CN110058111B

CN110058111B - Fault diagnosis method for T-type three-level inverter based on phase voltage residual errors

Info

Publication number: CN110058111B
Application number: CN201910321522.4A
Authority: CN
Inventors: 陈丹江
Original assignee: Zhejiang Wanli University
Current assignee: Hefei Jiuzhou Longteng Scientific And Technological Achievement Transformation Co ltd
Priority date: 2019-04-22
Filing date: 2019-04-22
Publication date: 2021-01-15
Anticipated expiration: 2039-04-22
Also published as: CN110058111A

Abstract

The invention discloses a T-type three-level inverter fault diagnosis method based on phase voltage residual errors, which comprises the steps of firstly obtaining three-phase voltage of a T-type three-level inverter to be subjected to fault diagnosis, and filtering, amplifying or reducing the three-phase voltage; calculating the residual voltage of each phase of reference voltage and each phase of processed voltage; judging whether each phase circuit has a fault according to the sampling voltage value in each phase residual voltage; under the premise of fault, calculating the average value and the positive and negative peak difference values of residual voltage in a time period from the sampling moment of the sampling voltage value with abnormal change; judging which device has an open-circuit fault according to the average value and the positive and negative peak difference values; the method has the advantages that only three phase voltages need to be obtained, original information of fault diagnosis is less, the fault diagnosis cost is low, the fault diagnosis accuracy rate is high, and the fault diagnosis result can be automatically and accurately positioned to a specific device, so that the working reliability of the T-type three-level inverter can be effectively improved.

Description

Fault diagnosis method for T-type three-level inverter based on phase voltage residual errors

Technical Field

The invention relates to an inverter fault detection technology, in particular to a T-type three-level inverter fault diagnosis method based on phase voltage residual errors.

Background

Multilevel inverters have been increasingly used in a wide range of power applications. Compared with the traditional two-level inverter, the multi-level inverter can obtain more levels, has less harmonic waves and can reduce the requirement of the device on voltage stress. In recent years, a topological structure called a T-type neutral-point-clamped (T-type-clamped) three-level inverter (hereinafter, referred to as a T-type three-level inverter or TNPC) has been proposed, and is mainly applied to high-efficiency occasions such as solar energy and electric vehicle inverters. During the operation of the circuit, various faults of the circuit can occur due to overload, temperature rise, irregular operation and the like, wherein the fault of the semiconductor switching device is the most common one. Since the semiconductor switching devices in the multilevel inverter increase with the increase of the output voltage level, and if only one of the semiconductor switching devices fails, the whole multilevel inverter fails and even causes serious consequences, so that the fault diagnosis research on the multilevel inverter is very necessary.

At present, many researches on the fault diagnosis problem of the T-type three-level inverter are carried out at home and abroad. For example: a Diagnosis and fault-tolerance strategy for open-circuit fault of T-type three-level inverter system (2014,50(1):495-508) is provided, which collects three phase currents, calculates the polarity of the average value of the three phase currents respectively, then judges the polarity of the midpoint voltage of the input direct current, and can determine which switching device in the circuit has the open-circuit fault according to different combinations of the phase currents and the polarity of the midpoint voltage. The method does not need a complex algorithm and has the advantage of high reliability. However, the method needs to detect both the current and the voltage of the circuit, and has many types of fault characteristics that need to be selected in the fault diagnosis process, so that the diagnosis cost is high in the actual implementation, and the hardware circuit of the diagnosis system is complex.

For another example: an article Fault detection and diagnosis of Fault detection and diagnosis in a PV grid-connected T-type three-level inverter (2015:933 937) published by 2015International Conference on Renewable Energy Research and Applications (2015 International Conference), namely, fernao Pires, d.foito, Tito g.amoral et al, proposes a method for diagnosing open-circuit faults of a switching device based on a histogram (histogram), which first detects phase voltages of three outputs, then represents each level of the phase voltages by a certain algorithm using the histogram, calculates the center of gravity of the histogram by an algorithm for calculating the center of gravity, and determines which switching device has a Fault according to the difference of the calculated center of gravity values. The method only needs to detect three current signals without being influenced by loads, and the rest is completed through software calculation, but the proposed software algorithm is relatively complex, and a hardware circuit including a singlechip minimum system and the like is required to be added in a software system.

