Converter module, converter and traction transmission system

Abstract

The invention provides a converter module, a converter and a traction transmission system. The converter module comprises a pre-charging unit and a filtering unit, the first input end of the at least one inversion unit is connected with the first end of the supporting capacitor, the second input end of the at least one inversion unit is connected with the second end of the supporting capacitor, the output end of the at least one inversion unit is connected with the traction motor, and the inversion unit comprises a three-phase inversion circuit. The three-phase inverter circuit comprises three branches which are in bridge connection with one another, and each branch comprises two SiC MOSFETs. By using a silicon carbide semiconductor device with high switching speed and low switching loss, the loss of the traction converter can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and in particular to a converter module, a converter and a traction drive system. Background Art

[0002] With the rapid development of urban rail transit in my country, the number of subway vehicles has increased year by year, and users have put forward higher and higher requirements for energy saving of vehicle traction systems, which has also promoted the continuous advancement of vehicle traction system technology. From the initial DC traction system to the asynchronous AC traction system, and then to the permanent magnet AC synchronous traction system that is gradually being promoted and applied, they are all moving towards the goal of lower energy consumption.

[0003] However, the power device commonly used in traditional traction inverters is IGBT (Insulated Gate Bipolar Transistor). Due to the increasingly high requirements for traction drive systems, the switching speed of IGBT is relatively slow and it is easy to generate more voltage harmonics, which will increase the energy consumption of traction motors.

[0004] Therefore, a new traction inverter is needed to solve the above problems. Summary of the invention

[0005] The main purpose of the present invention is to provide a converter module, a converter and a traction drive system to reduce the generation of voltage harmonics.

[0006] The present invention provides a converter module, comprising: a pre-charging unit, whose input end is connected to the first pole of a DC input end, and is used to charge a supporting capacitor in a filter unit when the converter is started; a filter unit, comprising a first inductor and a supporting capacitor, wherein the first end of the first inductor is connected to the output end of the pre-charging unit, the second end of the first inductor is connected to the first end of the supporting capacitor, and the second end of the supporting capacitor is connected to the second pole of the DC input end; at least one inverter unit, wherein the first input end of the at least one inverter unit is respectively connected to the first end of the supporting capacitor, the second input end of the at least one inverter unit is respectively connected to the second end of the supporting capacitor, and the output end of the at least one inverter unit is respectively connected to a traction motor, and the inverter unit comprises a three-phase inverter circuit, and the three-phase inverter circuit comprises three branches bridged to each other, and each branch comprises two SiC MOSFETs.

[0007] In one embodiment, the pre-charging unit includes: a first contactor, a second contactor and a charging resistor; wherein, the first end of the first contactor is connected to the first pole of the DC input terminal, the second end of the first contactor is connected to the first end of the first inductor, the first end of the second contactor is connected to the first pole of the DC input terminal, the second end of the second contactor is connected to the first end of the charging resistor, and the second end of the charging resistor is connected to the first end of the first inductor.

[0008] In one embodiment, it further includes: a first magnetic ring, the first magnetic ring surrounds the first pole and the second pole of the DC input terminal; and at least one second magnetic ring, the at least one second magnetic ring respectively surrounds the output terminal of at least one inverter unit.

[0009] In one embodiment, it further includes: at least one three-phase filter, the input end of the at least one three-phase filter is respectively connected to the output end of the at least one inverter unit, and the output end of the at least one three-phase filter is respectively connected to the traction motor.

[0010] In one embodiment, the three-phase filter includes at least: three second inductors and three filter capacitors; wherein the first ends of the three second inductors are respectively connected to the three-phase output ends of the inverter unit, the second ends of the three second inductors are respectively connected to the first ends of the three filter capacitors and the input end of the traction motor, and the second ends of the three filter capacitors are connected to each other.

[0011] In one embodiment, it further includes: a chopping unit, a first end of the chopping unit is connected to the first end of the supporting capacitor, and a second end of the chopping unit is connected to the second end of the supporting capacitor.

