Three-phase current comprehensive stability analysis method for range extender controller

Abstract

This invention specifically relates to a method for comprehensive stability analysis of three-phase current in range extender controllers, comprising the following steps: First, constructing a multi-condition gradient acquisition set covering the entire operating range of the range extender; acquiring time-domain data of three-phase current under all operating conditions and performing segmentation and frequency domain decomposition; then, determining the fundamental and harmonic characteristic frequencies based on motor parameters, and extracting the frequency domain amplitude sets of each order under all operating conditions; subsequently, calculating three types of stability coefficients: fundamental order, conventional harmonics, and unconventional harmonics; finally, calculating the comprehensive stability coefficient based on weighting rules, and completing the comprehensive current performance rating. This method enables pre-emptive, full-condition, quantitative analysis and comprehensive performance rating of three-phase current stability in range extender controllers, identifying control defects in advance, shortening product development cycles, and reducing R&D costs.

Description

Technical Field

[0001] This invention relates to the field of vehicle generator assembly technology for new energy range-extended vehicles, specifically to a three-phase current comprehensive stability analysis method for range extender controllers. Background Technology

[0002] With the rapid development of the new energy vehicle industry, range-extended electric vehicles (REEVs) have become one of the key technological routes in the new energy vehicle industry due to their core technological advantages such as no range anxiety, controllable energy consumption costs, and strong power adaptability. Their industrial application depth and market scale continue to expand. As the core power unit of REEVs, the range extender assembly's power generation efficiency, control precision, and operational reliability directly determine the vehicle's power performance, economic performance, NVH (noise, vibration, and harshness) performance, and driving experience. It is a key component of the vehicle's core competitiveness.

[0003] The range extender controller is the core control unit of the range extender assembly. Its core function is to convert the DC power output from the vehicle's power battery into three-phase AC power through a power inverter topology, driving the range extender motor and achieving controllable power generation. The current stability of the three-phase AC power output from the inverter is a key indicator characterizing the performance and output quality of the range extender controller. Insufficient current stability will directly lead to a decrease in the torque control accuracy of the range extender motor, an increase in power generation efficiency loss, and consequently, a series of reliability issues such as increased heating of the motor windings and accelerated insulation aging. At the same time, current distortion and fluctuations will excite electromagnetic vibration and noise in the motor, deteriorating the overall NVH performance of the vehicle, and also causing a decrease in the smoothness of the vehicle's ride and a reduction in driving range, seriously limiting the performance ceiling of the range extender assembly and the entire vehicle.

[0004] Currently, performance verification of three-phase AC power output from inverters in the industry largely relies on full-performance bench testing of the range extender assembly and vehicle-level real-vehicle verification. This type of verification requires prototype assembly and system integration in the later stages of product development before testing and verifying related indicators such as torque accuracy, NVH performance, and thermal management performance. It makes it impossible to conduct preliminary assessments and predictions of controller current output performance during the single-motor prototype development phase. This situation directly leads to delayed discovery of product design defects, lengthy design iteration cycles, and significant investment in testing resources, greatly increasing the R&D costs and risks of the range extender assembly and making it difficult to meet the rapidly iterating technological development needs of the range-extended electric vehicle industry.

[0005] Therefore, there is an urgent need to develop a three-phase current comprehensive stability analysis method for range extender controllers, which can enable rapid and accurate quantitative analysis and comprehensive evaluation of the current stability of the controller's inverter output three-phase AC power in the early stages of product forward design, effectively shortening the product development cycle and reducing R&D costs and risks. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for comprehensive three-phase current stability analysis of range extender controllers. This method enables proactive, full-condition, and quantitative analysis and comprehensive performance rating of the three-phase current stability of range extender controllers, allowing for early identification of control defects, shortening product development cycles, and reducing R&D costs.

[0007] The objective of this invention is achieved through the following approach:

[0008] A method for comprehensive stability analysis of three-phase current in a range extender controller includes the following steps:

[0009] 1) Based on the design parameters of the range extender, construct a multi-condition data acquisition set covering the entire operating range;

[0010] 2) Based on the collected operating condition set, collect the three-phase current time-domain data output by the controller during the full operating condition of the range extender motor. Divide the three-phase current time-domain data into multiple groups of time-domain grouped data. Then, use a frequency domain transformation algorithm to perform frequency domain decomposition on each group of time-domain grouped data to obtain the frequency domain decomposition results corresponding to each group under the full operating condition.

[0011] 3) Combining the real-time operating parameters and inherent structural parameters of the range extender motor, determine the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain group data, and obtain the frequency domain decomposition results corresponding to each group under the full operating condition according to step 2), and obtain the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition; the target harmonic characteristic frequency includes conventional harmonic characteristic frequency and unconventional harmonic characteristic frequency.

[0012] 4) Based on the frequency domain amplitude set corresponding to each order characteristic frequency under all operating conditions, calculate the stability coefficient corresponding to each order characteristic frequency. The stability coefficient includes the three-phase current basic order stability coefficient, the conventional harmonic order stability coefficient, and the unconventional harmonic order stability coefficient.

[0013] 5) Based on the stability coefficient obtained in step 4), the comprehensive stability coefficient of the range extender controller current is calculated in combination with the multi-dimensional weight allocation rule, and the comprehensive rating result of the range extender controller current performance is obtained in combination with the current performance grading and evaluation rule.

[0014] Preferably, in step 1), the set of acquisition conditions for the multi-condition gradient includes:

[0015] ① The maximum load condition of the range extender design, the acceleration operation condition from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate;

[0016] ② The acceleration operation condition of the range extender motor at 75% of its maximum design load, which is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate.

[0017] ③ Under the condition of 50% of the maximum load of the range extender, the speed increase operation condition is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate.

[0018] ④ Under the load condition of 25% of the maximum design load of the range extender, the speed increase operation condition is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate.

[0019] Preferably, step 2), which involves collecting the three-phase current time-domain data output by the controller during the full-condition operation of the range extender motor, and obtaining the frequency domain decomposition results corresponding to each group under the full-condition operation, includes:

[0020] 2-1) Current acquisition units are set on the three-way connection lines between the range extender motor and the controller. The three-phase current time domain data output by the controller is synchronously acquired through the current acquisition units during the full-speed operation of the range extender under various working conditions.

