An auxiliary converter state diagnosis method, device, system and medium

Abstract

The application discloses an auxiliary converter state diagnosis method, device, system and medium, and the method steps comprise the following: when a measured auxiliary converter is started and an output contactor of the measured auxiliary converter is not closed, obtaining inductance current by acquiring current data detected by a filter inductance input side sensor of the measured auxiliary converter, and acquiring output voltage detected by an output voltage sensor in the measured auxiliary converter; performing fundamental wave extraction on the obtained inductance current by using a second-order generalized integrator to obtain inductance current fundamental wave; performing fundamental wave extraction on the obtained output voltage by using the second-order generalized integrator and calculating a derivative to obtain the fundamental wave derivative of the output voltage; calculating the capacitance value of the capacitor in the filter circuit of the measured auxiliary converter according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage; and judging the fault state of the filter circuit capacitor according to the calculated capacitance value. The application has the advantages of simple implementation method operation, low cost, high diagnosis efficiency and high precision.

Description

Technical Field

[0001] This invention relates to the field of vehicle-mounted auxiliary converter fault diagnosis technology, and in particular to an auxiliary converter condition diagnosis method, device, system and medium. Background Technology

[0002] like Figure 1 As shown, the on-board auxiliary inverter uses pulse width modulation (PWM) to collect output voltage information from sensors. This information is compared with a reference value, and the closed-loop control system calculates and controls the IGBTs of the three-phase bridge to generate three-phase square wave voltages with a 120-degree phase difference. A low-pass filter circuit composed of inductors and capacitors then filters out high-order harmonic components from the square wave voltage, resulting in a three-phase sinusoidal AC current. However, if the filter circuit malfunctions, the actual inductor and capacitor capacitance will decrease, and the filter circuit will be unable to filter out high-order harmonics as designed. This leads to an increase in the harmonic content of the output voltage, affecting the output voltage performance of the auxiliary inverter and potentially triggering the auxiliary inverter's fault protection. Furthermore, because PWM generates a square wave voltage, the current in the filter inductors and capacitors contains high-order harmonic components, making it impossible to directly use the actual current of the filter circuit for condition diagnosis.

[0003] For fault diagnosis of the filter circuit in an on-board auxiliary converter, existing technologies typically use the analysis of harmonics in the output voltage under no-load conditions to determine if the filter capacitor is faulty. This involves first adjusting the on-board auxiliary converter to no-load conditions, then collecting the harmonics of the output voltage under these conditions, and assessing the harmonic state. If the output voltage fails to filter out higher-order harmonics as preset, the filter capacitor is considered faulty. However, the diagnostic accuracy of this method is not high, especially when the output voltage performance degradation is not significant. Because the state of harmonic filtering in the filter circuit cannot be directly determined, it is difficult to accurately determine the condition of the filter circuit.

[0004] Under normal circumstances, the capacitance value of the filter capacitor calculated based on the real-time operating status of the auxiliary converter should be consistent with the nominal capacitance value. Therefore, the capacitance value calculated based on the real-time operating status of the auxiliary converter can reflect the fault status of the filter capacitor. However, in the existing technology, the capacitance value detection of the filter capacitor is usually calculated based on the resonant current of the filter circuit in the resonant state, or by setting up additional detection equipment. This is not only complex and costly, but also usually requires the auxiliary converter to operate under specific conditions, which affects the normal operation of the auxiliary converter.

[0005] As disclosed in Chinese patent application CN110187204A, a neutral point clamped multi-level converter DC capacitor state detection method is disclosed. The scheme is aimed at the DC side capacitor of the neutral point clamped three-level inverter. The DC side capacitor is discharged first, then the two-phase bridge wall is controlled to generate pulse control switch tube action to make the LC filter circuit resonate, and the capacitance value is calculated according to the resonance current. The calculation is complex, and the DC side capacitor and the two-phase bridge wall must be controlled to work in a specific working condition, which will interfere with the normal operation of the converter, and the capacitance value cannot be diagnosed in the normal use process.

[0006] Chinese patent application CN106058930A discloses a photovoltaic grid-connected inverter bus capacitor value automatic detection system and method. The scheme installs an auxiliary test resistor on the DC side. The capacitor is fully charged in the disconnected state of the auxiliary test resistor, and then the auxiliary test resistor is connected to discharge the capacitor. The approximate capacitance value is calculated by calculating the discharge process, and the capacitance state is determined by comparing with the acceptable lower limit of the capacitance value. However, the test process is complex, and additional hardware needs to be installed, which increases the implementation cost and complexity. SUMMARY

[0007] The technical problem to be solved by the present application is to provide an auxiliary converter state diagnosis method, device, system and medium with simple implementation method, low cost, high diagnosis efficiency and precision.

[0008] To solve the above technical problems, the technical scheme provided by the present application is as follows:

[0009] An auxiliary converter state diagnosis method, comprising the following steps:

[0010] When the measured auxiliary converter is started and the output contactor of the measured auxiliary converter is not closed, the current data detected by the filter inductance input side sensor in the filter circuit of the measured auxiliary converter is obtained to obtain the inductance current, and the output voltage detected by the output voltage sensor in the measured auxiliary converter is obtained;

[0011] The obtained inductance current is subjected to fundamental wave extraction using a second-order generalized integrator to obtain the inductance current fundamental wave;

[0012] The obtained output voltage is subjected to fundamental wave extraction and derivative calculation using a second-order generalized integrator to obtain the fundamental wave derivative of the output voltage;

[0013] The capacitance value in the filter circuit of the measured auxiliary converter is calculated according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage;

[0014] The fault state of the filter circuit capacitor is judged according to the calculated capacitance value.

[0015] Further, the transfer function of the second-order generalized integrator is where ω is the angular frequency of the fundamental signal, and k is a gain coefficient.

[0016] Further, the capacitance value C in the filter circuit of the auxiliary converter to be measured is calculated according to the fundamental of the inductance current and the derivative of the output voltage according to the following formula:

[0017]

[0018] where i f is the fundamental of the capacitance current, is the fundamental derivative of the output voltage.

