A method and apparatus for common mode current suppression of a power converter, and a power converter

Abstract

The application discloses a common-mode current suppression method of a converter, comprising the following steps: insulating a power unit of the converter from the ground; connecting the power unit and a box shell of the converter through a wire to form a return path containing the power unit and the box shell for consuming common-mode current; and arranging a filter circuit between the power unit and the box shell. The method can effectively suppress the common-mode current and reduce the interference on trackside equipment. The application also discloses a common-mode current suppression device of a converter and a converter, both of which have the above technical effects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter, in particular to a common-mode current suppression method of a converter, and further relates to a common-mode current suppression device of a converter and a converter. BACKGROUND

[0002] The converter can convert direct current into three-phase alternating current with adjustable voltage and frequency, and is used for driving a traction motor. The fundamental phase angles of the voltages output by the output ends U, V and W of the converter are mutually different by 120°. Under the PWM control mode, the instantaneous value of the sum of the three-phase outputs is not zero, and a common-mode voltage exists. The power switching device of the converter is usually an IGBT switch. Under the PWM control mode, the IGBT switch generates a high dv / dt, that is, a high voltage change rate. The common-mode voltage and the high voltage change rate act on the parasitic capacitance of the converter, not only generating a charge-discharge current, but also causing the voltage of the power unit of the converter to rise due to the accumulation of the parasitic capacitance, thereby generating a common-mode current. The common-mode current is coupled to the vehicle body ground or negative line, thereby interfering with trackside equipment, and thus the common-mode current needs to be suppressed.

[0003] At present, the schemes for suppressing the common-mode current include: scheme 1, reducing the common-mode current of the converter through specific harmonic elimination PWM modulation; and scheme 2, adding an EMC capacitor inside the converter to provide a common-mode current return path. However, for scheme 1, since the switching frequency of the converter in the train is low (below 500 Hz), the effect of scheme 1 on high-order harmonics is limited, and the suppression effect of the common-mode current is poor. For scheme 2, since the train loop is complex, the selection of the EMC capacitor needs to refer to empirical data, and the system matching is complex. In addition, the capacitance value of the capacitor can change over time, which can cause the system to be unable to match, thereby failing to effectively suppress the common-mode current.

[0004] Therefore, how to efficiently suppress the common-mode current has become a technical problem to be solved by those skilled in the art. SUMMARY

[0005] The purpose of the present application is to provide a common-mode current suppression method of a converter, which can efficiently suppress the common-mode current and reduce the interference with trackside equipment. Another purpose of the present application is to provide a common-mode current suppression device of a converter and a converter, both of which have the above technical effects.

[0006] To solve the above technical problems, the present application provides a common-mode current suppression method of a converter, comprising:

[0007] insulating the power unit of the converter from the ground;

[0008] The power unit is connected with the box shell of the converter through a wire to form a return flow path containing the power unit and the box shell for consuming common-mode current.

[0009] A filter circuit is arranged between the power unit and the box shell.

[0010] Optionally, the filter circuit arranged between the power unit and the box shell comprises:

[0011] The filter circuit is arranged between the heat sink substrate of the power unit and the box shell.

[0012] Optionally, the filter circuit comprises a notch filter.

[0013] Optionally, the device further comprises:

[0014] A frequency band of a wayside device is acquired.

[0015] According to the acquired frequency band, a circuit parameter of the filter circuit is adjusted to change a peak value of the common-mode current.

[0016] To solve the above technical problems, the application further provides a common-mode current suppression device of a converter, comprising:

[0017] A first setting module is configured to insulate a power unit of a converter from the ground.

[0018] A connecting module is configured to connect the power unit with a box shell of the converter through a wire to form a return flow path containing the power unit and the box shell for consuming common-mode current.

[0019] A second setting module is configured to arrange a filter circuit between the power unit and the box shell.

[0020] Optionally, the second setting module is specifically configured to arrange the filter circuit between a heat sink substrate of the power unit and the box shell.

