit is connected to the output end of the common mode filter circuit, the output end of the differential mode filter circuit is the output end of the filter, and the output end of the filter is connected to the load through a connecting line, and the parameter design method comprises: The parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, wherein the three-phase common-mode inductor ,in, , is the minimum common-mode impedance of the variable frequency drive system; and the saturation current of the three-phase common-mode inductor ,in, is the three-phase working current of the load of the variable frequency drive system.

6. The parameter design method according to claim 5, characterized in that: The differential mode filter circuit includes a three-phase differential mode inductor and a three-phase RC absorption circuit, each RC absorption circuit includes a capacitor and a resistor, and the parameters of the common mode filter circuit and the differential mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, including: The three-phase differential mode inductor ,in, is the rated input voltage of the filter input, is the rated input power of the filter input, is the frequency of the rated input current at the input of the filter; and The capacitance of the RC absorption circuit ,in, is the rated input power of the filter input, is the switching frequency of the variable frequency drive system, is the DC input voltage of the variable frequency drive system.

7. The parameter design method according to claim 6, characterized in that: The parameters of the common mode filter circuit and the differential mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the variable frequency drive system to which the filter is applied, including: The three-phase differential mode inductance, the capacitance and the resistance of the RC absorption circuit are further determined based on the requirements of the variable frequency drive system for the voltage change rate and the maximum overvoltage, wherein the voltage change rate , the maximum overvoltage , , , , , T r is the required pulse rise time, l C is the length of the connection line, K is the voltage reflection coefficient of the load, v is the transmission speed of the wave in the connection line, L C is the inductance per unit length of the connecting line, C C is the capacitance per unit length of the connecting line, Z L is the impedance of the load, Z0 is the characteristic impedance of the connecting line, is the resistance of the RC absorption circuit.

8. A filter parameter design device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor is used to implement the steps of the filter parameter design method according to any one of claims 5 to 7 when executing the computer program stored in the memory.

9. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the steps of the filter parameter design method according to any one of claims 5 to 7 are implemented.

10. A SiC traction converter, comprising: An inverter module, wherein the inverter module adopts SiC power devices; as well as A filter module, wherein the input end of the filter module is connected to the output end of the inverter module, and the output end of the filter module is connected to the traction motor through a power cable. The filter module includes a common-mode filter circuit and a differential-mode filter circuit. The parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters and impedance characteristics of the traction drive system applied by the SiC traction converter and the insulation requirements of the traction motor. The common-mode filter circuit includes a three-phase common-mode inductor. ,in, , is the minimum common-mode impedance of the traction drive system; and the saturation current of the three-phase common-mode inductor ,in, is the three-phase working current of the traction motor.

11. The SiC traction converter according to claim 10, characterized in that: The inverter module is a three-phase inverter module. One end of the three-phase common-mode inductor is the input end of the filter module, which is used to reduce the common-mode interference current and the common-mode voltage at the traction motor end; as well as The differential mode filtering circuit comprises: A three-phase differential mode inductor, used to reduce the voltage change rate of the output end of the filter module, one end of the three-phase differential mode inductor is respectively connected to the other end of the three-phase common mode inductor, and the other end of the three-phase differential mode inductor is the output end of the filter module; as well as A three-phase RC absorption circuit is used to reduce the peak voltage amplitude of the output end of the filter module, one end of the three-phase RC absorption circuit is respectively connected to the other end of the three-phase differential mode inductor, and the other end of the three-phase RC absorption circuit is connected in parallel to form a neutral point, and the neutral point is suspended.

12. The SiC traction converter according to claim 11, characterized in that: The three-phase common-mode inductance ranges from 50uH to 300uH, and the saturation current of the three-phase common-mode inductance is greater than 5A.

13. The SiC traction converter according to claim 11, characterized in that: Each of the three-phase RC absorption circuits comprises: A capacitor and a resistor, one end of the capacitor and one end of the resistor are connected in series, the other end of the capacitor is connected to the other end of a corresponding phase difference mode inductor, and the other end of the resistor is connected to the neutral point.

