A method and system for beat suppression

Abstract

The embodiment of the present application relates to a beat frequency suppression method, comprising: processing the collected medium voltage real-time value to obtain a pulsating voltage current value and a pulsating voltage leading value; generating a medium voltage steady-state quantity according to the medium voltage real-time value and the pulsating voltage current value; obtaining a predicted medium voltage leading value according to the medium voltage steady-state quantity and the pulsating voltage leading value; calculating a modulation degree according to the predicted medium voltage leading value; the modulation degree comprises a beat frequency suppression modulation degree; calculating a pulse parameter according to the beat frequency suppression modulation degree, the current stator frequency and the rotor position of the motor; processing the pulse parameter to generate and output a pulse signal, thereby realizing beat frequency suppression.

Description

Technical Field

[0001] This invention relates to the field of converter control technology, and in particular to a beat frequency suppression method and system. Background Technology

[0002] In long-distance railway systems, a single-phase AC overhead contact line power supply is typically used. The traction drive system of the high-speed train adopts an "AC-DC-AC" structure, which uses transformers and four-quadrant rectifiers to convert the 25kV / 50Hz AC high voltage from the transmission line into DC power for the traction inverter and auxiliary converter. Due to the operating characteristics of the four-quadrant rectifier, a pulsating voltage component at twice the grid frequency (100Hz) is generated on its output DC voltage. The amplitude of the pulsating voltage is proportional to the downstream load.

[0003] The switching frequency of the traction inverter is limited by heat dissipation conditions, with a maximum allowable frequency of only a few hundred hertz. This is on the same order of magnitude as the pulsating voltage, with only a single-digit number of switching cycles within a single pulsation period, resulting in a very limited number of applications. If this pulsating voltage is directly used for modulation, the traction inverter output will generate additional harmonics, i.e., beat frequency components. When the traction inverter output frequency is near 100Hz or its integer multiples, even a small pulsating voltage can lead to a large beat frequency current, resulting in increased motor torque, severe motor vibration, noticeable noise, and even triggering overcurrent faults, affecting the safety and stability of the EMU train operation.

[0004] Currently, beat frequency suppression methods are broadly categorized into two types. The first involves adding a hardware resonant LC filter circuit to the DC link to absorb pulsating power on the DC side. While this method effectively suppresses pulsating voltage, the low resonant frequency results in a large size and weight for the filter unit, reducing the power density of the traction drive system and increasing costs. The second method uses software suppression in the traction inverter to adapt to pulsating voltage without requiring additional hardware; therefore, this method is increasingly being adopted in high-speed trains.

[0005] Compared with traditional asynchronous motors, permanent magnet motors have attracted increasing attention due to their advantages such as large starting torque, high efficiency, and low noise. They are gradually being applied to intercity and high-speed trains, meaning that permanent magnet traction systems will become the development direction of the next generation of traction systems.

[0006] However, existing methods do not specifically consider permanent magnet traction systems. In permanent magnet traction systems, to improve power density, permanent magnet motors have a higher number of pole pairs, resulting in a higher stator frequency for the same train speed compared to asynchronous motors. Specifically, 100Hz corresponds to a lower train speed, and lower speeds result in higher motor torque. Furthermore, the highest frequency of permanent magnet motors used in high-speed trains exceeds 300Hz, and significant beat frequency phenomena exist around 200Hz and 300Hz. Therefore, the same pulsating voltage has a greater impact on permanent magnet traction systems, leading to problems such as inaccurate pulsating voltage prediction and unsmooth suppression during multi-mode modulation switching. In other words, the inherent characteristics of permanent magnet motors place higher demands on beat frequency suppression methods. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing a beat frequency suppression method and system, which can improve the stability of permanent magnet traction systems.

[0008] To achieve the above objectives, the first aspect of the present invention provides a beat frequency suppression method, the beat frequency suppression method comprising:

[0009] The collected real-time medium-voltage values ​​are processed to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage;

[0010] Based on the real-time value of the medium voltage and the current value of the pulsating voltage, a steady-state quantity of the medium voltage is generated;

[0011] Based on the medium-voltage steady-state value and the pulsating voltage lead value, the predicted medium-voltage lead value is obtained;

[0012] The modulation index is calculated based on the predicted medium-pressure lead value; the modulation index includes beat frequency suppression modulation index.

