A machine-grid side collaborative control method and device of a permanent magnet traction system and a medium

Abstract

This application discloses a machine-grid side coordinated control method, device, and medium for a permanent magnet traction system, belonging to the field of control engineering technology. The method includes: determining the grid-side power of the permanent magnet traction system; sending the grid-side power to the machine-side controller of the permanent magnet traction system, so that the machine-side controller adjusts the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoids abnormalities in the DC bus of the permanent magnet traction system; receiving the machine-side power sent by the machine-side controller; the machine-side power is the power calculated by the machine-side controller based on the machine-side power of the permanent magnet traction system; and adjusting the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus. This method can ensure the safe and stable operation of the traction system containing the permanent magnet synchronous motor without increasing the hardware cost, space occupation, or control complexity of the traction system.

Description

Technical Field

[0001] This invention relates to the field of control engineering, and in particular to a machine-grid side coordinated control method, equipment and medium for a permanent magnet traction system. Background Technology

[0002] Due to its advantages such as high efficiency, high power density, excellent torque characteristics, and simple maintenance, permanent magnet synchronous motors have become the mainstream choice for traction systems. Traction systems using permanent magnet synchronous motors typically employ an AC-DC-AC topology, with the DC bus as the dividing line. The topology before and after the DC bus is referred to as the grid side and machine side, respectively.

[0003] If a fault occurs on the grid side and / or machine side of the traction system where the permanent magnet synchronous motor is located, the voltage of its internal DC bus will rise sharply. In this case, it will seriously affect the normal operation of the entire traction system and pose a great safety hazard. In order to stabilize the DC bus voltage within a preset range and ensure the safe operation of the entire traction system, the following two methods are usually used to regulate the DC bus voltage.

[0004] The first method is to modify the topology of the traction system, such as by adding a discharge circuit, a crowbar circuit, an energy feedback device, and a battery. When the voltage of the DC bus exceeds a preset threshold, the additional circuit modules in the traction system will be used to dissipate the excess voltage on the DC bus. However, this method not only increases the hardware cost and space occupied by the traction system, but also increases the weight of the traction system, which is not conducive to the lightweight design of the traction system. The second method employs a complex control strategy to regulate the traction system's state. When the DC bus voltage exceeds a preset threshold, the power transistors of the rectifier are controlled to switch the permanent magnet synchronous motor (PMSM) windings to a specific short-circuit state (such as a two-phase or three-phase short circuit). The internal impedance of the PMSM is then used to regulate the DC bus voltage. However, this method has complex control logic, and its control effectiveness varies significantly depending on the PMSM's speed and flux state. Furthermore, when the PMSM is operating at high speed, this control strategy can generate unacceptable short-circuit currents and torque ripples. In addition, this control strategy is also limited by the health of some power switches in the traction system; if a power switch fails, this control method may also fail.

[0005] Therefore, it is evident that ensuring the safe and stable operation of the traction system containing the permanent magnet synchronous motor without increasing the hardware cost, space occupancy, and control complexity of the traction system is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a machine-grid side coordinated control method, device, and medium for a permanent magnet traction system, so as to ensure the safe and stable operation of the traction system containing the permanent magnet synchronous motor without increasing the hardware cost, space occupation, or control complexity of the traction system. The specific solution is as follows: To address the aforementioned technical problems, this invention provides a machine-grid side coordinated control method for a permanent magnet traction system, applied to the grid-side controller of the permanent magnet traction system, comprising: Determine the power of the permanent magnet traction system on the grid side to obtain the grid-side power; The grid-side power is sent to the machine-side controller of the permanent magnet traction system so that the machine-side controller can adjust the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoid abnormalities in the DC bus of the permanent magnet traction system. Receive the machine-side power sent by the machine-side controller; the machine-side power is the power calculated by the machine-side controller for the power of the permanent magnet traction system on the machine side; The current of the rectifier in the permanent magnet traction system is adjusted according to the machine-side power to avoid abnormalities in the DC bus.

[0007] Preferably, determining the power of the permanent magnet traction system on the grid side to obtain the grid-side power includes: The grid-side power of the permanent magnet traction system is determined based on the current of the rectifier, the grid-side voltage of the permanent magnet traction system, and the transformer turns ratio, thus obtaining the grid-side power.

[0008] Preferably, the step of adjusting the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus includes: Based on the AC / DC power equivalent principle of the rectifier, and the current of the rectifier is determined according to the grid-side voltage of the permanent magnet traction system, the set current evaluation value is obtained; Determine the current value output by the voltage loop on the DC bus to obtain the voltage closed-loop output value; The target current sum is obtained by adding the set current evaluation value and the voltage closed-loop output value. The output current of the rectifier is adjusted based on the sum of the target currents to prevent abnormalities from occurring on the DC bus.

[0009] Preferred options also include: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, the secondary ripple phase of the DC bus is determined, and the secondary ripple amplitude of the DC bus sent by the machine-side controller is received. The secondary ripple phase of the DC bus is sent to the machine-side controller so that the machine-side controller can suppress the beat frequency of the permanent magnet synchronous motor according to the secondary ripple phase and amplitude of the DC bus. The low-order harmonics in the DC bus are suppressed based on the second-order ripple phase and the second-order ripple amplitude of the DC bus.

[0010] Preferably, determining the secondary ripple phase of the DC bus includes: The voltage signal corresponding to the single-phase voltage in the rotating coordinate system is determined based on the single-phase voltage and the target virtual signal; the target virtual signal is a signal virtualized by delaying the single-phase voltage by 90°. The phase of the single-phase voltage is obtained by using a phase-locked loop to lock the voltage signal corresponding to the single-phase voltage in a rotating coordinate system. The secondary ripple phase of the DC bus is determined based on the phase of the single-phase voltage.

[0011] Preferably, the step of suppressing low-order harmonics in the DC bus based on the second-order ripple phase and the second-order ripple amplitude of the DC bus includes: The instantaneous evaluation value of the secondary ripple is obtained by multiplying the secondary ripple phase of the DC bus and the secondary ripple amplitude of the DC bus. The difference between the DC bus voltage value and the instantaneous evaluation value of the second ripple is obtained to get the DC bus voltage processing value. The DC bus voltage is then adjusted according to the DC bus voltage processing value to suppress the low-order harmonics in the DC bus.

[0012] Preferred options also include: The preset carrier signal is dynamically adjusted based on the instantaneous evaluation value of the second ripple to suppress low-order harmonics in the DC bus; the preset carrier signal is the carrier signal corresponding to the modulation wave used to control the rectifier.