14. The SiC traction converter according to claim 13, characterized in that: The three-phase differential mode inductance ranges from 10uH to 100uH, the capacitance of each RC absorption circuit ranges from 20nF to 470nF, and the resistance of each RC absorption circuit ranges from 10Ω to 100Ω.

15. The SiC traction converter according to any one of claims 10 to 14, characterized in that: The differential mode filter circuit is a three-phase completely symmetrical circuit.

16. A parameter design method for a SiC traction converter, characterized in that: The SiC traction converter includes an inverter module and a filter module, wherein the inverter module adopts SiC power devices, the input end of the filter module is connected to the output end of the inverter module, and the output end of the filter module is connected to the traction motor through a power cable. The filter module includes a common-mode filter circuit and a differential-mode filter circuit, wherein the common-mode filter circuit includes a three-phase common-mode inductor, and the parameter design method includes: The parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters, impedance characteristics and insulation requirements of the traction drive system of the SiC traction converter, wherein the three-phase common-mode inductor ,in, , is the minimum common-mode impedance of the traction drive system; and the saturation current of the three-phase common-mode inductor ,in, is the three-phase working current of the traction motor.

17. The parameter design method according to claim 16, characterized in that: The three-phase common-mode inductance range determined by the parameter design method is 50uH~300uH, and the saturation current of the three-phase common-mode inductance is greater than 5A.

18. The parameter design method according to claim 16, characterized in that: The differential mode filter circuit includes a three-phase differential mode inductor and a three-phase RC absorption circuit, each RC absorption circuit includes a capacitor and a resistor, and the parameters of the common mode filter circuit and the differential mode filter circuit are calculated based on the basic electrical parameters of the application system of the SiC traction converter, the impedance characteristics and the insulation requirements of the traction motor, including: The three-phase differential mode inductor ,in, is the rated output voltage of the inverter module, is the rated output power of the inverter module, The frequency of the rated output current of the inverter module; and The capacitance of the RC absorption circuit ,in, is the rated output power of the inverter module, is the switching frequency of the inverter module, is the DC input voltage of the inverter module.

19. The parameter design method according to claim 18, characterized in that: The parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters and impedance characteristics of the application system of the SiC traction converter and the insulation requirements of the traction motor, and further include: The three-phase differential mode inductance, the capacitance and the resistance of the RC absorption circuit are further determined based on the requirements of the traction motor for the voltage change rate and the maximum overvoltage, wherein the voltage change rate , the maximum overvoltage , , , , , T r is the required pulse rise time, l C is the length of the power cable, K is the voltage reflection coefficient of the traction motor, v is the transmission speed of the wave in the power cable, L C is the inductance of the power cable per unit length, C C is the capacitance of the power cable per unit length, Z L is the impedance of the traction motor, Z0 is the characteristic impedance of the power cable, is the resistance of the RC absorption circuit.

20. The parameter design method according to claim 19, characterized in that: The parameters of the common-mode filter circuit and the differential-mode filter circuit are calculated based on the basic electrical parameters and impedance characteristics of the application system of the SiC traction converter and the insulation requirements of the traction motor, and further include: The voltage change rate is 1 kV / us~3 kV / us, the maximum overvoltage is less than 1.5 times the DC input voltage of the inverter module, and the voltage reflection coefficient is 0.8~0.

9.

21. The parameter design method according to claim 20, characterized in that: The range of the three-phase differential mode inductance determined by the parameter design method is 10uH~100uH, the range of the capacitance of each RC absorption circuit is 20nF~470nF; the range of the resistance of each RC absorption circuit is 10Ω~100Ω.

22. A parameter design device for a SiC traction converter, comprising a memory, a processor, and a computer program stored in the memory, characterized in that: The processor is used to implement the steps of the parameter design method of the SiC traction converter according to any one of claims 16 to 21 when executing the computer program stored in the memory.

23. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed, the steps of the parameter design method for the SiC traction converter according to any one of claims 16 to 21 are implemented.

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