[0013] Calculate the pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position;

[0014] The pulse parameters are processed to generate a pulse signal and output it, thereby achieving beat frequency suppression.

[0015] Preferably, the processing of the collected real-time medium-pressure values ​​specifically includes:

[0016] The collected medium-voltage real-time value is filtered by a first bandpass filter unit to generate a first filtering result. The first filtering result is then subjected to a first amplitude compensation process to generate the current value of the pulsating voltage. Furthermore, the collected medium-voltage real-time value is filtered by a second bandpass filter unit to generate a second filtering result. The second filtering result is then subjected to a second amplitude compensation process to generate the leading value of the pulsating voltage.

[0017] More preferably, before processing the collected real-time medium-pressure values, the method further includes:

[0018] The medium-voltage pulsating angular frequency is obtained from the AC power grid angular frequency.

[0019] More preferably, the first amplitude compensation processing on the first filtering result specifically includes:

[0020] Based on the medium-voltage pulsation angular frequency, determine the low-pass cutoff angular frequency and high-pass cutoff angular frequency of the first bandpass filter unit;

[0021] The first amplitude compensation coefficient is determined based on the low-pass cutoff angular frequency and the high-pass cutoff angular frequency of the first bandpass filter unit.

[0022] Based on the first amplitude compensation coefficient, the first filtering result is subjected to first amplitude compensation processing.

[0023] More preferably, the second filtering result is subjected to a second amplitude compensation process, specifically including:

[0024] The low-pass cutoff angular frequency of the second bandpass filter unit is determined based on the medium-voltage pulsation angular frequency.

[0025] Based on the low-pass cutoff angular frequency and the medium-voltage pulsation angular frequency of the second bandpass filter unit, determine the phase lag angle corresponding to the pulsation voltage lead value;

[0026] The total modulation delay is determined based on the current modulation cycle delay and the next modulation cycle delay.

[0027] Based on the total modulation delay and the medium-voltage pulsation angular frequency, determine the hysteresis angle caused by the modulation delay;

[0028] The phase lead angle corresponding to the pulsating voltage lead value is determined based on the phase lag angle corresponding to the pulsating voltage lead value and the lag angle caused by the modulation delay.

[0029] The high-pass cutoff angular frequency of the second bandpass filter unit is determined based on the phase lead angle corresponding to the pulsating voltage lead value and the medium-voltage pulsating angular frequency.

[0030] The second amplitude compensation coefficient is determined based on the high-pass cutoff angular frequency and low-pass cutoff angular frequency of the second bandpass filter unit.

[0031] The second amplitude compensation process is performed on the second filtering result based on the second amplitude compensation coefficient.

[0032] Preferably, the step of calculating the modulation index based on the predicted medium-pressure lead value specifically includes:

[0033] The modulation index is calculated based on the predicted medium-voltage lead value, motor voltage, and medium-voltage steady-state value; the modulation index also includes the frequency switching modulation index.

[0034] More preferably, after calculating the modulation, the method further includes:

[0035] Based on the frequency switching modulation index and the current stator frequency of the motor, determine whether frequency switching is required for the next modulation cycle, and determine the modulation cycle delay after frequency switching.

[0036] In a second aspect, the present invention provides a beat frequency suppression system, the beat frequency suppression system comprising:

[0037] The medium-voltage real-time value processing module is used to process the collected medium-voltage real-time values ​​to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage.

[0038] The medium-voltage steady-state quantity generation module is used to generate medium-voltage steady-state quantities based on the real-time value of the medium-voltage and the current value of the pulsating voltage.

[0039] The medium-voltage lead generation module is used to obtain the predicted medium-voltage lead value based on the medium-voltage steady-state quantity and the pulsating voltage lead value.

[0040] The modulation calculation module is used to calculate the modulation degree based on the predicted medium-voltage lead value; the modulation degree includes beat frequency suppression modulation degree.

[0041] The pulse parameter generation module is used to calculate pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position.

[0042] The pulse signal output module is used to process the pulse parameters, generate a pulse signal and output it, thereby achieving beat frequency suppression.

[0043] In a third aspect, the present invention provides a computer server, comprising: a memory, a processor, and a transceiver;

[0044] The processor is used to couple with the memory, read and execute instructions in the memory to implement the beat frequency suppression method according to any one of the first aspects;

[0045] The transceiver is coupled to the processor, and the processor controls the transceiver to send and receive messages.

