Auxiliary converter module and auxiliary converter device

Abstract

The utility model provides an auxiliary converter module and an auxiliary converter device. The auxiliary converter module comprises an input circuit, a processing circuit, a direct current end and an alternating current end, the input circuit is connected with the direct-current end and used for receiving a direct-current power supply; the processing circuit is coupled to the input circuit and the alternating current end and is used for carrying out inversion processing on the direct current power supply and outputting an alternating current signal to the alternating current end, and the alternating current signal comprises a plurality of phases; wherein the processing circuit comprises a first switching circuit, a second switching circuit, a first one-way conduction element and a second one-way conduction element under each phase; the input end of the first one-way conduction element is connected with the input circuit, the output end of the first one-way conduction element is connected with the first switching circuit, the input end of the second one-way conduction element is connected with the second switching circuit, and the output end of the second one-way conduction element is connected with the input circuit. According to the auxiliary converter module provided by the scheme of the invention, the control logic can be simplified, so that the stability and reliability of the converter are improved.

Description

Technical Field

[0001] This application relates to the field of rail transit technology, and in particular to an auxiliary converter module and auxiliary converter device. Background Technology

[0002] With the rapid development of rail transit, higher demands are being placed on vehicle performance and energy efficiency. In rail transit systems, auxiliary converter modules, as key power conversion devices, need to possess excellent stability and reliability to reduce downtime and ensure the stable operation of the system. Furthermore, different operating conditions, such as starting, acceleration, and braking, pose greater challenges to the dynamic response and load adaptability of auxiliary converter modules, requiring them to respond quickly and accurately to load changes and provide stable and reliable AC power.

[0003] In practical applications, the ANPC (Active Neutral Point Clamped) structure is widely used in auxiliary converter modules. The ANPC structure adds two switching devices to each phase of the traditional NPC (Neutral Point Clamped) structure, achieving active control of the neutral point potential, thereby improving the reliability and output waveform quality of the converter to some extent. However, the increased number of switching devices makes the control strategy more complex, requiring precise coordination of the on and off states of each device, thus increasing the control difficulty. Utility Model Content

[0004] This application provides an auxiliary converter module and auxiliary converter device to simplify control logic, thereby improving the stability and reliability of the converter.

[0005] In a first aspect, this application provides an auxiliary converter module, comprising: an input circuit, a processing circuit, a DC terminal, and an AC terminal; the input circuit is connected to the DC terminal and is used to receive DC power; the processing circuit is coupled to the input circuit and the AC terminal and is used to perform inverter processing on the DC power and output an AC signal to the AC terminal, the AC signal including multiple phases; wherein, the processing circuit includes a first switching circuit, a second switching circuit, a first unidirectional conducting element, and a second unidirectional conducting element under each phase; the input terminal of the first unidirectional conducting element is connected to the input circuit, the output terminal of the first unidirectional conducting element is connected to the first switching circuit, the input terminal of the second unidirectional conducting element is connected to the second switching circuit, and the output terminal of the second unidirectional conducting element is connected to the input circuit.

[0006] Optionally, the input circuit has a positive terminal, a negative terminal, and a ground terminal; one end of the first switching circuit under each phase is connected to the positive terminal, the other end of the first switching circuit under each phase is connected to one end of the second switching circuit under that phase, and the other end of the second switching circuit under that phase is connected to the negative terminal; the input terminal of the first unidirectional conducting element is connected to the ground terminal, and the output terminal of the second unidirectional conducting element is connected to the ground terminal.

[0007] Optionally, the first switching circuit under each phase includes: a first switching transistor and a second switching transistor; one end of the first switching transistor is connected to the positive terminal, the other end of the first switching transistor is connected to one end of the second switching transistor and the output terminal of the first unidirectional conducting element, and the other end of the second switching transistor is connected to the corresponding AC terminal, for turning on or off the transmission path between the positive terminal and the AC terminal according to the voltage state of the DC power supply.

[0008] Optionally, the second switching circuit under each phase includes a third switching transistor and a fourth switching transistor; one end of the third switching transistor is connected to the corresponding AC terminal, the other end of the third switching transistor is connected to the input terminal of the second unidirectional conducting element and one end of the fourth switching transistor, and the other end of the fourth switching transistor is connected to the negative terminal, for turning on or off the transmission path between the negative terminal and the AC terminal according to the voltage state of the DC power supply.

[0009] Optionally, the input circuit includes: a first capacitor and a second capacitor; one end of the first capacitor is connected to the positive terminal and one end of the first switching circuit under each phase, and the other end of the first capacitor is connected to the ground terminal and one end of the second capacitor; the other end of the second capacitor is connected to the negative terminal and the other end of the second switching circuit under each phase, for filtering the received DC power supply.

[0010] Optionally, the input circuit further includes: a protection circuit; one end of the protection circuit is connected to the positive terminal, one end of the first capacitor, and one end of the first switching circuit under each phase, and the other end of the protection circuit is connected to the negative terminal, the other end of the second capacitor, and the other end of the second switching circuit under each phase, for detecting the voltage across the first capacitor and the second capacitor, and balancing the voltage across the first capacitor and the second capacitor according to the detection result.