[0021] 2-2) Using the equal-length fixed-point grouping rule, the three-phase current time-domain data collected under each working condition is segmented to obtain multiple sets of mutually independent time-domain grouped data;

[0022] 2-3) The discrete Fourier transform algorithm is used to decompose the time-domain grouped data of each group into frequency domains to obtain the frequency domain decomposition results of each group under the full working condition.

[0023] The formula for calculating the frequency domain decomposition is as follows:

[0024]

[0025] In the formula, For operating condition identification; For three-phase identification and M represents the number of sampling points for a single set of three-phase current time-domain data. For frequency; For the first Under working conditions Frequency domain decomposition results of the corresponding groupings of phase currents; For the first Under working conditions The first group corresponding to the phase current One time-domain data point; This refers to the data point sequence number.

[0026] Preferably, step 3) involves obtaining the frequency domain amplitude set corresponding to the characteristic frequencies of each order under all operating conditions, including:

[0027] 3-1) Using the number of rotor poles of the range extender motor as the inherent structural parameter and the average speed corresponding to each time-domain grouped data as the real-time operating parameter, the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain grouped data are calculated.

[0028] Wherein, the fundamental characteristic frequency is the synchronous frequency corresponding to the fundamental order of the current, and the target harmonic characteristic frequency includes conventional harmonic characteristic frequency and unconventional harmonic characteristic frequency;

[0029] 3-2) Based on the frequency domain decomposition results of each group under the full operating condition obtained in step 2), extract the frequency domain amplitude of each time domain group data under the full operating condition at the fundamental characteristic frequency and each target harmonic characteristic frequency, and construct the basic order frequency domain amplitude set, the conventional harmonic order frequency domain amplitude set and the unconventional harmonic order frequency domain amplitude set respectively, which together form the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition.

[0030] Preferably, the conventional harmonic characteristic frequencies are the 5th, 7th, 11th, and 13th harmonics of the fundamental characteristic frequency, and the unconventional harmonic characteristic frequencies are the 2nd, 3rd, 4th, and 6th harmonics of the fundamental characteristic frequency.

[0031] Preferably, in step 4), the calculation steps for the three-phase current fundamental order stability coefficient include:

[0032] 4-1-1) For each operating condition in the data acquisition set, based on the basic order frequency domain amplitude set, calculate the basic order three-phase unbalance of the three-phase current corresponding to each group of time domain grouped data under that operating condition.

[0033] 4-1-2) For each operating condition in the collected operating condition set, based on the three-phase current basic order three-phase unbalance degree corresponding to all time-domain grouped data under that operating condition, and combined with the load weight coefficient corresponding to that operating condition, calculate the three-phase current basic order operating condition stability coefficient for that operating condition.

[0034] 4-1-3) Based on the three-phase current basic order stability coefficients corresponding to all operating conditions, and combined with the equally distributed weight coefficients, the three-phase current basic order stability coefficients are calculated.

[0035] Preferably, in step 4), the calculation steps for the conventional harmonic order stability coefficient include:

[0036] 4-2-1) For each operating condition and the target conventional harmonic order corresponding to each conventional harmonic characteristic frequency in the data acquisition set, calculate the three-phase current conventional harmonic order three-phase unbalance degree of each time-domain grouped data corresponding to the conventional harmonic order under the operating condition based on the frequency domain amplitude set of the conventional harmonic order.

[0037] 4-2-2) For each operating condition and each target conventional harmonic order in the data acquisition set, calculate the order operating condition stability coefficient corresponding to the order based on the three-phase unbalance degree of the conventional harmonic order of the three-phase current corresponding to all time-domain grouped data of the order under the obtained operating condition.

[0038] 4-2-3) For each working condition and each target conventional harmonic order in the data acquisition set, based on the frequency domain amplitude of all time domain grouped data of the conventional harmonic order under that working condition, and the frequency domain amplitude of the basic order of the same group under the same working condition, calculate the order working condition ratio coefficient corresponding to that order.

[0039] 4-2-4) Based on the order stability coefficient and order proportion coefficient corresponding to all working conditions and all target conventional harmonic orders in the data acquisition set, and combined with the conventional harmonic order performance calibration weight coefficient, the conventional harmonic order stability coefficient is calculated.

[0040] Preferably, in step 4), the calculation steps for the unconventional harmonic order stability coefficients include:

[0041] 4-3-1) For each operating condition and each unconventional harmonic characteristic frequency in the data acquisition set, calculate the average amplitude of the three-phase current unconventional harmonic order corresponding to each group of time-domain grouped data under the operating condition based on the frequency domain amplitude set of the unconventional harmonic order.

[0042] 4-3-2) For each unconventional harmonic order of each working condition and each target in the data acquisition set, based on the three-phase average amplitude of all time-domain grouped data corresponding to the unconventional harmonic order under the working condition, and the average amplitude of the conventional harmonic order of the same working condition and the same group, calculate the order working condition ratio coefficient corresponding to the unconventional harmonic order under the working condition.

[0043] 4-3-3) Based on the order proportion coefficients of all working conditions and all target unconventional harmonic orders in the data acquisition set, the stability coefficient of unconventional harmonic order is calculated by summing them up.

[0044] The beneficial effects of this invention are as follows:

[0045] (1) This invention establishes a complete analysis process covering "operating condition set construction, data acquisition and frequency domain decomposition, feature amplitude extraction, multi-dimensional stability coefficient calculation, and comprehensive performance rating," and establishes a set of full-operating-condition coverage, multi-dimensional evaluation, and quantifiable range extender controller current stability evaluation system. This effectively solves the core pain point of existing technologies that can only evaluate controller current performance through assembly bench or whole vehicle verification in the later stages of product development and cannot achieve pre-quantitative evaluation. It can complete the rapid and accurate evaluation of controller current output performance in the early stages of product forward design, significantly advance the discovery of design defects, shorten the product solution iteration cycle, and significantly reduce R&D costs and product development risks.

[0046] (2) This invention designs a gradient set of operating conditions with 25%, 50%, 75%, and 100% of the maximum design load, based on the actual operating characteristics of the range extender in the vehicle. Combined with a fixed-rate continuous speed-up operation mode from the minimum design operating speed of the range extender motor to the maximum design speed, this invention can fully cover the full load and full speed scenarios of the range extender in the actual operation of the vehicle, avoiding the one-sidedness of evaluation based on a single steady-state operating condition. This ensures the comprehensiveness and authenticity of the analysis results from the data source. At the same time, it also provides a standardized operating condition basis for the subsequent quantitative evaluation of differentiated load weights, further improving the engineering practicality of the evaluation results.