[0019] Further, when detecting the inductance current in the filter circuit of the auxiliary converter to be measured, the detected current is further filtered through a band-pass filter.

[0020] Further, the fault state of the filter capacitor is determined according to the calculated capacitance value, which includes comparing the calculated capacitance value with the nominal capacitance value, and if the deviation exceeds the preset threshold, it is determined that the capacitor in the filter circuit of the auxiliary converter is damaged.

[0021] An auxiliary converter state diagnosis method, comprising the steps of:

[0022] After starting the auxiliary converter to be measured and closing the output contactor of the auxiliary converter to be measured, the inductance current is obtained by acquiring the current data detected by the filter inductance input side sensor in the filter circuit of the auxiliary converter to be measured, and the output voltage is obtained by acquiring the output voltage detected by the output voltage sensor in the auxiliary converter to be measured.

[0023] The fundamental of the inductance current is extracted by using a second-order generalized integrator on the obtained inductance current, and the fundamental of the inductance current is obtained.

[0024] The fundamental of the output voltage is extracted by using a second-order generalized integrator on the obtained output voltage, and the derivative is calculated, and the fundamental derivative of the output voltage is obtained.

[0025] The fundamental of the capacitance current is calculated according to the fundamental derivative of the output voltage and the nominal capacitance value, and the fundamental of the output current of the auxiliary converter to be measured is calculated according to the fundamental of the inductance current and the fundamental of the capacitance current.

[0026] The state of the current auxiliary converter is solved by using the fourth-order Runge-Kutta method based on the calculated fundamental.

[0027] Further, the transfer function of the second-order generalized integrator is The fundamental of the output current is represented as:

[0028] io = i f = -i c

[0029]

[0030]

[0031] wherein ω is the angular frequency of the fundamental signal, k is a gain coefficient, i o is the output current, i f is the fundamental of the inductive current, i c is the fundamental of the capacitive current, C is the filter capacitance value, and u is the output voltage.

[0032] Further, the solving of the state of the current auxiliary converter according to the calculated fundamental further comprises a fault diagnosis step, comprising:

[0033] comparing the difference between the calculated two-phase output currents in the measured auxiliary converter, and comparing the measured values of the two-phase output current sensors in the measured auxiliary converter;

[0034] if the difference between the measured values of the two-phase output current sensors is greater than a first preset threshold value, and the difference between the calculated values of the two-phase output currents is less than a second preset threshold value, it is determined that the output current sensor has a fault;

[0035] if the difference between the measured values of the two-phase output current sensors is less than a second preset threshold value, and the difference between the calculated values of the two-phase output currents is greater than a first preset threshold value, it is determined that the output current sensor is normal, and that there is a fault in other sensors, and the final fault location is determined by comparing the measured values of each sensor with the corresponding calculated values.

[0036] An auxiliary converter state diagnosis method, comprising the steps of:

[0037] when the output contactor of the measured auxiliary converter is not closed, diagnosing the state of the filter circuit of the measured auxiliary converter according to the first diagnosis method described above to obtain a first diagnosis result;

[0038] after the output contactor of the measured auxiliary converter is closed, diagnosing the state of the filter circuit of the measured auxiliary converter according to the second diagnosis method described above to obtain a second diagnosis result;

[0039] obtaining a final diagnosis result according to the first diagnosis result and the second diagnosis result.

[0040] An auxiliary converter state diagnosis device, comprising:

[0041] a data acquisition module, configured to acquire, when the auxiliary converter under test is started and an output contactor of the auxiliary converter under test is not closed, an inductance current detected by an inductance input side sensor in a filter circuit of the auxiliary converter under test, and acquire an output voltage detected by an output voltage sensor in the auxiliary converter under test;

[0042] a current processing module, configured to perform fundamental wave extraction on the acquired inductance current by using a second-order generalized integrator to obtain an inductance current fundamental wave;

[0043] a voltage processing module, configured to perform fundamental wave extraction on the acquired output voltage by using a second-order generalized integrator and calculate a derivative to obtain a fundamental wave derivative of the output voltage;

[0044] a capacitance calculation module, configured to calculate a capacitance value of a capacitor in the filter circuit of the auxiliary converter under test according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage;

[0045] a fault judgment module, configured to judge a fault state of the capacitor in the filter circuit according to the calculated capacitance value.

[0046] An auxiliary converter state diagnosis device, comprising:

[0047] a data acquisition module, configured to acquire, when the auxiliary converter under test is started and an output contactor of the auxiliary converter under test is closed, an inductance current detected by an inductance input side sensor in a filter circuit of the auxiliary converter under test, and acquire an output voltage detected by an output voltage sensor in the auxiliary converter under test;

[0048] a current processing module, configured to perform fundamental wave extraction on the acquired inductance current by using a second-order generalized integrator to obtain an inductance current fundamental wave;

[0049] a voltage processing module, configured to perform fundamental wave extraction on the acquired output voltage by using a second-order generalized integrator and calculate a derivative to obtain a fundamental wave derivative of the output voltage;

[0050] a calculation module, configured to calculate a capacitor current fundamental wave according to the fundamental wave derivative of the output voltage and a nominal capacitance value, and calculate an output current fundamental wave of the auxiliary converter under test according to the inductance current fundamental wave and the capacitor current fundamental wave;

[0051] a state solving module, configured to solve a state of the auxiliary converter under test according to the calculated fundamental waves.

[0052] An auxiliary converter state diagnosis system, comprising:

[0053] The first diagnostic device is used for diagnosing the filter circuit state of the auxiliary converter under the condition that the output contactor of the auxiliary converter is not closed, and obtaining a first diagnostic result output.

[0054] The second diagnostic device is used for diagnosing the filter circuit state of the auxiliary converter under the condition that the output contactor of the auxiliary converter is closed, and obtaining a second diagnostic result.

[0055] The diagnostic output device is used for obtaining a final diagnostic result output according to the first diagnostic result and the second diagnostic result.

[0056] An electronic device comprises a processor and a memory, the memory is used for storing a computer program, and the processor is used for executing the computer program to execute the above method.

[0057] A computer readable storage medium storing a computer program, the computer program is executed by a processor to implement the above method.