The following steps are repeated: a Fast On-Line Diagnostic Method for Open-Circuit Faults of a T-Type multi-level inverter Based On SiC-MOSFET (2017,53(3): 2948) -2958) published by Jiangbiao He, Nabel A.O. Demerdash, Nathan Weise, Ramin Katebi et al in IEEE Transactions On Industrial Applications introduces an online non-invasive Diagnostic Method for detecting Open-Circuit Faults in a T-Type multi-level inverter, which firstly detects abnormal changes of a direct current bus neutral point current, then detects three-phase current signals, and combines information such as the detection instant Circuit Switch state to judge which Switch device in the current Circuit has the Open-Circuit fault. The method has high reliability, but the method needs to detect direct current neutral point current and three-phase current and acquire the switch state in the circuit, and the original information of fault diagnosis is more in demand.

Disclosure of Invention

The invention aims to solve the technical problem of providing a fault diagnosis method of a T-type three-level inverter based on phase voltage residual errors, which only needs to acquire three phase voltages, has less requirements on original information of fault diagnosis, low fault diagnosis cost and high fault diagnosis accuracy, and can automatically and accurately position a fault diagnosis result to a specific device, thereby effectively improving the working reliability of the T-type three-level inverter.

The technical scheme adopted by the invention for solving the technical problems is as follows: a T-type three-level inverter fault diagnosis method based on phase voltage residual errors is characterized by comprising the following steps:

the method comprises the following steps: building a T-type three-level inverter, wherein the T-type three-level inverter can work normally or is a T-type three-level inverter added with an open-circuit fault; the added open-circuit fault is one of 12 open-circuit faults, and the 1 st to 12 th open-circuit faults correspond to the first insulated gate bipolar transistor S of the a-phase_a1A second insulated gate bipolar transistor S of phase a_a2A third insulated gate bipolar transistor S of a phase_a3And a phase fourth insulated gate bipolar transistor S_a4B phase first insulated gate bipolar transistor S_b1B phase second insulated gate bipolar transistor S_b2B phase third insulated gate bipolar transistor S_b3B phase fourth insulated gate bipolar transistor S_b4C-phase first insulated gate bipolar transistor S_c1C-phase second insulated gate bipolar transistor S_c2C-phase third insulated gate bipolar transistor S_c3C-phase fourth insulated gate bipolar transistor S_c4An open circuit fault occurs;

step two: obtaining a-phase voltage, b-phase voltage and c-phase voltage of the T-type three-level inverter, and correspondingly marking the voltage as U_an、U_bnAnd U_cn(ii) a Then to U_anThe voltage after the high-frequency noise removal was recorded as "U'_an(ii) a Likewise, for U_bnThe voltage after the high-frequency noise removal was recorded as "U'_bn(ii) a To U_cnThe voltage after the high-frequency noise removal was recorded as "U'_cn(ii) a Then using a phase reference voltage U_refaFor reference, to U'_anPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_an(ii) a Similarly, reference voltage U is referred to as phase b_refbFor reference, to U'_bnTo make an enlargement or a reductionSmall processing, marking the voltage after the enlargement or reduction as U "_bn(ii) a With reference voltage U of phase c_refcFor reference, to U'_cnPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_cn(ii) a Wherein, U_an、U_bn、U_cn、U'_an、U'_bn、U'_cn、U”_an、U”_bn、U”_cn、U_refa、U_refb、U_refcAll units of (a) are volts;

