Counter-electromotive force suppression system and method for electric locomotive, and electric locomotive

Abstract

The present invention relates to the technical field of power control. Disclosed are a counter-electromotive force suppression system and method for an electric locomotive, and an electric locomotive. The counter-electromotive force suppression system is sequentially connected to a four-quadrant rectifier, a transformer and a power grid; a permanent magnet traction motor is used for driving a locomotive to operate under a traction working condition and braking the locomotive under a braking working condition; one end of a traction inverter is connected to the four-quadrant rectifier, and the other end of the traction inverter is connected to the permanent magnet traction motor; an isolation switch is arranged between the permanent magnet traction motor and the traction inverter; a power battery system is connected to the traction inverter; a traction control system is connected to the traction inverter; an auxiliary system is connected to the traction inverter to consume electric energy generated by the permanent magnet traction motor; and the traction inverter, the power battery system and the auxiliary system share an intermediate direct current loop. The counter-electromotive force suppression system reduces the impact of counter-electromotive force on a locomotive traction converter system when an electric locomotive passes a neutral zone, thereby improving the operation stability of the electric locomotive and the service life of a contactor.

Description

Back electromotive force suppression system and method for electric locomotive and electric locomotive Technical Field

[0001] The present application relates to the field of power control technology, and in particular to a back electromotive force suppression system and method for an electric locomotive, and the electric locomotive. Background Art

[0002] Currently, electric locomotives using permanent magnet traction motors offer higher efficiency, lower noise, better energy-saving performance, and environmental advantages. Furthermore, permanent magnet traction motors offer higher torque and speed response speeds, which improves the acceleration performance of electric locomotives. When passing through a split-phase, dead zone, electric locomotives must disconnect the locomotive's electrical load, allowing the pantograph to glide through the dead zone without current, before resuming the locomotive's electrical load. However, when passing through the split-phase, dead zone, the permanent magnets of the permanent magnet traction motor still generate a stable magnetic field, inducing back EMF in the stator. This back EMF can cause the following hazards:

[0003] (1) When an electric locomotive passes through a split-phase power-off zone at a high speed, the permanent magnet traction motor will generate a very high back electromotive force, causing the overvoltage protection of the traction converter system to operate, and even causing damage to the power devices of the locomotive traction converter system.

[0004] (2) When the grid voltage recovers after the locomotive passes through the phase separation area, due to the existence of the back electromotive force of the permanent magnet traction motor, electrical equipment such as the permanent magnet traction motor and traction inverter may suffer a large instantaneous current shock, causing damage and reducing the reliability of the locomotive electrical equipment.

[0005] (3) Continuous back EMF may cause the locomotive traction converter system, main transformer and other electrical equipment to be subjected to abnormal back EMF shock for a long time, affecting their normal working life.

[0006] Based on this, there is an urgent need for a technical solution for back electromotive force suppression of electric locomotives to solve the above problems.

[0007] Summary of the Invention

[0008] In order to provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not an extensive review, nor is it intended to identify key / critical elements or delineate the scope of protection of these embodiments, but rather serves as a prelude to the detailed description that follows.

[0009] In response to the deficiencies of the prior art, the embodiments of the present disclosure provide a back-electromotive force suppression system, method, and electric locomotive for an electric locomotive, so as to reduce the impact of the back-electromotive force on the locomotive traction converter system when the electric locomotive passes through the phase separation region, thereby improving the stability of the electric locomotive operation and the life of the contactor.

[0010] In a first aspect, an embodiment of the present disclosure provides a back-EMF suppression system for an electric locomotive, wherein the back-EMF suppression system is sequentially connected to a four-quadrant rectifier, a transformer, and a power grid, and includes a permanent magnet traction motor, a traction inverter, an isolating switch, a power battery system, a traction control system, and an auxiliary system. The permanent magnet traction motor is used to drive the locomotive in traction mode and brake the locomotive in braking mode; one end of the traction inverter is connected to the four-quadrant rectifier and the other end is connected to the permanent magnet traction motor for converting three phases of alternating current into direct current; the isolating switch is provided between the permanent magnet traction motor and the traction inverter; the power battery system is connected to the traction inverter for storing and outputting energy; the traction control system is connected to the traction inverter; and the auxiliary system is connected to the traction inverter to consume the electrical energy generated by the permanent magnet traction motor; wherein the traction inverter, the power battery system, and the auxiliary system share an intermediate DC circuit.

[0011] In the above-mentioned preferred technical solution of the back-EMF suppression system for electric locomotives, the back-EMF suppression system also includes: a train operation monitoring device, which is connected to the traction control system and is used to monitor the operating status and road condition information of the electric locomotive, wherein the operating status and road condition information at least include line speed limit, line slope, kilometer mark and phase zone position.

