Permanent magnet traction system

Abstract

The embodiment of the invention provides a permanent magnet traction system. The permanent magnet traction system comprises a permanent magnet motor. The traction converter is connected with the permanent magnet motor; the traction converter comprises a pre-charging loop, a four-quadrant rectification module, a supporting capacitor, a discharging resistor, a grounding detection loop, a chopping loop and a three-phase inverter. The pre-charging loop is connected with the three-phase inverter through the four-quadrant rectification module, the supporting capacitor, the discharging resistor, the grounding detection loop and the chopping loop in sequence; the three-phase inverter is connected with the permanent magnet motor through a three-pole isolation contactor; when the permanent magnet traction system works at a high speed, in the process that the three-pole isolation contactor is not completely disconnected, the three-phase inverter is controlled to be subjected to flux weakening to restrain back electromotive force, and back electromotive force recharge is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of permanent magnet traction electric transmission systems for rail transit, and in particular to a permanent magnet traction system. Background Art

[0002] With the rapid development of the rail transit industry, permanent magnet synchronous traction system technology will become the main technical development direction of the new generation of rail transit. The permanent magnet traction system has significant advantages such as high efficiency and high power density. It is in line with the technical development direction of green, efficient, energy-saving and environmentally friendly rail transit and has broad application prospects.

[0003] However, in the existing traction system, when the traction motor operates at high speed, if the traction inverter does not work, the back electromotive force of the traction motor will be rectified to the intermediate circuit through the traction inverter diode, causing the traction inverter IGBT device and various components of the intermediate circuit to be subjected to higher voltage and cause component damage.

[0004] Therefore, how to solve the above problems is an issue that needs to be solved urgently. Summary of the invention

[0005] The present application provides a permanent magnet traction system, aiming to improve the above-mentioned problems.

[0006] In a first aspect, the present application provides a permanent magnet traction system, comprising:

[0007] Permanent magnet motor;

[0008] A traction converter, wherein the traction converter is connected to the permanent magnet motor;

[0009] Wherein, the traction converter comprises:

[0010] Pre-charging circuit, four-quadrant rectifier module, supporting capacitor, discharge resistor, ground detection circuit, chopper circuit and three-phase inverter;

[0011] The pre-charging circuit is connected to the three-phase inverter through the four-quadrant rectifier module, the support capacitor, the discharge resistor, the ground detection circuit and the chopper circuit in sequence;

[0012] The three-phase inverter is connected to the permanent magnet motor via a three-pole isolation contactor;

[0013] Among them, when the permanent magnet traction system operates at high speed, when the three-pole isolation contactor is not completely disconnected, the three-phase inverter is controlled to suppress back electromotive force with weak magnetic field to avoid back electromotive force recharge.

[0014] In a possible embodiment, the pre-charging circuit includes a charging contactor, a shorting contactor, a charging resistor and an input current sensor; one end of the charging contactor and the shorting contactor are respectively connected to one end of the secondary winding of the transformer; the other end of the charging contactor is connected to one end of the charging resistor;

[0015] The other end of the charging resistor and the other end of the short-circuit contactor are both connected to the four-quadrant rectifier module;

[0016] One end of the input current sensor is connected to the four-quadrant rectifier module, and the other end of the input current sensor is connected to the other end of the secondary winding of the transformer.

[0017] In a possible embodiment, the four-quadrant rectifier module includes 8 IGBT half-bridge modules, and two parallel half-bridge circuits in the four-quadrant rectifier module are connected to the charging resistor and the other end of the short-circuit contactor through a copper busbar;

[0018] The other two parallel half-bridge circuits in the four-quadrant rectifier module are connected to the input current sensor.

[0019] In a possible embodiment, it further includes: a first voltage transformer;

[0020] The first voltage transformer is arranged at two ends of the four-quadrant rectifier module;

[0021] The first voltage transformer is arranged in parallel with the supporting capacitor.

[0022] In a possible embodiment, the ground detection circuit includes:

[0023] A first grounding resistor, a second grounding resistor, a second voltage transformer and a grounding capacitor;

[0024] The first grounding resistor and the second grounding resistor are arranged in series, the other end of the first grounding resistor is connected to the first voltage transformer; the other end of the second grounding resistor is connected to the first voltage transformer;

[0025] The second voltage transformer and the grounding capacitor are arranged in series;

[0026] The second voltage transformer is arranged in parallel with the first grounding resistor or the second grounding resistor;

[0027] One end of the second voltage transformer is connected to the first grounding resistor; one end of the grounding capacitor is connected to the second grounding resistor.