[0012] In one embodiment, the chopping unit includes: a switching tube, a first diode, a second diode and a braking resistor; wherein the control end of the switching tube receives a control signal, the first end of the switching tube is connected to the first end of the supporting capacitor and the cathode of the first diode, the second end of the switching tube is connected to the first end of the braking resistor, the anode of the first diode and the cathode of the second diode, the second end of the braking resistor is connected to the second end of the supporting capacitor, and the anode of the second diode is connected to the second end of the supporting capacitor.

[0013] In one embodiment, the traction motor includes a permanent magnet synchronous traction motor; the converter module also includes: at least one three-phase isolation contactor, the input ends of the at least one three-phase isolation contactor are respectively connected to the output ends of the at least one inverter unit, and the output ends of the at least one three-phase isolation contactor are respectively connected to the traction motor.

[0014] The present invention provides a converter, comprising the above converter module.

[0015] The present invention provides a traction drive system, comprising the above-mentioned converter.

[0016] The present invention provides a converter module, which can reduce the loss of the traction converter by using a silicon carbide semiconductor device (SiC MOSFET) with high switching speed and low switching loss, and reduce the harmonic content of the three-phase voltage on the AC output side by increasing the switching frequency of the inverter circuit, thereby reducing the harmonic loss of the traction motor, and ultimately achieving energy saving and emission reduction of the traction system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute a part of the present application, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

[0018] In the figure:

[0019] Figure 1 is a circuit topology diagram of a converter module according to an embodiment of the present application;

[0020] Figure 2 is a circuit topology diagram of a converter module according to a second embodiment of the present application;

[0021] Figure 3 is a circuit topology diagram of a converter module according to a third embodiment of the present application;

[0022] Figure 4 is a circuit topology diagram of a converter module according to a fourth embodiment of the present application;

[0023] Figure 5 is a schematic structural diagram of a three-phase filter according to an embodiment of the present application;

[0024] Figure 6 Schematic diagram of the structure of a three-phase filter according to another embodiment of the present application. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] refer to Figure 1 The present embodiment provides a converter module, including: a pre-charging unit 100, whose input end is connected to the first pole of the DC input end, and is used to charge the support capacitor C in the filter unit 200 when the converter is started; the filter unit 200, including a first inductor L and a support capacitor C, the first end of the first inductor L is connected to the output end of the pre-charging unit 100, the second end of the first inductor L is connected to the first end of the support capacitor C, and the second end of the support capacitor C is connected to the second pole of the DC input end; at least one inverter unit 300, the first input end of at least one inverter unit 300 is respectively connected to the first end of the support capacitor C, the second input end of at least one inverter unit 300 is respectively connected to the second end of the support capacitor C, the output end of at least one inverter unit 300 is respectively connected to the traction motor (M1~M4, PM1~PM4), the inverter unit 300 includes a three-phase inverter circuit, the three-phase inverter circuit includes three branches bridged to each other, and each branch includes two SiC MOSFETs.

[0027] In this embodiment, the number of inverter units can be multiple. When driving a permanent magnet synchronous traction motor, each inverter unit can be set to drive a permanent magnet synchronous motor respectively. When driving an asynchronous traction motor, one inverter unit can drive multiple asynchronous traction motors at the same time. The number of inverter units can also be configured according to the power requirements of the vehicle. This application does not make any specific limitations on this.

[0028] In the converter module of this embodiment, SiC MOSFET is used to replace the conventional IGBT. Since SiC MOSFET has a higher switching speed, the energy consumption during each switching process is much lower than that of the traditional IGBT device, thereby reducing the loss during the operation of the converter module; since the switching loss of SiC MOSFET devices is lower, under the same heat dissipation conditions, SiC MOSFET devices can operate at a higher switching frequency; when the three-phase AC output voltage is modulated by PWM (Pulse Width Modulation, pulse width modulation circuit), the high switching frequency of SiC MOSFET devices can reduce the harmonic content of the output voltage. The three-phase AC output voltage is the input voltage of the traction motor. Reducing the voltage harmonic content can reduce the harmonic loss of the traction motor. The interference of grid-side harmonics on the converter module can be reduced by the filtering unit 200.

[0029] refer to Figure 4 In another embodiment, the converter module may further include: a first current detection unit 700, which may include a first current sensor BC11 and a second current sensor BC12, the first current sensor BC11 is connected between the first pole of the DC input terminal and the input terminal of the pre-charging unit 100, and the second current sensor BC12 is connected between the second pole of the DC input terminal and the second end of the supporting capacitor C.