[0046] In a fourth aspect, the present invention provides a storage medium including a program or instructions that, when run on a computer, implement the beat frequency suppression method described in any of the first aspects.

[0047] The beat frequency suppression method provided in this invention processes the collected real-time medium voltage value to obtain the current value and the leading value of the pulsating voltage. The steady-state quantity of the medium voltage is extracted from the current value of the pulsating voltage. In this way, even when the load power changes suddenly or the medium voltage control is unstable, the medium voltage change can be accurately identified. Based on the real-time prediction of the leading value of the pulsating voltage, the impact of medium voltage fluctuations in the two cycles on beat frequency suppression can be effectively reduced. Furthermore, the leading value of the medium voltage can be accurately predicted. Then, the beat frequency suppression modulation is calculated based on the predicted leading value of the medium voltage. Finally, beat frequency suppression is achieved based on the beat frequency suppression modulation, which solves the problem of unsmooth suppression and improves the stability and safety of the permanent magnet traction system of the EMU. Attached Figure Description

[0048] Figure 1 This is one of the flowcharts of the beat frequency suppression method provided in the embodiments of the present invention;

[0049] Figure 2 This is the second flowchart of the beat frequency suppression method provided in the embodiments of the present invention;

[0050] Figure 3 This is a schematic diagram illustrating the process of generating the current value of the pulsating voltage according to an embodiment of the present invention;

[0051] Figure 4 This is the third flowchart of the beat frequency suppression method provided in the embodiments of the present invention;

[0052] Figure 5 This is a schematic diagram of the total modulation delay provided in an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram illustrating the process of generating the pulsating voltage lead value provided in an embodiment of the present invention;

[0054] Figure 7 This is one of the schematic diagrams illustrating the application effect of the beat frequency suppression method provided in the embodiments of the present invention;

[0055] Figure 8 This is the second schematic diagram illustrating the application effect of the beat frequency suppression method provided in this embodiment of the invention;

[0056] Figure 9 This is the third schematic diagram illustrating the application effect of the beat frequency suppression method provided in this embodiment of the invention;

[0057] Figure 10 This is the fourth schematic diagram illustrating the application effect of the beat frequency suppression method provided in this embodiment of the invention;

[0058] Figure 11 This is the fifth schematic diagram illustrating the application effect of the beat frequency suppression method provided in this embodiment of the invention;

[0059] Figure 12This is a structural diagram of the beat frequency suppression system module provided in an embodiment of the present invention. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0061] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0062] The present invention provides a beat frequency suppression method, which is applied to the permanent magnet traction system of EMU trains. It solves the problems of inaccurate prediction of pulsating voltage and unsmooth suppression when switching between multiple modes using the current software suppression method, and improves the stability and safety of the permanent magnet traction system.

[0063] Figure 1 This is one of the flowcharts of the beat frequency suppression method provided in the embodiments of the present invention, which is described below in conjunction with... Figure 1 The technical solution of the present invention will be described with reference to specific embodiments.

[0064] The beat frequency suppression method provided in this embodiment of the invention mainly includes the following steps:

[0065] Step 110: Process the collected real-time medium voltage value to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage.

[0066] Specifically, the medium-voltage real-time value can be understood as an abbreviation for the intermediate DC voltage between the four-quadrant rectifier and the traction inverter, which can be represented by u. dc The current value of the pulsating voltage is represented by Δu. dc_now express.

[0067] Before processing the collected real-time medium-pressure values, the method also includes:

[0068] The medium-voltage pulsating angular frequency is obtained from the AC power grid angular frequency.

[0069] Specifically, the angular frequency of the AC power grid is ω. net The angular frequency of medium-pressure pulsation is represented by ω. wave It means that ω wave =2*ω net .

[0070] In a specific example, the angular frequency ω of the AC power grid net =100π, then, the angular frequency of medium-pressure pulsation ω wave =200π.

[0071] Processing the collected real-time medium-pressure values ​​mainly involves two steps:

[0072] S11, the collected medium-voltage real-time value is filtered by the first bandpass filter unit to generate the first filtering result, and the first amplitude compensation processing is performed on the first filtering result to generate the current value of the pulsating voltage.