[0058] Compared with the prior art, the present application has the following advantages:

[0059] 1、The present application uses the relationship between the bridge arm current and the capacitor current when the auxiliary converter is started and the output contactor is not closed, and uses the sensor data inside the auxiliary converter to calculate the capacitor value in real time, judges the fault state of the filter circuit capacitor according to the calculated capacitor value, can accurately predict the fault state of the capacitor in advance, so as to perform protection in advance, and uses the bandpass characteristic of the second-order generalized integrator to calculate the fundamental wave of the voltage and current and the derivative of the output voltage fundamental wave in real time, obtains the current and voltage derivative signal without high-order harmonic, avoids high-frequency noise interference, and also avoids phase delay and amplitude loss, obtains the fundamental wave and the corresponding derivative information of the circuit state without phase and amplitude deviation, effectively improves the accuracy of the capacitor value calculation, does not need to increase the hardware cost, can greatly reduce the implementation cost and complexity, and can perform state diagnosis in real time during the normal operation of the auxiliary converter, without affecting the real-time control and normal operation of the auxiliary inverter.

[0060] 2、The application combines the inductive current detected by the sensor inside the auxiliary converter and the output voltage, calculates the fundamental wave of the output current by using the fundamental wave of the inductive current and the derivative of the output voltage fundamental wave, and solves the circuit state of the auxiliary converter based on each fundamental wave, so that the real-time state diagnosis and converter state monitoring of the auxiliary converter can be quickly realized without additional hardware devices, the arrangement of sensors is minimized, the normal operation of the auxiliary converter is not affected, the band-pass characteristic of the second-order generalized integrator is used to calculate the fundamental wave of the voltage and current and the derivative of the output voltage fundamental wave in real time, the current and voltage derivative signals without high-order harmonics can be obtained, phase delay and amplitude loss can be avoided, the calculation accuracy of the output current is effectively ensured, and the state diagnosis accuracy of the auxiliary converter is improved. BRIEF DESCRIPTION OF DRAWINGS

[0061] Figure 1 is a structural schematic diagram of a vehicle-mounted auxiliary converter.

[0062] Figure 2 is a specific structure and control principle schematic diagram of an auxiliary converter using a two-level inverter.

[0063] Figure 3 is an implementation flow schematic diagram of the auxiliary converter state diagnosis method of the embodiment 1 of the application.

[0064] Figure 4 is a control principle schematic diagram of the auxiliary converter in the embodiment 1 of the application.

[0065] Figure 5 is an implementation flow schematic diagram of the auxiliary converter state diagnosis method in the embodiment 2 of the application. DETAILED DESCRIPTION

[0066] The application will be further described below in combination with the drawings of the specification and specific preferred embodiments, but the protection scope of the application is not limited by this.

[0067] As shown in the disclosure of the application, unless the context clearly indicates otherwise, "one", "a", "an" and / or "the" do not specifically refer to the singular, but can also include the plural. The "first", "second" and similar words used in the disclosure of the application do not represent any order, quantity or importance, but are only used to distinguish different components. Similarly, "include" or "contain" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0068] Taking an auxiliary converter using a two-level inverter as an example, Figure 2As shown, a filter circuit is arranged at the output end of the auxiliary converter, which includes an output filter inductor L and an output filter capacitor C, the output filter capacitor C adopts a delta connection, and the output end of the auxiliary converter controls the output on and off through an output contactor KMA. The auxiliary converter is internally provided with an input current sensor SC1 for detecting the input current, sensors SC2 and SC3 arranged at the input end of the inductor for detecting the bridge arm current, an input voltage sensor SV1 for detecting the input voltage, a sensor SV2 for detecting the capacitor voltage at the DC input end, an output voltage sensor SV3 and SV4 for detecting the output voltage. The auxiliary converter is controlled by a control unit, which can specifically adopt a high-performance digital controller, accurately collects the output voltage of the auxiliary inverter, and controls in combination with the DC voltage and the output current. The control unit specifically includes a digital input and output DIO, an analog input APA, a pulse conversion, a logic control SMC, a signal processing LSC, a digital operation ACC, etc. If the filter capacitor C fails, such as the actual inductance capacitor capacity decreases, the filter circuit will not be able to filter out high-order harmonics according to the predetermined design, which will cause the harmonic content of the output voltage of the auxiliary converter to rise, thereby affecting the output voltage performance of the auxiliary inverter.

[0069] The filter capacitor in the filter circuit of the auxiliary converter satisfies:

[0070]

[0071] Wherein, C is the capacitance of the output filter capacitor, u is the voltage across the filter capacitor, i c is the current of the filter capacitor.

[0072] From formula (1), to calculate the capacitance value of the filter capacitor, the voltage and current at both ends of the filter capacitor need to be determined and derivative calculation needs to be performed. Although the capacitor current can be obtained through the inductor current sensor before the contactor is closed, the capacitor current contains a large number of high harmonic components. The fundamental wave of the voltage and current signals and the derivative calculation cannot be directly detected by the hardware sensor inside the auxiliary converter. If the detection is performed through a sensor or the like, the implementation cost is increased. The differential derivation produces a large amount of high-frequency noise interference. If a low-pass filter is used, a certain phase delay and amplitude loss are also brought, which is not conducive to real-time state calculation. The second-order generalized integrator has a band-pass characteristic and can generate a 90-degree phase difference signal. Therefore, the second-order generalized integrator can output the quadrature signal to obtain the fundamental wave derivative information of the phase voltage, and the obtained signal does not contain harmonic information. The present application considers the above problems. The inductor current and the output voltage detected by the internal sensor of the auxiliary converter are obtained when the output contactor of the measured auxiliary converter is not closed. The band-pass characteristic of the second-order generalized integrator is used to calculate the fundamental wave of the voltage and current and the derivative of the fundamental wave of the output voltage in real time. The current and voltage derivative signals without high-order harmonics can be effectively obtained, high-frequency noise interference can be avoided, phase delay and amplitude loss can also be avoided, the fundamental wave and the corresponding derivative information of the circuit state without phase and amplitude deviation can be obtained, and therefore the obtained fundamental wave and derivative information combined with the detection signal of the internal sensor of the auxiliary converter can realize real-time and accurate state diagnosis of the filter circuit during the normal operation of the auxiliary converter, without relying on additional hardware detection equipment or a complex control process.