[0011] Optionally, the protection circuit includes: a first sensor and a second sensor; one end of the first sensor is connected to the positive terminal, one end of the first capacitor, and one end of the first switching circuit under each phase; the other end of the first sensor is connected to one end of the second sensor and the ground terminal; the other end of the second sensor is connected to the negative terminal, the other end of the second capacitor, and the other end of the second switching circuit under each phase.

[0012] Optionally, the input circuit further includes: a first resistor and a second resistor; one end of the first resistor is connected to the positive terminal, one end of the protection circuit, one end of the first capacitor, and one end of the first switching circuit under each phase; the other end of the first resistor is connected to one end of the second resistor and the ground terminal; the other end of the second resistor is connected to the negative terminal, the other end of the protection circuit, the other end of the second capacitor, and the other end of the second switching circuit under each phase.

[0013] Optionally, the first unidirectional conducting element and the second unidirectional conducting element include: a silicon carbide diode.

[0014] Secondly, this application provides an auxiliary converter device, including: a drive board and the aforementioned auxiliary converter module.

[0015] Optionally, the auxiliary converter also includes: a signal configuration board; the wiring within the auxiliary converter module is all integrated on the signal configuration board.

[0016] The auxiliary converter module and auxiliary converter device provided in this application include: an input circuit, a processing circuit, a DC terminal, and an AC terminal; the input circuit is connected to the DC terminal and is used to receive DC power; the processing circuit is coupled to the input circuit and the AC terminal and is used to invert the DC power and output an AC signal to the AC terminal, the AC signal including multiple phases; wherein, the processing circuit includes a first switching circuit, a second switching circuit, a first unidirectional conducting element, and a second unidirectional conducting element under each phase; the input terminal of the first unidirectional conducting element is connected to the input circuit, the output terminal of the first unidirectional conducting element is connected to the first switching circuit, the input terminal of the second unidirectional conducting element is connected to the second switching circuit, and the output terminal of the second unidirectional conducting element is connected to the input circuit. The solution of this application, based on the traditional NPC structure, adds unidirectional conducting elements to replace switching transistors, thereby simplifying the control logic. During operation, only the opening and closing control of the first and second switching circuits under each phase needs to be performed according to the input state of the DC power and the load demand of the AC terminal to achieve effective inversion conversion of DC power to AC signal, thereby improving the stability and reliability of the converter. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] Figure 1 This is a schematic diagram of the structure of an auxiliary converter module provided in Embodiment 1 of this application;

[0019] Figure 2 The current and voltage waveforms of an example converter are shown below.

[0020] Figure 3A schematic diagram showing the switching status and commutation path of each device in the auxiliary converter module;

[0021] Figure 4 A comparison of the on-state voltage drop of silicon carbide-based MOSFETs and silicon-based IGBTs of the same specification;

[0022] Figure 5 A comparison chart of switching losses of power devices;

[0023] Figure 6 This is a schematic diagram of an auxiliary converter module structure provided in Embodiment 2 of this application;

[0024] Figure 7 This is a diagram showing the distribution of components in the auxiliary converter module;

[0025] Figure 8 For the auxiliary converter module outline drawing;

[0026] Figure 9 Outline diagram of the signal configuration board.

[0027] Figure labeling: 11 Input circuit, 12 Processing circuit, 13 DC terminal, 14 AC terminal, 121 First switch circuit, 122 Second switch circuit, D5 First unidirectional conducting element, D6 Second unidirectional conducting element, P positive terminal, N negative terminal, 0 ground terminal, T1 / D1 First switch transistor, T2 / D2 Second switch transistor, T3 / D3 Third switch transistor, T4 / D4 Fourth switch transistor, DCPT1 First sensor, DCPT2 Second sensor, FC1 First capacitor, FC2 Second capacitor, R1 First resistor, R2 Second resistor, UVW Three-phase AC terminal.

[0028] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0029] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples consistent with some aspects of this application as detailed in the appended claims.

[0030] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0031] Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover but not exclude inclusion. For example, a product or device that includes a series of components is not necessarily limited to those explicitly listed, but may include other components not explicitly listed or inherent to such product or device. As used in this application, the term "module" means any known or subsequently developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code capable of performing the functions associated with that element.

[0032] With the rapid development of rail transit technology, the requirements for vehicle auxiliary converter modules are becoming increasingly miniaturized, lightweight, and efficient. Currently, most auxiliary converter modules use IGBTs (Insulated Gate Bipolar Transistors) based primarily on traditional silicon (Si) materials as their core power devices. However, due to material limitations, the performance of silicon-based power electronic devices is nearing its limit, and it is difficult to significantly improve the power density and efficiency of converters using silicon power devices. Compared to traditional silicon-based power devices like IGBTs, silicon carbide (SiC) power devices have superior characteristics, including lower switching losses, higher thermal conductivity, and the ability to operate at high switching frequencies. Auxiliary converter modules using silicon carbide power devices can significantly reduce weight, size, and cost, while improving the efficiency and performance of the converter.