[0021] Optionally, the device further comprises:

[0022] An acquiring module is configured to acquire a frequency band of a wayside device.

[0023] An adjusting module is configured to adjust a circuit parameter of the filter circuit according to the acquired frequency band to change a peak value of the common-mode current.

[0024] To solve the above technical problems, the application further provides a converter, a power unit of the converter is insulated from the ground; the power unit is connected to a cabinet shell of the converter through a wire to form a return path containing the power unit and the cabinet for consuming common-mode current; and a filter circuit is arranged between the power unit and the cabinet shell.

[0025] Optionally, the filter circuit comprises a notch filter.

[0026] Optionally, the filter circuit is located between a heat sink substrate of the power unit and the cabinet shell.

[0027] The common-mode current suppression method of the converter provided by the application comprises the following steps: insulating a power unit of the converter from the ground; connecting the power unit to a cabinet shell of the converter through a wire to form a return path containing the power unit and the cabinet shell for consuming common-mode current; and arranging a filter circuit between the power unit and the cabinet shell.

[0028] As can be seen, the common-mode current suppression method of the converter provided by the application insulates the power unit of the converter from the ground, thereby cutting off the path through which the common-mode current flows into the ground terminal and fundamentally suppressing the common-mode current from being conducted to the negative line wheel rail. The power unit is connected to the cabinet shell of the converter through a wire to form a return path containing the power unit and the cabinet, so that the common-mode current is consumed in the return path. In addition, by arranging the filter circuit between the power unit and the cabinet shell, the common-mode current generated by the power unit can circulate and be consumed more in the return path containing the power unit and the cabinet. The more the common-mode current in the return path, the less the interference on the external transmission, thereby effectively reducing the interference on the wayside equipment.

[0029] The common-mode current suppression device of the converter and the converter provided by the application have the above technical effects. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the prior art and embodiments. Obviously, the drawings in the following description only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0031] Figure 1 A flowchart of a common-mode current suppression method of a converter provided by an embodiment of the application;

[0032] Figure 2 A schematic diagram of a converter provided by an embodiment of the application;

[0033] Figure 3 A schematic view of a common-mode current suppression device of a converter provided by an embodiment of the present application. DETAILED DESCRIPTION

[0034] The core of the present application is to provide a common-mode current suppression method of a converter, which can efficiently suppress common-mode current and reduce interference on trackside equipment. Another core of the present application is to provide a common-mode current suppression device of a converter and a converter, both of which have the above technical effects.

[0035] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] Please refer to Figure 1 , Figure 1 A flowchart of a common-mode current suppression method of a converter provided by an embodiment of the present application, as shown in Figure 1 , the method comprises the following steps.

[0037] S101: insulating a power unit of a converter from ground;

[0038] Specifically, insulating the power unit of the converter from ground means disconnecting the power unit of the converter from ground, that is, the power unit of the converter is not grounded. The power unit of the converter can be regarded as an interference source, and the common-mode current generated by the power unit will be conducted to the wheel rail to interfere with trackside equipment. By insulating the power unit of the converter from ground, the common-mode current generated by the power unit can be fundamentally suppressed from being conducted to the wheel rail, thereby reducing interference on trackside equipment. The so-called trackside equipment refers to equipment arranged near the train wheel rail.

[0039] S102: connecting the power unit and a box shell of the converter by a wire to form a return path containing the power unit and the box shell for consuming common-mode current;

[0040] Specifically, this step aims to insulate the power unit and the box shell of the converter, and only connect the power unit and the box shell by a wire to form a return path containing the power unit and the box shell, in which the common-mode current circulates and is consumed. In addition, the box shell is connected to the grounding system by a wire.

[0041] The return path contains the power unit and the box shell, and also contains motor three-phase lines, motor shell, etc.

[0042] S103: Setting a filter circuit between the power unit and the box housing.