[0073] Embodiment 1

[0074] In consideration of the case that the auxiliary converter is started but the output contactor KMA is not closed, since the output current i o is 0, the inductor current i L is the capacitor current i c at this time. The inductor current i L at this time can be detected by the internal sensor SC2 / SC3 of the auxiliary converter, and the capacitor current i c is obtained. The real-time value of the output voltage detected by the output voltage sensors SV3 and SV4 inside the auxiliary converter is used to obtain the fundamental wave of the current and the fundamental wave derivative of the voltage by using the second-order generalized integrator. The fundamental wave of the inductor current and the fundamental wave derivative of the output voltage are combined with formula (1) to quickly and accurately calculate the capacitance value of the filter capacitor.

[0075] As shown in Figure 3 , the steps of the auxiliary converter state diagnosis method of the present embodiment include:

[0076] Step S01. When the measured auxiliary converter is started and the output contactor of the measured auxiliary converter is not closed, the inductance current detected by the filter inductance input side sensor of the measured auxiliary converter is obtained, and the output voltage detected by the output voltage sensor of the measured auxiliary converter is obtained.

[0077] Step S02. The fundamental wave of the obtained inductance current is extracted by using the second-order generalized integrator to obtain the inductance current fundamental wave.

[0078] Step S03. The fundamental wave of the obtained output voltage is extracted by using the second-order generalized integrator and the derivative is calculated to obtain the fundamental wave derivative of the output voltage.

[0079] Step S04. The capacitance value of the filter circuit of the measured auxiliary converter is calculated according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage.

[0080] Step S05. The fault state of the filter circuit capacitor is judged according to the calculated capacitance value.

[0081] In this embodiment, by utilizing the relationship between the bridge arm current and the capacitor current when the measured auxiliary converter is started and the output contactor is not closed, the capacitance value is calculated in real time by means of the sensor data inside the auxiliary converter. According to the calculated capacitance value, the fault state of the filter circuit capacitor is judged, the fault state of the capacitor can be accurately predicted in advance, so that protection can be performed in advance. At the same time, by utilizing the band-pass characteristic of the second-order generalized integrator, the fundamental wave of the voltage and current is calculated in real time, and the derivative of the output voltage fundamental wave is calculated, so as to obtain the current and voltage derivative signal without high-order harmonic, avoid high-frequency noise interference, and also avoid phase delay and amplitude loss, so as to obtain the fundamental wave and the corresponding derivative information of the circuit state without phase and amplitude deviation, effectively improve the accuracy of the capacitance value calculation, and without additional hardware cost, the implementation cost and complexity can be greatly reduced. At the same time, the state diagnosis can be performed in real time during the normal operation of the auxiliary converter, which will not affect the real-time control and normal operation of the auxiliary inverter.

[0082] In this embodiment, the transfer function of the second-order generalized integrator is Wherein, ω is the angular frequency of the fundamental wave signal, k is the gain coefficient, which determines the filtering performance and response speed of the second-order generalized integrator, and can be selected as 1.414. Then the fundamental wave of the inductance current is extracted by using the second-order generalized integrator, and the expression of the fundamental wave of the inductance current is:

[0083]

[0084] The derivative information of the output voltage fundamental wave obtained by using the second-order generalized integrator is:

[0085]

[0086] In this embodiment, the capacitance value C in the filter circuit of the auxiliary converter under test is calculated according to the following formula based on the fundamental frequency of the inductor current and the derivative of the output voltage:

[0087]

[0088] Among them, i f It is the fundamental frequency of the capacitor current. Let be the fundamental waveguide of the output voltage.

[0089] This allows for the calculation of the capacitor value C. No additional hardware is required. The capacitor value C can be calculated accurately and in real time during the normal operation of the auxiliary converter, thereby enabling real-time diagnosis of the fault status of the filter capacitor.

[0090] In this embodiment, when detecting the inductor current in the filter circuit of the auxiliary converter under test, the detected current is also filtered by a bandpass filter to filter out other frequency signals, further avoiding high-frequency noise interference, phase delay and amplitude loss, and ensuring detection accuracy.

[0091] like Figure 4 As shown, where V ref For reference output voltage, V o H2(s) represents the actual output voltage, and K represents the voltage loop PI controller. pwm The equivalent amplification factor of the inverter bridge is given by L, where L is the inductance value, r is the equivalent series resistance of the inductor, and C is the actual capacitance value. During auxiliary converter operation, the control error is obtained by comparing the output voltage with a reference voltage. After passing through a PI controller, the output control signal controls the inverter bridge switching transistors to generate voltage pulses. These pulses then pass through a low-pass filter circuit composed of inductors and capacitors to obtain a sinusoidal output voltage. The inductor current detected by the bridge arm current sensor is used as the capacitor current i. c Input to the first and second order generalized integrator (transfer function denoted as) Calculate the fundamental current and output voltage V. o Input to the second-order generalized integrator (transfer function denoted as) Calculate the voltage fundamental waveguide, and connect the outputs of the first and second order generalized integrators to a divider to calculate the capacitance value in real time.

[0092] In the embodiment, the fault state of the capacitor of the filter circuit is determined according to the calculated capacitance value, including: comparing the calculated capacitance value with a nominal capacitance value, and if a deviation value exceeds a preset threshold, it is determined that the capacitor in the auxiliary converter filter circuit is damaged. Under normal circumstances, the calculated capacitance value is not much different from the nominal capacitance value, and when there is a large deviation between the calculated actual capacitance value and the nominal capacitance value, it can be determined that the capacitor is damaged, and rapid real-time fault diagnosis can be realized.

[0093] The auxiliary converter state diagnosis device in the embodiment includes:

[0094] The data acquisition module is configured to acquire the inductance current detected by the filter inductance input side sensor in the filter circuit of the measured auxiliary converter when the measured auxiliary converter is started and the output contactor of the measured auxiliary converter is not closed, and acquire the output voltage detected by the output voltage sensor in the measured auxiliary converter.