[0047] (3) To ensure the accuracy and horizontal comparability of the full-condition analysis structure, this invention uses a three-phase line synchronous acquisition method to ensure the timing consistency of the current time-domain data, eliminating the impact of acquisition timing deviation on the three-phase unbalance calculation results from the root. It employs a grouping rule with equal-length fixed points to segment the time-domain data, unifying the frequency resolution of the full-condition frequency domain decomposition and achieving horizontal comparability of analysis results under different loads and speeds. Simultaneously, it clarifies the discrete Fourier transform calculation formula adapted to the continuous variable speed operation of the range extender, realizing accurate conversion of the time-domain current signal to frequency-domain features, providing reliable data support for subsequent feature amplitude extraction and stability quantification calculations.

[0048] (4) This invention combines the inherent structural parameters and real-time operating parameters of the range extender motor to effectively achieve dynamic and accurate positioning of characteristic frequencies and classification and aggregation of harmonic components. Specifically, this invention uses the number of rotor poles of the motor as the inherent structural parameter and the average speed corresponding to a single set of data as the real-time operating parameter to dynamically calculate the fundamental and harmonic characteristic frequencies corresponding to each group of data. This effectively avoids the characteristic frequency positioning deviation in continuously variable speed scenarios and ensures the accuracy of frequency domain amplitude extraction. At the same time, harmonics are divided into two categories: conventional harmonics and unconventional harmonics, and corresponding frequency domain amplitude sets are constructed for each category. This achieves the classification, aggregation, and independent evaluation of harmonics of different causes, which not only significantly improves the accuracy of current stability analysis but also endows this method with the ability to trace the source of current performance defects.

[0049] (5) This invention closely matches the actual working characteristics of the range extender motor and inverter, accurately delineates the harmonic orders that have a critical impact on motor performance, fully covers the key components that have a core impact on motor torque accuracy, NVH performance, and operational reliability, and effectively eliminates interference from irrelevant orders, ensuring that stability calculations always focus on core performance indicators, further improving the relevance of evaluation results and adaptability to engineering scenarios.

[0050] (6) After extracting the characteristic amplitudes for all operating conditions and all critical orders, this invention constructs a three-level progressive calculation logic for the fundamental order components that determine the basic control performance of the controller: "single-group three-phase unbalance calculation, single-condition stability coefficient solution, and comprehensive coefficient integration for all operating conditions." In other words, this invention, through differentiated load weight coefficients, effectively aligns with the usage characteristic that high-load current stability has a greater impact on vehicle performance during actual operation; and through the final integration method with equal weights across all operating conditions, it effectively avoids the masking of control defects under low-load conditions due to excessively high load weights, achieving a comprehensive and balanced quantitative evaluation of the controller's basic current control accuracy, and laying a core data foundation for the subsequent overall evaluation of current stability.

[0051] (7) This invention constructs a two-dimensional coupled quantitative evaluation system for conventional harmonic components that directly affect the performance of range extenders. This system can simultaneously take into account the two core dimensions of three-phase imbalance and relative proportion of harmonics. At the same time, this invention balances the degree of influence of the two on current performance through differentiated weight settings, accurately quantifies the controller's ability to suppress inherent harmonics in motor operation, and fills the technical gap in the prior art where the harmonic performance of range extenders related to NVH cannot be quantitatively evaluated in the early stage of development, further improving the evaluation dimensions of this method.

[0052] (8) For unconventional harmonic components that can directly characterize control defects and deviations such as three-phase control imbalance of the controller, inverter dead zone effect, and power device nonlinearity, this invention adopts a relative proportion calculation method, with a fixed reference harmonic as a reference, to eliminate the evaluation deviation caused by the fluctuation of the fundamental amplitude under different speeds and loads. It can accurately quantify the relative content of unconventional harmonics, realize the pre-quantification identification of hard control defects and nonlinear deviations of the controller, help R&D personnel avoid design risks in advance, and significantly reduce the cost of later product rectification and rework. Attached Figure Description

[0053] Figure 1 This refers to the three-phase current data collected under the maximum load condition in this embodiment of the invention.

[0054] Figure 2 This is the result of current frequency domain decomposition of a certain set of data under maximum load conditions in an embodiment of the present invention;

[0055] Figure 3 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the basic order frequency of the three-phase current under the maximum load condition is shown.

[0056] Figure 4 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the 5th order frequency under the maximum load condition;

[0057] Figure 5 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the 7th order frequency under the maximum load condition;

[0058] Figure 6 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the 11th order frequency under the maximum load condition is shown.

[0059] Figure 7 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the 13th order frequency under the maximum load condition is shown.

[0060] Figure 8 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the second-order frequency under the maximum load condition is shown.

[0061] Figure 9 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the third-order frequencies under the maximum load condition is shown.

[0062] Figure 10 In this embodiment of the invention, the curves connecting the frequency domain amplitudes corresponding to the fourth-order frequencies under the maximum load condition are shown.

[0063] Figure 11 In this embodiment of the invention, the curve formed by connecting the frequency domain amplitudes corresponding to the 6th order frequency under the maximum load condition;

[0064] Figure 12 This is a flowchart of the present invention. Detailed Implementation

[0065] like Figures 1 to 12 As shown, this embodiment focuses on a comprehensive current stability analysis of a permanent magnet synchronous motor and its controller for a vehicle range extender. The inherent parameters of the range extender motor are: number of rotor poles... Design maximum speed The range extender motor is designed to operate at a minimum speed of 500 rpm. .

[0066] The three-phase current comprehensive stability analysis method for the range extender controller specifically includes the following steps:

[0067] 1) Based on the range extender's design parameters (design load, speed range parameters), a multi-condition data collection set covering the full load and full speed range is constructed. This set comprehensively covers core scenarios in actual vehicle operation, such as idling, urban cruising, highway climbing, and full-load acceleration, avoiding the limitations of evaluating a single steady-state condition. The data collection set includes the following four sets of continuous acceleration operation conditions, as detailed below:

[0068] ① Under the maximum load condition designed for the range extender, the minimum operating speed of the range extender motor is 500 rpm. by The rate of change of the constant speed is increased to the design maximum speed. The speed-up operation condition; specifically, the minimum operating speed of the range extender motor is the starting speed of the range extender motor in the speed-up operation condition. It is the lower limit of the speed at which the range extender motor collects three-phase current data under all operating conditions during the current stability analysis test. It is used to match the lowest operating speed scenario (such as idling condition) in the actual operation of the range extender vehicle.