[0033] In practical applications, the topology of three-level auxiliary converter modules is mostly ANPC (Automatic National Bus) structure, requiring six all-silicon carbide (SiC) switches per phase. Compared to the traditional NPC (Non-Standard Bus) structure, this adds two SiC switches, increasing the hardware cost of the converter. Furthermore, the addition of two switches increases control complexity, rendering traditional NPC control methods unusable and requiring redesigned control systems. In addition, the auxiliary converter module has numerous internal control circuits, and the use of wiring harnesses increases wiring workload and complexity, hindering production and maintenance. Simultaneously, electromagnetic interference is easily generated between wiring harnesses, affecting the reliable operation of the converter.

[0034] The technical content provided in this application aims to solve the aforementioned technical problems in related technologies. In the embodiments of this application, the auxiliary converter module includes: an input circuit, a processing circuit, a DC terminal, and an AC terminal; the input circuit is connected to the DC terminal and is used to receive DC power; the processing circuit is coupled to the input circuit and the AC terminal, used to invert the DC power and output an AC signal to the AC terminal, the AC signal including multiple phases; wherein, the processing circuit includes a first switching circuit, a second switching circuit, a first unidirectional conducting element, and a second unidirectional conducting element under each phase; the input terminal of the first unidirectional conducting element is connected to the input circuit, the output terminal of the first unidirectional conducting element is connected to the first switching circuit, the input terminal of the second unidirectional conducting element is connected to the second switching circuit, and the output terminal of the second unidirectional conducting element is connected to the input circuit. The solution of this application, based on the traditional NPC structure, adds unidirectional conducting elements to replace switching transistors, thereby simplifying the control logic. During operation, only the opening and closing control of the first and second switching circuits under each phase needs to be performed according to the input state of the DC power and the load demand of the AC terminal to achieve effective inversion conversion of DC power to AC signal, thereby improving the stability and reliability of the converter.

[0035] The technical solution of this application and how it solves the above-mentioned technical problems will be described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will be described below with reference to the accompanying drawings.

[0036] Example 1

[0037] Figure 1 This is a schematic diagram of the structure of an auxiliary converter module provided in Embodiment 1 of this application, as shown below. Figure 1 As shown, this embodiment provides an auxiliary converter module, including: an input circuit 11, a processing circuit 12, a DC terminal 13, and an AC terminal 14;

[0038] Input circuit 11 is connected to DC terminal 13 and is used to receive DC power.

[0039] The processing circuit 12 is coupled to the input circuit 11 and the AC terminal 14. It is used to perform inverter processing on the DC power supply and output an AC signal to the AC terminal 14. The AC signal includes multiple phases.

[0040] The processing circuit 12 includes a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 for each phase. The input terminal of the first unidirectional conducting element D5 is connected to the input circuit 11, the output terminal of the first unidirectional conducting element D5 is connected to the first switching circuit 121, the input terminal of the second unidirectional conducting element D6 is connected to the second switching circuit 122, and the output terminal of the second unidirectional conducting element D6 is connected to the input circuit 11.

[0041] In this example, the auxiliary converter module includes an input circuit 11, a processing circuit 12, a DC terminal 13, and an AC terminal 14. The input circuit 11 receives DC power from the DC terminal 13. The processing circuit 12, coupled to the input circuit 11 and the AC terminal 14, inverts the received DC power and outputs an AC signal to the AC terminal 14, effectively converting the DC power into three-phase AC power and outputting it to the load connected to the AC terminal 14, thereby driving the load. The load includes, but is not limited to, lighting bulbs, motors, and air conditioning compressors in a rail transit system. The three-phase AC power includes three phases: U, V, and W.

[0042] As an example, such as Figure 1 As shown, the processing circuit 12 includes a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 under phase U; a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 under phase V; and a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 under phase W. In one example, the first unidirectional conducting element D5 and the second unidirectional conducting element D6 include silicon carbide diodes. Figure 1 As shown, both the first unidirectional conducting element D5 and the second unidirectional conducting element D6 are silicon carbide diodes. Specifically, the input terminal of the first unidirectional conducting element D5 is connected to the input circuit 11, and the output terminal is connected to the first switching circuit 121. Its main function is to conduct DC power unidirectionally to the first switching circuit 121, providing a stable input current for the inverter process. The input terminal of the second unidirectional conducting element D6 is connected to the second switching circuit 122, and the output terminal is connected to the input circuit 11. Its main function is to feed current back to the input circuit 11 when the second switching circuit 122 is turned on, forming a regenerative energy loop. In the above example, the fast switching characteristics of silicon carbide diodes ensure efficient energy recovery during switching, reducing energy loss and improving the energy utilization efficiency of the system. At the same time, the low conduction loss and high withstand voltage characteristics of silicon carbide diodes also ensure stable operation under high voltage and high current conditions.

[0043] Specifically, the processing circuit 12 is the core component of the auxiliary converter module. It is responsible for converting DC power into AC signals to meet the needs of AC loads. In this example, the processing circuit 12 employs a unique topology, including a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 for each phase. This design allows DC power to be converted and transmitted through different paths, achieving efficient inverter processing.