step three: calculating a-phase residual voltage of the T-type three-level inverter and recording the a-phase residual voltage as U_cca，U_cca＝U_refa-U”_an(ii) a Then judges U_ccaIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that the a-phase circuit of the T-type three-level inverter fails, and then executing the step four; if not, judging that the a-phase circuit of the T-type three-level inverter has no fault, and then executing the step five; wherein, U_ccaThe unit of the sampling point is volt, and the sampling period is set to be T' and the number of the sampling points is Num in the process of acquiring the sampling voltage value;

step four: will U_ccaTaking the sampling time of the 1 st sampling voltage value which is greater than +2 volts or less than-2 volts as the starting time; then from U_ccaVoltage of one time period starting from the initial extraction time is recorded as U'_cca(ii) a Then calculate U'_ccaAverage value of and U'_ccaThe difference between positive and negative peaks of (1) is correspondingly marked as U_a,aveAnd U_a,PN，

U_a,PN＝||U_a,pos|-|U_a,negL; then according to U_a,aveAnd U_a,PNDetermining whether an open-circuit fault occurs in an a-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the A-phase circuit_a,ave> 0 and U_a,PN＞V_thThen, the first IGBT S of the a phase in the T-type three-level inverter is determined_a1An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave> 0 and U_a,PN＜V_thJudging the second insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a2An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＞V_thJudging the third insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a3An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the a phase in the T-type three-level inverter_a4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_cca、U_a,ave、U_a,PN、U_a,_po_s、U_a,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_a,posRepresents U'_ccaPositive peak value of, U_a,negRepresents U'_ccaNegative peak value of, V_thFor a set voltage threshold, V_thIn volts;

step five: calculating b-phase residual voltage of the T-type three-level inverter and recording as U_ccb，U_ccb＝U_refb-U”_bn(ii) a Then judges U_ccbIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that a b-phase circuit of the T-type three-level inverter fails, and executing a sixth step; if not, judging that the b-phase circuit of the T-type three-level inverter has no fault, and then executing the seventh step; wherein, U_ccbThe unit of the sampling point is volt, and the sampling period is set to be T' and the number of the sampling points is Num in the process of acquiring the sampling voltage value;

step six: will U_ccbTaking the sampling time of the 1 st sampling voltage value which is greater than +2 volts or less than-2 volts as the starting time; then from U_ccbVoltage of one time period starting from the initial extraction time is recorded as U'_ccb(ii) a Then calculate U'_ccbAverage value of and U'_ccbThe difference between positive and negative peaks of (1) is correspondingly marked as U_b,aveAnd U_b,PN，

U_b,PN＝||U_b,pos|-|U_b,negL; then according to U_b,aveAnd U_b,PNDetermining whether an open-circuit fault occurs in a b-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the B-phase circuit_b,ave> 0 and U_b,PN＞V_thThen, the first IGBT S of the b phase in the T-type three-level inverter is determined_b1An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave> 0 and U_b,PN＜V_thJudging the second insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b2An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave< 0 and U_b,PN＞V_thJudging the third insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b3An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave< 0 and U_b,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_ccb、U_b,ave、U_b,PN、U_b,pos、U_b,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_b,posRepresents U'_ccbPositive peak value of, U_b,negRepresents U'_ccbNegative peak value of, V_thFor a set voltage threshold, V_thIn volts;

step seven: calculating c-phase residual voltage of the T-type three-level inverter and recording the c-phase residual voltage as U_ccc，U_ccc＝U_refc-U”_cn(ii) a Then judges U_cccIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that the c-phase circuit of the T-type three-level inverter fails, and then executing the step eight; if not, judging that the c-phase circuit of the T-type three-level inverter has no fault, and then executing the step nine; wherein, U_cccIn volts, to obtain the sampled powerSetting a sampling period as T' and the number of sampling points as Num in the process of pressure value;

step eight: will U_cccTaking the sampling time of the 1 st sampling voltage value which is greater than +2 volts or less than-2 volts as the starting time; then from U_cccVoltage of one time period starting from the initial extraction time is recorded as U'_ccc(ii) a Then calculate U'_cccAverage value of and U'_cccThe difference between positive and negative peaks of (1) is correspondingly marked as U_c,aveAnd U_c,PN，