[0069] ② Under 75% load conditions of the range extender's maximum design load, the range extender motor's minimum design operating speed is 500 rpm. by The rate of change of the constant speed is increased to the design maximum speed. The accelerated operation condition;

[0070] ③ Under 50% load conditions of the range extender's maximum design load, the range extender motor's minimum design operating speed is 500 rpm. by The rate of change of the constant speed is increased to the design maximum speed. The accelerated operation condition;

[0071] ④ Under 25% load conditions of the range extender's maximum design load, the range extender motor's minimum design operating speed is 500 rpm. by The rate of change of the constant speed is increased to the design maximum speed. The accelerated operation condition.

[0072] This step, through gradient load settings and full-speed continuous acceleration mode, not only ensures the comprehensiveness and authenticity of the analysis results from the data source, but also provides a standardized working condition basis for the subsequent quantitative evaluation of differentiated load weights, thereby improving the engineering applicability of the evaluation results.

[0073] 2) Based on the data acquisition set constructed in step 1), collect the three-phase current time-domain data output by the controller during the full-condition operation of the range extender motor. After segmenting the three-phase current time-domain data, perform frequency domain conversion to provide reliable data support for subsequent feature extraction and stability calculation. Specific steps include:

[0074] 2-1) Current acquisition units are set on the U, V, and W three-way connection lines between the range extender motor and the controller. In this embodiment, the current acquisition unit adopts a high-precision current clamp. The current acquisition unit synchronously acquires the U, V, and W three-phase current time domain data output by the controller during the full-speed operation of the range extender under various working conditions.

[0075] The current data sampling frequency is set to 51200Hz. This sampling frequency can accurately capture high-frequency harmonic components during motor operation, avoid frequency aliasing, and ensure the accuracy and integrity of the collected data. In this embodiment, the three-phase current time-domain data collected under maximum load conditions is as follows: Figure 1 As shown.

[0076] 2-2) Using a fixed-point grouping rule of equal length, the three-phase current time-domain data collected under each operating condition is segmented. In this embodiment, 25,600 sampling points are used as a group to continuously segment the full-process time-domain data under a single operating condition, resulting in multiple independent groups of time-domain data.

[0077] By grouping data into equal-length fixed-point groups, the frequency resolution of each group of data in the frequency domain decomposition can be guaranteed to be completely consistent, ensuring that the frequency domain analysis results under different speeds and loads are horizontally comparable, and effectively eliminating the interference of data length on frequency domain calculation.

[0078] 2-3) The discrete Fourier transform algorithm is used to decompose the time-domain grouped data of each group into frequency domains to obtain the frequency domain decomposition results of each group under the full working condition.

[0079] The formula for calculating the frequency domain decomposition is as follows:

[0080]

[0081] In the formula, This is a working condition identifier used to distinguish between four different load conditions: 25%, 50%, 75%, and 100%. It is a three-phase identifier, and , respectively, correspond to the U phase, V phase, and W phase of the range extender motor; M is the number of sampling points for a single set of three-phase current time-domain data. In this embodiment, M=25600; For frequency; For the first Under working conditions Frequency domain decomposition results of the corresponding groupings of phase currents; For the first Under working conditions The first group corresponding to the phase current One time-domain data point; This refers to the data point sequence number.

[0082] Following the above formula, frequency domain decomposition is performed on all time-domain grouped data under the four load conditions to obtain the frequency domain decomposition results for each group under the full load condition:

[0083] ① The following are the frequency domain decomposition results corresponding to the maximum load (100% load) operating condition:

[0084]

[0085]

[0086]

[0087] In the formula, This is the frequency domain decomposition result of the first group of U-phase current data under maximum load conditions; This is the frequency domain decomposition result of the first group of grouped data of V-phase current under maximum load conditions; This is the frequency domain decomposition result of the first group of grouped data of the W-phase current under maximum load conditions; This is the nth time-domain data point of the first group of U-phase current data under maximum load conditions. This is the nth time-domain data point of the first group of V-phase current data under maximum load conditions. This is the nth time-domain data point of the first group of W-phase current data under maximum load conditions. For frequency; This refers to the data point sequence number.

[0088] Using the same method, the frequency domain decomposition results of the remaining data sets under the maximum load condition were obtained sequentially. , , ...

[0089] Similarly, the frequency domain decomposition results for the 75% maximum load condition, the 50% maximum load condition, and the 25% maximum load condition are calculated respectively, where:

[0090] ② 75% load condition: Using the same frequency domain decomposition method as the maximum load condition, the frequency domain decomposition results of the three-phase currents U, V, and W under this condition are obtained and denoted as follows: , , , , , ...

[0091] ③ 50% load condition: Using the same frequency domain decomposition method as the maximum load condition, the frequency domain decomposition results of the three-phase currents U, V, and W under this condition are obtained and denoted as follows: , , , , , ...

[0092] ④ 25% load condition: Using the same frequency domain decomposition method as the maximum load condition, the frequency domain decomposition results of the three-phase currents U, V, and W under this condition are obtained and denoted as follows: , , , , , ...

[0093] In this embodiment, the structure of the current frequency domain decomposition of a certain set of data under the maximum load condition is as follows: Figure 2 As shown.

[0094] 3) Combining the real-time operating parameters and inherent structural parameters of the range extender motor, determine the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain group of data. Based on the frequency domain decomposition results obtained in step 2) for each group under the full operating condition, obtain the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition. The specific steps are as follows:

[0095] 3-1) Based on the number of rotor poles of the range extender motor As an inherent structural parameter, the average rotational speed corresponding to each time-domain grouped data is used. As real-time operating parameters, the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain grouped data are calculated; wherein, the fundamental characteristic frequency is the synchronization frequency corresponding to the fundamental order of the current.

[0096] The target harmonic characteristic frequencies include conventional harmonic characteristic frequencies and unconventional harmonic characteristic frequencies. The classification of these two types of harmonics is based on their generation mechanism and their impact on motor performance, wherein:

[0097] The characteristic frequencies of conventional harmonics are the 5th, 7th, 11th, and 13th harmonics of the fundamental frequency. These harmonics are inherent low-order harmonics generated when a three-phase inverter drives a motor during normal operation, and are the core harmonic orders that affect motor performance and torque fluctuations.