[0044] More specifically, the input terminal of the first unidirectional conducting element D5 is connected to the input circuit 11, receiving DC power from the DC end. When DC power is input, the first unidirectional conducting element D5 allows current to flow in one direction, thus providing a stable input for the subsequent switching circuit. The output terminal of the first unidirectional conducting element D5 is connected to the first switching circuit 121. The first switching circuit 121 switches the input DC current according to the corresponding control signal, realizing discontinuous and continuous current control, thereby generating AC pulse signals. The input terminal of the second unidirectional conducting element D6 is connected to the second switching circuit 122. The second switching circuit 122 switches according to the corresponding control signal, working in conjunction with the first switching circuit 121. The output terminal of the second unidirectional conducting element D6 is connected back to the input circuit 11, forming a feedback and regeneration mechanism.

[0045] In the above example, a unidirectional conducting element is added to replace the switching transistor on the basis of the traditional NPC structure, which simplifies the control logic. During operation, only the opening and closing control of the first and second switching circuits under each phase needs to be performed according to the input state of the DC power supply and the load demand of the AC terminal to achieve effective inversion and conversion of DC power supply to AC signal, thereby improving the stability and reliability of the converter.

[0046] In one example, the input circuit 11 has a positive terminal P, a negative terminal N, and a ground terminal O; one end of the first switching circuit 121 under each phase is connected to the positive terminal P, the other end of the first switching circuit 121 under each phase is connected to one end of the second switching circuit 122 under that phase, and the other end of the second switching circuit 122 under that phase is connected to the negative terminal N; the input terminal of the first unidirectional conducting element D5 is connected to the ground terminal O, and the output terminal of the second unidirectional conducting element D6 is connected to the ground terminal O.

[0047] In this example, it is still as follows Figure 1As shown, the input circuit 11 has a positive terminal P, a negative terminal N, and a ground terminal O, each serving a different function. The positive terminal P is the high-potential terminal of the input circuit 11, connected to the positive terminal of the DC power supply. One end of the first switching circuit 121 under each phase is connected to the positive terminal P. The negative terminal N is the low-potential terminal of the input circuit 11, connected to the negative terminal of the DC power supply. The other end of the second switching circuit 122 under each phase is connected to the negative terminal N. When the second switching circuit 122 is turned on, current can flow through it to the negative terminal N, completing the current loop and enabling current flow during the inverter process. The ground terminal O is the reference potential point of the input circuit 11, used to ensure the potential stability and safety of the entire system. The input terminal of the first unidirectional conducting element D5 is connected to the ground terminal O, and the output terminal of the second unidirectional conducting element D6 is connected to the ground terminal O. This example scheme can efficiently and stably convert DC power into multiphase AC signals, meeting the needs of various loads in rail transit systems.

[0048] Based on the previous example, still as Figure 1 As shown, the first switching circuit 121 under each phase includes: a first switching transistor T1 / D1 and a second switching transistor T2 / D2; one end of the first switching transistor T1 / D1 is connected to the positive terminal P, the other end of the first switching transistor T1 / D1 is connected to one end of the second switching transistor T2 / D2 and the output terminal of the first unidirectional conducting element D5, and the other end of the second switching transistor T2 / D2 is connected to the corresponding AC terminal, for turning on or off the transmission path between the positive terminal P and the AC terminal 14 according to the voltage state of the DC power supply.

[0049] Specifically, one end of the first switching transistor T1 / D1 is connected to the positive terminal P of the input circuit 11, and the other end of the first switching transistor T1 / D1 is connected to one end of the second switching transistor T2 / D2 and the output terminal of the first unidirectional conducting element D5. The other end of the second switching transistor T2 / D2 is connected to the corresponding AC terminal. Current can flow from the positive terminal P through the first switching transistor T1 / D1 to the second switching transistor T2 / D2 and then to the corresponding AC terminal, and through the first unidirectional conducting element D5 to carry the current from the ground terminal O to the second switching transistor T2 / D2 and then to the corresponding AC terminal, or current can flow from the corresponding AC terminal through the second switching transistor T2 / D2 to the first switching transistor T1 / D1 and then to the positive terminal P. The first switching transistor T1 / D1 and the second switching transistor T2 / D2 include, but are not limited to, silicon-based IGBTs, silicon carbide-based IGBTs, silicon-based MOSFETs, and silicon carbide-based MOSFETs.

[0050] Still Figure 1As shown, in one example, the second switching circuit 122 under each phase includes: a third switch T3 / D3 and a fourth switch T4 / D4; one end of the third switch T3 / D3 is connected to the corresponding AC terminal, the other end of the third switch T3 / D3 is connected to the input terminal of the second unidirectional conducting element D6 and one end of the fourth switch T4 / D4, and the other end of the fourth switch T4 / D4 is connected to the negative terminal N, for turning on or off the transmission path between the negative terminal N and the AC terminal 14 according to the voltage state of the DC power supply.