[0030] The first current sensor BC11 and the second current sensor BC12 detect the currents at the first pole and the second pole of the DC input terminal respectively, so that it is possible to determine whether a ground fault occurs in the back-end circuit according to the difference between the currents measured by the first current sensor BC11 and the second current sensor BC12.

[0031] In this embodiment, the first current detection unit may also be replaced by other short-circuit protection devices (eg, an overload relay) to protect the circuit, and those skilled in the art may make a selection as needed.

[0032] Continue to refer Figure 4In one embodiment, it may also include: a second current detection unit 800, which may include a third current sensor BC31~BC61 and a fourth current sensor BC32~BC62, and the third current sensor BC31~BC61 and the fourth current sensor BC32~BC62 may be respectively connected in series on two of the three-phase output lines of the inverter unit 300.

[0033] Continue to refer Figure 4 In one embodiment, it may also include: a first voltage sensor BV1 and a second voltage sensor BV2, the first voltage sensor BV1 is connected between the first pole and the second pole of the DC input terminal, and is used to detect the input grid voltage, and the second voltage sensor BV2 is connected between the first end and the second end of the supporting capacitor C, and is used to detect the voltage across the supporting capacitor C.

[0034] In one embodiment, the pre-charging unit 100 may include: a first contactor KM1, a second contactor KM2 and a charging resistor R1; wherein, the first end of the first contactor KM1 is connected to the first pole of the DC input terminal, the second end of the first contactor KM1 is connected to the first end of the first inductor L, the first end of the second contactor KM2 is connected to the first pole of the DC input terminal, the second end of the second contactor KM2 is connected to the first end of the charging resistor R1, and the second end of the charging resistor R1 is connected to the first end of the first inductor L.

[0035] In one embodiment, it may also include: a first magnetic ring Z1, the first magnetic ring Z1 surrounds the first pole and the second pole of the DC input terminal; at least one second magnetic ring Z2~Z5, at least one second magnetic ring Z2~Z5 surrounds the output terminal of at least one inverter unit 300 respectively.

[0036] The high switching speed of SiC MOSFET devices can increase the voltage change speed at the output of the inverter unit, thereby increasing the slope of voltage rise and fall, which may introduce high-frequency voltage harmonics into the circuit. High-frequency voltage harmonics may cause high-frequency electromagnetic radiation.

[0037] In this embodiment, by providing the first magnetic ring Z1 at the DC input end and the second magnetic ring Z2 at the output end of the inverter unit, possible high-frequency electromagnetic radiation in the circuit can be effectively suppressed.

[0038] In one embodiment, the system may further include: a chopping unit 500 , wherein a first end of the chopping unit 500 is connected to a first end of the supporting capacitor C, and a second end of the chopping unit 500 is connected to a second end of the supporting capacitor C.

[0039] In one embodiment, the chopping unit 500 includes: a switch tube Q, a first diode D1, a second diode D2 and a braking resistor R2; wherein the control end of the switch tube Q receives a control signal, the first end of the switch tube Q is connected to the first end of the supporting capacitor C and the cathode of the first diode D1, the second end of the switch tube Q is connected to the first end of the braking resistor R2, the anode of the first diode D1 and the cathode of the second diode D2, the second end of the braking resistor R2 is connected to the second end of the supporting capacitor C, and the anode of the second diode D2 is connected to the second end of the supporting capacitor C.

[0040] The switch tube may be an IGBT or other switching device that meets the requirements, and this application does not make any specific limitation on this.

[0041] In this embodiment, when the voltage across the supporting capacitor C is too high, the overvoltage can be released through the braking resistor R2 by turning on the switch tube.

[0042] In another embodiment, it may further include: a fifth current sensor BC2 connected in series between the second end of the switch tube Q and the first end of the braking resistor R2, for detecting the chopping current.

[0043] refer to Figure 2 and Figure 4 In one embodiment, it may also include: at least one three-phase filter 400, the input end of at least one three-phase filter 400 is respectively connected to the output end of at least one inverter unit 300, and the output end of at least one three-phase filter 400 is respectively connected to the traction motor.