[0012] In the above-mentioned preferred technical solution of the back-EMF suppression system for electric locomotives, the back-EMF suppression system also includes a chopper module, a discharge resistor and an energy management unit. One end of the chopper module is connected to the intermediate DC circuit, and the other end is connected to the discharge resistor, which is used to consume the high voltage electricity on the DC circuit when the DC circuit is overvoltage; the energy management unit is connected to the power battery system, auxiliary system, and train operation monitoring device, and is used to monitor the energy status of the power grid and the power battery system to manage the charging and discharging of the power battery system.

[0013] In a second aspect, an embodiment of the present disclosure provides a back-EMF suppression method for an electric locomotive, which is applied to a back-EMF suppression system as described above, and the back-EMF suppression method includes: determining the operating conditions of the locomotive; suppressing the back-EMF generated by the permanent magnet traction motor through the back-EMF suppression system according to the operating conditions of the locomotive; wherein, in traction conditions where the locomotive has no strict speed requirements, the back-EMF generated by the permanent magnet traction motor is suppressed by magnetic weakening control; in braking conditions where the locomotive has no strict speed requirements, the back-EMF generated by the permanent magnet traction motor is suppressed by adaptively adjusting the braking force of the permanent magnet traction motor; in traction conditions where the locomotive has strict speed requirements, the back-EMF generated by the permanent magnet traction motor is suppressed by adopting a power battery system; in braking conditions where the locomotive has strict speed requirements, the back-EMF generated by the permanent magnet traction motor is suppressed by the power battery system according to the operating status of the vehicle.

[0014] In the preferred technical solution of the back-electromotive force suppression method for electric locomotives, in the traction operating condition where the locomotive running speed requirement is not strict, the back-electromotive force suppression method includes that before entering the power-free section of the phase-splitting grid, the traction control system controls the traction inverter to reduce the excitation current and reduce the output traction torque of the permanent magnet traction motor; when entering the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor is reduced to 0 through the traction inverter, and the back-electromotive force generated by the permanent magnet traction motor is suppressed through weak magnetic control, wherein the weak magnetic control is for the stator of the permanent magnet traction motor to generate a magnetic field opposite to the rotor, thereby reducing the rotor magnetic flux; after passing the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor is gradually restored.

[0015] In the preferred technical solution of the back-electromotive force suppression method for electric locomotives, in the braking condition where the locomotive running speed requirement is not strict, the back-electromotive force suppression method includes: before entering the power-free section of the phase-splitting grid, the traction control system controls the traction inverter to reduce the output traction torque of the permanent magnet traction motor to 0, and switches the permanent magnet traction motor to the braking mode; when entering the power-free section of the phase-splitting grid, the traction inverter adaptively adjusts the braking force of the permanent magnet traction motor according to the actual operating conditions to achieve a balance between the energy generated by the permanent magnet traction motor and the energy demand of the auxiliary system; after passing the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to the traction mode, and the output traction torque of the permanent magnet traction motor is gradually restored.

[0016] In the preferred technical solution of the back-electromotive force suppression method for electric locomotives, in the traction operating conditions where the locomotive has strict speed requirements, the back-electromotive force suppression method includes: when entering the power-free section of the phase-separated grid, the locomotive uses a power battery system to provide power to the auxiliary system and the permanent magnet traction motor, thereby suppressing the back-electromotive force generated by the permanent magnet traction motor.

[0017] In the preferred technical solution of the back-electromotive force suppression method for electric locomotives, in the braking condition where the locomotive has strict operating speed requirements, the back-electromotive force suppression method includes: before entering the power-free section of the phase-splitting grid, the traction control system controls the traction inverter to reduce the output traction torque of the permanent magnet traction motor to 0; when entering the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to the braking mode, and when the vehicle needs to accelerate, the power battery system provides power to the auxiliary system and the permanent magnet traction motor, and when the vehicle needs to decelerate, the power battery system absorbs excess locomotive braking energy that cannot be consumed by the auxiliary system; after passing the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to the traction mode, and the output traction torque of the permanent magnet traction motor is gradually restored.

[0018] In the preferred technical solution of the back-EMF suppression method for electric locomotives, the back-EMF suppression method also includes: controlling the ratio of the permanent magnet traction motor in braking mode and in traction mode; when entering the power-free section of the phase-splitting grid, dynamically adjusting the traction torque of the permanent magnet traction motor in traction mode and the braking torque of the permanent magnet traction motor in braking mode according to the operation needs of the locomotive in the power-free section of the phase-splitting grid; wherein, when the locomotive needs to speed up, the braking torque of the permanent magnet traction motor in braking mode is controlled to be 0, the traction motor in traction mode is powered by the power battery system, and the traction torque of the traction mode motor is adjusted according to the locomotive running speed requirements; when the locomotive needs to decelerate, the output torque of the permanent magnet traction motor in traction mode is controlled to be 0, and the braking torque of the braking mode motor is dynamically adjusted according to the locomotive running speed requirements.

[0019] In a third aspect, an embodiment of the present disclosure provides an electric locomotive, which includes the aforementioned back-EMF suppression system, or adopts the aforementioned back-EMF suppression method.