[0051] Specifically, one end of the third switch T3 / D3 is connected to the corresponding AC terminal, and the other end of the third switch T3 / D3 is connected to the input terminal of the second unidirectional conducting element D6 and one end of the fourth switch T4 / D4. The other end of the fourth switch T4 / D4 is connected to the negative terminal N. Current can flow from the negative terminal N through the fourth switch T4 / D4 to the third switch T3 / D3 and then to the corresponding AC terminal, or current can flow from the corresponding AC terminal through the third switch T3 / D3 to the fourth switch T4 / D4 and then to the negative terminal N, and through the second unidirectional conducting element D6, the current from the corresponding AC terminal can flow to the third switch T3 / D3 and then to the ground terminal 0. The third switch T3 / D3 and the fourth switch T4 / D4 include, but are not limited to, silicon-based IGBTs, silicon carbide-based IGBTs, silicon-based MOSFETs, and silicon carbide-based MOSFETs.

[0052] Figure 2 This is a current and voltage waveform diagram of an example converter. (Example:) Figure 2 As shown, in this example, when the topology uses SPWM modulation, both voltage u and current i are sine waves, and their expressions are shown in formula (1).

[0053]

[0054] Where u represents voltage; U m Represents the maximum peak value of the voltage; ω represents the angular frequency; t represents time; φ represents the phase angle of the voltage waveform relative to the current waveform; I m This indicates the maximum peak value (amplitude) of the current.

[0055] according to Figure 2 The zero-crossing of voltage and current can divide a modulation cycle into four regions. Figure 3 This diagram illustrates the switching states and commutation paths of the components in the auxiliary converter module. Taking a single phase as an example:

[0056] (1) Region ①: The converter operates in the 0~π-φ region, the voltage u is positive, the current i flows out, the switching mode of the switching transistor switches between 1100 and 0110, the output level of the bridge arm switches between "+" and "0", the devices involved in the commutation are T1, T2, and D5, and the current flow loop is as follows: Figure 3 As shown in (a).

[0057] (2) Region ②: The converter operates in the π-φ~π region, the voltage u is negative, the current i flows out, and the output level of the bridge arm switches between "0" and "-". The devices involved in the commutation are T2, D3, D4, and D5. The current flow loop is as follows: Figure 3 As shown in (b).

[0058] (3) Region ③: The converter operates in the π~2π-φ region, the voltage u is negative, the current i flows in, and the output level of the bridge arm switches between "-" and "0". The devices involved in the commutation are T3, T4, and D6. The current flow loop is as follows: Figure 3 As shown in (c).

[0059] (4) Region ④: The converter operates in the 2π-φ~2π region, the voltage u is positive, the current i flows in, and the output level of the bridge arm switches between "0" and "+". The devices involved in the commutation are T3, D1, D2, and D6. The current flow loop is as follows: Figure 3 As shown in (d).

[0060] The device losses during the commutation process of a type I three-level circuit at various switching states are summarized in Table 1. Here, Econ represents the conduction loss of the power device, Eon and Eoff represent the switching losses of the power device, and Erec represents the reverse recovery loss of the diode.

[0061] Table 1 Relationship between switching timing and power loss

[0062]

[0063] Note: Switch states 1 and 0 indicate on and off, respectively. For example, 1100 indicates that the first and second switches are on, while the third and fourth switches are off.

[0064] It can be seen that in the inverter state, transistors T2 and T3 have the longest conduction time and high conduction losses, while transistors T1 and T4, and diodes D5 and D6 have a high number of switching cycles and high switching losses. In the rectification state, transistors D3 and D4, and diodes D1 and D2 have the longest conduction time and high conduction losses, while transistors T2 and T3, and diodes D1 and D4 have a high number of switching cycles and high switching losses. The power factor of the auxiliary inverter load in rail transit is generally greater than 0.85, but due to the influence of the converter LC filter, the power factor of the auxiliary converter module at different load rates is generally above 0.75, and can reach as high as above 0.95. Table 2 below shows the power factor of the auxiliary converter module under different loads in this example.

[0065] Table 2 Power Factor Table for Auxiliary Converter Modules

[0066] load rate Output power Output current Current angle Output voltage Voltage angle Power factor 20％ 48 39.34 -13.5 667 32.8 0.96 40％ 96 80.5 -21.9 675 34.1 0.90 60％ 144 122 -24.6 686 35.4 0.87 80％ 192 164 -26 697 36.6 0.84 100％ 240 206 -26.8 708 37.7 0.82 120％ 288 248 -27.5 718 38.7 0.81 140％ 336 288 -28.2 730 39.6 0.79 160％ 384 330 -28.6 742 40.5 0.78 180％ 432 372 -28.9 753 41.4 0.76 200％ 480 414 -29.1 765 42.3 0.75

[0067] Figure 4 The graph shows a comparison of the on-state voltage drops of silicon carbide-based MOSFETs and silicon-based IGBTs of the same specification (1700V / 300A). It can be seen that under low current conditions (less than 70A), the on-state voltage drop of silicon carbide-based MOSFETs is smaller than that of IGBTs, while under medium to high current conditions, the on-state voltage drop of silicon carbide-based MOSFETs is larger than that of IGBTs.