[0044] refer to Figure 2 In one embodiment, the three-phase filter 400 may include at least: three second inductors Lf1~Lf4 and three filter capacitors Cf1~Cf4; wherein the first ends of the three second inductors Lf1~Lf4 are respectively connected to the three-phase output terminals U1~U4, V1~V4 and W1~W4 of the inverter unit 300, the second ends of the three second inductors Lf1~Lf4 are respectively connected to the first ends of the three filter capacitors Cf1~Cf4 and the input terminal of the traction motor, and the second ends of the three filter capacitors Cf1~Cf4 are connected to each other.

[0045] refer to Figure 4In one embodiment, the three-phase filter 410 may include: three second inductors Lf1~Lf4, three filter capacitors Cf1~Cf4 and three filter resistors Rf1~Rf4; wherein the first ends of the three second inductors Lf1~Lf4 are respectively connected to the three-phase output terminals U1~U4, V1~V4 and W1~W4 of the inverter unit 300, the second ends of the three second inductors Lf1~Lf4 are respectively connected to the first ends of the three filter capacitors Cf1~Cf4 and the input end of the traction motor, the second ends of the three filter capacitors Cf1~Cf4 are respectively connected to the first ends of the three filter resistors Rf1~Rf4, and the second ends of the three filter resistors Rf1~Rf4 are connected to each other.

[0046] refer to Figure 5 In one embodiment, the three-phase filter 420 may include: three second inductors Lf1, three third inductors Lf5 and three filter capacitors Cf1; wherein the first ends of the three second inductors Lf1 are respectively connected to the three-phase output ends of the inverter unit 300, the second ends of the three second inductors Lf1 are respectively connected to the first ends of the three filter capacitors Cf1 and the first ends of the three third inductors Lf5, the second ends of the three filter capacitors Cf1 are connected to each other, and the second ends of the three third inductors Lf5 are connected to the input end of the traction motor.

[0047] refer to Figure 6 In one embodiment, the three-phase filter 420 may include: three second inductors Lf1, three third inductors Lf5, three filter capacitors Cf1 and three filter resistors Rf1; wherein, the first ends of the three second inductors Lf1 are respectively connected to the three-phase output ends of the inverter unit 300, the second ends of the three second inductors Lf1 are respectively connected to the first ends of the three filter capacitors Cf1 and the first ends of the three third inductors Lf5, the second ends of the three filter capacitors Cf1 are respectively connected to the first ends of the three filter resistors Rf1, the second ends of the three filter resistors Rf1 are connected to each other, and the second ends of the three third inductors Lf5 are connected to the input end of the traction motor.

[0048] The high switching speed of SiC MOSFET devices can increase the voltage change speed at the output of the inverter unit, thereby increasing the slope of voltage rise and fall, which may introduce high-frequency voltage harmonics into the circuit. High-frequency voltage harmonics may cause overvoltage in the circuit. When the overvoltage is high, the insulation design of the traction motor winding may be damaged.

[0049] In this embodiment, by providing a three-phase filter at the output end of each inverter unit, the overvoltage in the circuit can be effectively reduced and the insulation of the traction motor winding can be prevented from being damaged.

[0050] exist Figure 1 and Figure 2In the embodiment, the traction motor may include four asynchronous traction motors.

[0051] exist Figure 3 and Figure 4 In the embodiment, the traction motor may include a permanent magnet synchronous traction motor; the converter module may also include: at least one three-phase isolation contactor 600 (KM3~KM6), the input end of at least one three-phase isolation contactor KM3~KM6 is respectively connected to the output end of at least one inverter unit 300, and the output end of at least one three-phase isolation contactor is respectively connected to the traction motor.

[0052] In this embodiment, by setting up a three-phase isolation contactor, each permanent magnet synchronous traction motor can be isolated to prevent the back electromotive force generated by the permanent magnet synchronous traction motor from affecting the normal operation of other functional units when a permanent magnet synchronous traction motor fails during vehicle operation.

[0053] This embodiment provides a converter, including the above converter module.