[0028] In a possible embodiment, the discharge resistor includes a first discharge resistor and a second discharge resistor;

[0029] The first discharge resistor and the second discharge resistor are arranged in parallel;

[0030] One end of the first discharge resistor is connected to one end of the first grounding resistor;

[0031] One end of the second discharge resistor is connected to one end of the second grounding resistor.

[0032] In a possible embodiment, the chopper circuit includes: a first current detection sensor and a chopper resistor;

[0033] One end of the first current detection sensor is connected to the three-phase inverter;

[0034] The other end of the first current detection sensor is connected to one end of the second grounding resistor through the chopper resistor.

[0035] In a possible embodiment, the three-phase inverter includes a first group of IGBT half-bridge modules, a second group of IGBT half-bridge modules, a third group of IGBT half-bridge modules and a fourth group of IGBT half-bridge modules;

[0036] The first group of IGBT half-bridge modules, the second group of IGBT half-bridge modules, the third group of IGBT half-bridge modules and the fourth group of IGBT half-bridge modules are arranged in parallel;

[0037] The midpoint of the first group of IGBT half-bridge modules is connected to one end of the second grounding resistor through the first current detection sensor and the chopper resistor;

[0038] The second group of IGBT half-bridge modules is connected to the three-pole isolation contactor via a second current detection sensor;

[0039] The third group of IGBT half-bridge modules is connected to the three-pole isolation contactor through a third current detection sensor;

[0040] The fourth group of IGBT half-bridge modules is connected to the three-pole isolation contactor.

[0041] In a possible embodiment, the first group of IGBT half-bridge modules, the second group of IGBT half-bridge modules, the third group of IGBT half-bridge modules and the fourth group of IGBT half-bridge modules each include two IGBT half-bridge modules arranged in series.

[0042] In a possible embodiment, the pulse blocking time of the three-phase inverter is shorter than the back electromotive force feedback time.

[0043] The above-mentioned permanent magnet traction system provided by the present application is connected to the three-phase inverter through the pre-charging circuit in sequence through the four-quadrant rectifier module, the supporting capacitor, the discharge resistor, the grounding detection circuit and the chopper circuit; the three-phase inverter is connected to the permanent magnet motor through a three-pole isolation contactor; so that when the permanent magnet traction system is operating at high speed, when the three-pole isolation contactor is not completely disconnected, the three-phase inverter is controlled to weakly suppress the back electromotive force to avoid the back electromotive force back-injection and damage to components causing serious consequences. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 A schematic diagram of the circuit structure of a permanent magnet traction system provided in an embodiment of the present application;

[0046] Figure 2 for Figure 1 A schematic diagram of a local circuit at I in the permanent magnet traction system shown;

[0047] Figure 3 for Figure 1 The local circuit schematic diagram of the permanent magnet traction system at II shown;

[0048] Figure 4 for Figure 1 The local circuit schematic diagram at III in the permanent magnet traction system shown. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0050] Example:

[0051] Reference Figure 1 - Figure 4 As shown, an embodiment of the present application provides a permanent magnet traction system, which includes: a permanent magnet motor 10, a traction inverter 20 and a three-pole isolation contactor 30.

[0052] The traction converter 20 includes: a pre-charging circuit 21, a four-quadrant rectifier module 22, a support capacitor C1, a discharge resistor, a ground detection circuit 23, a chopper circuit and a three-phase inverter 24;

[0053] The pre-charging circuit 21 is connected to the three-phase inverter 24 through the four-quadrant rectifier module 22, the support capacitor C1, the discharge resistor, the ground detection circuit 23 and the chopper circuit in sequence;

[0054] The three-phase inverter 24 is connected to the permanent magnet motor 10 via a three-pole isolation contactor 30;

[0055] Among them, when the permanent magnet traction system operates at high speed, when the three-pole isolation contactor is not completely disconnected, the three-phase inverter is controlled to suppress back electromotive force with weak magnetic field to avoid back electromotive force recharge.

[0056] Alternatively, if Figure 2 As shown, the pre-charging circuit 21 includes a charging contactor KM2, a short-circuit contactor KM1, a charging resistor and an input current sensor L1; one end of the charging contactor KM2 and the short-circuit contactor KM1 are respectively connected to one end of the secondary winding of the transformer; the other end of the charging contactor KM2 is connected to one end of the charging resistor; the other end of the charging resistor and the other end of the short-circuit contactor KM1 are both connected to the four-quadrant rectifier module 22; one end of the input current sensor L1 is connected to the four-quadrant rectifier module 22, and the other end of the input current sensor L1 is connected to the other end of the secondary winding of the transformer.

[0057] Optionally, continue to refer to Figure 2 The four-quadrant rectifier module 22 includes 8 IGBT half-bridge modules, two of which are connected in parallel to the charging resistor and the other end of the short-circuit contactor KM1 through a copper bus; the other two parallel half-bridge circuits in the four-quadrant rectifier module 22 are connected to the input current sensor L1.