[0043] Specifically, this step aims to connect the power unit to the housing of the converter via a wire to form a return path including the power unit and the housing, and then further provide a filter circuit in this return path, specifically between the power unit and the housing. Under the action of the filter circuit, common-mode current circulates and is consumed more easily in this return path. When the total amount of interference sources is constant, the more common-mode current in the return path, the less common-mode current will naturally be conducted externally, and the less external interference will be, thereby reducing interference with trackside equipment.

[0044] Wherein, in a specific embodiment, the setting of the filter circuit between the power unit and the box shell includes: setting the filter circuit between the heat sink substrate of the power unit and the box shell.

[0045] Specifically, in this embodiment, a filter circuit is provided between the heat sink substrate of the power unit and the housing of the converter. In this case, the return path includes the power unit, the heat sink substrate, the filter circuit, the housing, the motor three-phase wires, the motor housing, etc.

[0046] In addition, in a specific implementation, the filtering circuit includes a notch filter.

[0047] Specifically, in this embodiment, the filtering circuit specifically includes a notch filter, and the notch filter specifically can be arranged between the heat sink substrate and the box housing of the converter.

[0048] For example, reference Figure 2 As shown, Figure 2 Ces represents the parasitic capacitance between the power components and the laminated busbar in the power unit and the heat sink baseplate, and Csf represents the parasitic capacitance between the motor's three-phase cables and the motor housing. Reference numeral 10 denotes the power unit, reference numeral 20 denotes the heat sink baseplate, reference numeral 30 denotes the notch filter, reference numeral 40 denotes the converter housing and the train body, reference numeral 50 denotes the motor housing, and reference numeral 60 denotes the motor's three-phase cables.

[0049] The power devices and laminated busbar, parasitic capacitor Ces, notch filter, box housing, motor housing, parasitic capacitor Csf, and motor three-phase wire form a complete return path ( Figure 2 The common-mode current circulates and is consumed in this return path).

[0050] It can be understood that the embodiment of the filter circuit including the notch filter is only one implementation provided by the present application, but not the only limitation, and other filters can also be used.

[0051] Further, based on the above embodiment, as a specific implementation, the method can further include: obtaining a frequency band of the trackside equipment; and adjusting a circuit parameter of the filter circuit according to the obtained frequency band, so as to change the peak value of the common-mode current.

[0052] Specifically, by adjusting the circuit parameter of the filter circuit, the peak value of the common-mode current of different frequency bands in the return path can be changed, so as to reduce the interference to the trackside equipment.

[0053] For example, the metro train is generally provided with an axle counter device beside the track, and the frequency band of the axle counter device that is easily interfered is certain, and the peak value of the conducted interference only needs to be less than the frequency band of the interfered axle counter device. Therefore, by adjusting the circuit parameter of the filter circuit, the peak value of the conducted interference can be changed, so that the peak value of the conducted interference is less than the frequency band of the interfered axle counter device, thereby reducing the interference to the axle counter device.

[0054] For the case that the filter circuit includes the notch filter, by adjusting the parameter of the notch filter, the peak value of the conducted interference can be changed, and the interference to the trackside equipment is reduced. Therefore, the above method of suppressing the common-mode current has good universality.

[0055] In summary, the method of suppressing the common-mode current of the converter provided by the present application includes: insulating the power unit of the converter from the ground; connecting the power unit and the box shell of the converter through a wire to form a return path containing the power unit and the box shell for consuming the common-mode current; and arranging a filter circuit between the power unit and the box shell. It can be seen that the method of suppressing the common-mode current of the converter provided by the present application insulates the power unit of the converter from the ground, cuts off the path of the common-mode current flowing into the ground terminal, and fundamentally suppresses the common-mode current from being conducted to the negative line rail. The power unit and the box shell of the converter are connected through a wire to form a return path containing the power unit and the box shell, so that the common-mode current is consumed in the return path. In addition, by arranging a filter circuit between the power unit and the box shell, the common-mode current generated by the power unit can circulate and be consumed more in the return path containing the power unit and the box shell. The more the common-mode current in the return path, the less the interference to the outside, so that the interference to the trackside equipment can be effectively reduced.