[0020] The back-electromotive force suppression system, method, and electric locomotive provided by the embodiments of the present disclosure can achieve the following technical effects:

[0021] The back-EMF suppression system adopts the back-EMF suppression method to reduce the influence of the back-EMF on the locomotive traction converter system when the electric locomotive passes through the phase separation area, thereby improving the stability of the electric locomotive operation and the life of the contactor.

[0022] The above general description and the following description are exemplary and explanatory only and are not intended to limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] One or more embodiments are exemplarily described by corresponding drawings. These exemplary descriptions and drawings do not limit the embodiments. Elements with the same reference numerals in the drawings are shown as similar elements. The drawings do not constitute a scale limitation. In addition,

[0024] FIG1 shows a schematic diagram of a back electromotive force suppression system for an electric locomotive provided by the present invention;

[0025] FIG2 shows a schematic flow chart of a back electromotive force suppression method for an electric locomotive provided by the present invention.

[0026] Figure numerals: 1. Permanent magnet traction motor; 2. Traction inverter; 3. Isolating switch; 4. Power battery system; 5. Traction control system; 6. Auxiliary system; 7. Train operation monitoring device; 8. Chopper module; 9. Discharge resistor; 10. Energy management unit; 11. Four-quadrant rectifier; 12. Transformer; 13. Power grid. DETAILED DESCRIPTION

[0027] In order to be able to understand the features and technical content of the embodiments of the present disclosure in more detail, the implementation of the embodiments of the present disclosure is described in detail below in conjunction with the accompanying drawings. The accompanying drawings are for reference only and are not used to limit the embodiments of the present disclosure. In the following technical description, for the sake of convenience of explanation, a full understanding of the disclosed embodiments is provided through multiple details. However, one or more embodiments can still be implemented without these details. In other cases, to simplify the drawings, well-known structures and devices can be simplified for display.

[0028] In the description and claims of the embodiments of the present disclosure, as well as in the accompanying drawings, the terms "first," "second," and the like are used to distinguish similar items and are not necessarily used to describe a particular order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate to describe the embodiments of the present disclosure herein. In addition, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions.

[0029] In the embodiments of the present disclosure, the terms "upper", "lower", "inside", "middle", "outside", "front", "back" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe the embodiments of the present disclosure and their embodiments, and are not intended to limit the indicated devices, elements or components to having a specific direction, or to be constructed and operated in a specific direction. Moreover, in addition to being used to indicate directions or positional relationships, some of the above terms may also be used to indicate other meanings. For example, the term "upper" may also be used to indicate a certain dependency or connection relationship in certain circumstances. For those of ordinary skill in the art, the specific meanings of these terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0030] Furthermore, the terms "disposed," "connected," and "fixed" should be interpreted broadly. For example, "connected" can mean a fixed connection, a removable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediary, or an internal connection between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the embodiments of this disclosure based on the specific circumstances.

[0031] Unless otherwise stated, the term "plurality" means two or more.

[0032] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present disclosure can be combined with each other.

[0033] As shown in Figure 1, an embodiment of the present disclosure provides a back-EMF suppression system for an electric locomotive. The back-EMF suppression system is sequentially connected to a four-quadrant rectifier 11, a transformer 12, and a power grid 13. The back-EMF suppression system includes a permanent magnet traction motor 1, a traction inverter 2, an isolating switch 3, a power battery system 4, a traction control system 5, and an auxiliary system 6. The permanent magnet traction motor 1 is used to drive the locomotive during traction operation and brake the locomotive during braking operation. The traction inverter 2 is connected to the four-quadrant rectifier 11 at one end and to the permanent magnet traction motor 1 at the other end for converting three phases of alternating current (AC) into direct current (DC). The isolating switch 3 is disposed between the permanent magnet traction motor 1 and the traction inverter 2. The power battery system 4 is connected to the traction inverter 2 for storing and outputting energy. The traction control system 5 is connected to the traction inverter 2. The auxiliary system 6 is connected to the traction inverter 2 to consume the electrical energy generated by the permanent magnet traction motor 1. The traction inverter 2, the power battery system 4, and the auxiliary system 6 share a common intermediate DC circuit.