[0013] To address the aforementioned technical problems, this invention also provides a machine-grid side coordinated control method for a permanent magnet traction system, applied to the machine-side controller of the permanent magnet traction system, comprising: Receive the grid-side power sent by the grid-side controller of the permanent magnet traction system; the grid-side power is the power calculated by the grid-side controller on the grid side of the permanent magnet traction system; The torque of the permanent magnet synchronous motor in the permanent magnet traction system is adjusted according to the grid-side power, and abnormalities in the DC bus of the permanent magnet traction system are avoided. Determine the power of the permanent magnet traction system on the machine side to obtain the machine-side power; The machine-side power is sent to the grid-side controller so that the grid-side controller can adjust the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus.

[0014] Preferably, the step of adjusting the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoiding abnormalities in the DC bus of the permanent magnet traction system, includes: The torque corresponding to the permanent magnet synchronous motor when it reaches a power balance state is determined based on the grid-side power and the rotational speed of the permanent magnet synchronous motor, and the torque setting value is obtained. The torque of the permanent magnet synchronous motor is adjusted according to the torque setting value and the torque setpoint of the permanent magnet synchronous motor to avoid abnormalities in the DC bus.

[0015] Preferably, determining the power of the permanent magnet traction system on the machine side to obtain the machine-side power includes: When the inverter in the permanent magnet traction system is in normal operation, the three-phase voltage output by the inverter is determined according to the voltage of the DC bus and the corresponding pulse signal on the inverter. The three-phase current output by the inverter is sampled to obtain the three-phase current sample values; The power of the permanent magnet traction system at the machine side is determined based on the three-phase current sampling values ​​and the three-phase voltage output by the inverter, thus obtaining the machine-side power; When the inverter in the permanent magnet traction system is in an abnormal operating state, the three-phase current output by the inverter is sampled to obtain the three-phase current sample value. The back electromotive force of the permanent magnet synchronous motor is determined based on the three-phase current sampling values, the voltage of the DC bus, and the rotor position information of the permanent magnet synchronous motor. The power of the permanent magnet traction system on the machine side is determined based on the back electromotive force of the permanent magnet synchronous motor, thus obtaining the machine-side power.

[0016] Preferred options also include: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, the secondary ripple amplitude of the DC bus is determined, and the secondary ripple phase of the DC bus sent by the grid-side controller is received. The second-order ripple amplitude of the DC bus is sent to the grid-side controller so that the grid-side controller can suppress the low-order harmonics in the DC bus according to the second-order ripple phase and the second-order ripple amplitude of the DC bus. Beat frequency suppression is performed on the permanent magnet synchronous motor based on the secondary ripple phase and the secondary ripple amplitude of the DC bus.

[0017] Preferably, determining the secondary ripple amplitude of the DC bus includes: The secondary ripple amplitude of the DC bus is determined based on the power conservation principle of the permanent magnet traction system.

[0018] Preferably, determining the secondary ripple amplitude of the DC bus based on the power conservation principle of the permanent magnet traction system includes: Based on the power conservation principle of the permanent magnet traction system, a target mathematical model corresponding to the secondary ripple amplitude of the DC bus is created; The secondary ripple amplitude of the DC bus is determined based on the target mathematical model and the machine-side power. The expression for the target mathematical model is as follows: ; In the formula, The amplitude of the secondary ripple of the DC bus is given. The angular frequency of the second-order ripple of the DC bus is given. The fundamental angular frequency of the grid-side voltage in the permanent magnet traction system is given. This refers to the secondary ripple current of the DC bus. This refers to the supporting capacitor in the permanent magnet traction system. The power on the machine side, For short-circuit impedance, The DC voltage level of the DC bus is specified.

[0019] Preferably, the step of suppressing the beat frequency of the permanent magnet synchronous motor based on the secondary ripple phase and the secondary ripple amplitude of the DC bus includes: The instantaneous evaluation value of the secondary ripple is obtained by multiplying the secondary ripple phase of the DC bus and the secondary ripple amplitude of the DC bus. The voltage of the DC bus is predicted based on the DC component of the DC bus and the instantaneous evaluation value of the secondary ripple, and the predicted value of the DC bus voltage is obtained. The control signal corresponding to the inverter in the permanent magnet traction system is adjusted according to the predicted DC bus voltage value in order to suppress the beat frequency of the permanent magnet synchronous motor.

[0020] To address the aforementioned technical problems, the present invention also provides a machine-grid side coordinated control device for a permanent magnet traction system, comprising: Memory, used to store computer programs; A processor is configured to execute the computer program to implement the steps of a machine-network side coordinated control method for a permanent magnet traction system as disclosed above.

[0021] To address the aforementioned technical problems, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of a machine-network side coordinated control method for a permanent magnet traction system as disclosed above.

[0022] Beneficial Effects: In the grid-machine side coordinated control method for the permanent magnet traction system provided by this invention, the permanent magnet traction system includes a grid-side controller and a machine-side controller. In this method, the grid-side controller in the permanent magnet traction system first determines the power of the permanent magnet traction system on the grid side, obtains the grid-side power, and sends the grid-side power to the machine-side controller. This allows the machine-side controller to adjust the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoids abnormalities in the DC bus of the permanent magnet traction system. The machine-side controller calculates the power of the permanent magnet traction system on the machine side, obtains the machine-side power, and also sends the machine-side power to the grid-side controller. When the grid-side controller receives the machine-side power sent by the machine-side controller, it adjusts the current of the rectifier in the permanent magnet traction system according to the machine-side power, and avoids abnormalities in the DC bus of the permanent magnet traction system.

[0023] Compared to existing technologies, the method provided in this application does not require modification of the permanent magnet traction system's topology or the addition of extra hardware modules, thus avoiding increased hardware costs and space requirements. Furthermore, this control method utilizes coordinated control between the grid-side controller and the machine-side controller to regulate the DC bus voltage in the permanent magnet traction system, preventing DC bus anomalies. The control logic is simple, and there is no need to switch the permanent magnet synchronous motor to a specific short-circuit state during control. Excess energy in the permanent magnet traction system is dissipated using the motor's internal impedance. Therefore, the safe and stable operation of the traction system with the permanent magnet synchronous motor is ensured without increasing hardware costs, space requirements, or control complexity.

