An impedance full-working-condition identification method and system for an alternating current driving system power battery

Abstract

The application discloses an impedance full-working-condition identification method and system of an alternating-current driving system power battery, and belongs to the field of battery impedance identification. The method comprises the following steps: determining the frequency of the required impedance and the corresponding excitation amplitude; determining the frequency and amplitude of the motor direct-axis current according to the frequency of the required impedance, so as to determine the required number and mode of the motor direct-axis current cycles; implementing alternating-current excitation injection and controlling the motor driving inverter; measuring the battery voltage and current signals when the alternating-current excitation injection is implemented, and performing frequency domain analysis and impedance calculation. The application can shorten the time required for one-time impedance identification by injecting multiple frequency components at one time, and realizes battery impedance identification under the full-working-condition conditions of the alternating-current driving system operation, stopping and charging, so as to monitor the battery state.

Description

Technical Field

[0001] This invention relates to the field of battery impedance identification, and more specifically, to a method and system for full-condition impedance identification of power batteries in AC drive systems. Background Technology

[0002] In recent years, with the rapid development of electric vehicle technology, battery operating status and battery safety have become core concerns for the development of electric vehicles. However, since a battery is a closed and complex physicochemical system, only a limited number of external characteristic indicators such as voltage, current, and temperature are available. Therefore, it is necessary to infer the changes in physicochemical properties occurring inside the battery from these limited external characteristics. Calculating the battery's impedance characteristics using its voltage and current information is an effective way to estimate battery state. Battery impedance is divided into online impedance and offline impedance. Offline impedance is usually more stable and reflects the parameters of the battery when it is not in operation, but it requires offline measurement. Online impedance, on the other hand, can reflect the battery's state in real time during charging and discharging, and can play an important role in judging and warning of performance degradation and early warning signs of accidents that occur during operation.

[0003] Offline battery impedance detection primarily utilizes specialized equipment such as electrochemical workstations. However, this method requires the battery to be individually removed from the load, making the detection process cumbersome and unable to monitor the battery status during charging and discharging. Online impedance identification, on the other hand, involves controlling the load or charging current to superimpose an AC signal onto the DC current, or connecting an AC current source in parallel or an AC voltage source in series with the battery. This causes AC fluctuations in the battery's voltage and current, allowing the measurement of these fluctuations to identify the battery's impedance. Patent CN115267584A discloses an online battery pack impedance identification scheme using a parallel current source for AC excitation. However, its embodiment 2, which uses a drive converter for impedance identification, can cause noise and vibration during motor operation. CN115047366A's method, which uses an electric vehicle charger for impedance identification, relies on an external power supply connection and is only applicable during charging. Impedance identification cannot be performed when the battery is parked and not charging, or during startup. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method and system for impedance identification of power batteries in AC drive systems under all operating conditions. The method utilizes the AC motor and motor drive inverter of the AC drive system to perform AC excitation for battery impedance identification, thereby achieving full-condition identification of battery impedance in the AC drive system during system charging, operation, or shutdown. During impedance identification, the method does not cause adverse effects such as noise or vibration to the motor.

[0005] To achieve the above objectives, the present invention provides a method for impedance identification of a power battery in an AC drive system under all operating conditions, comprising the following steps:

[0006] S1. Determine the frequency of the impedance to be identified and the corresponding battery excitation current amplitude. The typical amplitude is between 0.1A and 0.2A to ensure... Meet the battery's linear operating range and signal-to-noise ratio; determine the motor's direct-axis current based on the frequency of the required impedance identification. The frequency and amplitude are used to determine the required injection. Number of cycles and method and The relationship between frequency and amplitude is determined by the following instantaneous equation:

[0007]

[0008] Among them, V dc The battery voltage is known, the DC current is known, and R is... s It is the stator phase resistance of the motor, L d These are the direct-axis inductances of the motor, and are all constant parameters of the motor.

[0009] Since the above instantaneous value expression only contains and its second differential term, therefore frequency and Consistent;

[0010] when When there is only one angular frequency component ω, The angular frequency is 2ω. The angular frequency is also 2ω;

[0011] when It has multiple angular frequency components ω1, ω2, ..., ω n hour, and The angular frequencies are second harmonics 2ω₁, 2ω₂, ..., 2ω₃. n Difference frequency ω i -ω j With frequency ω i +ω j (i>j and i,j∈[1,n]).