[0034] Specifically, high-voltage three-phase AC power from the power grid 13, for example, 25 kV, is converted to low-voltage single-phase DC power, for example, 1000 V, by a transformer 13. After passing through a four-quadrant rectifier 11, it is output to the DC circuit where the traction inverter 2 resides. During traction operation, the traction inverter 2 converts the DC power from the DC circuit into three-phase AC power with a specific frequency and voltage, which is supplied to the permanent magnet traction motor 1 to drive the motor. During traction operation, the stator windings of the permanent magnet traction motor 1 convert the three-phase AC power into a rotating magnetic field, which interacts with the magnetic field of the rotor's permanent magnets to generate electromagnetic torque that drives the locomotive. During braking operation, the traction inverter 2 converts the three-phase AC power generated by the permanent magnet traction motor 13 into DC power and outputs it to the DC circuit. During braking operation, the rotating rotor magnetic field of the permanent magnet traction motor 1 induces current in the stator, which converts the locomotive's kinetic energy into three-phase AC power, achieving braking. The disconnector 3 is located between the traction inverter 2 and the permanent magnet traction motor 1 and is used to disconnect or disconnect a faulty permanent magnet traction motor 1. The auxiliary system 6 is a system other than the traction system and may include the traction cooling system, brake air compressor system, lighting, air conditioning, and network. The traction control system 5 controls the traction inverter 2, outputting control commands to adjust the output voltage and frequency of the traction inverter 2, thereby achieving precise control of the permanent magnet traction motor 1. The power battery system 4, as the locomotive's energy storage device, is responsible for balancing energy demand during traction and braking. The capacity and power of the power battery system 4 can be tailored to the locomotive's operating conditions to meet energy requirements in different operating environments. For operating environments with strict speed requirements, the locomotive is equipped with a power battery with a larger capacity and power. When passing through the phase split region, the power battery system 4 is the primary source of power, supplemented by braking energy feedback. For operating environments with less stringent speed requirements, the capacity and power of the power battery system 4 can be reduced. When passing through the phase split region, braking energy feedback is the primary source, supplemented by the power battery system 4, reducing the cost of the electric locomotive. The system improves the operational stability of electric locomotives and reduces the impact of the back electromotive force of the permanent magnet traction motor 1 on the traction current transformer. It overcomes the problems of frequent contactor operation and reduced service life in traditional methods.

[0035] As shown in Figure 1, in the preferred technical solution of the present application, the back-electromotive force suppression system also includes: a train operation monitoring device 7, which is connected to the traction control system 5 and is used to monitor the operating status and road condition information of the electric locomotive, wherein the operating status and road condition information at least include line speed limit, line slope, kilometer mark and phase zone position.

[0036] Specifically, the train operation monitoring device 7 is communicatively connected to the traction control system 5 , and is capable of monitoring the electric locomotive in real time and providing the traction control system 5 with road condition information.

[0037] As shown in Figure 1, in the preferred technical solution of the present application, the back electromotive force suppression system also includes a chopper module 8, a discharge resistor 9 and an energy management unit 10. One end of the chopper module 8 is connected to the intermediate DC circuit, and the other end is connected to the discharge resistor 9, which is used to consume the high voltage electricity on the DC circuit when the DC circuit is overvoltage; the energy management unit 10 is connected to the power battery system 4, the auxiliary system 6, and the train operation monitoring device 7, and is used to monitor the energy status of the power grid 13 and the power battery system 4 to manage the charging and discharging of the power battery system 4.

[0038] Specifically, the traction control system 5 is communicatively connected to the chopper module 8. When the DC circuit voltage overvoltage occurs, it can also control the chopper module 8 to conduct, dissipating the high voltage in the DC circuit through the discharge resistor 9. The chopper module 8 achieves this voltage release by conducting the discharge circuit 9. The energy management unit 10 is responsible for energy distribution and scheduling throughout the electric locomotive. It monitors the energy requirements of each subsystem in real time and manages the charge and discharge of the power battery system 4 to ensure optimal energy utilization under various operating conditions.

[0039] By controlling the on-duty cycle of the brake chopper module 8, when the power battery system 4 fails, the excessive back electromotive force generated by the permanent magnet traction motor 1 is consumed through the discharge resistor 9, thereby suppressing the influence of the back electromotive force of the permanent magnet traction motor 1 on the traction converter system.

[0040] According to different operating environments and requirements, multiple operating modes can be set, such as energy-saving mode, high-performance mode, etc. By switching the operating mode, dynamic adjustment of system performance and energy consumption can be achieved.

[0041] As shown in FIG2 , an embodiment of the present disclosure provides a back EMF suppression method for an electric locomotive, which is applied to the back EMF suppression system described above. The back EMF suppression method includes:

[0042] Step S1: Determine the operating condition of the locomotive;

[0043] Step S2: According to the operating condition of the locomotive, the back electromotive force generated by the permanent magnet traction motor 1 is suppressed by the back electromotive force suppression system;

[0044] Among them, in the traction working condition where the locomotive has no strict speed requirements, the back electromotive force generated by the permanent magnet traction motor 1 is suppressed by means of weak magnetic control; in the braking working condition where the locomotive has no strict speed requirements, the back electromotive force generated by the permanent magnet traction motor 1 is suppressed by adaptively adjusting the braking force of the permanent magnet traction motor 1; in the traction working condition where the locomotive has strict speed requirements, the back electromotive force generated by the permanent magnet traction motor 1 is suppressed by means of the power battery system 4; in the braking working condition where the locomotive has strict speed requirements, the back electromotive force generated by the permanent magnet traction motor 1 is suppressed by means of the power battery system 4 according to the operating state of the vehicle.