[0073] Specifically, since the phase of the current value of the pulsating voltage cannot be leading or lagging, the first bandpass filter unit can be understood as a bandpass filter with phase complementarity. As is known to those skilled in the art, a bandpass filter allows waves of a specific frequency band to pass through while blocking waves of other frequency bands. The two cutoff frequencies of the bandpass filter are the low-pass cutoff frequency and the high-pass cutoff frequency. It is understandable that the first bandpass filter unit can also be generated by combining a low-pass filter and a high-pass filter. However, due to the phase lag of the low-pass filter and the phase lead of the high-pass filter, to obtain the current value of the pulsating voltage, the lagging phase of the low-pass filter needs to be equal to the leading phase of the high-pass filter to achieve phase complementarity. Therefore, the first filter unit only needs to satisfy the phase complementarity function; this application does not impose specific limitations.

[0074] More specifically, such as Figure 2 As shown:

[0075] S111, determine the low-pass cutoff angular frequency and high-pass cutoff angular frequency of the first bandpass filter unit based on the medium-voltage pulsation angular frequency.

[0076] Specifically, the cutoff angular frequency = 2π * cutoff frequency. Here, the low-pass cutoff angular frequency of the first bandpass filter unit is denoted by ω. l_now The high-pass cutoff angular frequency is represented by ω. h_now express.

[0077] The low-pass cutoff angular frequency, high-pass cutoff angular frequency, and medium-voltage pulsation angular frequency of the first bandpass filter unit satisfy the following relationship:

[0078] ω l_now *ω h_now =ω wave *ω wave

[0079] For example, the low-pass cutoff angular frequency ω of the first bandpass filter unit l_now A medium-pressure pulsation angular frequency ω can be selected as 1 to 3 times. wave The Qualcomm cutoff angular frequency ω h_now A medium-pressure pulsation angular frequency ω can be selected from 1 / 3 to 1 times. wave This achieves phase cancellation and complementarity.

[0080] S112, determine the first amplitude compensation coefficient based on the low-pass cutoff angular frequency and high-pass cutoff angular frequency of the first bandpass filter unit.

[0081] Specifically, the first amplitude compensation coefficient is A now express.

[0082]

[0083] Among them, the medium-pressure pulsation angular frequency ω wave =200π, the low-pass cutoff angular frequency ω of the first bandpass filter unit l_now and the high-pass cutoff angular frequency ω h_now Both are 200π.

[0084] S113, perform first amplitude compensation processing on the first filtering result according to the first amplitude compensation coefficient.

[0085] Specifically, after performing amplitude compensation processing on the first filtering result, the current value of the pulsating voltage can be obtained. For example... Figure 3 As shown, the real-time value u of the medium voltage is filtered by a first bandpass filter unit with phase complementarity. dc After filtering and corresponding processing, the current value Δu of the pulsating voltage is obtained. dc_now .

[0086] S12 filters the acquired medium-voltage real-time value through the second bandpass filter unit to generate a second filtering result. The second filtering result is then subjected to a second amplitude compensation process to generate a pulsating voltage leading value.

[0087] Specifically, because the phase of the pulsating voltage lead needs to be ahead, the second bandpass filter unit can be understood as a bandpass filter with delay compensation. Similar to the first bandpass filter unit, it has two cutoff frequencies: a low-pass cutoff frequency and a high-pass cutoff frequency. The pulsating voltage lead is denoted by Δu. dc_lead Indicates. For example... Figure 6 The figure shows the real-time value of medium pressure u. dc After filtering and processing by the second bandpass filter unit, the pulsating voltage lead value Δu is obtained. dc_lead The process involves employing a second bandpass filter unit that considers modulation delay to predict the pulsating voltage lead value in real time, effectively reducing the impact of voltage fluctuations between the two cycles on beat frequency suppression.

[0088] More specifically, such as Figure 4 As shown:

[0089] S121, determine the low-pass cutoff angular frequency of the second bandpass filter unit based on the medium-voltage pulsation angular frequency.

[0090] As an example, not a limitation, the low-pass cutoff angular frequency of the second bandpass filter unit is ω. l_lead This indicates that the angular frequency ω of the medium-pressure pulsation can be selected from 1 to 3 times. wave .

[0091] S122, based on the low-pass cutoff angular frequency and the medium-voltage pulsation angular frequency of the second bandpass filter unit, determine the phase lag angle corresponding to the pulsation voltage lead value.