[0024] Correspondingly, the other machine-grid side coordinated control method for a permanent magnet traction system, the machine-grid side coordinated control device for a permanent magnet traction system, and the computer-readable storage medium provided by the present invention also have the above-mentioned beneficial effects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1 A flowchart of a machine-grid side coordinated control method for a permanent magnet traction system provided in an embodiment of the present invention; Figure 2 This is a structural topology diagram of a permanent magnet traction system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the principle of adjusting the current of the rectifier in a permanent magnet traction system. Figure 4 This is a schematic diagram illustrating the principle of a permanent magnet traction system applied to a locomotive according to an embodiment of the present invention; Figure 5 This is a schematic diagram illustrating the principle of coordinated control of the permanent magnet traction system by the grid-side controller and the machine-side controller, where the grid-side voltage in the permanent magnet traction system is a single-phase voltage. Figure 6 A flowchart of another machine-grid side coordinated control method for a permanent magnet traction system provided in an embodiment of the present invention; Figure 7 This is a schematic diagram illustrating the principle of adjusting the torque of a permanent magnet synchronous motor according to an embodiment of the present invention. Figure 8 This is a structural diagram of a machine-grid side coordinated control device for a permanent magnet traction system provided in an embodiment of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Please see Figure 1 , Figure 1This is a flowchart illustrating a grid-side coordinated control method for a permanent magnet traction system provided in an embodiment of the present invention. The method is applied to the grid-side controller of the permanent magnet traction system and includes: Step S11: Determine the power of the permanent magnet traction system on the grid side to obtain the grid-side power; Step S12: Send the grid-side power to the machine-side controller of the permanent magnet traction system so that the machine-side controller can adjust the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power and avoid abnormalities in the DC bus of the permanent magnet traction system. Step S13: The machine-side power transmitted by the receiver-side controller; the machine-side power is the power calculated by the machine-side controller for the power of the permanent magnet traction system on the machine side; Step S14: Adjust the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus.

[0029] To enable those skilled in the art to more clearly understand the implementation principle of this application, the working principle of the permanent magnet synchronous motor is briefly explained here. The operation of a permanent magnet synchronous motor is based on the interaction between the constant magnetic field generated by the permanent magnets in its internal rotor and the rotation of the stator windings. When the rotor of the permanent magnet synchronous motor rotates, the constant magnetic field generated by the permanent magnets cuts the stator windings, inducing an electromotive force, i.e., a back electromotive force. Under normal driving conditions of the traction system, the back electromotive force generated by the permanent magnet synchronous motor is lower than the terminal voltage output by the converter, and the current generated by the converter can flow normally into the permanent magnet synchronous motor. The back electromotive force is an inherent physical phenomenon in which the permanent magnet synchronous motor achieves electromechanical energy conversion. However, under certain faults or abnormal operating conditions, the back electromotive force generated by the permanent magnet synchronous motor can cause serious safety hazards, mainly in the following aspects: First, when permanent magnet synchronous motors (PMSMs) are applied in locomotive control, if the power supply to the locomotive or EMU is abnormal, the grid-side four-quadrant rectifier is blocked, or the main circuit breaker is open, preventing the normal bidirectional flow of energy, the PMSM will enter a "generator state." Driven by the vehicle's inertia, the PMSM will rotate at high speed. In this situation, the amplitude of the back electromotive force (EMF) generated by the PMSM will increase linearly with its rotational speed. When the peak value of the back EMF generated by the PMSM exceeds the withstand voltage rating of the DC-side capacitor and power devices of the traction converter, it will cause the DC bus voltage to rise. At this time, the back EMF generated by the PMSM will charge the DC-side capacitor through the motor windings and the freewheeling diodes of the converter. If there is no effective energy discharge path in the traction system, the DC bus voltage will continue to rise. An excessively high DC bus voltage can easily break down the supporting capacitor and damage power devices such as switching transistors, even threatening the electrical safety of the entire traction system, causing costly hardware losses and operational interruptions.

[0030] Secondly, when abnormalities occur in the permanent magnet synchronous motor, such as motor-side inverter blockage or output contactor disconnection, leading to abnormal energy levels in the traction system, the four-quadrant rectifier, which typically operates on a closed-loop basis based on the DC bus voltage, exhibits a lag in response. This causes the DC bus voltage to rise. Furthermore, the back electromotive force generated by the permanent magnet synchronous motor flows to the DC bus, further contributing to the voltage increase. In this situation, excessively high DC bus voltage can easily cause the support capacitor to break down, damage power devices such as switching transistors, and even threaten the electrical safety of the entire traction system, resulting in significant economic losses.

[0031] Therefore, ensuring the stability of the DC bus voltage in a permanent magnet traction system is a core issue in guaranteeing the safe and stable operation of the traction system. In existing technologies, to ensure the safe and stable operation of the traction system, the topology of the traction system is usually modified or complex control strategies are used to regulate the system's state, thereby ensuring that the DC bus voltage remains stable within a preset range even when encountering grid-side and / or machine-side faults. However, these methods either increase the hardware cost and space requirements of the traction system, or involve complex control logic that is difficult to operate and control.

[0032] In this embodiment, a machine-grid side coordinated control method for a permanent magnet traction system is provided. This method is described with the grid-side controller in the permanent magnet traction system as the execution subject. Using this method, the safe and stable operation of the traction system containing the permanent magnet synchronous motor can be guaranteed without increasing the hardware cost, space occupation, or control complexity of the traction system.

[0033] In permanent magnet traction systems containing permanent magnet synchronous motors, an AC-DC-AC topology is typically used. The topology upstream of the DC bus in this AC-DC-AC topology is called the grid side, and the topology downstream of the DC bus is called the machine side. Please see [link to relevant documentation]. Figure 2 , Figure 2 This is a structural topology diagram of a permanent magnet traction system provided in an embodiment of the present invention. Figure 2 In this diagram, K0 represents the main circuit breaker, T represents the transformer, K1 represents the input contactor, UR represents the rectifier, DC-Bus represents the DC bus, C represents the supporting capacitor, UI represents the inverter, K2 represents the output contactor, and M represents the permanent magnet synchronous motor. The topology to the left of the DC bus is the grid side, while the topology to the rear of the DC bus is the machine side. The controller that controls the various devices on the grid side is called the grid-side controller, and the controller that controls the various devices on the machine side is called the machine-side controller.

[0034] It should be noted that the permanent magnet traction system described in this application can be either a traction system containing a permanent magnet synchronous motor in the field of locomotive control, or a traction system containing a permanent magnet synchronous motor in the field of general industrial control. In other words, Figure 2 The power source for the transformer T can be either single-phase AC or three-phase AC.

[0035] Since grid-side power and generator-side power are key factors affecting the stability of the DC bus voltage, to prevent DC bus anomalies, the grid-side controller first determines the grid-side power of the permanent magnet traction system. Specifically, grid-side power refers to the transformer's power. After determining the grid-side power, the grid-side controller sends it to the generator-side controller. Upon receiving the grid-side power, the generator-side controller adjusts the torque of the permanent magnet synchronous motor based on the grid-side power, thus preventing DC bus anomalies in the permanent magnet traction system.

[0036] Meanwhile, the machine-side controller also calculates the power of the permanent magnet synchronous motor at the machine side. Once the machine-side controller determines the power of the permanent magnet traction system at the machine side, it sends the machine-side power to the grid-side controller. When the grid-side controller receives the machine-side power from the machine-side controller, it adjusts the rectifier current according to the machine-side power to prevent abnormalities in the DC bus of the permanent magnet traction system.