U_c,PN＝||U_c,pos|-|U_c,negL; then according to U_c,aveAnd U_c,PNDetermining whether an open-circuit fault occurs in a c-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the C-phase circuit_c,ave> 0 and U_c,PN＞V_thThen, the first IGBT S of the c phase in the T-type three-level inverter is determined_c1An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave> 0 and U_c,PN＜V_thJudging the second insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c2An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＞V_thJudging the third insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c3An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_ccc、U_c,ave、U_c,PN、U_c,pos、U_c,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_c,posRepresents U'_cccPositive peak value of, U_c,negRepresents U'_cccNegative peak value of, V_thFor a set voltage threshold, V_thIn volts;

step nine: and continuing to carry out fault diagnosis on the T-type three-level inverter.

In the second step, the filtering method is a low-pass filtering method.

In the second step, the process of determining the scale of the enlarging or reducing process is as follows: under the condition that the T-type three-level inverter normally works, a-phase voltage, b-phase voltage and c-phase voltage under the normal work are obtained and are correspondingly marked as U_normal-an、U_normal-bnAnd U_normal-cn(ii) a Then put U_normal-anPeak value and U of_refaIs U 'as the ratio of the peak value of'_anScale up or down the process, will U_normal-bnPeak value and U of_refbIs U 'as the ratio of the peak value of'_bnScale up or down the process, will U_normal-cnPeak value and U of_refcIs U 'as the ratio of the peak value of'_cnScale up or down of the process; wherein, U_normal-an、U_normal-bnAnd U_normal-cnAll units of (a) are volts.

Compared with the prior art, the invention has the advantages that:

1) the method only needs to sample the three-phase voltage of the T-type three-level inverter, namely the a-phase voltage, the b-phase voltage and the c-phase voltage, then compares the reference voltage of each phase with the voltage obtained after the filtering processing and the amplification or reduction processing of the voltage of each phase to obtain the residual voltage, analyzes the residual voltage, and judges which specific device in the T-type three-level inverter has the open-circuit fault according to the analysis result.

2) The method only needs to add three voltage sensors when being realized, saves a large number of voltage and current sensors required by the traditional fault diagnosis method, and reduces the fault diagnosis cost.

3) The method is simple and easy to implement, and the fault diagnosis result can be obtained only by analyzing the residual voltage and calculating the average value and the positive and negative peak difference values of the residual voltage with variation in a time period.

Drawings

FIG. 1 is a main circuit of a T-type three-level inverter;

FIG. 2 is a block diagram of an overall implementation of the method of the present invention;

FIG. 3 is a signal diagram of the control system output of the T-type three-level inverter;

FIG. 4a shows a-phase reference voltage U of a T-type three-level inverter under normal operation_refaA waveform diagram of (a);

FIG. 4b shows the a-phase voltage U obtained from the T-type three-level inverter under normal operation_anVoltage U after filtering and enlarging or reducing "_anA waveform diagram of (a);

FIG. 4c shows the a-phase residual voltage U of the T-type three-level inverter under normal operation_ccaA waveform diagram of (a);

FIG. 5a shows the a-phase residual voltage U of a T-type three-level inverter with the 1 st open-circuit fault added_ccaA waveform diagram of (a);

FIG. 5b shows the a-phase residual voltage U of the T-type three-level inverter with the 2 nd open-circuit fault added_ccaA waveform diagram of (a);

FIG. 5c shows the a-phase residual voltage U of the T-type three-level inverter with the addition of the 3 rd open-circuit fault_ccaA waveform diagram of (a);

FIG. 5d shows the a-phase residual voltage U of the T-type three-level inverter with the 4 th open-circuit fault added_ccaA waveform diagram of (a).