[0095] The current processing module is configured to use a second-order generalized integrator to extract a fundamental wave of the acquired inductance current to obtain an inductance current fundamental wave.

[0096] The voltage processing module is configured to use a second-order generalized integrator to extract a fundamental wave of the acquired output voltage and calculate a derivative to obtain a fundamental wave derivative of the output voltage.

[0097] The capacitance value calculation module is configured to calculate a capacitance value in the filter circuit of the measured auxiliary converter according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage.

[0098] The fault judgment module is configured to determine a fault state of the capacitor of the filter circuit according to the calculated capacitance value.

[0099] In the embodiment, the current processing module specifically adopts a first second-order generalized integrator to input the inductance current detected by the input current detection module and as a capacitor current, and obtains a capacitor current fundamental wave output after the second-order generalized integration, and the voltage processing module adopts a second second-order generalized integrator to input the output voltage detected by the input voltage processing module, and obtains a fundamental wave derivative output of the output voltage after the second-order generalized integration.

[0100] In the embodiment, the capacitance value calculation module includes a divider, which respectively inputs the capacitor current fundamental wave i f and the fundamental wave derivative of the output voltage According to the measured auxiliary converter filter circuit capacitance C is calculated.

[0101] The auxiliary converter state diagnosis device in the embodiment corresponds to the auxiliary converter state diagnosis method described above, and will not be described again.

[0102] Example 2:

[0103] During operation, auxiliary converters require monitoring of the status of various components. However, in practice, only bridge arm current sensors and output voltage sensors may be installed, without other sensors (such as output current sensors), making it impossible to obtain status information such as the output current of the auxiliary converter. To monitor the various states of the auxiliary converter, additional sensors would be needed. However, adding various sensors is not only costly, but also generates significant high-frequency noise interference due to the high-order harmonics in the AC side inductor current of the auxiliary converter, making real-time calculations difficult. Using low-pass filters would introduce phase delay and amplitude loss, which is also detrimental to real-time status calculations.

[0104] For example Figure 2 Taking the DC-side inductor current of the auxiliary converter as an example, the actual inductance in the circuit often differs from the ideal inductance. Therefore, it can be equivalent to an ideal inductance plus an equivalent series resistance. Let rx1 be the voltage across the ideal inductor and rx1 be the voltage across the equivalent series resistance of the inductor. Then the voltage across the actual inductor is equal to... That is, it satisfies the following formula:

[0105]

[0106] Where x1 represents the inductor current.

[0107] Therefore, the input voltage equals the inductor voltage plus the capacitor voltage, which is... The following observer can then be obtained:

[0108]

[0109] in The observed value represents the inductor current.

[0110] Subtracting the two equations above, we get:

[0111]

[0112] in This represents the error between the observed value and the actual value.

[0113] Then there is That is, when time approaches infinity, the difference between the observed value and the true value is 0, indicating that the observed value equals the true value. Therefore, by constructing an observer, the DC-side inductor current can be observed in real time. The calculation of the DC-side inductor current can be achieved using methods such as the first-order Euler iteration method or the fourth-order Runge-Kutta method.

[0114]

[0115] wherein k represents the time of sampling, T represents the interval of two sampling points, and the above equation is substituted into

[0116]

[0117] According to the above equation, the value of x at the next time (k+1 time) can be obtained from the value of k time.

[0118] As for the AC side of the auxiliary converter, in the case that the auxiliary converter is started but the output contactor KMA is closed, the output current i o is the difference between the inductance current i L and the capacitance current i c , i.e. i o = i f -i c . As shown in equation (1), the capacitance current i c can be calculated using the derivative of the output voltage. In this embodiment, the real-time value of the output voltage detected by the output voltage sensors SV3 and SV4 inside the auxiliary converter is obtained, and the first harmonic derivative thereof is obtained through a second-order generalized integrator, and then the capacitance current i c is obtained, and the inductance current i L is detected by the sensor SC2 / SC3 inside the auxiliary converter, and the output current i o is calculated using the first harmonic of the inductance current, and the state of the filter circuit in the current auxiliary converter is solved according to the calculated first harmonics, so that the diagnosis of various states of the auxiliary converter can be quickly realized without adding additional hardware devices, and the additional sensors and other devices are avoided, and the normal operation of the auxiliary converter is not affected, and the first harmonic of the voltage and current and the derivative of the output voltage first harmonic are calculated in real time through the band-pass characteristic of the second-order generalized integrator, the current and voltage derivative signals without high-order harmonics are obtained, the high-frequency noise interference is avoided, the phase delay and amplitude loss are also avoided, the first harmonic and the corresponding derivative information of the circuit state without phase and amplitude deviation are obtained, and the diagnosis accuracy is ensured.

[0119] As shown in Figure 5 , the steps of the auxiliary converter state diagnosis method of this embodiment include:

[0120] S01. After starting the measured auxiliary converter and closing the output contactor of the measured auxiliary converter, obtaining the inductance current from the current data detected by the filter inductance input side sensor in the filter circuit of the measured auxiliary converter, and obtaining the output voltage detected by the output voltage sensor in the measured auxiliary converter;

[0121] ​S02. The fundamental wave of the inductance current is extracted by using the second-order generalized integrator on the acquired inductance current, to obtain the inductance current fundamental wave;

[0122] S03. The fundamental wave of the output voltage is extracted by using the second-order generalized integrator on the acquired output voltage and the derivative is calculated, to obtain the fundamental wave derivative of the output voltage;

[0123] S04. The fundamental wave of the capacitor current is calculated according to the fundamental wave derivative of the output voltage and the nominal capacitor value, and the fundamental wave of the output current of the measured auxiliary converter is calculated according to the inductance current fundamental wave and the capacitor current fundamental wave;

[0124] S05. The state of the filter circuit in the current auxiliary converter is solved according to the calculated fundamental waves.