[0037] Compared to existing technologies, the method provided in this application does not require modification of the permanent magnet traction system's topology or the addition of extra hardware modules, thus avoiding increased hardware costs and space requirements. Furthermore, this control method utilizes coordinated control between the grid-side controller and the machine-side controller to regulate the DC bus voltage in the permanent magnet traction system, preventing DC bus anomalies. The control logic is simple, and there is no need to switch the permanent magnet synchronous motor to a specific short-circuit state during control. Excess energy in the permanent magnet traction system is dissipated using the motor's internal impedance. Therefore, the safe and stable operation of the traction system with the permanent magnet synchronous motor can be guaranteed without increasing hardware costs, space requirements, or control complexity.

[0038] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above steps: determining the power of the permanent magnet traction system on the grid side and obtaining the grid-side power, include: The grid-side power of the permanent magnet traction system is determined by the rectifier current, the grid-side voltage in the permanent magnet traction system, and the transformer turns ratio.

[0039] In this application, when determining the grid-side power of the permanent magnet traction system on the grid side, the grid-side controller can determine the grid-side power of the permanent magnet synchronous motor on the grid side based on the rectifier current, the grid-side voltage in the permanent magnet traction system (i.e., the voltage on the primary side of the transformer), and the transformer turns ratio.

[0040] When permanent magnet traction systems are applied in locomotive control, railway power grids are mostly single-phase, with frequencies of 50Hz, 60Hz, or 16.7Hz (corresponding to periods of 20ms, 16.7ms, or 60ms). The real-time power on the grid side is constantly changing, and the time period of this power change is half the voltage time period. To accurately obtain grid-side power information, the grid-side voltage, rectifier current, and transformer turns ratio are multiplied to obtain the instantaneous grid-side power. Then, half the period corresponding to the grid-side voltage frequency is selected as the calculation window, and the instantaneous grid-side power is accumulated using a continuous windowing method. Finally, the average of the accumulated instantaneous grid-side power values ​​is calculated to obtain the grid-side power. Specifically, in this case, the expression for calculating grid-side power is: Formula 1: ; In the formula, For grid-side power, This indicates calculating the average value. For transformer turns ratio, The current of the rectifier. This is the grid-side voltage. Indicates the integration time. This represents half the time of the power grid voltage frequency corresponding to the cycle.

[0041] Obviously, through the technical solution provided in this embodiment, the grid-side controller can accurately determine the grid-side power of the permanent magnet traction system on the grid side.

[0042] Based on the above embodiments, this embodiment further explains and optimizes the above technical solution. As a preferred implementation, the above steps: adjusting the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus, include: Step 1: Based on the AC / DC power equivalent principle of the rectifier and the grid-side voltage of the permanent magnet traction system, determine the current of the rectifier and obtain the set current evaluation value; Step 2: Determine the current value output by the voltage loop on the DC bus to obtain the voltage closed-loop output value; Step 3: Add the set current evaluation value and the voltage closed-loop output value to obtain the target current sum value; Step 4: Adjust the output current of the rectifier based on the sum of the target currents to avoid abnormalities in the DC bus.

[0043] In practical applications, to maintain a stable DC bus voltage, a voltage loop is typically used to regulate it, and the output value of the voltage loop on the DC bus is the rectifier's current setpoint. However, when the permanent magnet traction system malfunctions or experiences an anomaly, such as a permanent magnet synchronous motor failure, inverter blockage on the machine side, or contactor disconnection on the permanent magnet synchronous motor input side, the energy on the DC bus will change drastically. In such cases, relying solely on the rectifier's setpoint to adjust the DC bus voltage will not achieve the desired effect.

[0044] To avoid the aforementioned technical problems, in this application, after receiving the machine-side power sent by the machine-side controller, the grid-side controller will adjust the rectifier current according to the machine-side power and prevent abnormal DC bus voltage.

[0045] Specifically, when the grid-side controller adjusts the rectifier current based on the generator-side power, it first determines the rectifier current based on the AC / DC power equivalence principle and the grid-side voltage, obtaining a set current assessment value. Secondly, the grid-side controller determines the current value output by the DC bus voltage loop, obtaining a voltage closed-loop output value. Then, the grid-side controller adds the set current assessment value and the voltage closed-loop output value to obtain a target current sum value. This target current sum value is used as a reference to adjust the rectifier's output current, thereby preventing overvoltage or undervoltage on the DC bus. Please refer to [link to relevant documentation]. Figure 3 , Figure 3 This is a schematic diagram illustrating the principle of adjusting the current of the rectifier in a permanent magnet traction system. Figure 3 The method shown can regulate the current of the rectifier, which can significantly improve the speed of the rectifier in regulating the DC bus voltage under abnormal conditions and enable the DC bus voltage to quickly reach a stable state.

[0046] Clearly, the technical solution provided in this embodiment allows for more rapid regulation of the DC bus voltage under abnormal conditions.

[0047] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above method further includes: Step 1: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, determine the secondary ripple phase of the DC bus and receive the secondary ripple amplitude of the DC bus sent by the receiver-side controller. Step 2: Send the secondary ripple phase of the DC bus to the machine-side controller so that the machine-side controller can suppress the beat frequency of the permanent magnet synchronous motor based on the secondary ripple phase and amplitude of the DC bus. Step 3: Suppress low-order harmonics in the DC bus based on the second-order ripple phase and amplitude of the DC bus.

[0048] When a permanent magnet traction system is applied in locomotive control, the grid-side voltage in the permanent magnet traction system is a single-phase voltage. Please refer to [link to relevant documentation]. Figure 4 , Figure 4 This is a schematic diagram illustrating the principle of a permanent magnet traction system applied to a locomotive, as provided in an embodiment of the present invention. Figure 4 In the diagram, M represents pantograph, K0 represents main circuit breaker, T represents transformer, K1 represents input contactor, UR represents rectifier, DC-Bus represents DC bus, C represents supporting capacitor, UI represents inverter, K2 represents output contactor, and M represents permanent magnet synchronous motor.

[0049] Please see Figure 5 , Figure 5 This diagram illustrates the principle of coordinated control between the grid-side controller and the machine-side controller in a permanent magnet traction system where the grid-side voltage is single-phase. To ensure the safe and stable operation of the permanent magnet traction system, the grid-side controller first sends the grid-side power of the permanent magnet traction system to the machine-side controller. Upon receiving the grid-side power, the machine-side controller adjusts the torque of the permanent magnet synchronous motor based on the grid-side power, preventing abnormalities in the DC bus of the permanent magnet traction system. Simultaneously, the grid-side controller receives the machine-side power of the permanent magnet traction system from the machine-side controller and adjusts the rectifier current accordingly to prevent abnormalities in the DC bus.