[0098] Unconventional harmonic characteristic frequencies are the 2nd, 3rd, 4th, and 6th harmonics of the fundamental characteristic frequency. These harmonics are mainly generated by abnormal factors such as three-phase control imbalance of the controller, inverter dead zone effect, and nonlinearity of power devices. They can directly reflect the control defects and abnormal operating conditions of the controller.

[0099] The above classification allows for independent evaluation of the controller's basic control performance and abnormal control deviations, significantly improving the accuracy of current stability analysis and problem localization capabilities.

[0100] 3-2) Based on the frequency domain decomposition results of each group under the full operating condition obtained in step 2), extract the frequency domain amplitude of each time domain group data under the full operating condition at the fundamental characteristic frequency and each target harmonic characteristic frequency, and construct the basic order frequency domain amplitude set, the conventional harmonic order frequency domain amplitude set and the unconventional harmonic order frequency domain amplitude set respectively, which together form the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition.

[0101] 3-2-1) The method for obtaining the fundamental order frequency domain amplitude is as follows:

[0102] Under 100% maximum load conditions, the fundamental order frequency domain amplitude of the first group of data from the three phases U, V, and W is denoted as... , , The calculation formula is as follows:

[0103] ; ;

[0104] ;

[0105] In the formula, The frequency domain amplitude corresponding to the basic order frequency of the first group of U-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the basic order frequency of the first group of V-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the basic order frequency of the first group of W-phase current data under 100% maximum load conditions; This represents the average motor speed corresponding to a single set of time-domain data, in rpm. This refers to the number of poles of the motor rotor; The frequency domain decomposition results of the first group of U-phase current data; This is the frequency domain decomposition result of the first group of V-phase current data; This is the frequency domain decomposition result of the first group of data for the W-phase current.

[0106] Under 100% maximum load conditions, the fundamental order frequency domain amplitude of the second group of three-phase data (U, V, W) is denoted as... , , :

[0107] ; ;

[0108] ;

[0109] The fundamental order frequency domain magnitudes of the subsequent groups are denoted as follows: , , … , , , where N is the total number of groups under a single working condition.

[0110] The fundamental order frequency domain amplitudes under the following conditions—75% maximum load, 50% maximum load, and 25% maximum load—were calculated using the method described above and denoted as follows:

[0111] Under 75% load conditions of maximum load: , , , , , ......

[0112] Under 50% load conditions of maximum load: , , , , , ......

[0113] Under 25% load conditions of maximum load: , , , , , ......

[0114] In this embodiment, the curve connecting the frequency domain amplitudes corresponding to the fundamental order frequency of the three-phase current under maximum load conditions is as follows: Figure 3 As shown.

[0115] 3-2-2) The method for obtaining the frequency domain amplitude of conventional harmonic orders is as follows:

[0116] The conventional harmonic orders include the 5th, 7th, 11th, and 13th orders. Their frequency domain amplitudes are extracted using the same method as those for the fundamental orders, as detailed below:

[0117] ① Calculate the 5th harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0118] ; ; ......

[0119] ② Calculate the 7th harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0120] ; ; Subsequent groups are calculated sequentially according to the same rules.

[0121] ③ Calculate the 11th harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0122] ; ; Subsequent groups are calculated sequentially according to the same rules.

[0123] ④ Calculate the 13th harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0124] ; ; Subsequent groups are calculated sequentially according to the same rules.

[0125] In the formula, The frequency domain amplitude corresponding to the 5th harmonic frequency of the first group of U-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 5th harmonic frequency of the first group of V-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 5th harmonic frequency of the first group of W-phase current data under 100% maximum load conditions; The frequency domain decomposition results of the first group of U-phase current data; This is the frequency domain decomposition result of the first group of V-phase current data; This is the frequency domain decomposition result of the first group of data for the W-phase current; The frequency domain amplitude corresponding to the 7th harmonic frequency of the first group of U-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 7th harmonic frequency of the first group of V-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 7th harmonic frequency of the first group of W-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 11th harmonic frequency of the first group of U-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 11th harmonic frequency of the first group of V-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 11th harmonic frequency of the first group of W-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 13th harmonic frequency of the first group of U-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 13th harmonic frequency of the first group of V-phase current data under 100% maximum load conditions; The frequency domain amplitude corresponding to the 13th harmonic frequency of the first group of W-phase current data under 100% maximum load conditions; This represents the average motor speed corresponding to a single set of time-domain data, in rpm. This refers to the number of poles of the motor rotor;

[0126] Following the above method, the frequency domain amplitudes of each conventional harmonic order under 75%, 50%, and 25% load conditions were calculated respectively. In this embodiment, the curves connecting the frequency domain amplitudes of the 5th, 7th, 11th, and 13th order frequencies under the maximum load condition are shown below. Figure 4 , Figure 5 , Figure 6 , Figure 7 As shown.

[0127] 3-2-3) The method for obtaining the frequency domain amplitude of unconventional harmonic orders is as follows:

[0128] Unconventional harmonic orders include the 2nd, 3rd, 4th, and 6th orders. Their frequency domain amplitudes are extracted using the same method as those of the fundamental orders, as detailed below:

[0129] ① Calculate the second harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0130] ; ; ......

[0131] ② Calculate the third harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0132] ; ; ......

[0133] ③ Calculate the fourth harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0134] ; ; ......

[0135] ④ Calculate the 6th harmonic frequency domain amplitude of each group of data under 100% maximum load conditions using the following formula:

[0136] ; ; ......

[0137] In the formula, , , , The values ​​represent the frequency domain amplitudes corresponding to the 2nd, 3rd, 4th, and 6th harmonic frequencies of the first group of U-phase current data under 100% maximum load conditions. , , , These are the frequency domain amplitudes of the first group of V-phase current data corresponding to the order harmonics under 100% maximum load conditions. , , , These are the frequency domain amplitudes of the first group of W-phase current data under 100% maximum load conditions, corresponding to the order harmonics; the definitions of the remaining symbols are consistent with the formula for the basic order amplitude.

[0138] The frequency domain amplitude of each subsequent group of data is calculated sequentially according to the above formula.

[0139] Following the method described above, the frequency domain amplitudes of each unconventional harmonic order under 75%, 50%, and 25% load conditions were calculated. In this embodiment, the curves connecting the frequency domain amplitudes of the 2nd, 3rd, 4th, and 6th order frequencies under the maximum load condition are shown below. Figure 8 , Figure 9 , Figure 10 , Figure 11 As shown.