[0054] The converter module of the present invention can effectively reduce the loss of the traction converter, and by increasing the switching frequency of the inverter unit, the voltage harmonic content of the AC output end can be reduced, the harmonic loss of the traction motor can be reduced, and ultimately the overall efficiency of the traction system can be improved.

[0055] This embodiment provides a traction drive system, including the above-mentioned converter.

[0056] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. When the terms "include" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0057] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of this application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that the terms used in this way can be interchangeable under appropriate circumstances.

[0058] It should be understood that the exemplary embodiments in this specification can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps. These embodiments are provided to make the disclosure of this application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art, and should not be construed as limitations on the present invention.

[0059] Although the spirit and principle of the present invention have been described with reference to several specific embodiments, it should be understood that the present invention is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined to benefit, and such division is only for the convenience of expression. The present invention is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A converter module, characterized in that: include: A pre-charging unit, whose input terminal is connected to the first pole of the DC input terminal, and is used to charge the support capacitor in the filter unit when the converter is started; The filtering unit comprises a first reactor and a supporting capacitor, wherein a first end of the first reactor is connected to an output end of the pre-charging unit, a second end of the first reactor is connected to a first end of the supporting capacitor, and a second end of the supporting capacitor is connected to a second pole of the DC input end; At least one inverter unit, a first input end of at least one inverter unit is respectively connected to the first end of the support capacitor, a second input end of at least one inverter unit is respectively connected to the second end of the support capacitor, and an output end of at least one inverter unit is respectively connected to the traction motor, wherein the inverter unit comprises a three-phase inverter circuit, wherein the three-phase inverter circuit comprises three branches bridged to each other, and each branch comprises two SiC MOSFETs.

2. The converter module according to claim 1, characterized in that: The pre-charging unit comprises: A first contactor, a second contactor and a charging resistor; Among them, the first end of the first contactor is connected to the first pole of the DC input end, the second end of the first contactor is connected to the first end of the first inductor, the first end of the second contactor is connected to the first pole of the DC input end, the second end of the second contactor is connected to the first end of the charging resistor, and the second end of the charging resistor is connected to the first end of the first inductor.

3. The converter module according to claim 1, characterized in that: Also includes: a first magnetic ring, wherein the first magnetic ring surrounds a first pole and a second pole of the DC input terminal; At least one second magnetic ring, wherein at least one second magnetic ring respectively surrounds at least one output end of the inverter unit.

4. The converter module according to claim 1, characterized in that: Also includes: At least one three-phase filter, the input end of at least one of the three-phase filters is respectively connected to the output end of at least one of the inverter units, and the output end of at least one of the three-phase filters is respectively connected to the traction motor.

5. The converter module according to claim 4, characterized in that: The three-phase filter comprises at least: three second reactors and three filter capacitors; Among them, the first ends of the three second inductors are respectively connected to the three-phase output ends of the inverter unit, the second ends of the three second inductors are respectively connected to the first ends of the three filter capacitors and the input end of the traction motor, and the second ends of the three filter capacitors are connected to each other.

6. The converter module according to claim 1, characterized in that: Also includes: A chopping unit, wherein a first end of the chopping unit is connected to a first end of the supporting capacitor, and a second end of the chopping unit is connected to a second end of the supporting capacitor.

7. The converter module according to claim 6, characterized in that: The chopping unit comprises: A switch tube, a first diode, a second diode and a braking resistor; Among them, the control end of the switch tube receives a control signal, the first end of the switch tube is connected to the first end of the support capacitor and the cathode of the first diode, the second end of the switch tube is connected to the first end of the braking resistor, the anode of the first diode and the cathode of the second diode, the second end of the braking resistor is connected to the second end of the support capacitor, and the anode of the second diode is connected to the second end of the support capacitor.

8. The converter module according to claim 1, characterized in that: The traction motor comprises a permanent magnet synchronous traction motor; The converter module further comprises: At least one three-phase isolation contactor, the input end of at least one of the three-phase isolation contactors is respectively connected to the output end of at least one of the inverter units, and the output end of at least one of the three-phase isolation contactors is respectively connected to the traction motor.

9. A converter, characterized in that: The invention comprises a converter module as claimed in any one of claims 1 to 8.

10. A traction drive system, characterized in that: Comprising the converter as claimed in claim 9.

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