[0050] Due to the influence of the single-phase power grid, secondary ripples will exist on the DC bus of the permanent magnet traction system, which will affect the safe and stable operation of the system. To eliminate the impact of secondary ripples on the DC bus, AC input side, and AC output side, the grid-side controller also determines the secondary ripple phase of the DC bus. When the grid-side controller determines the secondary ripple phase of the DC bus, it sends this phase to the machine-side controller. Simultaneously, the machine-side controller determines the secondary ripple amplitude of the DC bus. When the machine-side controller determines the secondary ripple phase of the DC bus, it sends this phase to the grid-side controller. When the machine-side controller receives the secondary ripple phase of the DC bus from the grid-side controller, it also performs beat frequency suppression on the permanent magnet synchronous motor based on the secondary ripple phase and amplitude. When the grid-side controller receives the second-order ripple amplitude of the DC bus from the machine-side controller, it will suppress the low-order harmonics in the DC bus based on the second-order ripple phase and amplitude of the DC bus.

[0051] Obviously, the technical solution provided in this embodiment can eliminate the impact of secondary pulsation on the DC bus.

[0052] In a preferred embodiment, the above step of determining the secondary ripple phase of the DC bus includes: Step 1: Determine the voltage signal corresponding to the single-phase voltage in the rotating coordinate system based on the single-phase voltage and the target virtual signal; the target virtual signal is a virtual signal generated by delaying the single-phase voltage by 90°. Step 2: Use a phase-locked loop to lock the voltage signal corresponding to the single-phase voltage in the rotating coordinate system to obtain the phase of the single-phase voltage; Step 3: Determine the secondary ripple phase of the DC bus based on the phase of the single-phase voltage.

[0053] In this embodiment, when the grid-side controller determines the secondary ripple phase of the DC bus, in order to obtain the phase of the single-phase voltage more quickly, it first creates a virtual signal with a 90° delay based on the single-phase voltage to obtain the target virtual signal; then, it treats the single-phase voltage and the target virtual signal as the voltage signals corresponding to the single-phase voltage (at this time, the single-phase voltage is regarded as a three-phase voltage) in a rotating coordinate system; then, it uses a phase-locked loop to lock the voltage signal corresponding to the single-phase voltage in the rotating coordinate system, and thus obtains the phase of the single-phase voltage.

[0054] Since there is an inherent and specific relationship between the phase of the single-phase voltage and the phase of the secondary ripple of the DC bus, the phase of the secondary ripple of the DC bus can be determined based on the phase of the single-phase voltage.

[0055] Specifically, when the grid-side voltage in the permanent magnet traction system is a single-phase voltage, the grid-side voltage and the rectifier current are in phase. Based on this, we deduce the relationship between the phase of the single-phase voltage and the phase of the secondary ripple of the DC bus.

[0056] Formula 2: ; Formula 3: ; In the above formula, The instantaneous voltage of a single-phase voltage. For the instantaneous current of a single-phase voltage, It is a single-phase voltage. This is the current value of the rectifier. For the phase of a single-phase voltage, For time.

[0057] Therefore, the instantaneous power of a single-phase voltage is: Formula 4: ; In the above formula, This refers to the instantaneous power of a single-phase voltage. The instantaneous voltage of a single-phase voltage. For the instantaneous current of a single-phase voltage, It is a single-phase voltage. This is the current value of the rectifier. For the phase of a single-phase voltage, For time.

[0058] Since the pulsating power is absorbed by the supporting capacitor on the DC bus, Equation 4 can be transformed into Equation 5, that is: Formula 5: ; In the above formula, This is the capacitance value of the DC capacitor. This is the DC bus voltage. This refers to the secondary ripple phase of the DC bus. It is a single-phase voltage. This is the current value of the rectifier. For the phase of a single-phase voltage, For time.

[0059] Integrating Equation 5, we obtain Equation 6, which is: Formula 6: ; As can be seen from Formula 6, by subtracting 90° from the phase of the single-phase voltage obtained by phase locking, and then multiplying the obtained phase value by 2, the secondary ripple phase of the DC bus can be obtained.

[0060] Obviously, the secondary ripple phase of the DC bus can be accurately calculated using the technical solution provided in this embodiment.

[0061] In a preferred embodiment, the above step of suppressing low-order harmonics in the DC bus based on the second-order ripple phase and amplitude of the DC bus includes: Step 1: Multiply the secondary ripple phase of the DC bus by the secondary ripple amplitude of the DC bus to obtain the instantaneous evaluation value of the secondary ripple; Step 2: Calculate the difference between the DC bus voltage value and the instantaneous evaluation value of the second ripple to obtain the DC bus voltage processing value, and adjust the DC bus voltage according to the DC bus voltage processing value to suppress the low-order harmonics in the DC bus.

[0062] In this application, when the grid-side controller suppresses low-order harmonics in the DC bus based on the second-order ripple phase and amplitude of the DC bus, it first multiplies the second-order ripple phase and amplitude of the DC bus to obtain an instantaneous evaluation value of the second-order ripple. Then, the grid-side controller calculates the difference between the DC bus voltage value and the instantaneous evaluation value of the second-order ripple to obtain a processed DC bus voltage value. Using this processed DC bus voltage value as a reference, the controller uses a voltage loop to regulate the DC bus voltage. This reduces low-order harmonics caused by the second-order ripple of the DC bus, thereby achieving the purpose of suppressing low-order harmonics in the DC bus.

[0063] Obviously, the technical solution provided in this embodiment can suppress low-order harmonics in the DC bus.

[0064] In a preferred embodiment, the above method further includes: The preset carrier signal is dynamically adjusted based on the instantaneous evaluation value of the second ripple to suppress low-order harmonics in the DC bus; the preset carrier signal is the carrier signal corresponding to the modulation wave used to control the rectifier.

[0065] In this application, after obtaining the instantaneous evaluation value of the second ripple, the preset carrier signal can be dynamically adjusted according to the instantaneous evaluation value of the second ripple. This can compensate for the low-order harmonics generated by the difference between the peak value of the preset carrier signal and the voltage of the actual DC bus, thereby achieving the purpose of suppressing the low-order harmonics in the DC bus again.

[0066] Clearly, the technical solution provided in this embodiment can better suppress low-order harmonics in the DC bus.