[0125] In the embodiment, the transfer function of the second-order generalized integrator is specifically Wherein, ω is the angular frequency of the fundamental wave signal, k is the gain coefficient, which determines the filtering performance and response speed of the second-order generalized integrator, and can be specifically taken as 1.414. The differential derivation will produce a large amount of high-frequency noise, and the low-pass filter will bring a certain phase delay, which is not conducive to real-time state calculation. In the embodiment, the second-order generalized integrator is used to extract the fundamental wave of the inductance current and the output voltage and to calculate the derivative, so that the fundamental wave and the corresponding derivative information of the circuit state without phase and amplitude deviation can be obtained, and the accurate real-time output current fundamental wave component can be obtained, so that the state of the auxiliary converter can be diagnosed in real time.

[0126] In the embodiment, the inductance current fundamental wave obtained by using the second-order generalized integrator can be specifically represented as:

[0127]

[0128] The fundamental wave of the capacitor current obtained by using the second-order generalized integrator can be represented as:

[0129]

[0130] Wherein, C is the filter capacitor value, and u is the output voltage.

[0131] The fundamental wave of the output current is:

[0132] i o =i f -i c (9)

[0133] In this embodiment, the fourth-order Runge-Kutta method can be used to solve the equation in step S05, that is, after the fundamental waves are extracted, the data is substituted into the fourth-order Runge-Kutta method to solve the equation, and then the state information of the converter can be obtained. The calculated information of the inductor current and the output voltage is compared with the detection information of the internal sensor (bridge arm current sensor and output voltage sensor) of the converter to determine whether the converter has a fault. If the comparison result is consistent, it indicates that the sensor does not have a fault, and the other state information can be fully utilized. If the error exceeds a certain range, it is determined that there is a fault, and the fault needs to be repaired.

[0134] In this embodiment, the circuit state is quickly solved by using the data of the internal sensor of the auxiliary converter, and then the solving result is combined with the data of the internal sensor of the auxiliary converter to diagnose the fault. The data of the internal sensor of the auxiliary converter can be fully utilized to realize fault diagnosis and converter state monitoring, and the number of additional sensors can be reduced as much as possible. Therefore, the state of the converter can be effectively monitored with as few sensors as possible.

[0135] It can be understood that, in addition to the fourth-order Runge-Kutta method, other solving methods can also be used to solve the circuit state.

[0136] In this embodiment, after the state of the auxiliary converter is solved according to the calculated fundamental waves, a fault diagnosis step S06 is further included. The specific steps of step S06 include:

[0137] Step S601. The difference between the calculated two-phase output currents of the measured auxiliary converter is compared, and the measurement values of the two-phase output current sensors of the measured auxiliary converter are compared.

[0138] Step S602. If the difference between the measurement values of the two-phase output current sensors is greater than a first preset threshold value, and the difference between the calculated values of the two-phase output currents is less than a second preset threshold value, it is determined that the output current sensor has a fault.

[0139] Step S603. If the difference between the measurement values of the two-phase output current sensors is less than the second preset threshold value, and the difference between the calculated values of the two-phase output currents is greater than the first preset threshold value, it is determined that the output current sensor is normal, and other sensors have a fault. The final fault position is determined by comparing the measurement values of the sensors with the corresponding calculated values.

[0140] If two-phase output sensors are installed in the auxiliary converter, the measured values of the output sensors should be consistent with the calculated output current values, so the above scheme can be used to realize the fault diagnosis of the output sensors. Specifically, after the output current of the auxiliary converter is solved by the above method of the embodiment, the measured values of the two-phase output current sensors are compared. If there is a large difference, i.e., imbalance, and the calculated output current values are not greatly different, it is determined that the output current sensors have a fault. If the measured values of the two-phase output current sensors are not greatly different, but the calculated two-phase output current values are greatly different, it is determined that the output current sensors are normal and the remaining sensors are abnormal, e.g., the inductance current sensor or the output voltage sensor has a fault. Further, the measured data of each sensor is compared with the corresponding calculated data to finally determine the fault position. For example, the measured value of the inductance current sensor is compared with the calculated inductance current value. If they are consistent, it is determined that the inductance current sensor is normal, otherwise, it is determined that the inductance current sensor has a fault.

[0141] When the alternating current inductance current value is solved, the specific calculation formula is:

[0142]

[0143] The above formula can be solved by using the first-order Euler method or the fourth-order Runge-Kutta method in a similar way to the calculation of the direct current side inductance current.

[0144] If the state of the alternating current output voltage sensor is to be determined, the output voltage is calculated according to the following formula:

[0145]

[0146] where U out is the output voltage, U B is the output of the inverter bridge, which is controlled and thus known in real time, and I f is the fundamental wave extracted by the second-order generalized integrator.

[0147] It can be understood that, in addition to the above calculation methods, the specific calculation method can also be determined according to the actual circuit structure.

[0148] The auxiliary converter state diagnosis device of the embodiment comprises:

[0149] a data acquisition module, configured to acquire an inductance current detected by an inductance input side sensor in a filter circuit of the auxiliary converter under test when the auxiliary converter under test is started and an output contactor of the auxiliary converter under test is not closed, and acquire an output voltage detected by an output voltage sensor in the auxiliary converter under test;

[0150] a current processing module, configured to perform fundamental wave extraction on the acquired inductance current by using a second-order generalized integrator to obtain an inductance current fundamental wave;

[0151] a voltage processing module, configured to perform fundamental wave extraction on the acquired output voltage by using a second-order generalized integrator and calculate a derivative to obtain a fundamental wave derivative of the output voltage;

[0152] a capacitance calculation module, configured to calculate a capacitance value of a capacitor in the filter circuit of the auxiliary converter under test according to the inductance current fundamental wave and the fundamental wave derivative of the output voltage;

[0153] a fault judgment module, configured to judge a fault state of the capacitor in the filter circuit according to the calculated capacitance value.

[0154] The auxiliary converter state diagnosis device of this embodiment corresponds to the auxiliary converter state diagnosis method described above, and will not be described again.