[0068] Figure 5 The comparison chart of switching losses of power devices shows that, under the same current and temperature, the switching loss of silicon carbide-based MOSFETs is much smaller than that of IGBTs, and the reverse recovery loss of silicon carbide diodes is extremely small, close to 0, which is also much smaller than that of ordinary silicon diodes.

[0069] Based on the above characteristics, in order to reduce the switching losses of transistors T1 / T4 and D5 / D6, the auxiliary converter module uses silicon carbide-based MOSFETs with a rated current of 300A for T1 / T4; and silicon carbide diodes with a rated current of 300A for D5 / D6. This reduces switching losses while increasing the switching frequency. In order to reduce the conduction losses of transistors T2 / T3, silicon-based IGBTs with a rated current of 600A are used to reduce conduction losses and save on the cost of power devices.

[0070] Tables 3, 4, and 5 below show the simulation results of losses and junction temperatures for four schemes—a traditional auxiliary converter module (switching frequencies of 4350Hz and 13350Hz), a fully silicon carbide-based MOSFET, and a silicon carbide-based MOSFET + silicon-based IGBT—under power factor conditions of 0.95, 0.85, and 0.75, respectively. It can be seen that:

[0071] 1. The traditional silicon-based IGBT switching frequency can only operate at 4350Hz, and its losses are relatively large;

[0072] 2. Both the silicon carbide-based MOSFET + silicon-based IGBT in this example and the all-silicon carbide-based MOSFET can operate at a switching frequency of 13350Hz, and the losses and junction temperatures of the two are very similar under all operating conditions. In some operating conditions, this example is superior to the all-silicon carbide-based MOSFET solution.

[0073] Table 3 Comparison of losses and junction temperature (power factor 0.95)

[0074]

[0075]

[0076] Table 4 Comparison of losses and junction temperature (power factor 0.85)

[0077]

[0078] Table 5 Comparison of losses and junction temperature (power factor 0.75)

[0079]

[0080] Note: ①62+405, 62 is the on-state loss, and 405 is the switching loss; ②Water-cooled radiator parameters: thermal resistance 0.01K / W, inlet temperature 65℃.

[0081] In the above example, the first, second, third, and fourth switching circuits use hybrid (SiC / Si) power devices of silicon carbide-based MOSFETs and silicon-based IGBTs. This reduces hardware costs while achieving the performance of all-silicon carbide devices. At the same time, it adopts the control strategy of the traditional NPC structure, reducing the software development cost of the project.

[0082] In one example, the input circuit 11 includes: a first capacitor and a second capacitor; one end of the first capacitor is connected to the positive terminal P and one end of the first switching circuit 121 under each phase, and the other end of the first capacitor is connected to the ground terminal O and one end of the second capacitor; the other end of the second capacitor is connected to the negative terminal N and the other end of the second switching circuit 122 under each phase, for filtering the received DC power supply.

[0083] In this example, the auxiliary converter module needs to process DC power from batteries, rectifiers, or other power supply devices. These power supplies may introduce various noises and ripples during conversion, affecting the performance and reliability of the auxiliary converter module. By incorporating a first capacitor and a second capacitor in the input circuit 11, effective filtering of the DC power supply can be achieved. The first and second capacitors can absorb high-frequency noise and ripple in the DC power supply, reducing their impact on subsequent circuits and improving the stability and purity of the power supply. During switching circuit transitions, the first and second capacitors can temporarily store and release energy, helping to maintain voltage stability and reduce voltage fluctuations. By absorbing and releasing energy, voltage spikes and current surges can be reduced, protecting other components in the circuit and extending the lifespan of the entire system. Through the solution in this example, the first and second capacitors provide a stable and pure DC power supply for the auxiliary converter module, ensuring the efficient and reliable operation of the entire system.

[0084] Based on the aforementioned example, the input circuit 11 further includes: a protection circuit; one end of the protection circuit is connected to the positive terminal P, one end of the first capacitor, and one end of the first switching circuit 121 under each phase, and the other end of the protection circuit is connected to the negative terminal N, the other end of the second capacitor, and the other end of the second switching circuit 122 under each phase, for detecting the voltage across the first capacitor and the second capacitor, and balancing the voltage across the first capacitor and the second capacitor according to the detection result.

[0085] In this example, the protection circuit detects the voltage across the first and second capacitors, acquiring their voltage values ​​in real time and comparing them with a preset safe voltage threshold. In one example, the protection circuit includes a first sensor and a second sensor. One end of the first sensor is connected to the positive terminal P, one end of the first capacitor, and one end of the first switching circuit 121 under each phase; the other end of the first sensor is connected to one end of the second sensor and the ground terminal N. The other end of the second sensor is connected to the negative terminal N, the other end of the second capacitor, and the other end of the second switching circuit 122 under each phase. When the first and second sensors detect that the voltage across either capacitor exceeds the safe threshold, an balancing mechanism is automatically activated to ensure that the voltages across the two capacitors remain balanced, preventing capacitor damage due to excessively high or low voltage. In addition to voltage balancing, when an abnormal situation is detected (such as a voltage surge, capacitor short circuit, etc.), the power supply is immediately cut off to prevent the fault from escalating and protect the entire auxiliary converter module from damage. This example solution enables effective monitoring and balancing of the voltage across the capacitors, improving the system's reliability and safety.