[0012] When it is necessary to identify the battery impedance corresponding to a single angular frequency ω, then it should be made The frequency is ω / 2. Generally, 5-6 cycles need to be injected, of which the first 2-3 cycles are the transient transition process of AC signal, and the last 2-3 cycles are for voltage and current sampling measurement.

[0013] When it is necessary to identify the battery impedance corresponding to multiple frequencies, one can identify the impedance corresponding to the required frequencies. The frequencies are injected sequentially, following the steps for identifying a single-frequency impedance; alternatively, multiple frequency components can be used. and The corresponding relationship is to inject multiple frequencies at the same time. Generally, it is necessary to inject 5-6 cycles of the lowest frequency component among the multiple frequencies. The first 2-3 cycles are the transient transition process of AC signal, and the last 2-3 cycles are used for voltage and current sampling measurement to ensure that the AC excitation has reached steady state when sampling measurement.

[0014] S2. Determine the required injection based on the above. The cycle number and method are used to implement AC excitation injection, controlling the motor to drive the inverter;

[0015] S201. Measure the motor angle θ using a position sensor and the three-phase motor current i using a current sensor. a i b i c ;

[0016] S202. Calculate the motor current i in the dq coordinate system using the Park transformation. d i q ;

[0017]

[0018] S203. As determined in S1 The d-axis reference current i d * If the electric vehicle is charging or parked, the q-axis reference current i q * If the q-axis reference current i is 0 when the electric vehicle is in motion, then... q * To be determined based on the actual working conditions of the electric vehicle;

[0019] S204. The d-axis current error i d * -i d Input the d-axis current regulator to adjust the q-axis current error i. q * -i q Input q-axis current regulator;

[0020] The d-axis current regulator is a proportional-quasi-resonant controller (QPR). The transfer function of the quasi-resonant controller is:

[0021]

[0022] Its resonant frequency is n angular frequencies ω i (i = 1, 2, ..., n), cutoff frequency ω ci Typically, the frequency is set to 1-2Hz, and the proportional gain K... p With resonant gain K ri The value that yielded the best control effect was determined through experiments.

[0023] The q-axis current regulator is a proportional-integral (PI) controller, and its transfer function is:

[0024]

[0025] Where the proportional gain K p With resonant gain K i The value that yielded the best control effect was determined through experiments.

[0026] The S205 d-axis current regulator outputs a d-axis voltage u. d The output of the q-axis current regulator is the d-axis voltage u. q By using space vector PWM modulation, a drive signal is generated to control the motor to drive the inverter;

[0027] S3. Measure the battery voltage and current signals when implementing the AC excitation injection control algorithm, and perform frequency domain analysis and impedance calculation;

[0028] S301. The battery voltage v corresponding to the last 2-3 cycles of the injected signal cycle at each frequency. dc Current i dc Perform sampling;

[0029] S302. Calculate v through frequency domain or time-frequency analysis (such as Fourier analysis, wavelet transform, etc.). dc i dc The impedance frequency component that needs to be identified in S2, i.e. The corresponding frequency ω i By considering the amplitude and phase, we can obtain the frequency ω corresponding to the battery voltage. i The voltage phasor under the following conditions is Current corresponding to frequency ω i The current phasor below is

[0030] S303. Calculate the corresponding frequency ω i Battery impedance Z ωi ;

[0031]

[0032] The present invention also provides an impedance full-condition identification of a power battery for an AC drive system, characterized in that it includes a computer-readable storage medium and a processor;

[0033] The computer-readable storage medium is used to store executable instructions;

[0034] The processor is used to read the executable instructions stored in the computer-readable storage medium and execute the above-described method for identifying the impedance of the AC drive system power battery under all operating conditions.

[0035] Compared with the prior art, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0036] (1) When performing impedance identification, this technical solution utilizes an AC drive motor and its drive inverter, without changing the hardware architecture of the AC drive system or adding an additional AC excitation source, which has the advantages of low cost and high reliability.

[0037] (2) This technical solution generates AC voltage and current signals in the battery by controlling the motor current through the control of the motor drive inverter. Since the drive system consisting of the battery, inverter and motor always maintains circuit connection, this solution can be implemented regardless of the state of the battery. Thus, it can realize battery impedance identification for battery status monitoring under all working conditions such as operation, stop and charging of AC drive system.