[0155] Embodiment 3:

[0156] The steps of the auxiliary converter state diagnosis method of this embodiment include:

[0157] When the output contactor of the auxiliary converter under test is not closed, the diagnosis method of embodiment 1 is used to diagnose the state of the filter circuit of the auxiliary converter under test to obtain a first diagnosis result;

[0158] After the output contactor of the auxiliary converter under test is closed, the diagnosis method of embodiment 2 is used to diagnose the state of the filter circuit of the auxiliary converter under test to obtain a second diagnosis result;

[0159] The final diagnosis result is obtained according to the first diagnosis result and the second diagnosis result.

[0160] The diagnosis method of embodiment 1 can be used to diagnose the fault state of the filter capacitor in the filter circuit in real time before the output contactor of the auxiliary converter under test is closed without increasing hardware, but it is not suitable for the scenario after the output contactor of the auxiliary converter under test is closed. This embodiment combines the advantages of the two methods, uses different diagnosis methods in different scenarios before and after the output contactor of the auxiliary converter under test is closed, respectively, and then obtains the final diagnosis result by comprehensively considering the two diagnosis results, which can further improve the diagnosis accuracy and reliability.

[0161] In a specific application example, when the final diagnosis result is obtained according to the first diagnosis result and the second diagnosis result, if the first diagnosis result and the second diagnosis result diagnose that there is a fault at the same time, it can be determined that there is a fault inside the auxiliary converter, and the specific fault position can be determined by comprehensively combining the two diagnosis results; if the first diagnosis result and the second diagnosis result diagnose that there is no fault, it can be determined that the auxiliary converter is in a normal state before the output contactor of the output converter is closed and during the whole process after the output contactor is closed, and the diagnosis accuracy can be improved by combining the two diagnosis results.

[0162] The auxiliary converter state diagnosis system in the embodiment comprises:

[0163] a first diagnosis device configured to diagnose the state of the filter circuit of the auxiliary converter under test according to the diagnosis method in Embodiment 1 when the output contactor of the auxiliary converter under test is not closed, and output a first diagnosis result;

[0164] a second diagnosis device configured to diagnose the state of the filter circuit of the auxiliary converter under test according to the diagnosis method in Embodiment 2 when the output contactor of the auxiliary converter under test is closed, and output a second diagnosis result;

[0165] a diagnosis output device configured to obtain a final diagnosis result according to the first diagnosis result and the second diagnosis result.

[0166] In the embodiment, when the final diagnosis result is obtained according to the first diagnosis result and the second diagnosis result by the diagnosis output device, if the first diagnosis result and the second diagnosis result diagnose that there is a fault at the same time, it can be determined that there is a fault inside the auxiliary converter, and the specific fault position can be determined by comprehensively combining the two diagnosis results; if the first diagnosis result and the second diagnosis result diagnose that there is no fault, it can be determined that the auxiliary converter is in a normal state before the output contactor of the output converter is closed and during the whole process after the output contactor is closed, and the diagnosis accuracy and reliability can be improved by combining the two diagnosis results.

[0167] The auxiliary converter state diagnosis system in the embodiment corresponds to the auxiliary converter state diagnosis method described above, and will not be described again.

[0168] The application further provides an electronic device comprising a processor and a memory, the memory being configured to store a computer program, and the processor being configured to execute the computer program to perform the diagnosis method described above.

[0169] The application further provides a computer-readable storage medium storing a computer program, the computer program being configured to be executed by a processor to implement the diagnosis method described above.

[0170] Those skilled in the art will appreciate that the embodiments of the present application described above can be provided as a method, system, or computer program product. Accordingly, the present application can take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application can take the form of a computer program product on one or more computer readable storage media (including, but not limited to, disk memory, CD-ROMs, optical storage devices, etc.) embodying computer readable program code. The present application is described in terms of flowcharts and / or block diagrams in accordance with embodiments of the application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processing system, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. These computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more flowcharts and / or block diagrams. Figure 1 one or more flowcharts and / or block diagrams. Figure 1 one or more flowcharts and / or block diagrams. Figure 1 one or more flowcharts and / or block diagrams. Figure 1 one or more flowcharts and / or block diagrams. Figure 1 one or more flowcharts and / or block diagrams.

[0171] The foregoing is merely illustrative of the principles of the application, and various modifications can be made by those skilled in the art without departing from the scope of the application. The above description is embodied in the best mode presently contemplated by the inventors. The application, however, is capable of other embodiments and of being practiced and carried out in various ways. Accordingly, the application is not intended to be limited to the embodiments described above but is to be accorded the widest scope consistent with the principles and features disclosed herein.

Claims

1. A method for diagnosing the condition of an auxiliary converter, characterized in that the steps include... include: When the auxiliary converter under test is started and the output contactor of the auxiliary converter under test is not closed, the current data detected by the sensor on the input side of the filter inductor in the filter circuit of the auxiliary converter under test is obtained to obtain the inductor current, and the output voltage detected by the output voltage sensor in the auxiliary converter under test is obtained. The fundamental frequency of the obtained inductor current is extracted using a second-order generalized integrator. The fundamental wave of the obtained output voltage is extracted using a second-order generalized integrator, and its derivative is calculated to obtain the fundamental wave derivative of the output voltage. The capacitance value in the filter circuit of the auxiliary converter under test is calculated based on the fundamental derivative of the inductor current and the fundamental derivative of the output voltage. The fault status of the filter circuit capacitor is determined based on the calculated capacitance value.

2. The auxiliary converter condition diagnosis method according to claim 1, characterized in that, The transfer function of the second-order generalized integrator is: Where ω is the angular frequency of the fundamental signal, and k is the gain coefficient.

3. The auxiliary converter condition diagnosis method according to claim 1, characterized in that, The capacitance C in the filter circuit of the auxiliary converter under test is calculated according to the following formula based on the fundamental frequency of the inductor current and the derivative of the output voltage: Among them, i f This is the fundamental frequency of the capacitor current. Let be the fundamental waveguide of the output voltage.

4. The auxiliary converter condition diagnosis method according to claim 1, characterized in that, The process of detecting the inductor current in the filter circuit of the auxiliary converter under test also includes filtering the detected current through a pass filter.

5. The auxiliary converter condition diagnosis method according to any one of claims 1 to 4, characterized in that, The step of determining the fault status of the filter circuit capacitor based on the calculated capacitance value includes: comparing the calculated capacitance value with the nominal capacitance value; if the deviation exceeds a preset threshold, it is determined that the capacitor in the auxiliary converter filter circuit is damaged.