[0067] Please see Figure 6 , Figure 6This is a flowchart of another machine-grid side coordinated control method for a permanent magnet traction system provided in an embodiment of the present invention. The method is applied to the machine-side controller of the permanent magnet traction system and includes: Step S21: Receive the grid-side power sent by the grid-side controller in the permanent magnet traction system; the grid-side power is the power calculated by the grid-side controller for the power of the permanent magnet traction system on the grid side; Step S22: Adjust the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoid abnormalities in the DC bus of the permanent magnet traction system; Step S23: Determine the power of the permanent magnet traction system on the machine side to obtain the machine-side power; Step S24: Send the generator-side power to the grid-side controller so that the grid-side controller can adjust the current of the rectifier in the permanent magnet traction system according to the generator-side power to avoid abnormalities in the DC bus.

[0068] This embodiment provides a machine-grid side coordinated control method for a permanent magnet traction system. This method describes the aforementioned machine-grid side coordinated control method for a permanent magnet traction system from the perspective of the machine-side controller. Since the content of this method is consistent with the previously disclosed machine-grid side coordinated control method for a permanent magnet traction system, it will not be repeated here.

[0069] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above steps: adjusting the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoiding abnormalities in the DC bus of the permanent magnet traction system, include: Step 1: Determine the torque of the permanent magnet synchronous motor when it reaches a power balance state based on the grid-side power and the speed of the permanent magnet synchronous motor, and obtain the torque setting value; Step 2: Adjust the torque of the permanent magnet synchronous motor according to the torque setting value and the torque setpoint of the permanent magnet synchronous motor to avoid abnormalities in the DC bus.

[0070] In this application, when the machine-side controller receives power from the grid side, it adjusts the torque of the permanent magnet synchronous motor according to the grid-side power and avoids abnormalities on the DC bus. Please refer to [link to relevant documentation]. Figure 7 , Figure 7This is a schematic diagram illustrating the principle of torque adjustment for a permanent magnet synchronous motor (PMSM) according to an embodiment of the present invention. When adjusting the torque of the PMSM, the machine-side controller first determines the torque corresponding to the PMSM reaching power balance based on the grid-side power and the PMSM's rotational speed, thus obtaining a torque setpoint. Then, the machine-side controller adjusts the PMSM's torque based on the torque setpoint and the given torque value, while preventing abnormal voltage on the DC bus.

[0071] Specifically, if the torque setpoint of the permanent magnet synchronous motor is within ±10% of the calculated torque setting value, the torque of the permanent magnet synchronous motor can be adjusted according to the torque setpoint. If the torque setpoint is less than 0.9 times the calculated torque setting value, the torque of the permanent magnet synchronous motor can be limited by 0.9 times the torque setpoint to obtain the final torque value, and the torque of the permanent magnet synchronous motor can be adjusted according to the final torque value. If the torque setpoint is greater than 1.1 times the calculated torque setting value, the torque of the permanent magnet synchronous motor can be limited by 1.1 times the torque setpoint to obtain the final torque value, and the torque of the permanent magnet synchronous motor can be adjusted according to the final torque value. This torque regulation method can significantly improve the torque regulation response speed of permanent magnet synchronous motors under abnormal scenarios and enable the DC bus voltage to quickly reach a stable state, thereby avoiding safety accidents.

[0072] Obviously, the technical solution provided in this embodiment can achieve the purpose of adjusting the torque of the permanent magnet synchronous motor.

[0073] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above steps: determining the power of the permanent magnet traction system on the machine side and obtaining the machine-side power, include: Step 1: When the inverter in the permanent magnet traction system is in normal operation, determine the three-phase voltage output by the inverter based on the voltage of the DC bus and the corresponding pulse signal on the inverter. Step 2: Sample the three-phase current output by the inverter to obtain the sampled three-phase current values; Step 3: Determine the power of the permanent magnet traction system on the machine side based on the three-phase current sampling values ​​and the three-phase voltage output by the inverter, and obtain the machine-side power; Step 4: When the inverter in the permanent magnet traction system is in an abnormal operating state, sample the three-phase current output by the inverter to obtain the three-phase current sampling value. Step 5: Determine the back electromotive force of the permanent magnet synchronous motor based on the three-phase current sampling values, the DC bus voltage, and the rotor position information of the permanent magnet synchronous motor; Step 6: Determine the power of the permanent magnet traction system on the machine side based on the back electromotive force of the permanent magnet synchronous motor, and obtain the machine side power.

[0074] In this application, when determining the machine-side power of the permanent magnet traction system, the machine-side controller first checks whether the inverter in the permanent magnet traction system is in normal operating condition, and then calculates the machine-side power of the permanent magnet traction system based on the inverter's operating status. It should be noted that in practical applications, the machine-side power of the permanent magnet traction system refers to the power output by the permanent magnet synchronous motor.

[0075] If the inverter is in normal operating condition, the machine-side controller will determine the three-phase voltage output by the inverter based on the DC bus voltage and the corresponding pulse signals on the inverter. Secondly, the machine-side controller will use current sensors to sample the three-phase current output by the inverter, obtaining the three-phase current sample values. Once the machine-side controller has determined the three-phase current sample values ​​and the three-phase voltage output by the inverter, it only needs to multiply the three-phase current sample values ​​and the three-phase voltage output by the inverter to obtain the machine-side power of the permanent magnet traction system.

[0076] If the inverter is in an abnormal operating state, the machine-side controller will sample the three-phase current output by the inverter to obtain the three-phase current sample values. Based on the three-phase current sample values, the DC bus voltage, and the rotor position of the permanent magnet synchronous motor (PMSM), the machine-side controller will determine the back electromotive force (EMF) of the PMSM. After the machine-side controller calculates the back EMF of the PMSM, it can determine the machine-side power of the PMSM by combining the specific fault type of the permanent magnet traction system (i.e., the fault cause corresponding to the abnormal operating state of the machine-side controller).

[0077] Obviously, the machine-side power of the permanent magnet traction system can be accurately and reliably calculated using the technical solution provided in this embodiment.

[0078] Based on the above embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation, the above method further includes: Step 1: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, determine the secondary ripple amplitude of the DC bus and receive the secondary ripple phase of the DC bus sent by the grid-side controller. Step 2: Send the secondary ripple amplitude of the DC bus to the grid-side controller so that the grid-side controller can suppress the low-order harmonics in the DC bus according to the secondary ripple phase and the secondary ripple amplitude of the DC bus. Step 3: Suppress beat frequency in the permanent magnet synchronous motor based on the secondary ripple phase and amplitude of the DC bus.

[0079] This embodiment describes the aforementioned generator-grid coordinated control method for a permanent magnet traction system from the perspective of the generator-side controller when the grid-side voltage is a single-phase voltage. Since this content is consistent with the aforementioned generator-grid coordinated control method for a permanent magnet traction system when the grid-side voltage is a single-phase voltage, please refer to [link to relevant documentation]. Figure 5 The textual descriptions of the accompanying diagrams and their corresponding figures will not be repeated here.