[0045] Specifically, locomotive operating conditions generally include traction and braking, but there are both strict and non-strict speed requirements. Based on road conditions and the locomotive's different operating conditions, the control strategy of the permanent magnet traction motor 1 in the split-phase region is predicted and adjusted in advance to achieve optimal energy balance and reduce the back EMF and inrush current of the permanent magnet traction motor 1. By suppressing the back EMF generated by the permanent magnet traction motor 1 through the back EMF suppression system, the operating stability of the electric locomotive is improved, and the impact of the back EMF of the permanent magnet traction motor 1 on the traction current transformer is reduced. This overcomes the problems of frequent contactor operation and reduced lifespan in traditional methods.

[0046] In the preferred technical solution of the present application, in the traction operating condition where the locomotive running speed requirement is not strict, the back electromotive force suppression method includes: before entering the power-free section of the phase-splitting grid, the traction control system 5 controls the traction inverter 2 to reduce the excitation current, thereby reducing the output traction torque of the permanent magnet traction motor 1; when entering the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor 1 is reduced to 0 through the traction inverter 2, and the back electromotive force generated by the permanent magnet traction motor 1 is suppressed through weak magnetic control, wherein the weak magnetic control generates a magnetic field opposite to the rotor for the stator of the permanent magnet traction motor 1, thereby reducing the rotor magnetic flux; after passing through the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor 1 is gradually restored.

[0047] Specifically, under traction operating conditions where locomotive speed requirements are less stringent, the locomotive's operating speed can be varied, and maintaining speed through energy provided by the power battery system 4 is not a consideration. Under these conditions, locomotive control is divided into three phases, each with its own specific approach. The traction control system 5 employs an adaptive control strategy, dynamically adjusting control parameters, including the magnitude of field weakening and output torque, based on the real-time status and operating conditions of the permanent magnet traction motor 1 to achieve optimal control at different operating speeds. Before entering the de-energized section of the phase-splitting grid, the train operation monitoring device 7 provides the traction control system 5 with road condition information. Based on this information, the traction control system 5 controls the traction inverter 2 to apply an excitation current to the permanent magnet traction motor 1, generating a magnetic field opposite to that of the rotor's permanent magnets, reducing the magnetic induction intensity and, therefore, the magnitude of the back electromotive force. When entering the de-energized section of the phase-splitting grid, two main steps are performed: first, controlling the output torque of the permanent magnet traction motor 1 to zero, and second, suppressing excessive back electromotive force generated by the permanent magnet traction motor 1 through field weakening control. After passing through the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor 1 is gradually restored to achieve a smooth transition.

[0048] In the preferred technical solution of the present application, in the braking condition where the locomotive running speed requirement is not strict, the back electromotive force suppression method includes: before entering the power-free section of the phase-splitting grid, the traction control system 5 controls the traction inverter 2 to reduce the output traction torque of the permanent magnet traction motor 1 to 0, and converts the permanent magnet traction motor 1 to the braking mode; when entering the power-free section of the phase-splitting grid, the traction inverter 2 adaptively adjusts the braking force of the permanent magnet traction motor 1 according to the actual operating conditions to achieve a balance between the energy generated by the permanent magnet traction motor 1 and the energy demand of the auxiliary system 6; after passing the power-free section of the phase-splitting grid, the permanent magnet traction motor 1 is converted to the traction mode, and the output traction torque of the permanent magnet traction motor 1 is gradually restored.

[0049] Specifically, in the braking condition where the locomotive speed requirements are not strict, the permanent magnet traction motor 1 is switched to the braking mode in the phase separation area. By controlling the braking torque of the permanent magnet traction motor 1, the power generated by the permanent magnet traction motor 1 can just meet the requirements of the auxiliary system 6, thereby suppressing the back electromotive force generated by the permanent magnet traction motor 1 and maintaining the stability of the locomotive DC circuit voltage, thereby improving the locomotive operation stability.

[0050] In the preferred technical solution of the present application, in the traction operating condition where the locomotive has strict speed requirements, the back electromotive force suppression method includes: when entering the power-free section of the phase-separated grid, the locomotive uses the power battery system 4 to provide power to the auxiliary system 6 and the permanent magnet traction motor 1, thereby suppressing the back electromotive force generated by the permanent magnet traction motor 1.

[0051] Specifically, in traction conditions where the locomotive has strict speed requirements, the power battery system 4 is used as an energy buffer and storage device to provide power to the permanent magnet traction motor 1 and the auxiliary system 6 in the phase-splitting and power-free area, thereby preventing the locomotive from excessively slowing down in the over-phase area and improving the locomotive's operating performance and safety. When the locomotive is running, the power battery always maintains the minimum voltage of the intermediate DC. In the power area, the output voltage of the four-quadrant rectifier 11 is higher than the power battery voltage. At this time, the locomotive uses the power of the power grid 13. When the power grid 13 is in the power-free area, the power battery is used to provide power. Since the locomotive's intermediate DC is always powered, the permanent magnet traction motor 1 is always in a normal traction condition, which suppresses the generation of back electromotive force.