[0056] The present application also provides a device for suppressing the common-mode current of a converter, which can be correspondingly referred to the above-described method. Please refer to Figure 3 , Figure 3A schematic diagram of a common-mode current suppression device for a converter provided in an embodiment of the present application, combined with Figure 3 As shown, the device includes:

[0057] A first setting module 1 is used to isolate the power unit of the converter from the ground;

[0058] a connection module 2, configured to connect the power unit to the housing of the converter via a wire, thereby forming a return path including the power unit and the housing for consuming common-mode current;

[0059] The second setting module 3 is used to set a filter circuit between the power unit and the box shell.

[0060] Specifically, the first configuration module 1 isolates the converter's power unit from ground, disconnecting the converter's power unit from ground. This means that the converter's power unit is not grounded. The power unit can be considered an interference source. The common-mode current generated by the power unit can be conducted to the wheels and rails, interfering with trackside equipment. By isolating the converter's power unit from ground, the common-mode current generated by the power unit can be fundamentally prevented from being conducted to the wheels and rails, thereby reducing interference with trackside equipment.

[0061] The connection module 2 is used to insulate the power unit and the converter housing, connecting the power unit and the housing only through wires, forming a return path including the power unit and the housing, so that the common mode current circulates and is consumed in this return path.

[0062] Among them, the return path includes not only the power unit and the box shell, but also the motor three-phase line, motor shell, etc.

[0063] After connection module 2 connects the power unit to the converter housing via wires, forming a return path encompassing the power unit and the housing, second configuration module 3 further configures a filter circuit within this return path. Specifically, second configuration module 3 installs the filter circuit between the power unit and the housing. The filter circuit allows common-mode current to circulate and be consumed more easily within this return path. Given a constant total amount of interference sources, the more common-mode current in the return path, the less common-mode current is conducted externally, resulting in less external interference and reduced interference with trackside equipment.

[0064] Based on the above embodiment, optionally, the second setting module 3 is specifically configured to set the filter circuit between the heat sink substrate of the power unit and the box housing.

[0065] Specifically, in the embodiment, the second setting module 3 specifically sets the filter circuit between the heat sink substrate of the power unit and the box shell of the converter. At this time, the backflow path includes the power unit, the heat sink substrate, the filter circuit, the box shell, the motor three-phase line, the motor shell, etc. The common mode current circulates and consumes in the backflow path containing the power unit, the heat sink substrate, the filter circuit, the box shell, and the motor.

[0066] On the basis of the above-mentioned embodiment, optionally, the filter circuit includes a notch filter.

[0067] Specifically, the filter circuit specifically includes a notch filter, which can be specifically arranged between the heat sink substrate and the converter box shell. At this time, the backflow path includes the power unit, the heat sink substrate, the notch filter, the box shell, the motor three-phase line, and the motor shell.

[0068] On the basis of the above-mentioned embodiment, optionally, further comprising:

[0069] The acquisition module is configured to acquire the frequency band of the wayside equipment.

[0070] The adjustment module is configured to adjust the circuit parameter of the filter circuit according to the acquired frequency band, so as to change the peak value of the common mode current.

[0071] Specifically, the frequency band of the wayside equipment is acquired by the acquisition module, and the circuit parameter of the filter circuit is adjusted by the adjustment module according to the acquired frequency band, so as to change the peak value of the common mode current of different frequency bands in the backflow path, thereby reducing the interference on the wayside equipment.

[0072] For example, the metro train is generally provided with an axle counting device beside the rail, and the frequency band of the axle counting device that is easy to be interfered is certain. The conducted interference peak value only needs to be less than the frequency band of the interfered axle counting device. Therefore, by adjusting the circuit parameter of the filter circuit, the conducted interference peak value can be changed to be less than the frequency band of the interfered axle counting device, so as to reduce the interference on the axle counting device.