6. A method for auxiliary converter condition diagnosis, characterized in that the steps include... include: After starting the auxiliary converter under test and closing the output contactor of the auxiliary converter under test, obtain the current data detected by the sensor on the input side of the filter inductor in the filter circuit of the auxiliary converter under test to obtain the inductor current, and obtain the output voltage detected by the output voltage sensor in the auxiliary converter under test. The fundamental frequency of the obtained inductor current is extracted using a second-order generalized integrator. The fundamental wave of the obtained output voltage is extracted using a second-order generalized integrator, and its derivative is calculated to obtain the fundamental wave derivative of the output voltage. The fundamental wave of the capacitor current is calculated based on the fundamental derivative of the output voltage and the nominal capacitance value, and the fundamental wave of the output current of the auxiliary converter under test is calculated based on the fundamental wave of the inductor current and the fundamental wave of the capacitor current. The current state of the auxiliary converter is determined based on the calculated fundamental frequencies.

7. The auxiliary converter condition diagnosis method according to claim 6, characterized in that, The state of the auxiliary converter is solved using the fourth-order Runge-Kutta method based on the obtained fundamental wave information.

8. The auxiliary converter condition diagnosis method according to claim 6, characterized in that, The transfer function of the second-order generalized integrator is: The fundamental frequency of the output current is expressed as: i o =i f -i c Where ω is the angular frequency of the fundamental signal, k is the gain coefficient, and i o For the output current, i f i is the fundamental frequency of the inductor current. c denoted as the fundamental frequency of the capacitor current, C is the capacitance of the filter capacitor, and u is the output voltage.

9. The auxiliary converter condition diagnosis method according to claim 6, 7, or 8, characterized in that, The process of determining the current state of the auxiliary converter based on the calculated fundamental frequencies also includes a fault diagnosis step, comprising: Compare the difference between the calculated two-phase output currents in the auxiliary converter under test, and compare the measured values ​​of the two-phase output current sensors in the auxiliary converter under test. If the difference between the measured values ​​of the two-phase output current sensors is greater than the first preset threshold, and the difference between the calculated values ​​of the two-phase output current is less than the second preset threshold, then the output current sensor is determined to be faulty. If the difference between the measured values ​​of the two phase output current sensors is less than the second preset threshold, and the difference between the calculated values ​​of the two phase output currents is greater than the first preset threshold, then the output current sensor is determined to be normal, and other sensors are faulty. The final fault location is determined by comparing the measured values ​​of each sensor with the corresponding calculated values.

10. A method for diagnosing the condition of an auxiliary converter, characterized in that the steps include... include: When the output contactor of the auxiliary converter under test is not closed, the state of the filter circuit of the auxiliary converter under test is diagnosed according to the diagnostic method described in any one of claims 1 to 5, and a first diagnostic result is obtained. After the output contactor of the auxiliary converter under test is closed, the state of the filter circuit of the auxiliary converter under test is diagnosed according to the diagnostic method described in any one of claims 6 to 9, and a second diagnostic result is obtained. The final diagnosis is obtained based on the first and second diagnostic results.

11. An auxiliary converter condition diagnostic device, characterized in that, include: The data acquisition module is used to acquire the current data detected by the sensor on the input side of the filter inductor in the filter circuit of the auxiliary converter under test to obtain the inductor current, and to acquire the output voltage detected by the output voltage sensor in the auxiliary converter under test when the auxiliary converter under test is started and the output contactor of the auxiliary converter under test is not closed. The current processing module is used to extract the fundamental frequency of the acquired inductor current using a second-order generalized integrator to obtain the fundamental frequency of the inductor current. The voltage processing module is used to extract the fundamental wave of the acquired output voltage using a second-order generalized integrator and calculate the derivative to obtain the fundamental wave derivative of the output voltage. The capacitance calculation module is used to calculate the capacitance value in the filter circuit of the auxiliary converter under test based on the fundamental wave of the inductor current and the fundamental derivative of the output voltage. The fault diagnosis module is used to determine the fault status of the capacitor in the filter circuit based on the calculated capacitance value.

12. An auxiliary converter condition diagnosis device, characterized in that, include: The data acquisition module is used to acquire the current data detected by the sensor on the input side of the filter inductor in the filter circuit of the auxiliary converter under test after the auxiliary converter under test is started and the output contactor of the auxiliary converter under test is closed, to obtain the inductor current, and to acquire the output voltage detected by the output voltage sensor in the auxiliary converter under test. The current processing module is used to extract the fundamental frequency of the acquired inductor current using a second-order generalized integrator to obtain the fundamental frequency of the inductor current. The voltage processing module is used to extract the fundamental wave of the acquired output voltage using a second-order generalized integrator and calculate the derivative to obtain the fundamental wave derivative of the output voltage. The calculation module is used to calculate the fundamental wave of the capacitor current based on the fundamental derivative of the output voltage and the nominal capacitance value, and to calculate the fundamental wave of the output current of the auxiliary converter under test based on the fundamental wave of the inductor current and the fundamental wave of the capacitor current. The state solution module is used to solve the current state of the auxiliary converter based on the calculated fundamental frequencies.

13. An auxiliary converter condition diagnosis system, characterized in that, include: The first diagnostic device is used to diagnose the state of the filter circuit of the auxiliary converter under test according to the diagnostic method described in any one of claims 1 to 5 when the output contactor of the auxiliary converter under test is not closed, and to output a first diagnostic result. The second diagnostic device is used to diagnose the state of the filter circuit of the auxiliary converter under test according to the diagnostic method described in any one of claims 6 to 9 after the output contactor of the auxiliary converter under test is closed, and to obtain a second diagnostic result. A diagnostic output device is used to output a final diagnostic result based on the first diagnostic result and the second diagnostic result.

14. An electronic device comprising a processor and a memory, the memory being used to store a computer program, characterized in that, The processor is used to execute the computer program to perform the method as described in any one of claims 1 to 10.

15. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the method as described in any one of claims 1 to 10.

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