[0052] In the preferred technical solution of the present application, the locomotive operates under strict braking conditions at a speed requirement, and the back-electromotive force suppression method includes: before entering the power-free section of the phase-splitting grid, the traction control system 5 controls the traction inverter 2 to reduce the output traction torque of the permanent magnet traction motor 1 to 0; when entering the power-free section of the phase-splitting grid, the permanent magnet traction motor 1 is switched to the braking mode, and when the vehicle needs to accelerate, the power battery system 4 provides power to the auxiliary system 6 and the permanent magnet traction motor 1, and when the vehicle needs to decelerate, the power battery system 4 absorbs excess locomotive braking energy that cannot be consumed by the auxiliary system 6; after passing the power-free section of the phase-splitting grid, the permanent magnet traction motor 1 is switched to the traction mode, and the output traction torque of the permanent magnet traction motor 1 is gradually restored.

[0053] Specifically, the power battery system 4 in the system is used as an energy buffer and storage device to absorb excess braking energy that cannot be consumed by the auxiliary system 6 when deceleration and electric braking are required in the phase-splitting area; and when the locomotive passes through the phase-splitting area at a low speed and the braking feedback energy is insufficient, energy is replenished for the auxiliary system 6, reducing the demand for braking force on the permanent magnet traction motor 1, maintaining the normal operation of the auxiliary system 6, and achieving energy balance of the electric locomotive in the phase-splitting area, thereby suppressing the back electromotive force of the permanent magnet traction motor 1, improving energy utilization, avoiding excessive speed reduction of the locomotive in the phase-splitting area, and improving the operating performance and safety of the locomotive.

[0054] In the preferred technical solution of the present application, the back-electromotive force suppression method also includes: controlling the ratio of the permanent magnet traction motor 1 in braking mode and in traction mode; when entering the power-free interval of the phase-splitting grid, dynamically adjusting the traction torque in traction mode and the braking torque in braking mode according to the locomotive's operation needs in the power-free interval of the phase-splitting grid; wherein, when the locomotive needs to speed up, the braking torque of the permanent magnet traction motor 1 in braking mode is controlled to be 0, the permanent magnet traction motor 1 in traction mode is powered by the power battery system 4, and the traction torque in traction mode is adjusted according to the locomotive running speed requirements; when the locomotive needs to decelerate, the output torque of the permanent magnet traction motor 1 in traction mode is controlled to be 0, and the braking torque of the permanent magnet traction motor 1 in braking mode is dynamically adjusted according to the locomotive running speed requirements.

[0055] Specifically, the train operation monitoring device 7 obtains road conditions and speed limit requirements when passing through the split-phase zone, and dynamically adjusts the number of permanent magnet traction motors 1 in braking and traction modes during the split-phase zone. When the locomotive needs to increase speed in the split-phase zone, the braking torque of the permanent magnet traction motors 1 in braking mode is controlled to zero, power is supplied to the permanent magnet traction motors 1 in traction mode via the power battery system 4, and the traction torque of the permanent magnet traction motors 1 in traction mode is adjusted according to the locomotive's operating speed. When the locomotive needs to decelerate in the split-phase de-energized zone, the output torque of the permanent magnet traction motors 1 in traction mode is controlled to zero, and the braking torque of the permanent magnet traction motors 1 in braking mode is dynamically adjusted according to the locomotive's operating speed. This control method effectively avoids frequent switching between traction and braking modes of the permanent magnet traction motors 1 in the split-phase zone due to road conditions and other factors, reducing voltage and current shocks to the permanent magnet traction motors 1. This improves the speed and stability of the locomotive during the split-phase zone.

[0056] Preferably, a back-EMF suppression system for a permanent magnet traction motor 1 for an electric locomotive includes at least four permanent magnet traction motors 1 and four traction inverters 2. When the locomotive passes through a split-phase zone, some permanent magnet traction motors 1 are switched to braking mode, while the remaining permanent magnet traction motors 1 remain in traction mode. The traction torque in traction mode and the braking torque in braking mode are dynamically adjusted based on the locomotive's operating needs in the split-phase zone. The back-EMF suppression system can also utilize a power battery system 4 as an energy buffer and storage device to provide power to the permanent magnet traction motors 1 and auxiliary systems 6 in the split-phase, power-free zone.

[0057] A method for suppressing back electromotive force of a permanent magnet traction motor 1 for an electric locomotive comprises the following steps:

[0058] (1) During the traction and braking process of the locomotive, an excitation current is applied to the permanent magnet traction motor 1 through the traction inverter 2, generating a magnetic field opposite to that of the permanent magnet, reducing the magnetic flux linkage of the permanent magnet rotor and the magnetic induction intensity, thereby reducing the magnitude of the back electromotive force.