[0058] Optionally, continue to refer to Figure 2 The charging resistor includes a first charging resistor R1 and a second charging resistor R2, and the first charging resistor R1 and the second charging resistor R2 are arranged in parallel; one end of the first charging resistor R1 is connected to the other end of the charging contactor KM2, and the other end of the first charging resistor R1 is connected to one end of the second charging resistor R2, and the other end of the second charging resistor R2 is respectively connected to the other end of the short-circuit contactor KM1 and two of the parallel half-bridge circuits in the four-quadrant rectifier module 22.

[0059] Optionally, continue to refer to Figure 2, further comprising: a first voltage transformer V1; the first voltage transformer V1 is arranged at both ends of the four-quadrant rectifier module 22; the first voltage transformer V1 is arranged in parallel with the supporting capacitor.

[0060] Reference Figure 2 -3, the grounding detection circuit 23 includes: a first grounding resistor R3, a second grounding resistor R4, a second voltage transformer V2 and a grounding capacitor C2; the first grounding resistor R3 and the second grounding resistor R4 are arranged in series, and the other end of the first grounding resistor R3 is connected to the first voltage transformer V2; the other end of the second grounding resistor R4 is connected to the first voltage transformer V1; the other end of the second grounding resistor R4 is connected to the other end of the grounding capacitor C2; the second voltage transformer V2 and the grounding capacitor C2 are arranged in series; the second voltage transformer V2 is arranged in parallel with the first grounding resistor R3 or the second grounding resistor R4; one end of the second voltage transformer V2 is connected to the first grounding resistor R3; one end of the grounding capacitor C2 is connected to the second grounding resistor R4.

[0061] Optionally, the discharge resistor includes a first discharge resistor R5 and a second discharge resistor R6; the first discharge resistor R5 and the second discharge resistor R6 are arranged in parallel; one end of the first discharge resistor R5 is connected to one end of the first grounding resistor R3; one end of the second discharge resistor R6 is connected to one end of the second grounding resistor R4. A support capacitor C1 is arranged in parallel with the first discharge resistor R5 and the second discharge resistor R6.

[0062] Reference Figure 2 -4, the chopper circuit includes: a first current detection sensor L2 and a chopper resistor R7; one end of the first current detection sensor L2 is connected to the three-phase inverter 24; the other end of the first current detection sensor L2 is connected to one end of the second grounding resistor R6 through the chopper resistor R7.

[0063] Optionally, the three-phase inverter 24 includes a first group of IGBT half-bridge modules, a second group of IGBT half-bridge modules, a third group of IGBT half-bridge modules and a fourth group of IGBT half-bridge modules; the first group of IGBT half-bridge modules, the second group of IGBT half-bridge modules, the third group of IGBT half-bridge modules and the fourth group of IGBT half-bridge modules are arranged in parallel; the midpoint of the first group of IGBT half-bridge modules is connected to one end of the second grounding resistor R6 through the first current detection sensor L2 and the chopper resistor R7; the second group of IGBT half-bridge modules is connected to the three-pole isolation contactor 30 through the second current detection sensor L3; the third group of IGBT half-bridge modules is connected to the three-pole isolation contactor 30 through the third current detection sensor L4; the fourth group of IGBT half-bridge modules is connected to the three-pole isolation contactor 30.

[0064] Optionally, each group of IGBT half-bridge modules consists of two IGBT half-bridge modules, and the two IGBT half-bridge modules are arranged in series.

[0065] Optionally, the pulse blocking time of the three-phase inverter is shorter than the back electromotive force feedback time.

[0066] Optionally, the pulse blocking time Δt is much shorter than the back electromotive force back injection time Δt'.

[0067] That is to say, in the preferred mode of this embodiment, a short-time blocking pulse △t (△t is much smaller than the back electromotive force back-injection time △t') is used, and then weak magnetic field is performed until the three-pole isolation contactor is completely disconnected, so as to avoid the damage to the system caused by the 3 times back electromotive force voltage caused by the short-time two-phase short circuit caused by the asynchronism of the three-pole isolation contactor, further improve the control logic of the permanent magnet traction system for high-speed disconnection of the three-pole isolation contactor, and avoid the higher back electromotive force damage caused by the short-time two-phase short circuit of the permanent magnet traction system caused by the asynchronism of the three-pole isolation contactor.

[0068] It should be understood that the term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship, but it may also indicate an "and / or" relationship. Please refer to the context for specific understanding.