[0140] 4) Based on the frequency domain amplitude set corresponding to each order characteristic frequency under all operating conditions, calculate the stability coefficient corresponding to each order characteristic frequency. The stability coefficient includes the three-phase current basic order stability coefficient, the conventional harmonic order stability coefficient, and the unconventional harmonic order stability coefficient. The specific calculation process is as follows:

[0141] 4-1) The three-phase current fundamental order stability coefficient is a core indicator for evaluating the fundamental current control accuracy of the controller. It directly determines the torque control accuracy and power output smoothness of the range extender motor. The specific calculation steps include:

[0142] 4-1-1) For each operating condition in the data acquisition set, based on the basic order frequency domain amplitude set, calculate the three-phase unbalance degree of the basic order of the three-phase current corresponding to each group of time domain grouped data under that operating condition, so as to accurately quantify the consistency of the fundamental amplitude of the three-phase current under a single group of data.

[0143] 4-1-2) For each operating condition in the collected operating condition set, based on the three-phase current basic order three-phase unbalance degree corresponding to all time-domain grouped data under that operating condition, and combined with the load weight coefficient corresponding to that operating condition, calculate the three-phase current basic order operating condition stability coefficient for that operating condition.

[0144] The formulas for calculating the basic order stability coefficient for each load condition are as follows:

[0145] The basic order stability factor for the 100% maximum load condition is:

[0146] The basic order stability factor for the 75% maximum load condition is:

[0147] The basic order stability factor for the 50% maximum load condition is:

[0148] The basic order stability factor for the 25% maximum load condition is:

[0149] In the formula, The basic order stability coefficient of the three-phase current under maximum load conditions; The basic order stability coefficient of three-phase current under 75% maximum load condition; The basic order stability coefficient of three-phase current under 50% maximum load condition; The three-phase current basic order stability coefficient under 25% maximum load condition; N is the total number of time-domain groups under a single condition.

[0150] Among them, 1, 0.9, 0.8, and 0.7 are the load weight coefficients for the corresponding operating conditions. The weight is set based on the fact that the current stability under high load conditions has a greater impact on the smoothness of power output, torque control accuracy, and thermal management performance during vehicle operation. Therefore, it is given a higher weight. This setting can make the evaluation results more in line with the actual use scenario of the range extender.

[0151] In this embodiment, the basic order stability coefficients of the three-phase current under various load conditions are shown in Table 1 below:

[0152] Table 1

[0153]

[0154] 4-1-3) Based on the three-phase current basic order stability coefficients corresponding to all operating conditions, and combined with the equally distributed weighting coefficients, the three-phase current basic order stability coefficients are calculated. The calculation formula is as follows:

[0155]

[0156] in, With equal weighting coefficients, the four operating conditions cover the entire load range. Equal weighting can effectively ensure that the performance of each load range is fully considered, and avoid the control defects of low load conditions being masked by excessive weighting of high load conditions.

[0157] In this embodiment, the basic order stability coefficient of the three-phase current is obtained through calculation. .

[0158] 4-2) Conventional harmonic order stability coefficients are used to evaluate the controller's ability to suppress inherent harmonics during normal motor operation. The specific steps for obtaining these coefficients include:

[0159] 4-2-1) For each operating condition and each target conventional harmonic order in the data acquisition set, based on the frequency domain amplitude set of the conventional harmonic order, calculate the three-phase current conventional harmonic order three-phase unbalance degree of each group of time domain grouped data under the operating condition.

[0160] 4-2-2) For each operating condition and each target conventional harmonic order in the data acquisition set, calculate the order operating condition stability coefficient corresponding to the order based on the three-phase unbalance degree of the conventional harmonic order of the three-phase current corresponding to all time-domain grouped data of the order under the obtained operating condition.

[0161] The formulas for calculating the order stability coefficients of each conventional harmonic order under 100% maximum load conditions are as follows:

[0162] The order-condition stability coefficient of the 5th harmonic:

[0163] The order-condition stability coefficient of the 7th harmonic:

[0164] The order-condition stability coefficient of the 11th harmonic:

[0165] The order-condition stability coefficient of the 13th harmonic:

[0166] In the formula, The three-phase current stability coefficient of the fifth order under maximum load conditions; The three-phase current stability coefficient of the seventh order under maximum load conditions; The three-phase current stability coefficient of the 11th order under maximum load conditions; It is the 13th-order three-phase current stability coefficient under maximum load conditions.

[0167] Similarly, the stability coefficients for each order of operating conditions under the 75% load condition, 50% load condition, and 25% load condition of the maximum load are calculated according to the above formula.

[0168] 4-2-3) For each operating condition and each target conventional harmonic order in the data acquisition set, based on the frequency domain amplitude of all time-domain grouped data of the conventional harmonic order under that operating condition, and the frequency domain amplitude of the basic order in the same group under the same operating condition, calculate the corresponding order operating condition proportion coefficient. The proportion coefficient characterizes the relative magnitude of the harmonic content; a higher proportion indicates a greater impact of harmonics on the current waveform and a poorer harmonic suppression capability of the controller.

[0169] The formula for calculating the order proportion coefficient of each conventional harmonic order under 100% maximum load is as follows:

[0170] 5th harmonic order operating condition proportion factor:

[0171] 7th harmonic order operating condition proportion factor:

[0172] 11th harmonic order operating condition proportion factor:

[0173] 13th harmonic order operating condition proportion factor:

[0174] In the formula, The order proportion coefficient of the 5th harmonic order under maximum load conditions; The order proportion coefficient of the 7th harmonic order under maximum load conditions; The order proportion coefficient of the 11th harmonic order under maximum load conditions; This is the order proportion coefficient of the 13th harmonic order under maximum load conditions.

[0175] Similarly, the percentage coefficients of each operating condition under the 75% load condition, 50% load condition, and 25% load condition of the maximum load are calculated according to the above formula.

[0176] In this embodiment, the stability coefficients of all conventional harmonic orders and their proportion coefficients are shown in Table 2 below.

[0177] Table 2

[0178]

[0179] 4-2-4) Based on the order stability coefficients and order proportion coefficients corresponding to all operating conditions and all target conventional harmonic orders in the data acquisition set, and combined with the conventional harmonic order performance calibration weighting coefficients, the conventional harmonic order stability coefficients are calculated. The calculation formula is as follows:

[0180] + + + + + + + + + + + + + + +

[0181] Since both the three-phase imbalance of harmonics and the harmonic content affect current stability, and the harmonic content has a more direct impact on current waveform distortion, a stability coefficient of 0.5 and a proportion coefficient of 1.0 are assigned to balance the degree of influence of the two on current performance. All weight values ​​are obtained through calibration tests.