[0038] (3) This technical solution proposes a fast frequency detection method to determine the frequency of the impedance to be identified. By injecting multiple frequency components at once, the time required for impedance identification can be shortened. Compared with sequential injection, this solution saves identification time and better guarantees signal resolution compared with methods such as injecting square waves and pseudo-random signals.

[0039] (4) This solution is designed for use when electric vehicles are stationary or charging. It ensures that the motor torque is not affected when performing battery impedance identification, that is, no torque is generated when stationary or charging, and the torque does not change significantly during normal operation, thus ensuring reliability and safety. Attached Figure Description

[0040] Figure 1 The invention provides a flowchart of a method for identifying the impedance of a power battery in an AC drive system under all operating conditions.

[0041] Figure 2 is i d Injected system control block diagram;

[0042] Figure 3 This is a schematic diagram of the circuit structure of an AC drive system, taking a three-phase AC motor as an example.

[0043] Figure 4is i d The injected signal contains 10Hz, 30Hz, 40Hz, and 50Hz i d Frequency decomposition results;

[0044] Figure 5 is i d The injected signal contains the frequency decomposition results of the battery current at 10Hz, 30Hz, 40Hz, and 50Hz. Detailed Implementation

[0045] 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 and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0046] This invention provides a method for identifying the impedance of a power battery during normal operation of a drive motor and a motor-driven inverter, by generating an AC excitation signal. The impedance identification results are of great significance for battery state monitoring. A method for full-condition impedance identification of a power battery in an AC drive system is provided, as follows: Figure 1 As shown, it includes the following steps:

[0047] S1. Determine the frequency of the impedance to be identified and the corresponding amplitude of the excitation. The typical amplitude is between 0.1A and 0.2A to ensure... Meet the battery's linear operating range and signal-to-noise ratio; determine the motor's direct-axis current based on the frequency of the required impedance identification. The frequency and amplitude are used to determine the required injection. Number of cycles and method and The relationship between frequency and amplitude is determined by the following instantaneous equation:

[0048]

[0049] Among them, V dc The battery voltage is known, the DC current is known, and R is... s It is the stator phase resistance of the motor, L d These are the direct-axis inductances of the motor, and are all constant parameters of the motor.

[0050] Since the above instantaneous value expression only contains and its second differential term, therefore frequency and Consistent;

[0051] when When there is only one angular frequency component ω, The angular frequency is 2ω. The angular frequency is also 2ω;

[0052] when It has multiple angular frequency components ω1, ω2, ..., ω n hour, and The angular frequencies are second harmonics 2ω₁, 2ω₂, ..., 2ω₃. n Difference frequency ω i -ω j With frequency ω i +ω j (i>j and i,j∈[1,n]).

[0053] When it is necessary to identify the battery impedance corresponding to a single angular frequency ω, then it should be made The frequency is ω / 2. Generally, 5-6 cycles need to be injected, of which the first 2-3 cycles are the transient transition process of AC signal, and the last 2-3 cycles are for voltage and current sampling measurement.

[0054] When it is necessary to identify the battery impedance corresponding to multiple frequencies, one can identify the impedance corresponding to the required frequencies. The frequencies are injected sequentially, following the steps for identifying a single-frequency impedance; alternatively, multiple frequency components can be used. and The corresponding relationship is to inject multiple frequencies at the same time. Generally, it is necessary to inject 5-6 cycles of the lowest frequency component among the multiple frequencies. The first 2-3 cycles are the transient transition process of AC signal, and the last 2-3 cycles are used for voltage and current sampling measurement to ensure that the AC excitation has reached steady state when sampling measurement.