[0059] (2) When the locomotive passes through the phase separation area, the braking torque of the permanent magnet traction motor 1 is controlled so that the power generated by the permanent magnet traction motor 1 just meets the needs of the auxiliary system 6, thereby suppressing the back electromotive force generated by the permanent magnet traction motor 1 and maintaining the stability of the locomotive DC circuit voltage.

[0060] An embodiment of the present disclosure provides an electric locomotive, which includes the aforementioned back-EMF suppression system, or adopts the aforementioned back-EMF suppression method.

[0061] The back-electromotive force suppression system and method of the present invention are intended to reduce the impact of the back-electromotive force on the locomotive traction converter system when the locomotive passes through the phase separation region, thereby improving the stability of the electric locomotive operation and the life of the contactor.

[0062] The implementation of this invention not only improves the operational stability of electric locomotives and mitigates the impact of the back EMF of the permanent magnet traction motor 1 on the traction current generator, but also further improves energy efficiency through the rational distribution of electrical energy and the use of energy storage devices. Furthermore, this invention overcomes the problems of frequent contactor operation and reduced lifespan in traditional methods, reducing maintenance costs for electric locomotives and extending equipment lifespan. The present invention is highly versatile and applicable to different types of permanent magnet traction motors 1 and electric locomotives, helping to promote the application of permanent magnet traction motors 1 in the electric locomotive field.

[0063] During the traction and braking process of the locomotive, an excitation current is applied to the permanent magnet traction motor 1 through the traction inverter 2 to generate a magnetic field opposite to that of the permanent magnet, reducing the permanent magnet rotor flux linkage and the magnetic induction intensity, thereby reducing the magnitude of the back electromotive force.

[0064] In the split-phase area, the permanent magnet traction motor 1 is switched to the braking mode. By controlling the braking torque of the permanent magnet traction motor 1, the power generated by the permanent magnet traction motor 1 can just meet the needs of the auxiliary system, thereby suppressing the back electromotive force generated by the motor and maintaining the stability of the locomotive DC circuit voltage.

[0065] The power battery system 4 is used as an energy buffer and storage device to provide power to the permanent magnet traction motor 1 and the auxiliary system 6 in the phase-splitting power-free area of ​​the locomotive, thereby preventing the locomotive from excessively slowing down in the excessive phase-splitting area.

[0066] The capacity and power of the power battery system 4 can be matched according to the operating conditions of the locomotive to meet the energy requirements under different operating environments.

[0067] When the locomotive passes through the phase-splitting area, some permanent magnet traction motors 1 are switched to braking mode, and the remaining permanent magnet traction motors 1 remain in traction mode. The traction torque of the motor in traction mode and the electric braking torque in electric braking mode are dynamically adjusted according to the operation needs of the locomotive in the phase-splitting area.

[0068] The monitoring system obtains the road conditions and speed limit requirements when passing through the phase-splitting area, and dynamically adjusts the number of motors in braking and traction modes when passing through the phase-splitting area.

[0069] The flowcharts and block diagrams in the accompanying drawings show the possible implementation architectures, functions and operations of the systems, methods and computer program products according to the embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, program segment or part of the code, and the module, program segment or part of the code contains one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different boxes can also occur in an order different from that disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps can actually be executed substantially in parallel, or they can sometimes be executed in the opposite order, which can depend on the functions involved. Each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, may be implemented by a dedicated hardware-based system that performs the specified function or action, or may be implemented by a combination of dedicated hardware and computer instructions.

Claims

1. A back electromotive force suppression system for an electric locomotive, characterized in that: The back-EMF suppression system is connected in sequence to a four-quadrant rectifier, a transformer and a power grid, and the back-EMF suppression system includes: A permanent magnet traction motor, which is used to drive the locomotive in traction mode and brake the locomotive in braking mode; A traction inverter, one end of which is connected to the four-quadrant rectifier, and the other end of which is connected to the permanent magnet traction motor, for converting three-phase alternating current and direct current; An isolating switch, the isolating switch being arranged between the permanent magnet traction motor and the traction inverter; A power battery system, the power battery system is connected to the traction inverter and is used to store and output energy; a traction control system connected to the traction inverter; an auxiliary system connected to the traction inverter to consume the electric energy generated by the permanent magnet traction motor; The traction inverter, the power battery system and the auxiliary system share an intermediate DC circuit.

2. The back electromotive force suppression system according to claim 1, characterized in that: The back-electromotive force suppression system also includes: a train operation monitoring device, which is connected to the traction control system and is used to monitor the operating status and road condition information of the electric locomotive, wherein the operating status and road condition information at least include line speed limit, line ramp, kilometer mark and phase zone position.

3. The back electromotive force suppression system according to claim 2, characterized in that: The reverse potential suppression system further comprises: A chopper module and a discharge resistor, one end of the chopper module is connected to the intermediate DC circuit, and the other end is connected to the discharge resistor, which is used to consume the high voltage on the DC circuit when the DC circuit is over-voltage. Piezoelectric; An energy management unit is connected to the power battery system, the auxiliary system and the train operation monitoring device, and is used to monitor the energy status of the power grid and the power battery system to manage the charging and discharging of the power battery system.