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

Fig. 1 shows a main circuit of a T-type three-level inverter, which comprises a first power switch S of phase a_a1A second power switch device S of a phase_a2A third power switch device S of a phase_a3A phase fourth power switch device S_a4B phase first power switch device S_b1B phase second power switch device S_b2B phase third power switch device S_b3B phase fourth power switch device S_b4C-phase first power switch device S_c1C phase second power switch device S_c2C-phase third power switch device S_c3C-phase fourth power switch device S_c4The phase voltage of a is U_an(voltage between point a and point n in FIG. 1), and the phase b voltage is U_bn(voltage between point b and point n in FIG. 1), and the phase voltage of c is U_cn(voltage between point c and point n in FIG. 1); the 12 power switch devices are all insulated gate bipolar transistors. If S in the main circuit shown in FIG. 1_a1、S_a2、S_a3、S_a4、S_b1、S_b2、S_b3、S_b4、S_c1、S_c2、S_c3、S_c4If any one of the power switching devices has an open-circuit fault, the fault is one fault type, and there are 12 fault types, and no matter which fault type occurs, the main circuit cannot normally work.

The invention provides a fault diagnosis method for a T-type three-level inverter based on phase voltage residual errors, which is generally realized as shown in a block diagram in figure 2 and comprises the following steps:

the method comprises the following steps: a T-shaped three-level inverter is built by adopting the existing components, as shown in figure 1, the T-shaped three-level inverter can work normally or is a T-shaped three-level inverter added with an open-circuit fault; the added open-circuit fault is one of 12 open-circuit faults, and the 1 st to 12 th open-circuit faults correspond to the first insulated gate bipolar transistor S of the a-phase_a1A second insulated gate bipolar transistor S of phase a_a2A third insulated gate bipolar transistor S of a phase_a3And a phase fourth insulated gate bipolar transistor S_a4B phase first insulated gate bipolar transistor S_b1B phase second insulated gate bipolar transistor S_b2B phase third insulated gate bipolar transistor S_b3Fourth insulation of phase bGate bipolar transistor S_b4C-phase first insulated gate bipolar transistor S_c1C-phase second insulated gate bipolar transistor S_c2C-phase third insulated gate bipolar transistor S_c3C-phase fourth insulated gate bipolar transistor S_c4An open circuit fault occurs.

Step two: obtaining a-phase voltage, b-phase voltage and c-phase voltage of the T-type three-level inverter, and correspondingly marking the voltage as U_an、U_bnAnd U_cn(ii) a Then to U_anThe voltage after the high-frequency noise removal was recorded as "U'_an(ii) a Likewise, for U_bnThe voltage after the high-frequency noise removal was recorded as "U'_bn(ii) a To U_cnThe voltage after the high-frequency noise removal was recorded as "U'_cn(ii) a Then using a phase reference voltage U_refaFor reference, to U'_anPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_an(ii) a Similarly, reference voltage U is referred to as phase b_refbFor reference, to U'_bnPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_bn(ii) a With reference voltage U of phase c_refcFor reference, to U'_cnPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_cn(ii) a Wherein, U_an、U_bn、U_cn、U'_an、U'_bn、U'_cn、U”_an、U”_bn、U”_cn、U_refa、U_refb、U_refcAll units of (a) are volts.

Here, U_refa、U_refb、U_refcGiven by the DSP control system. FIG. 3 shows a control system of a T-type three-level inverter, wherein the T-type three-level inverter is controlled by a DSP control system, the DSP control system provides various control signals for normal operation of the T-type three-level inverter, and U_refa、U_refb、U_refcDirectly output by a DSP control system, U_an、U_bnAnd U_cnDivided by three voltage sensorsRespectively obtained from the three-phase load of the T-shaped three-level inverter.