[0182] In this embodiment, the conventional harmonic order stability coefficient is calculated. .

[0183] 4-3) The unconventional harmonic order stability coefficient is used to evaluate the controller's ability to suppress abnormal harmonics, reflects the controller's control defects and nonlinear deviations, and is the core indicator for identifying implicit design problems of the controller.

[0184] Since unconventional harmonics are generated by control anomalies, their three-phase imbalance is not a core evaluation dimension. The relative content of harmonics more directly reflects the severity of control defects. Therefore, this dimension is only quantitatively evaluated through the relative proportion of harmonics. The specific steps for obtaining this information include:

[0185] 4-3-1) For each unconventional harmonic order of each working condition and each target in the data acquisition set, based on the frequency domain amplitude set of the unconventional harmonic order, calculate the average amplitude of the three-phase current unconventional harmonic order of each time domain group data corresponding to the unconventional harmonic order under the working condition, that is, the arithmetic mean of the frequency domain amplitude of the three phases U, V and W of the single data.

[0186] 4-3-2) For each unconventional harmonic order of each working condition and each target in the data acquisition set, based on the three-phase average amplitude of all time-domain grouped data corresponding to the unconventional harmonic order under the working condition, and the average amplitude of the conventional harmonic order of the same working condition and the same group, calculate the order working condition ratio coefficient corresponding to the unconventional harmonic order under the working condition.

[0187] In this embodiment, the reference conventional harmonic order is the 5th harmonic. Using the 5th harmonic as the reference can eliminate the evaluation deviation caused by the change of fundamental amplitude under different loads and speeds, and accurately quantify the relative content of unconventional harmonics.

[0188] The formula for calculating the order proportion coefficient of each unconventional harmonic order under 100% maximum load is as follows:

[0189] 2nd harmonic order operating condition proportion factor:

[0190] 3rd harmonic order operating condition proportion factor:

[0191] 4th harmonic order operating condition proportion factor:

[0192] 6th harmonic order operating condition proportion factor:

[0193] In the formula, The order ratio coefficient of the second harmonic order under maximum load conditions; The order ratio coefficient of the 3rd harmonic order under maximum load conditions; The order ratio coefficient of the 4th harmonic order under maximum load conditions; This represents the order proportion coefficient of the 6th harmonic order under maximum load conditions.

[0194] Similarly, using the above formula, the order-specific operating condition ratio coefficients for each order under the 75% maximum load, 50% maximum load, and 25% maximum load conditions are calculated respectively and denoted as follows: , , , ; , , , ; , , , .

[0195] In this embodiment, the proportion coefficients of unconventional harmonic orders under all operating conditions are shown in Table 3 below:

[0196] Table 3. Proportion of Unconventional Harmonic Orders under All Operating Conditions

[0197]

[0198] 4-3-3) Based on the proportion coefficients of the order of all working conditions and all targets in the data acquisition set, the stability coefficient of the unconventional harmonic order is calculated by summing them up. The calculation formula is as follows:

[0199] Among them, the content of unconventional harmonics directly reflects the nonlinear control deviation and three-phase imbalance defect of the controller. The smaller the cumulative value, the stronger the abnormal harmonic suppression capability of the controller and the better the current stability.

[0200] In this embodiment, the unconventional harmonic order stability coefficient is obtained through calculation. .

[0201] 5) Based on the stability coefficients corresponding to the frequency domain amplitude sets of the characteristic frequencies of each order under all operating conditions, and combined with the multi-dimensional weight allocation rules, the comprehensive stability coefficient of the range extender controller current is calculated. Then, combined with the current performance grading and evaluation rules, the comprehensive rating result of the range extender controller current performance is obtained, specifically including:

[0202] First, calculate the overall current stability coefficient of the range extender controller according to the following formula. :

[0203] + +

[0204] In the formula, The comprehensive stability coefficient of the range extender controller current; The basic order stability coefficient of three-phase current; These are the stability coefficients for conventional harmonic orders; This represents the stability coefficient for unconventional harmonic orders.

[0205] The weighting is set in this way because the stability of the fundamental harmonics is the core of the controller's current control, directly determining the torque control accuracy and power output smoothness of the motor, and therefore it is given the highest weight. Conventional harmonics primarily affect the motor's NVH performance, and are therefore secondary. Unconventional harmonics reflect control anomalies and have the lowest weight. Combining these three factors enables a multi-dimensional and comprehensive evaluation of the controller's current performance, taking into account fundamental performance, NVH performance, and anomaly identification. In this embodiment, all weight values ​​were obtained through calibration experiments.

[0206] In this embodiment, the final calculated comprehensive stability coefficient of the range extender controller current is obtained. .

[0207] Then, based on the following current performance grading and evaluation rules, the current performance of the range extender controller is scored and comprehensively rated. The performance rating rules are shown in Table 4 below:

[0208] Table 4. Scoring and Rating Table for Overall Current Stability of Range Extender Controller

[0209]

[0210] In this embodiment, the overall current stability coefficient of the range extender controller The value is within the range of 0.15 to 0.2, corresponding to a score of 6, and the performance level is qualified.

[0211] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for comprehensive stability analysis of three-phase current in a range extender controller, characterized in that, Includes the following steps: 1) Based on the design parameters of the range extender, construct a multi-condition data acquisition set covering the entire operating range; 2) Based on the collected operating condition set, collect the three-phase current time-domain data output by the controller during the full operating condition of the range extender motor. Divide the three-phase current time-domain data into multiple groups of time-domain grouped data. Then, use a frequency domain transformation algorithm to perform frequency domain decomposition on each group of time-domain grouped data to obtain the frequency domain decomposition results corresponding to each group under the full operating condition. 3) Combining the real-time operating parameters and inherent structural parameters of the range extender motor, determine the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain group data, and obtain the frequency domain decomposition results corresponding to each group under the full operating condition according to step 2), and obtain the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition; the target harmonic characteristic frequency includes conventional harmonic characteristic frequency and unconventional harmonic characteristic frequency. 4) Based on the frequency domain amplitude set corresponding to each order characteristic frequency under all operating conditions, calculate the stability coefficient corresponding to each order characteristic frequency. The stability coefficient includes the three-phase current basic order stability coefficient, the conventional harmonic order stability coefficient, and the unconventional harmonic order stability coefficient. 5) Based on the stability coefficient obtained in step 4), the comprehensive stability coefficient of the range extender controller current is calculated in combination with the multi-dimensional weight allocation rule, and the comprehensive rating result of the range extender controller current performance is obtained in combination with the current performance grading and evaluation rule.

2. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, In step 1), the set of working conditions for acquiring the multi-condition gradient includes: ① The maximum load condition of the range extender design, the acceleration operation condition from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate; ② The acceleration operation condition of the range extender motor at 75% of its maximum design load, which is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate. ③ Under the condition of 50% of the maximum load of the range extender, the speed increase operation condition is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate. ④ Under the load condition of 25% of the maximum design load of the range extender, the speed increase operation condition is the speed increase from the minimum design operating speed of the range extender motor to the maximum design speed at a fixed speed change rate.

3. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, Step 2), which involves collecting the three-phase current time-domain data output by the controller during the full-condition operation of the range extender motor, and obtaining the frequency domain decomposition results corresponding to each group under the full-condition operation, includes the following steps: 2-1) Current acquisition units are set on the three-way connection lines between the range extender motor and the controller. The three-phase current time domain data output by the controller is synchronously acquired through the current acquisition units during the full-speed operation of the range extender under various working conditions. 2-2) Using the equal-length fixed-point grouping rule, the three-phase current time-domain data collected under each working condition is segmented to obtain multiple sets of mutually independent time-domain grouped data; 2-3) The discrete Fourier transform algorithm is used to decompose the time-domain grouped data of each group into frequency domains to obtain the frequency domain decomposition results of each group under the full working condition. The formula for calculating the frequency domain decomposition is as follows: ； In the formula, For operating condition identification; For three-phase identification and M represents the number of sampling points for a single set of three-phase current time-domain data. For frequency; For the first Under working conditions Frequency domain decomposition results of the corresponding groupings of phase currents; For the first Under working conditions The first group corresponding to the phase current One time-domain data point; This refers to the data point sequence number.

4. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, Step 3) involves obtaining the frequency domain amplitude set corresponding to the characteristic frequencies of each order under all operating conditions, including: 3-1) Using the number of rotor poles of the range extender motor as the inherent structural parameter and the average speed corresponding to each time-domain grouped data as the real-time operating parameter, the fundamental characteristic frequency and target harmonic characteristic frequency corresponding to each time-domain grouped data are calculated. Wherein, the fundamental characteristic frequency is the synchronous frequency corresponding to the fundamental order of the current, and the target harmonic characteristic frequency includes conventional harmonic characteristic frequency and unconventional harmonic characteristic frequency; 3-2) Based on the frequency domain decomposition results of each group under the full operating condition obtained in step 2), extract the frequency domain amplitude of each time domain group data under the full operating condition at the fundamental characteristic frequency and each target harmonic characteristic frequency, and construct the basic order frequency domain amplitude set, the conventional harmonic order frequency domain amplitude set and the unconventional harmonic order frequency domain amplitude set respectively, which together form the frequency domain amplitude set corresponding to each order characteristic frequency under the full operating condition.

5. The three-phase current comprehensive stability analysis method according to claim 4, characterized in that, The conventional harmonic characteristic frequencies are the 5th, 7th, 11th, and 13th harmonics of the fundamental characteristic frequency, and the unconventional harmonic characteristic frequencies are the 2nd, 3rd, 4th, and 6th harmonics of the fundamental characteristic frequency.

6. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, Step 4) includes the following steps for calculating the basic order stability coefficient of the three-phase current: 4-1-1) For each operating condition in the data acquisition set, based on the basic order frequency domain amplitude set, calculate the basic order three-phase unbalance of the three-phase current corresponding to each group of time domain grouped data under that operating condition. 4-1-2) For each operating condition in the collected operating condition set, based on the three-phase current basic order three-phase unbalance degree corresponding to all time-domain grouped data under that operating condition, and combined with the load weight coefficient corresponding to that operating condition, calculate the three-phase current basic order operating condition stability coefficient for that operating condition. 4-1-3) Based on the three-phase current basic order stability coefficients corresponding to all operating conditions, and combined with the equally distributed weight coefficients, the three-phase current basic order stability coefficients are calculated.

7. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, Step 4) includes the following steps for calculating the conventional harmonic order stability coefficient: 4-2-1) For each operating condition and the target conventional harmonic order corresponding to each conventional harmonic characteristic frequency in the data acquisition set, calculate the three-phase current conventional harmonic order three-phase unbalance degree of each time-domain grouped data corresponding to the conventional harmonic order under the operating condition based on the frequency domain amplitude set of the conventional harmonic order. 4-2-2) For each operating condition and each target conventional harmonic order in the data acquisition set, calculate the order operating condition stability coefficient corresponding to the order based on the three-phase unbalance degree of the conventional harmonic order of the three-phase current corresponding to all time-domain grouped data of the order under the obtained operating condition. 4-2-3) For each working condition and each target conventional harmonic order in the data acquisition set, based on the frequency domain amplitude of all time domain grouped data of the conventional harmonic order under that working condition, and the frequency domain amplitude of the basic order of the same group under the same working condition, calculate the order working condition ratio coefficient corresponding to that order. 4-2-4) Based on the order stability coefficient and order proportion coefficient corresponding to all working conditions and all target conventional harmonic orders in the data acquisition set, and combined with the conventional harmonic order performance calibration weight coefficient, the conventional harmonic order stability coefficient is calculated.

8. The three-phase current comprehensive stability analysis method according to claim 1, characterized in that, Step 4) includes the following steps for calculating the unconventional harmonic order stability coefficient: 4-3-1) For each operating condition and each unconventional harmonic characteristic frequency in the data acquisition set, calculate the average amplitude of the three-phase current unconventional harmonic order corresponding to each group of time-domain grouped data under the operating condition based on the frequency domain amplitude set of the unconventional harmonic order. 4-3-2) For each unconventional harmonic order of each working condition and each target in the data acquisition set, based on the three-phase average amplitude of all time-domain grouped data corresponding to the unconventional harmonic order under the working condition, and the average amplitude of the conventional harmonic order of the same working condition and the same group, calculate the order working condition ratio coefficient corresponding to the unconventional harmonic order under the working condition. 4-3-3) Based on the order proportion coefficients of all working conditions and all target unconventional harmonic orders in the data acquisition set, the stability coefficient of unconventional harmonic order is calculated by summing them up.

Images