[0092] Specifically, the phase lag angle corresponding to the pulsating voltage lead is denoted by θ. l The specific calculation process is as follows:

[0093]

[0094] S123, determine the total modulation delay based on the current modulation cycle delay and the next modulation cycle delay.

[0095] Specifically, in applications involving high-power traction drives and high-speed operation of permanent magnet synchronous motors, to reduce switching losses of switching devices and decrease the computational burden on the controller, the motor control system is required to operate under low carrier ratio conditions. However, as the carrier ratio decreases, the sampling period time increases, resulting in significant digital control delays. For example... Figure 5 As shown, the process from the Digital Signal Processor (DSP) calculating pulse parameters to the Field Programmable Gate Array (FPGA) actually generating and outputting the pulse signal involves a certain modulation delay. Furthermore, in the medium-to-high-speed segmented synchronous modulation range, the modulation delay continuously changes with the stator frequency and carrier ratio.

[0096] The current modulation period delay is denoted by T1, the next modulation period delay by T2, and the total modulation delay by T. d It means that T d =T1+0.5T2.

[0097] in,

[0098] N1 is the carrier ratio of the current frequency division, N2 is the carrier ratio of the frequency division corresponding to the next modulation period, and f0 is the stator frequency.

[0099] It should be noted that if frequency switching is not required, T2 = T1; if frequency switching is required, then T2 is the modulation period delay after frequency switching. The specific determination of the modulation period delay after frequency switching will be discussed later.

[0100] S124, determine the hysteresis angle caused by the modulation delay based on the total modulation delay and the medium voltage pulsation angular frequency.

[0101] Specifically, firstly, based on the medium-pressure pulsation angular frequency ω wave The pulsating voltage period is obtained. The pulsating voltage period is represented by T. wave It means that T wave =2π / ω wave .

[0102] Then, based on the pulsating voltage period and the total modulation delay, the hysteresis angle caused by the modulation delay is determined.

[0103] The hysteresis angle caused by the modulation delay is denoted by θ. d This can be expressed using a formula. Calculated.

[0104] S125, determine the phase lead angle corresponding to the pulsating voltage lead value based on the phase lag angle corresponding to the pulsating voltage lead value and the lag angle caused by the modulation delay.

[0105] Specifically, the phase lead angle corresponding to the pulsating voltage lead value is denoted by θ. h The phase lead angle corresponding to the pulsating voltage lead is equal to the sum of the phase lag angle corresponding to the pulsating voltage lead and the lag angle caused by the modulation delay, i.e., θ. h =θ l+ θ d .

[0106] S126, determine the high-pass cutoff angular frequency of the second bandpass filter unit based on the phase lead angle corresponding to the pulsating voltage lead value and the medium voltage pulsating angular frequency.

[0107] Specifically, the high-pass cutoff angular frequency of the second bandpass filter unit is ω. h_lead This can be expressed using a formula. Calculated.

[0108] S127, determine the second amplitude compensation coefficient based on the high-pass cutoff angular frequency and low-pass cutoff angular frequency of the second bandpass filter unit.

[0109] Among them, the second amplitude compensation coefficient is A lead The specific calculation is as follows:

[0110]

[0111] S128, Perform second amplitude compensation processing on the second filtering result according to the second amplitude compensation coefficient.

[0112] The following uses the angular frequency ω of the AC power grid net When the oscillator frequency f0 is 70Hz and the frequency is 100π, the frequency is divided by 15 and then by 12. The low-pass cutoff angular frequency of the second bandpass filter unit is ω. l_lead Select 1 times the medium-pressure pulsation angular frequency ωwave The calculation process of the second amplitude compensation coefficient will be explained in detail using an example.

[0113] The first step is to calculate the phase lag angle θ corresponding to the pulsating voltage lead value. l .

[0114]

[0115] The second step is to calculate the total modulation delay T. d .

[0116] The carrier ratio N1 is 30 with a frequency division of 15, and the current modulation period delay is... The carrier ratio N2 is 24 (divided by 12). The next modulation cycle is delayed. Total modulation delay T d =0.0008163s.

[0117] The third step is to calculate the pulsating voltage period T. wave .

[0118] T wave =2π / ω wave =2π / 2ω net =π / 100π = 0.01s

[0119] The fourth step is to calculate the hysteresis angle θ caused by the modulation delay. d .