[0086] In one example, the input circuit 11 further includes: a first resistor and a second resistor; one end of the first resistor is connected to the positive terminal P, one end of the protection circuit, one end of the first capacitor, and one end of the first switching circuit 121 under each phase; the other end of the first resistor is connected to one end of the second resistor and the ground terminal O; the other end of the second resistor is connected to the negative terminal N, the other end of the protection circuit, the other end of the second capacitor, and the other end of the second switching circuit 122 under each phase.

[0087] In this example, the primary function of the first and second resistors is to limit the current flowing through the circuit. During circuit startup or sudden load changes, the first and second resistors prevent excessive current surges, protecting sensitive components such as capacitors and switching devices. They can also be used to divide the voltage, providing appropriate operating voltages to other components in the circuit. By precisely selecting the resistor values, it can be ensured that each part of the circuit operates at its optimal voltage, thereby improving the efficiency and reliability of the entire system.

[0088] The auxiliary converter module provided in this embodiment includes: an input circuit 11, a processing circuit 12, a DC terminal 13, and an AC terminal 14. The input circuit 11 is connected to the DC terminal 13 and is used to receive DC power. The processing circuit 12 is coupled to the input circuit 11 and the AC terminal 13, and is used to invert the DC power and output an AC signal to the AC terminal 14. The AC signal includes multiple phases. The processing circuit 12 includes a first switching circuit 121, a second switching circuit 122, a first unidirectional conducting element D5, and a second unidirectional conducting element D6 for each phase. The input terminal of the first unidirectional conducting element D5 is connected to the input circuit 11, and its output terminal is connected to the first switching circuit 121. The input terminal of the second unidirectional conducting element D6 is connected to the second switching circuit 122, and its output terminal is connected to the input circuit 11. This application's solution, based on the traditional NPC structure, adds unidirectional conducting elements to replace the switching transistors, thus simplifying the control logic. During operation, the first and second switching circuits under each phase can be switched on and off according to the input status of the DC power supply and the load requirements of the AC terminal to achieve effective inversion and conversion of DC power supply to AC signal, thereby improving the stability and reliability of the converter.

[0089] Example 2

[0090] The auxiliary converter module structure provided in this application will be described in detail below with a specific embodiment.

[0091] Figure 6 This is a schematic diagram of an auxiliary converter module structure provided in Embodiment 2 of this application. Figure 6As shown in the diagram, P represents the positive terminal; N represents the negative terminal; 0 represents the ground terminal; DCPT1 represents the first sensor; DCPT2 represents the second sensor; FC1 represents the first capacitor; FC2 represents the second capacitor; R1 represents the first resistor; R2 represents the second resistor; T1 / D1 represents the first switching transistor under each phase; T2 / D2 represents the second switching transistor under each phase; T3 / D3 represents the third switching transistor under each phase; T4 / D4 represents the fourth switching transistor under each phase; D5 represents the first unidirectional conducting element; D6 represents the second unidirectional conducting element; UVW represents the three-phase AC terminals.

[0092] In summary, the auxiliary converter module provided in this embodiment simplifies the control logic by adding unidirectional conducting elements to replace switching transistors on the basis of the traditional NPC structure. During operation, only the opening and closing control of the first and second switching circuits under each phase needs to be performed according to the input state of the DC power supply and the load demand of the AC terminal to achieve effective inversion and conversion of DC power supply to AC signal, thereby improving the stability and reliability of the converter.

[0093] Example 3

[0094] This application also provides an auxiliary converter device, including: a driver board and an auxiliary converter module as in any of the foregoing examples. Figure 7 This is a diagram showing the distribution of components in the auxiliary converter module. Figure 8 The diagram below shows the external appearance of the auxiliary converter module. Specifically, the driver board is directly soldered onto the first, second, third, and fourth switching transistors, the first unidirectional conducting element, and the second unidirectional conducting element. The driver board's external interface uses a 20-pin connector, the definition of which is shown in Table 6.

[0095] Table 6 External Interfaces of the Driver Board

[0096]

[0097] In one example, the auxiliary converter also includes a signal configuration board; all wiring within the auxiliary converter module is integrated onto the signal configuration board. Specifically, the signal configuration board is located at the bottom of the auxiliary converter module. Its main function is signal processing and distribution. It performs logic conversion on the control signals from the controller and sends them to the driver boards accordingly. Simultaneously, it performs logic conversion on the feedback signals from each driver board and sends them to the control unit. Furthermore, the configuration board distributes the DC 15V gate power supply to each driver board. A diagram of the signal configuration board is shown below. Figure 9 As shown, the signal distribution board has a total of 11 external connectors. The 6-pin connector CN1 is the 15V power input interface, the 50-pin connector CN2 is the signal input and feedback interface, and the nine 10-pin connectors CN3 to CN11 are the interfaces between the signal configuration board and the driver board. The driver board and the signal configuration board are connected by a wiring harness.