[0055] S2. Determine the required injection based on the above. The cycle number and method are used to implement AC excitation injection, controlling the motor to drive the inverter;

[0056] S201. Measure the motor angle θ using a position sensor and the three-phase motor current i using a current sensor. a i b i c ;

[0057] S202. Calculate the motor current i in the dq coordinate system using the Park transformation. d i q ; Figure 2 is i d Injected system control block diagram;

[0058]

[0059] S203. As determined in S1 The d-axis reference current i d * If the electric vehicle is charging or parked, the q-axis reference current i q * If the q-axis reference current i is 0 when the electric vehicle is in motion, then... q * To be determined based on the actual working conditions of the electric vehicle;

[0060] S204. The d-axis current error i d * -i d Input the d-axis current regulator to adjust the q-axis current error i. q * -i q Input q-axis current regulator;

[0061] The d-axis current regulator is QPR, and its transfer function is:

[0062]

[0063] Its resonant frequency is n angular frequencies ω i (i = 1, 2, ..., n), cutoff frequency ω ci Typically, the frequency is set to 1-2Hz, and the proportional gain K... p With resonant gain K ri The value that yielded the best control effect was determined through experiments.

[0064] The q-axis current regulator is a PI controller, and its transfer function is:

[0065]

[0066] Where the proportional gain K p With resonant gain K i The value that yielded the best control effect was determined through experiments.

[0067] The S205 d-axis current regulator outputs a d-axis voltage u. d The output of the q-axis current regulator is the d-axis voltage u. q By using space vector PWM modulation, a drive signal is generated to control the motor to drive the inverter;

[0068] S3. Measure the battery voltage and current signals when implementing the AC excitation injection control algorithm, and perform frequency domain analysis and impedance calculation;

[0069] S301. The battery voltage v corresponding to the last 2-3 cycles of the injected signal cycle at each frequency. dc Current idc Perform sampling;

[0070] S302. Calculate v through frequency domain or time-frequency analysis (such as Fourier analysis, wavelet transform, etc.). dc i dc The impedance frequency component that needs to be identified in S2, i.e. The corresponding frequency ω i By considering the amplitude and phase, we can obtain the frequency ω corresponding to the battery voltage. i The voltage phasor under the following conditions is Current corresponding to frequency ω i The current phasor below is

[0071] S303. Calculate the corresponding frequency ω i Battery impedance Z ωi ;

[0072]

[0073] The technical solution is described below through three embodiments:

[0074] Example 1: Monitoring the impedance of the battery from 0.1Hz to 1000Hz when the electric vehicle is parked.

[0075] Because a battery is a complex physicochemical system, its internal composition and structure change with the number of cycles and usage time. For a battery nearing a fault state, even when it is not in operation, a "micro-short circuit" may still occur internally, causing the fault to amplify. External factors such as temperature changes or physical impacts may also cause the battery to fail even when not in operation. Therefore, it is of practical significance to determine the battery status in real time through battery impedance when it is not in a fault state.

[0076] S1. Determine the frequency of the impedance to be identified and the corresponding battery excitation current amplitude. Determine the motor direct-axis current based on the frequency at which the required impedance is identified. The frequency and amplitude are used to determine the required injection. Number of cycles and method. Divide the frequency 0.1Hz-1000Hz into 100 equal parts on a logarithmic scale, i.e., 1000Hz, ..., 0.10965Hz, 0.1Hz. The relationship between angular frequency ω and frequency f is ω=2πf, then the corresponding... The angular frequencies should be ω1 = 2πf1 = 500 * 2π, ..., ω 100 ==2πf 100 =0.054824*2π,ω 101 =0.05*2π;

[0077] S2. When the electric vehicle is parked, the motor is stationary. The rotor position θ is measured using a rotor position sensor.

[0078] Battery impedance is identified using a frequency sweep method. First, the highest frequency ω1 in the target frequency range is injected, and this process is repeated for 5-6 injection cycles. During this period, the impedance is measured...

[0079] Measuring the three-phase current i of the motor a i b i c Measure the motor angle θ and perform coordinate transformation to obtain i. d i q ,at this time i q * =0, d-axis current regulator is That is, ω c The value is set to 2π. Other parameters of PI and QPR are determined based on actual control performance. An AC excitation injection control algorithm is implemented for 5-6 consecutive cycles. The cycle.

[0080] S3. Sample the battery voltage and current in the last 2-3 cycles and calculate the impedance at the corresponding frequency;

[0081] After completing the identification at this frequency, proceed to the impedance identification at the next frequency, and repeat the above steps until the impedance identification of the last frequency component is completed.

[0082] After performing a complete battery impedance identification, compare it with the historical data or parameters of the battery impedance to determine whether the battery is in an abnormal state. If an abnormal state is found, protective and isolation measures should be taken for the battery.