4. A back-EMF suppression method for electric locomotives, applied to the back-EMF suppression system as claimed in any one of claims 1 to 3, characterized in that: The back electromotive force suppression method comprises: Determine the operating conditions of the locomotive; According to the operating conditions of the locomotive, the back EMF generated by the permanent magnet traction motor is suppressed by the back EMF suppression system; Among them, in the traction working condition where the locomotive running speed requirement is not strict, the back EMF generated by the permanent magnet traction motor is suppressed by weak magnetic control; In the braking condition where the locomotive running speed requirement is not strict, the back electromotive force generated by the permanent magnet traction motor is suppressed by adaptively adjusting the braking force of the permanent magnet traction motor; In traction conditions where the locomotive has strict speed requirements, the back electromotive force generated by the permanent magnet traction motor is suppressed by using a power battery system; In braking conditions where the locomotive has strict speed requirements, the back electromotive force generated by the permanent magnet traction motor is suppressed through the power battery system according to the vehicle's operating status.

5. The back electromotive force suppression method according to claim 4, characterized in that: In the traction condition where the locomotive running speed requirement is not strict, the back EMF suppression method includes: Before entering the power-free section of the phase-splitting grid, the traction control system controls the traction inverter to reduce the excitation current and the output traction torque of the permanent magnet traction motor; When entering the power-free section of the phase-splitting area, the output traction torque of the permanent magnet traction motor is reduced to 0 through the traction inverter, and the back electromotive force generated by the permanent magnet traction motor is suppressed through the weak magnetic field control. The weak magnetic field control generates a magnetic field opposite to the rotor of the stator of the permanent magnet traction motor, thereby reducing the rotor flux; After passing through the power-free section of the phase-splitting grid, the output traction torque of the permanent magnet traction motor is gradually restored.

6. The back electromotive force suppression method according to claim 4, characterized in that: In the braking condition where the locomotive running speed requirement is not strict, the back EMF suppression method includes: Before entering the power-free section of the phase-splitting area, the traction control system controls the traction inverter to reduce the output traction torque of the permanent magnet traction motor to 0, and switches the permanent magnet traction motor to the braking mode; When entering the power-free section of the phase-splitting grid, the traction inverter adaptively adjusts the braking force of the permanent magnet traction motor according to the actual operating conditions to achieve a balance between the energy generated by the permanent magnet traction motor and the energy demand of the auxiliary system; After passing through the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to traction mode, and the output traction torque of the permanent magnet traction motor is gradually restored.

7. The back electromotive force suppression method according to claim 4, characterized in that: In the traction condition where the locomotive has strict running speed requirements, the back EMF suppression method includes: When entering the power-free section of the phase-splitting grid, the locomotive uses a power battery system to provide power to the auxiliary system and permanent magnet traction motor, thereby suppressing the back electromotive force generated by the permanent magnet traction motor.

8. The back electromotive force suppression method according to claim 4, characterized in that: In the braking condition where the locomotive has strict speed requirements, the back EMF suppression method includes: Before entering the power-free section of the phase-splitting grid, the traction control system controls the traction inverter to reduce the output traction torque of the permanent magnet traction motor to 0; When entering the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to braking mode. When the vehicle needs to accelerate, the power battery system provides power to the auxiliary system and the permanent magnet traction motor. When the vehicle needs to decelerate, the power battery system absorbs the excess locomotive braking energy that cannot be consumed by the auxiliary system. After passing through the power-free section of the phase-splitting grid, the permanent magnet traction motor is switched to traction mode, and the output traction torque of the permanent magnet traction motor is gradually restored.

9. The back electromotive force suppression method according to claim 4, characterized in that: The back electromotive force suppression method further comprises: Controlling the ratio of the permanent magnet traction motor being in a braking mode and being in a traction mode; When entering the power-free section of the phase-splitting area power grid, dynamically adjust the traction torque of the permanent magnet traction motor in the traction mode and the braking torque of the permanent magnet traction motor in the braking mode according to the operation needs of the locomotive in the power-free section of the phase-splitting area power grid; Among them, when the locomotive needs to speed up, the braking torque of the permanent magnet traction motor in the braking mode is controlled to be 0, the traction motor in the traction mode is powered by the power battery system, and the traction torque of the traction mode motor is adjusted according to the locomotive running speed requirements; when the locomotive needs to decelerate, the output torque of the permanent magnet traction motor in the traction mode is controlled to be 0, and the braking torque of the braking mode motor is dynamically adjusted according to the locomotive running speed requirements.

10. An electric locomotive, characterized in that: The electric locomotive comprises the back-EMF suppression system as claimed in any one of claims 1 to 3, or the electric locomotive adopts the back-EMF suppression method as claimed in any one of claims 4 to 9.

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