[0098] Since the auxiliary converter module has a lot of internal wiring, the use of a signal configuration board simplifies the internal wiring of the auxiliary converter module, making the auxiliary converter module structure look cleaner. At the same time, it reduces electromagnetic interference between wire harnesses and improves the reliability of the converter.

[0099] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the utility models disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0100] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. An auxiliary converter module, characterized in that, include: Input circuit, processing circuit, DC terminal and AC terminal; The input circuit is connected to the DC terminal and is used to receive DC power. The processing circuit is coupled to the input circuit and the AC terminal, and is used to perform inverter processing on the DC power supply and output an AC signal to the AC terminal, wherein the AC signal includes multiple phases; The processing circuit includes a first switching circuit, a second switching circuit, a first unidirectional conducting element, and a second unidirectional conducting element for each phase; the input terminal of the first unidirectional conducting element is connected to the input circuit, the output terminal of the first unidirectional conducting element is connected to the first switching circuit, the input terminal of the second unidirectional conducting element is connected to the second switching circuit, and the output terminal of the second unidirectional conducting element is connected to the input circuit.

2. The auxiliary converter module according to claim 1, characterized in that, The input circuit has a positive terminal, a negative terminal, and a ground terminal; One end of the first switching circuit under each phase is connected to the positive terminal, the other end of the first switching circuit under each phase is connected to one end of the second switching circuit under that phase, and the other end of the second switching circuit under that phase is connected to the negative terminal; the input terminal of the first unidirectional conducting element is connected to the ground terminal, and the output terminal of the second unidirectional conducting element is connected to the ground terminal.

3. The auxiliary converter module according to claim 2, characterized in that, The first switching circuit under each phase includes: a first switching transistor and a second switching transistor; One end of the first switching transistor is connected to the positive terminal, and the other end of the first switching transistor is connected to one end of the second switching transistor and the output terminal of the first unidirectional conducting element. The other end of the second switching transistor is connected to the corresponding AC terminal, which is used to turn on or off the transmission path between the positive terminal and the AC terminal according to the voltage state of the DC power supply.

4. The auxiliary converter module according to claim 2, characterized in that, The second switching circuit under each phase includes: a third switching transistor and a fourth switching transistor; One end of the third switch is connected to the corresponding AC terminal, the other end of the third switch is connected to the input terminal of the second unidirectional conducting element and one end of the fourth switch, and the other end of the fourth switch is connected to the negative terminal, for conducting or disconnecting the transmission path between the negative terminal and the AC terminal according to the voltage state of the DC power supply.

5. The auxiliary converter module according to claim 2, characterized in that, The input circuit includes: a first capacitor and a second capacitor; One end of the first capacitor is connected to the positive terminal and one end of the first switching circuit under each phase; the other end of the first capacitor is connected to the ground terminal and one end of the second capacitor; the other end of the second capacitor is connected to the negative terminal and the other end of the second switching circuit under each phase, for filtering the received DC power supply.

6. The auxiliary converter module according to claim 5, characterized in that, The input circuit also includes: a protection circuit; One end of the protection circuit is connected to the positive terminal, one end of the first capacitor, and one end of the first switching circuit under each phase. The other end of the protection circuit is connected to the negative terminal, the other end of the second capacitor, and the other end of the second switching circuit under each phase. It is used to detect the voltage across the first capacitor and the second capacitor, and to balance the voltage across the first capacitor and the second capacitor based on the detection result.

7. The auxiliary converter module according to claim 6, characterized in that, The protection circuit includes: a first sensor and a second sensor; One end of the first sensor is connected to the positive terminal, one end of the first capacitor, and one end of the first switching circuit under each phase; the other end of the first sensor is connected to one end of the second sensor and the ground terminal; the other end of the second sensor is connected to the negative terminal, the other end of the second capacitor, and the other end of the second switching circuit under each phase.

8. The auxiliary converter module according to claim 6, characterized in that, The input circuit further includes: a first resistor and a second resistor; One end of the first resistor is connected to the positive terminal, one end of the protection circuit, one end of the first capacitor, and one end of the first switching circuit under each phase; the other end of the first resistor is connected to one end of the second resistor and the ground terminal; the other end of the second resistor is connected to the negative terminal, the other end of the protection circuit, the other end of the second capacitor, and the other end of the second switching circuit under each phase.

9. The auxiliary converter module according to any one of claims 1-8, characterized in that, The first unidirectional conducting element and the second unidirectional conducting element include: silicon carbide diodes.

10. An auxiliary converter device, characterized in that, include: The driver board and the auxiliary converter module as described in any one of claims 1-9.

11. The auxiliary converter according to claim 10, characterized in that, The auxiliary converter device also includes a signal configuration board; all wiring within the auxiliary converter module is integrated on the signal configuration board.

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