[0073] The common mode current suppression device of the converter provided in the application insulates the power unit of the converter from the ground, and cuts off the path of the common mode current flowing into the ground terminal, thereby fundamentally suppressing the common mode current from being conducted to the negative line wheel rail. The power unit and the box of the converter are connected by a wire, forming a backflow path containing the power unit and the box, so that the common mode current circulates and consumes in the backflow path. In addition, by arranging a filter circuit between the power unit and the box, the common mode current generated by the power unit can circulate and consume more in the backflow path containing the power unit and the box. The more the common mode current in the backflow path, the less the external conducted interference, thereby effectively reducing the interference on the wayside equipment.

[0074] The application also provides a converter, a power unit of the converter is insulated from the ground; the power unit is connected to a box shell of the converter through a wire to form a return path containing the power unit and the box shell for consuming common-mode current; a filter circuit is arranged between the power unit and the box shell.

[0075] Specifically, in the application, the power unit of the converter is designed to be insulated from the ground. The power unit mainly includes a support capacitor, a laminated busbar and a heat sink. The specific composition of the power unit is not described here, and reference can be made to the existing power unit.

[0076] The power unit of the converter is insulated from the ground, which means that the power unit of the converter is disconnected from the ground, that is, the power unit of the converter is not grounded. The power unit can be regarded as an interference source, and the common-mode current generated thereby can be conducted to the rail, thereby interfering with the trackside equipment. By designing the power unit of the converter to be insulated from the ground, the common-mode current generated by the power unit can be fundamentally inhibited from being conducted to the rail, thereby reducing the interference with the trackside equipment.

[0077] In addition, in the application, the power unit of the converter is connected to the box of the converter only through a wire to form a return path containing the power unit and the box shell, so that the common-mode current circulates and is consumed in the return path.

[0078] The return path contains not only the power unit and the box shell, but also the motor three-phase line, the motor shell, etc.

[0079] In addition, on the basis of connecting the power unit to the box shell of the converter through a wire to form a return path containing the power unit and the box shell, a filter circuit is further arranged on the return path, specifically between the power unit and the box shell. Under the action of the filter circuit, the common-mode current is more easily and more consumed in the return path. In the case where the total amount of interference sources is constant, the more common-mode current in the return path, the less common-mode current conducted externally, and the less external interference, thereby reducing the interference with the trackside equipment.

[0080] Further, on the basis of arranging a filter circuit between the power unit and the box shell of the converter, by adjusting the circuit parameters of the filter circuit, the peak values of the common-mode current of different frequency bands in the return path can be changed, thereby reducing the interference with the trackside equipment.

[0081] For example, the subway train is generally designed with axle counting equipment beside the rail, the frequency band of the axle counting equipment is certain, and the conducted interference peak only needs to be less than the frequency band of the disturbed axle counting equipment, so that the conducted interference peak can be changed by adjusting the circuit parameters of the filter circuit, so that the conducted interference peak is less than the frequency band of the disturbed axle counting equipment, thereby reducing the interference to the axle counting equipment.

[0082] On the basis of the above-mentioned embodiment, optionally, the filter circuit comprises a notch filter.

[0083] Specifically, in this embodiment, the filter circuit specifically comprises a notch filter, and the notch filter can be specifically arranged between the heat sink base plate and the converter box shell. At this time, the backflow path comprises the power unit, the heat sink base plate, the notch filter, the box shell, and the motor shell.

[0084] On the basis of the above-mentioned embodiment, optionally, the filter circuit is located between the heat sink base plate of the power unit and the box shell.

[0085] Specifically, in this embodiment, the filter circuit is specifically arranged between the heat sink base plate of the power unit and the box shell of the converter. At this time, the backflow path comprises the power unit, the heat sink base plate, the filter circuit, the box shell, and the motor. The common mode current circulates and is consumed in the backflow path comprising the power unit, the heat sink base plate, the filter circuit, the box shell, and the motor shell.