[0120]

[0121] Fifth step: Calculate the phase lead angle θ corresponding to the pulsating voltage lead value. h .

[0122] θ h =θ l+ θ d =29.3868° + 45° = 74.3868°

[0123] Step 6: Calculate the high-pass cutoff angular frequency of the second bandpass filter unit using ω. h_lead .

[0124]

[0125] Step 7: Calculate the second amplitude compensation coefficient A lead .

[0126]

[0127] Step 120: Generate the medium-voltage steady-state quantity based on the real-time value of the medium-voltage and the current value of the pulsating voltage.

[0128] Specifically, the medium-voltage steady-state quantity can be obtained by subtracting the current value of the pulsating voltage from the real-time value of the medium-voltage. The medium-voltage steady-state quantity is represented by U. dc In other words, U dc =u dc -Δu dc_now For example... Figure 3 As shown, the current value Δu of the pulsating voltage is obtained by employing a first bandpass filter unit with phase complementarity. dc_now Thus, the steady-state quantity U under medium pressure is obtained. dc This way, even when the load power changes suddenly or the medium voltage control becomes unstable, the change in medium voltage can be accurately identified.

[0129] Step 130: Based on the steady-state medium voltage and the pulsating voltage lead value, obtain the predicted medium voltage lead value.

[0130] Specifically, the predicted medium-voltage lead can be obtained by summing the medium-voltage steady-state value and the pulsating voltage lead. The predicted medium-voltage lead is denoted by u. dc_lead u dc_lead =U dc +Δu dc_lead Based on the above discussion, when performing segmented synchronous modulation, the predicted pulsating voltage phase is corrected online in real time according to the current stator frequency and total modulation delay. This allows for accurate prediction of the pulsating voltage lead value and effectively reduces the impact of voltage fluctuations between the two cycles on beat frequency suppression.

[0131] Step 140: Calculate the modulation index based on the predicted medium-pressure lead value.

[0132] Specifically, since the amplitude of the medium-voltage fluctuation is proportional to the load on the downstream side, when the motor power is large, the beat frequency suppression modulation fluctuates drastically. If the beat frequency suppression modulation is directly used as the frequency cutting condition, it is easy to cause repeated frequency cutting. Therefore, the modulation system of this application includes both beat frequency suppression modulation and frequency cutting modulation. That is, using the frequency cutting modulation as a dedicated frequency cutting condition can avoid repeated frequency cutting and improve the stability of the permanent magnet traction system.

[0133] Furthermore, based on the predicted medium-voltage lead, motor voltage, and medium-voltage steady-state value, the modulation index is calculated. The beat frequency suppression modulation index is denoted by m, and the frequency cut-off modulation index is denoted by mclip. s The motor voltage is represented by U. m express.

[0134] Where m = U m / u dc_lead ,m s =U m / U dc .

[0135] Step 150: Calculate the pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position.

[0136] Specifically, the pulse parameters include the comparison value and the period value. The pulse parameters can be calculated by a digital signal processor (DSP) using the Space Vector Pulse Width Modulation (SVPWM) method.

[0137] Step 160: Process the pulse parameters to generate and output a pulse signal, thereby achieving beat frequency suppression.

[0138] Specifically, a Field Programmable Gate Array (FPGA) chip is used to process the pulse parameters logically to generate a pulse signal. This pulse signal is used to drive the switching transistors in the traction inverter to turn on and off, ultimately controlling the permanent magnet motor, which achieves beat frequency suppression.

[0139] Furthermore, the method also includes:

[0140] Based on the frequency switching modulation index and the current stator frequency of the motor, determine whether frequency switching is required for the next modulation cycle, determine the modulation cycle delay after frequency switching, and re-execute steps S12-S150.

[0141] Figures 7-11 The application effect diagram of this method is shown.

[0142] like Figure 7 As shown, the beat frequency suppression waveform during frequency switching is displayed. It can be seen that the motor current is smooth and without impact during frequency switching, and the beat frequency suppression effect is good, which indirectly reflects that the medium voltage lead value predicted by this method is relatively accurate.