[0069] In this application, "at least one" means one or more, and "more" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can be represented by: a, b, c, a-b, a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0070] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0071] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

Claims

1. A permanent magnet traction system, characterized in that: The system comprises: Permanent magnet motor; A traction converter, wherein the traction converter is connected to the permanent magnet motor; Wherein, the traction converter comprises: Pre-charging circuit, four-quadrant rectifier module, supporting capacitor, discharge resistor, ground detection circuit, chopper circuit and three-phase inverter; The pre-charging circuit is connected to the three-phase inverter through the four-quadrant rectifier module, the support capacitor, the discharge resistor, the ground detection circuit and the chopper circuit in sequence; The three-phase inverter is connected to the permanent magnet motor via a three-pole isolation contactor; Among them, when the permanent magnet traction system operates at high speed, when the three-pole isolation contactor is not completely disconnected, the three-phase inverter is controlled to suppress back electromotive force with weak magnetic field to avoid back electromotive force recharge.

2. The permanent magnet traction system according to claim 1, characterized in that: The pre-charging circuit includes a charging contactor, a short-circuit contactor, a charging resistor and an input current sensor; one end of the charging contactor and the short-circuit contactor are respectively connected to one end of the secondary winding of the transformer; the other end of the charging contactor is connected to one end of the charging resistor; The other end of the charging resistor and the other end of the short-circuit contactor are both connected to the four-quadrant rectifier module; One end of the input current sensor is connected to the four-quadrant rectifier module, and the other end of the input current sensor is connected to the other end of the secondary winding of the transformer.

3. The permanent magnet traction system according to claim 2, characterized in that: The four-quadrant rectifier module includes 8 IGBT half-bridge modules, and two parallel half-bridge circuits in the four-quadrant rectifier module are connected to the charging resistor and the other end of the short-circuit contactor through a copper busbar; The other two parallel half-bridge circuits in the four-quadrant rectifier module are connected to the input current sensor.

4. The permanent magnet traction system according to claim 3, characterized in that: Also includes: a first voltage transformer; The first voltage transformer is arranged at two ends of the four-quadrant rectifier module; The first voltage transformer is arranged in parallel with the supporting capacitor.

5. The permanent magnet traction system according to claim 4, characterized in that: The ground detection circuit comprises: A first grounding resistor, a second grounding resistor, a second voltage transformer and a grounding capacitor; The first grounding resistor and the second grounding resistor are arranged in series, the other end of the first grounding resistor is connected to the first voltage transformer; the other end of the second grounding resistor is connected to the first voltage transformer; The second voltage transformer and the grounding capacitor are arranged in series; The second voltage transformer is arranged in parallel with the first grounding resistor or the second grounding resistor; One end of the second voltage transformer is connected to the first grounding resistor; one end of the grounding capacitor is connected to the second grounding resistor.

6. The permanent magnet traction system according to claim 5, characterized in that: The discharge resistor includes a first discharge resistor and a second discharge resistor; The first discharge resistor and the second discharge resistor are arranged in parallel; One end of the first discharge resistor is connected to one end of the first grounding resistor; One end of the second discharge resistor is connected to one end of the second grounding resistor.

7. The permanent magnet traction system according to claim 6, characterized in that: The chopper circuit comprises: a first current detection sensor and a chopper resistor; One end of the first current detection sensor is connected to the three-phase inverter; The other end of the first current detection sensor is connected to one end of the second grounding resistor through the chopper resistor.

8. The permanent magnet traction system according to claim 7, characterized in that: The three-phase inverter includes a first group of IGBT half-bridge modules, a second group of IGBT half-bridge modules, a third group of IGBT half-bridge modules and a fourth group of IGBT half-bridge modules; The first group of IGBT half-bridge modules, the second group of IGBT half-bridge modules, the third group of IGBT half-bridge modules and the fourth group of IGBT half-bridge modules are arranged in parallel; The midpoint of the first group of IGBT half-bridge modules is connected to one end of the second grounding resistor through the first current detection sensor and the chopper resistor; The second group of IGBT half-bridge modules is connected to the three-pole isolation contactor via a second current detection sensor; The third group of IGBT half-bridge modules is connected to the three-pole isolation contactor through a third current detection sensor; The fourth group of IGBT half-bridge modules is connected to the three-pole isolation contactor.

9. The permanent magnet traction system according to claim 8, characterized in that: The first group of IGBT half-bridge modules, the second group of IGBT half-bridge modules, the third group of IGBT half-bridge modules and the fourth group of IGBT half-bridge modules each include two IGBT half-bridge modules arranged in series.

10. The permanent magnet traction system according to any one of claims 1 to 9, characterized in that: The pulse blocking time of the three-phase inverter is shorter than the back electromotive force backfeed time.

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