[0086] The converter provided in the present application insulates the power unit of the converter from the ground, cutting off the path of the common mode current flowing into the ground terminal, and fundamentally inhibits the common mode current from being conducted to the negative line rail. The power unit and the box shell of the converter are connected by a wire to form a backflow path comprising the power unit and the box shell, so that the common mode current circulates and is consumed in the backflow path. In addition, by arranging a filter circuit between the power unit and the box shell, the common mode current generated by the power unit can circulate and be consumed more in the backflow path comprising the power unit and the box shell. The more the common mode current in the backflow path, the less the external conducted interference, so that the interference to the rail-side equipment can be effectively reduced.

[0087] The embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts of each embodiment can be referred to each other. For the device, equipment and computer readable storage medium disclosed in the embodiments, since they correspond to the method disclosed in the embodiments, the description is relatively simple, and the related parts can be referred to the method part.

[0088] Those skilled in the art will further realize that the mere conception of the examples described herein is not inducing the patentable subject matter recited in each claim. The combinations of claim limitations noted in the following claims are not intended to require the claimant to cumulatively accumulate the recited limitations. Therefore, the claims are hereby defined to cover any such combination of the elements recited in each claim.

[0089] The steps of a method or algorithm described in connection with the embodiments disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in random access memory (RAM), flash memory, read-only memory (ROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, 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 the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can reside in an application-specific integrated circuit (ASIC).

[0090] The above provides a detailed description of the common-mode current suppression method, device and converter of the converter provided by the present application. The principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only for helping to understand the method of the present application and its core idea. It should be pointed out that, for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method of common-mode current suppression for a current transformer, the method comprising: The method comprises: insulating a power unit of a converter from the ground; connecting the power unit and a box shell of the converter through a wire to form a return flow path containing the power unit and the box shell for consuming common mode current; setting a filter circuit between the power unit and the box shell; the return flow path further contains motor three-phase lines, a motor shell and the filter circuit; acquiring a frequency band of a wayside device; adjusting a circuit parameter of the filter circuit according to the acquired frequency band to change a peak value of the common mode current.

2. The common-mode current suppression method of claim 1, wherein, The setting of the filter circuit between the power unit and the box shell comprises: setting the filter circuit between a radiator substrate of the power unit and the box shell.

3. The common-mode current suppression method of claim 1, wherein, The filter circuit comprises a notch filter.

4. A common-mode current suppression device for a power converter, comprising: The method comprises: a first setting module for insulating a power unit of a converter from the ground; a connecting module for connecting the power unit and a box shell of the converter through a wire to form a return flow path containing the power unit and the box shell for consuming common mode current; a second setting module for setting a filter circuit between the power unit and the box shell; the return flow path further contains motor three-phase lines, a motor shell and the filter circuit; an acquiring module for acquiring a frequency band of a wayside device; an adjusting module for adjusting a circuit parameter of the filter circuit according to the acquired frequency band to change a peak value of the common mode current.

5. The common-mode current suppression apparatus of claim 4, wherein, The second setting module is specifically configured to set the filter circuit between a radiator substrate of the power unit and the box shell.

6. A current transformer characterized by The power unit of the converter is insulated from the ground; the power unit and a box shell of the converter are connected through a wire to form a return flow path containing the power unit and the box shell for consuming common mode current; a filter circuit is set between the power unit and the box shell; the return flow path further contains motor three-phase lines, a motor shell and the filter circuit; a circuit parameter of the filter circuit is adjusted according to a frequency band of a wayside device to change a peak value of the common mode current.

7. The current transformer of claim 6, wherein, The filter circuit comprises a notch filter.

8. The current transformer of claim 6, wherein, The filter circuit is located between a radiator substrate of the power unit and the box shell.

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