[0143] Figure 8 , 9 Figures 1 and 10 show the beat frequency suppression waveforms when the stator frequency is divided at 100Hz, 200Hz, and 300Hz, which are near integer multiples of the medium-voltage pulsation frequency. As can be seen from the figures, during the beat frequency suppression process, there are no obvious low-order harmonics in the outer envelope of the motor current, and the beat frequency phenomenon is effectively suppressed.

[0144] Figure 11 The waveform of beat frequency suppression across the entire speed range is shown. It can be seen that during the entire acceleration process of the EMU, there are no obvious low-order harmonics in the motor current, the beat frequency phenomenon is effectively suppressed, and the beat frequency suppression process is smooth, stable and without impact.

[0145] The beat frequency suppression method provided in this invention processes the collected real-time medium voltage value to obtain the current value and the leading value of the pulsating voltage. By generating the current value of the pulsating voltage, the steady-state quantity of the medium voltage is extracted. In this way, even when the load power changes suddenly or the medium voltage control is unstable, the medium voltage change can be accurately identified. Based on the real-time prediction of the leading value of the pulsating voltage, the impact of medium voltage fluctuations in the two cycles on beat frequency suppression can be effectively reduced. Furthermore, the leading value of the medium voltage can be accurately predicted. Then, the beat frequency suppression modulation is calculated based on the predicted leading value of the medium voltage. Finally, beat frequency suppression is achieved based on the beat frequency suppression modulation, which solves the problem of non-smooth suppression and improves the stability and safety of the permanent magnet traction system of the EMU.

[0146] Example 2

[0147] Embodiment 2 of the present invention provides a beat frequency suppression system, such as Figure 12 As shown, the beat frequency suppression system specifically includes:

[0148] The medium-voltage real-time value processing module 10 is used to process the collected medium-voltage real-time values ​​to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage.

[0149] The medium-voltage steady-state quantity generation module 20 is used to generate medium-voltage steady-state quantities based on the real-time value of medium-voltage and the current value of pulsating voltage.

[0150] The medium-voltage lead generation module 30 is used to obtain the predicted medium-voltage lead value based on the medium-voltage steady-state quantity and the pulsating voltage lead value.

[0151] The modulation calculation module 40 is used to calculate the modulation based on the predicted medium-pressure lead value; the modulation includes beat frequency suppression modulation.

[0152] The pulse parameter generation module 50 is used to calculate pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position.

[0153] The pulse signal output module 60 is used to process pulse parameters, generate pulse signals and output them, thereby achieving beat frequency suppression.

[0154] Example 3

[0155] Embodiment 3 of the present invention provides a computer server, including: a memory, a processor, and a transceiver;

[0156] The processor is used to couple with the memory, read and execute instructions in the memory to implement the beat frequency suppression method described in any of the embodiments;

[0157] The transceiver is coupled to the processor, and the processor controls the transceiver to send and receive messages.

[0158] Example 4

[0159] Embodiment 4 of the present invention provides a storage medium including a program or instructions, which, when the program or instructions are run on a computer, implements the beat frequency suppression method described in any one of Embodiment 1.

[0160] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0161] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented in hardware, software modules executed by a processor, or a combination of both. The software modules can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disks, removable disks, CD-ROM power system control methods, or any other form of storage medium known in the art.

[0162] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A beat frequency suppression method, characterized in that, The beat frequency suppression method includes: The collected real-time medium-voltage values ​​are processed to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage; Based on the real-time value of the medium voltage and the current value of the pulsating voltage, a steady-state quantity of the medium voltage is generated; Based on the medium-voltage steady-state value and the pulsating voltage lead value, the predicted medium-voltage lead value is obtained; Based on the predicted medium voltage lead value, the beat frequency suppression modulation index is calculated, and based on the medium voltage steady-state value, the frequency switching modulation index is calculated; the beat frequency suppression modulation index is used to suppress beat frequency in real time, and the frequency switching modulation index is used to determine the modulation mode switching and avoid repeated frequency switching; Calculate the pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position; The pulse parameters are processed to generate a pulse signal and output it, thereby achieving beat frequency suppression.

2. The beat frequency suppression method according to claim 1, characterized in that, The processing of the collected real-time medium-pressure values ​​specifically includes: The collected medium-voltage real-time value is filtered by a first bandpass filter unit to generate a first filtering result. The first filtering result is then subjected to a first amplitude compensation process to generate the current value of the pulsating voltage. Furthermore, the collected medium-voltage real-time value is filtered by a second bandpass filter unit to generate a second filtering result. The second filtering result is then subjected to a second amplitude compensation process to generate the leading value of the pulsating voltage.