[0080] In a preferred embodiment, the above step of determining the secondary ripple amplitude of the DC bus includes: The secondary ripple amplitude of the DC bus is determined based on the power conservation principle of the permanent magnet traction system.

[0081] In this application, when the grid-side voltage is single-phase, since the rectifier is a single-phase rectifier and the inverter is a three-phase inverter, the inverter power is balanced, and the rectifier power changes over time. In this case, the rectifier power is mainly determined by the inverter power. Therefore, in order to quickly and accurately calculate the secondary ripple amplitude of the DC bus, a relevant mathematical model can be created based on the power conservation principle of the permanent magnet traction system, and the secondary ripple amplitude of the DC bus can be determined based on the created mathematical model.

[0082] Obviously, the secondary ripple amplitude of the DC bus can be calculated using the technical solution provided in this embodiment.

[0083] As a preferred embodiment, the above steps, including determining the secondary ripple amplitude of the DC bus based on the power conservation principle of the permanent magnet traction system, include: Step 1: Based on the power conservation principle of the permanent magnet traction system, create the target mathematical model corresponding to the secondary ripple amplitude of the DC bus; Step 2: Determine the secondary ripple amplitude of the DC bus based on the target mathematical model and the machine-side power; The expression for the target mathematical model is as follows: ; In the formula, This represents the secondary ripple amplitude of the DC bus. The angular frequency of the second-order ripple of the DC bus. This is the fundamental angular frequency of the grid-side voltage in a permanent magnet traction system. This refers to the secondary ripple current of the DC bus. This is a supporting capacitor in a permanent magnet traction system. For machine-side power, For short-circuit impedance, This refers to the DC voltage level of the DC bus.

[0084] To determine the secondary ripple amplitude of the DC bus, the equivalent circuit diagram of the permanent magnet traction system must first be determined. After determining the equivalent circuit diagram, a mathematical model corresponding to the secondary ripple amplitude of the DC bus can be created based on the power conservation principle of the permanent magnet traction system. Once the target mathematical model is obtained, substituting various operating parameters of the permanent magnet traction system into the target mathematical model allows for accurate calculation of the secondary ripple amplitude of the DC bus.

[0085] Obviously, the secondary ripple amplitude of the DC bus can be accurately calculated using the technical solution provided in this embodiment.

[0086] As a preferred embodiment, the above step of suppressing beat frequency in the permanent magnet synchronous motor based on the secondary ripple phase and amplitude of the DC bus includes: Step 1: Multiply the secondary ripple phase of the DC bus by the secondary ripple amplitude of the DC bus to obtain the instantaneous evaluation value of the secondary ripple; Step 2: Predict the DC bus voltage based on the DC component and the instantaneous evaluation value of the secondary ripple of the DC bus to obtain the predicted DC bus voltage value. Step 3: Adjust the control signal corresponding to the inverter in the permanent magnet traction system according to the predicted value of the DC bus voltage to suppress the beat frequency of the permanent magnet synchronous motor.

[0087] In this application, when the machine-side controller performs beat frequency suppression on the permanent magnet synchronous motor, it first multiplies the secondary ripple phase and amplitude of the DC bus to obtain the instantaneous evaluation value of the secondary ripple. After determining the instantaneous evaluation value of the secondary ripple, the machine-side controller integrates the DC component of the DC bus and the instantaneous evaluation value of the secondary ripple, and uses this to predict the instantaneous voltage value of the DC bus in the next pulse cycle, thereby obtaining the predicted value of the DC bus voltage.

[0088] Once the machine-side controller obtains the predicted value of the DC bus voltage, it can use the predicted value as a reference to regulate the control signal corresponding to the inverter, thereby achieving the purpose of suppressing the beat frequency of the permanent magnet synchronous motor and ensuring the safe and stable operation of the permanent magnet traction system.

[0089] Obviously, the beat frequency suppression of permanent magnet synchronous motors can be achieved through the technical solution provided in this embodiment.

[0090] Please see Figure 8 , Figure 8This is a structural diagram of a machine-grid side coordinated control device for a permanent magnet traction system provided in an embodiment of the present invention. The device includes: Memory 31 is used to store computer programs; The processor 32 is configured to execute the computer program to implement the steps of a machine-network side coordinated control method for a permanent magnet traction system as disclosed above.

[0091] The machine-grid side coordinated control device for a permanent magnet traction system provided in this embodiment of the invention has the beneficial effects of the machine-grid side coordinated control method for a permanent magnet traction system disclosed above.

[0092] Accordingly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a machine-network side coordinated control method for a permanent magnet traction system as disclosed above.

[0093] The computer-readable storage medium provided in this embodiment of the invention has the beneficial effects of the aforementioned machine-grid side coordinated control method for a permanent magnet traction system.

[0094] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0095] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0096] The above provides a detailed description of the machine-grid side coordinated control method, equipment, and medium for a permanent magnet traction system provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A machine-grid side coordinated control method for a permanent magnet traction system, characterized in that, The grid-side controller used in permanent magnet traction systems includes: Determine the power of the permanent magnet traction system on the grid side to obtain the grid-side power; The grid-side power is sent to the machine-side controller of the permanent magnet traction system so that the machine-side controller can adjust the torque of the permanent magnet synchronous motor in the permanent magnet traction system according to the grid-side power, and avoid abnormalities in the DC bus of the permanent magnet traction system. Receive the machine-side power sent by the machine-side controller; the machine-side power is the power calculated by the machine-side controller for the power of the permanent magnet traction system on the machine side; The current of the rectifier in the permanent magnet traction system is adjusted according to the machine-side power to avoid abnormalities in the DC bus.

2. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 1, characterized in that, Determining the power of the permanent magnet traction system on the grid side, and obtaining the grid-side power, includes: The grid-side power of the permanent magnet traction system is determined based on the current of the rectifier, the grid-side voltage of the permanent magnet traction system, and the transformer turns ratio, thus obtaining the grid-side power.

3. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 1, characterized in that, The adjustment of the rectifier current in the permanent magnet traction system based on the machine-side power to prevent abnormalities in the DC bus includes: Based on the AC / DC power equivalent principle of the rectifier, and the current of the rectifier is determined according to the grid-side voltage of the permanent magnet traction system, the set current evaluation value is obtained; Determine the current value output by the voltage loop on the DC bus to obtain the voltage closed-loop output value; The target current sum is obtained by adding the set current evaluation value and the voltage closed-loop output value. The output current of the rectifier is adjusted based on the sum of the target currents to prevent abnormalities from occurring on the DC bus.

4. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 1, characterized in that, Also includes: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, the secondary ripple phase of the DC bus is determined, and the secondary ripple amplitude of the DC bus sent by the machine-side controller is received. The secondary ripple phase of the DC bus is sent to the machine-side controller so that the machine-side controller can suppress the beat frequency of the permanent magnet synchronous motor according to the secondary ripple phase and amplitude of the DC bus. The low-order harmonics in the DC bus are suppressed based on the second-order ripple phase and the second-order ripple amplitude of the DC bus.

5. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 4, characterized in that, Determining the secondary ripple phase of the DC bus includes: The voltage signal corresponding to the single-phase voltage in the rotating coordinate system is determined based on the single-phase voltage and the target virtual signal; the target virtual signal is a signal virtualized by delaying the single-phase voltage by 90°. The phase of the single-phase voltage is obtained by using a phase-locked loop to lock the voltage signal corresponding to the single-phase voltage in a rotating coordinate system. The secondary ripple phase of the DC bus is determined based on the phase of the single-phase voltage.

6. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 4, characterized in that, The method of suppressing low-order harmonics in the DC bus based on the second-order ripple phase and the second-order ripple amplitude of the DC bus includes: The instantaneous evaluation value of the secondary ripple is obtained by multiplying the secondary ripple phase of the DC bus and the secondary ripple amplitude of the DC bus. The difference between the DC bus voltage value and the instantaneous evaluation value of the second ripple is obtained to get the DC bus voltage processing value. The DC bus voltage is then adjusted according to the DC bus voltage processing value to suppress the low-order harmonics in the DC bus.

7. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 6, characterized in that, Also includes: The preset carrier signal is dynamically adjusted based on the instantaneous evaluation value of the second ripple to suppress low-order harmonics in the DC bus; the preset carrier signal is the carrier signal corresponding to the modulation wave used to control the rectifier.

8. A machine-grid side coordinated control method for a permanent magnet traction system, characterized in that, The machine-side controller used in permanent magnet traction systems includes: Receive the grid-side power sent by the grid-side controller of the permanent magnet traction system; the grid-side power is the power calculated by the grid-side controller on the grid side of the permanent magnet traction system; The torque of the permanent magnet synchronous motor in the permanent magnet traction system is adjusted according to the grid-side power, and abnormalities in the DC bus of the permanent magnet traction system are avoided. Determine the power of the permanent magnet traction system on the machine side to obtain the machine-side power; The machine-side power is sent to the grid-side controller so that the grid-side controller can adjust the current of the rectifier in the permanent magnet traction system according to the machine-side power to avoid abnormalities in the DC bus.

9. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 8, characterized in that, The adjustment of the torque of the permanent magnet synchronous motor in the permanent magnet traction system based on the grid-side power, and the prevention of abnormalities in the DC bus of the permanent magnet traction system, includes: The torque corresponding to the permanent magnet synchronous motor when it reaches a power balance state is determined based on the grid-side power and the rotational speed of the permanent magnet synchronous motor, and the torque setting value is obtained. The torque of the permanent magnet synchronous motor is adjusted according to the torque setting value and the torque setpoint of the permanent magnet synchronous motor to avoid abnormalities in the DC bus.

10. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 8, characterized in that, Determining the power of the permanent magnet traction system on the machine side, and obtaining the machine-side power, includes: When the inverter in the permanent magnet traction system is in normal operation, the three-phase voltage output by the inverter is determined according to the voltage of the DC bus and the corresponding pulse signal on the inverter. The three-phase current output by the inverter is sampled to obtain the three-phase current sample values; The power of the permanent magnet traction system at the machine side is determined based on the three-phase current sampling values ​​and the three-phase voltage output by the inverter, thus obtaining the machine-side power; When the inverter in the permanent magnet traction system is in an abnormal operating state, the three-phase current output by the inverter is sampled to obtain the three-phase current sample value. The back electromotive force of the permanent magnet synchronous motor is determined based on the three-phase current sampling values, the voltage of the DC bus, and the rotor position information of the permanent magnet synchronous motor. The power of the permanent magnet traction system on the machine side is determined based on the back electromotive force of the permanent magnet synchronous motor, thus obtaining the machine-side power.

11. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 9, characterized in that, Also includes: When the grid-side voltage in the permanent magnet traction system is a single-phase voltage, the secondary ripple amplitude of the DC bus is determined, and the secondary ripple phase of the DC bus sent by the grid-side controller is received. The second-order ripple amplitude of the DC bus is sent to the grid-side controller so that the grid-side controller can suppress the low-order harmonics in the DC bus according to the second-order ripple phase and the second-order ripple amplitude of the DC bus. Beat frequency suppression is performed on the permanent magnet synchronous motor based on the secondary ripple phase and the secondary ripple amplitude of the DC bus.

12. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 11, characterized in that, Determining the secondary ripple amplitude of the DC bus includes: The secondary ripple amplitude of the DC bus is determined based on the power conservation principle of the permanent magnet traction system.

13. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 12, characterized in that, The step of determining the secondary ripple amplitude of the DC bus based on the power conservation principle of the permanent magnet traction system includes: Based on the power conservation principle of the permanent magnet traction system, a target mathematical model corresponding to the secondary ripple amplitude of the DC bus is created; The secondary ripple amplitude of the DC bus is determined based on the target mathematical model and the machine-side power. The expression for the target mathematical model is as follows: ； In the formula, The amplitude of the secondary ripple of the DC bus is given. The angular frequency of the second-order ripple of the DC bus is given. The fundamental angular frequency of the grid-side voltage in the permanent magnet traction system is given. This refers to the secondary ripple current of the DC bus. This refers to the supporting capacitor in the permanent magnet traction system. The power on the machine side, For short-circuit impedance, The DC voltage level of the DC bus is specified.

14. The machine-grid side coordinated control method for a permanent magnet traction system according to claim 11, characterized in that, The step of suppressing beat frequency in the permanent magnet synchronous motor based on the secondary ripple phase and amplitude of the DC bus includes: The instantaneous evaluation value of the secondary ripple is obtained by multiplying the secondary ripple phase of the DC bus and the secondary ripple amplitude of the DC bus. The voltage of the DC bus is predicted based on the DC component of the DC bus and the instantaneous evaluation value of the secondary ripple, and the predicted value of the DC bus voltage is obtained. The control signal corresponding to the inverter in the permanent magnet traction system is adjusted according to the predicted DC bus voltage value in order to suppress the beat frequency of the permanent magnet synchronous motor.

15. A machine-grid side coordinated control device for a permanent magnet traction system, characterized in that, include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the steps of the machine-grid side coordinated control method for a permanent magnet traction system as described in any one of claims 1 to 7 or the machine-grid side coordinated control method for a permanent magnet traction system as described in any one of claims 8 to 14.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the machine-network side coordinated control method for a permanent magnet traction system as described in any one of claims 1 to 7 or the machine-network side coordinated control method for a permanent magnet traction system as described in any one of claims 8 to 14.

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