[0083] Example 2: Monitoring battery status during electric vehicle charging.

[0084] During the charging process, a rapid chemical reaction occurs inside the battery, converting electrical energy into chemical energy for storage. The battery state, such as SOC, changes rapidly, accompanied by a rise in temperature. Data shows that the charging process of electric vehicles is a high-risk stage for battery explosion and fire accidents. Therefore, monitoring the battery state during the charging process is crucial.

[0085] like Figure 3 As shown, in the charging state, the battery charger and the drive inverter are connected in parallel. The battery charger provides a constant charging current, and the drive inverter provides an AC impedance identification current.

[0086] The motor remains stationary, and the rotor position is measured using a rotor position sensor.

[0087] As charging progresses, the battery state changes rapidly over time, thus requiring a high speed for impedance identification. Therefore, impedance injection is performed by superimposing multiple sinusoidal signal frequencies.

[0088] At this time, the impedance of the battery is detected at frequencies of 10Hz, 20Hz, ..., 100Hz. Since the state of the battery changes constantly during charging, it is necessary to shorten the time consumed by impedance identification. Impedance identification is performed by injecting multiple frequencies simultaneously.

[0089] Pick Right now If it contains frequency components of 10Hz, 30Hz, 40Hz, and 50Hz, then in The frequency components should include second harmonics (20Hz, 60Hz, 80Hz, 100Hz), difference frequencies (10Hz, 20Hz, 30Hz, 40Hz), and sum frequencies (40Hz, 50Hz, 60Hz, 70Hz, 80Hz, 90Hz), covering a frequency range of 10Hz from 10 to 100Hz. Figure 4 , Figure 5 The frequency decomposition results of one injection cycle current are given when the d-axis current is injected at 10Hz, 30Hz, 40Hz and 50Hz. It can be seen that injecting four frequency components can generate 10 frequency components in battery excitation, and their amplitudes are all large, ensuring that the signal-to-noise ratio meets the requirements.

[0090] Measuring the three-phase current i of the motor a i b i c And the rotor angle θ, and perform coordinate transformation to obtain i d i q ,at this time i q * =0, the transfer function of the d-axis current regulator is ω c The value is set to 2π. Other parameters of PI and QPR are determined based on actual control performance. An AC excitation injection control algorithm is implemented for 5-6 consecutive cycles. The longest period is 5-6 consecutive injections of 0.1s each. In the last 2-3 periods, the battery voltage and current are sampled to calculate the impedance at the corresponding frequency.

[0091] By comparing the impedance spectrum with historical parameters or standard battery parameters, the fault status and development during the charging process can be monitored in real time. At the same time, the battery's health status can be judged based on the battery's impedance, its aging status can be monitored, and the optimal charging current of the battery can be calculated. Under the condition of ensuring that the battery health is not seriously damaged, the charging current can be increased and the charging time can be shortened.

[0092] Example 3: Monitoring the battery status of an electric vehicle.

[0093] When an electric vehicle is running, its operating conditions change drastically. During the start-up and acceleration, the battery outputs a large current. During deceleration and kinetic energy recovery, the battery is in a charging state. These drastic changes in operating conditions can have a significant impact on battery safety. This embodiment provides a method for identifying battery impedance by implementing AC excitation injection under the operating conditions of an electric vehicle.

[0094] When an electric vehicle is running stably, the motor has a constant quadrature-axis current I. q At this time, the AC impedance of the battery at 500Hz is detected.

[0095] The frequency should be 250Hz. Measuring the three-phase current i of the motor a i b i c And the rotor angle θ, and perform coordinate transformation to obtain i d i q ,at this time The transfer function of the d-axis current regulator is ω. c The value is set to 2π. Other parameters of PI and QPR are determined based on actual control performance. An AC excitation injection control algorithm is implemented for 5-6 consecutive cycles. The cycle is 5-6 consecutive injections of 4ms each, and the battery voltage and current are sampled in the last 2-3 cycles to calculate the impedance at the corresponding frequency.

[0096] Due to the i during steady-state operation q There are significant differences, resulting in substantial variations in the DC component of the battery output current. This DC component also significantly impacts the battery impedance. Therefore, it is necessary to establish a joint relationship between battery state parameters, battery impedance, and operating current in order to make a more accurate estimate of the battery state. This allows for the timely detection of any abnormalities that occur during operation, and if necessary, to stop operation and issue warning messages to ensure the safety of the system and the driver.