3. The beat frequency suppression method according to claim 2, characterized in that, Before processing the collected real-time medium-pressure values, the process also includes: The medium-voltage pulsating angular frequency is obtained from the AC power grid angular frequency.

4. The beat frequency suppression method according to claim 3, characterized in that, The first amplitude compensation process for the first filtering result specifically includes: Based on the medium-voltage pulsation angular frequency, determine the low-pass cutoff angular frequency and high-pass cutoff angular frequency of the first bandpass filter unit; The first amplitude compensation coefficient is determined based on the low-pass cutoff angular frequency and the high-pass cutoff angular frequency of the first bandpass filter unit. Based on the first amplitude compensation coefficient, the first filtering result is subjected to first amplitude compensation processing.

5. The beat frequency suppression method according to claim 3, characterized in that, The second amplitude compensation process is performed on the second filtering result, specifically including: The low-pass cutoff angular frequency of the second bandpass filter unit is determined based on the medium-voltage pulsation angular frequency. Based on the low-pass cutoff angular frequency and the medium-voltage pulsation angular frequency of the second bandpass filter unit, determine the phase lag angle corresponding to the pulsation voltage lead value; The total modulation delay is determined based on the current modulation cycle delay and the next modulation cycle delay. Based on the total modulation delay and the medium-voltage pulsation angular frequency, determine the hysteresis angle caused by the modulation delay; The phase lead angle corresponding to the pulsating voltage lead value is determined based on the phase lag angle corresponding to the pulsating voltage lead value and the lag angle caused by the modulation delay. The high-pass cutoff angular frequency of the second bandpass filter unit is determined based on the phase lead angle corresponding to the pulsating voltage lead value and the medium-voltage pulsating angular frequency. The second amplitude compensation coefficient is determined based on the high-pass cutoff angular frequency and low-pass cutoff angular frequency of the second bandpass filter unit. The second amplitude compensation process is performed on the second filtering result based on the second amplitude compensation coefficient.

6. The beat frequency suppression method according to claim 1, characterized in that, The calculation of the modulation index based on the predicted medium-pressure lead value specifically includes: The modulation index is calculated based on the predicted medium-voltage lead value, motor voltage, and medium-voltage steady-state value; the modulation index also includes the frequency switching modulation index.

7. The beat frequency suppression method according to claim 6, characterized in that, Following the calculation of the modulation index, the following is also included: Based on the frequency switching modulation index and the current stator frequency of the motor, determine whether frequency switching is required for the next modulation cycle, and determine the modulation cycle delay after frequency switching.

8. A beat frequency suppression system, characterized in that, The beat frequency suppression system includes: The medium-voltage real-time value processing module is used to process the collected medium-voltage real-time values ​​to obtain the current value of the pulsating voltage and the leading value of the pulsating voltage. The medium-voltage steady-state quantity generation module is used to generate medium-voltage steady-state quantities based on the real-time value of the medium-voltage and the current value of the pulsating voltage. The medium-voltage lead generation module is used to obtain the predicted medium-voltage lead value based on the medium-voltage steady-state quantity and the pulsating voltage lead value. The modulation calculation module is used to calculate the beat frequency suppression modulation degree based on the predicted medium voltage lead value, and to calculate the frequency switching modulation degree based on the medium voltage steady-state value; the beat frequency suppression modulation degree is used to suppress beat frequency in real time, and the frequency switching modulation degree is used to determine the modulation mode switching and avoid repeated frequency switching; The pulse parameter generation module is used to calculate pulse parameters based on the beat frequency suppression modulation, the current stator frequency of the motor, and the rotor position. The pulse signal output module is used to process the pulse parameters, generate a pulse signal and output it, thereby achieving beat frequency suppression.

9. A computer server, characterized in that, include: Memory, processor, and transceiver; The processor is used to couple with the memory, read and execute instructions in the memory to implement the beat frequency suppression method according to any one of claims 1-7; The transceiver is coupled to the processor, and the processor controls the transceiver to send and receive messages.

10. A storage medium, characterized in that, Includes a program or instructions that, when run on a computer, implement the beat frequency suppression method as described in any one of claims 1 to 7.

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