[0097] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements 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 method for impedance identification of a power battery in an AC drive system under all operating conditions, characterized in that, Includes the following steps: S1. Determine the frequency of the impedance to be identified and the corresponding battery excitation current amplitude. Determine the motor direct-axis current based on the frequency at which the required impedance is identified. The frequency and amplitude are used to determine the required injection. Number of cycles and method; S2. Determine the required injection based on the above. The instructions for implementing AC excitation injection in terms of cycle number and mode are used to control the motor drive inverter; specifically, they include: S201. Measuring Motor Angle θ and motor three-phase current i a , i b , i c ; S202. Calculate the motor current in the dq coordinate system using the Park transformation. i d , i q ; S203. As determined in S1 d-axis reference current If the electric vehicle is charging or parked, the q-axis reference current... If the q-axis reference current is 0 when the electric vehicle is in motion, then... Set according to the required output power of the electric vehicle; S204. Adjust d-axis current error i d * - i d Input the d-axis current regulator to adjust the q-axis current error. i q * - i q Input q-axis current regulator; The d-axis current regulator is a proportional-quasi-resonant controller, and its transfer function is: Its resonant frequency is of n angular frequency , i =1,2,..., n , The cutoff frequency, K p and K ri These are the proportional gain and the resonant gain, respectively. s For the Laplace operator; The q-axis current regulator is a proportional-integral controller, and its transfer function is: in K p and K i These are the proportional gain and the resonant gain, respectively. The S205 d-axis current regulator outputs d-axis voltage. u d The output of the q-axis current regulator is the d-axis voltage. u q By using space vector PWM modulation, a drive signal is generated to control the motor to drive the inverter; S3. Measure the battery voltage and current signals when AC excitation is injected, and perform frequency domain analysis and impedance calculation.

2. The method according to claim 1, characterized in that, and The relationship between frequency and amplitude is determined by the following instantaneous equation: in, V dc It's the battery voltage. R s It is the stator phase resistance of the motor. L d It is the direct-axis inductance of the motor. frequency and Consistent.

3. The method according to claim 2, characterized in that, when Only one angular frequency component hour, The angular frequency is 2 , The angular frequency is also 2 ; when It has multiple angular frequency components , , , hour, and The angular frequency has a second harmonic. , , , Difference frequency - , and frequency + , i > j and i , j [1, n ].

4. The method according to claim 3, characterized in that, When it is necessary to identify a single angular frequency When the corresponding battery impedance is, The frequency is / 2, inject 5-6 cycles, of which the first 2-3 cycles are the transient transition process of AC signal, and the last 2-3 cycles are for voltage and current sampling measurement; When it is necessary to identify the battery impedance corresponding to multiple frequencies, based on the multiple frequency components and The corresponding relationship is to inject multiple frequencies simultaneously at one time, injecting 5-6 cycles of the lowest frequency component among the multiple frequencies. The first 2-3 cycles are the transient transition process of the AC signal, and the last 2-3 cycles are used for voltage and current sampling measurement to ensure that the AC excitation has reached a steady state when sampling measurement.

5. The method according to claim 3, characterized in that, When it is necessary to identify the battery impedance corresponding to multiple frequencies, the frequency corresponding to the required identification frequency is... The injections are performed sequentially based on frequency.

6. The method according to claim 4, characterized in that, S3 specifically includes: S301. The battery voltage corresponding to the last 2-3 cycles of the injected signal cycle at each frequency. v dc Current i dc Perform sampling; S302. Calculation through frequency domain analysis v dc , i dc The required impedance corresponds to the frequency component, i.e. corresponding frequency By considering the amplitude and phase, the frequency corresponding to the battery voltage can be obtained. The voltage phasor under the following conditions is Current corresponds to frequency The current phasor below is ; S303. Calculate the corresponding frequency Battery impedance ; 。 7. An impedance full-condition identification system for a power battery in an AC drive system, characterized in that, Includes computer-readable storage media and processors; The computer-readable storage medium is used to store executable instructions; The processor is used to read executable instructions stored in the computer-readable storage medium and execute the impedance full-condition identification method for AC drive system power battery according to any one of claims 1 to 6.

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