In this embodiment, in the second step, the filtering method is a low-pass filtering method; the scale of the enlargement or reduction process is determined by: under the condition that the T-type three-level inverter normally works, a-phase voltage, b-phase voltage and c-phase voltage under the normal work are obtained and are correspondingly marked as U_normal-an、U_normal-bnAnd U_normal-cn(ii) a Then put U_normal-anPeak value and U of_refaIs U 'as the ratio of the peak value of'_anScale up or down the process, will U_normal-bnPeak value and U of_refbIs U 'as the ratio of the peak value of'_bnScale up or down the process, will U_normal-cnPeak value and U of_refcIs U 'as the ratio of the peak value of'_cnScale up or down of the process; wherein, U_normal-an、U_normal-bnAnd U_normal-cnAll units of (a) are volts.

Step three: calculating a-phase residual voltage of the T-type three-level inverter and recording the a-phase residual voltage as U_cca，U_cca＝U_refa-U”_an(ii) a Then judges U_ccaIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that the a-phase circuit of the T-type three-level inverter fails, and then executing the step four; if not, judging that the a-phase circuit of the T-type three-level inverter has no fault, and then executing the step five; wherein, U_ccaThe unit of (a) is volt, the sampling period is set to T 'and the number of sampling points is Num in the process of acquiring the sampling voltage value, and in this embodiment, T' is 20 milliseconds, and Num is 1000.

FIG. 4a shows a-phase reference voltage U of a T-type three-level inverter under normal operation_refaFig. 4b shows the a-phase voltage U obtained from the T-type three-level inverter under normal operation_anVoltage U after filtering and enlarging or reducing "_anFig. 4c shows the a-phase residual voltage U of the T-type three-level inverter under normal operation_ccaA waveform diagram of (a). As can be seen from fig. 4c, when the T-type three-level inverter is normalIn operation, a phase residual voltage U_ccaAlmost equal to 0, there is no sampled voltage value greater than +2 volts or less than-2 volts, and therefore it is determined that the a-phase circuit of the T-type three-level inverter has not failed.

Fig. 5a shows the a-phase residual voltage U of a T-type three-level inverter to which the 1 st open-circuit fault has been added_ccaFig. 5b shows the a-phase residual voltage U of a T-type three-level inverter to which the 2 nd open-circuit fault has been added_ccaFig. 5c shows the a-phase residual voltage U of a T-type three-level inverter to which the 3 rd open-circuit fault has been added_ccaFig. 5d shows the a-phase residual voltage U of a T-type three-level inverter to which the 4 th open-circuit fault has been added_ccaA waveform diagram of (a). As can be seen from fig. 5a to 5d, there are sample voltage values greater than +2 volts or less than-2 volts, and thus it is determined that the a-phase circuit of the T-type three-level inverter has failed.

U_a,PN＝||U_a,pos|-|U_a,negL; then according to U_a,aveAnd U_a,PNDetermining whether an open-circuit fault occurs in an a-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the A-phase circuit_a,ave> 0 and U_a,PN＞V_thThen, the first IGBT S of the a phase in the T-type three-level inverter is determined_a1An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave> 0 and U_a,PN＜V_thJudging the second insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a2An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＞V_thJudging the third insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a3An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the a phase in the T-type three-level inverter_a4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_cca、U_a,ave、U_a,PN、U_a,pos、U_a,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_a,posRepresents U'_ccaPositive peak value of, U_a,negRepresents U'_ccaNegative peak value of, V_thFor a set voltage threshold, V_thIn volts, in this example, V_th2.5 volts.

Step five: calculating b-phase residual voltage of the T-type three-level inverter and recording as U_ccb，U_ccb＝U_refb-U”_bn(ii) a Then judges U_ccbIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that a b-phase circuit of the T-type three-level inverter fails, and executing a sixth step; if not, judging that the b-phase circuit of the T-type three-level inverter has no fault, and then executing the seventh step; wherein, U_ccbThe unit of (a) is volt, the sampling period is set to T 'and the number of sampling points is Num in the process of acquiring the sampling voltage value, and in this embodiment, T' is 20 milliseconds, and Num is 1000.

U_b,PN＝||U_b,pos|-|U_b,negL; then according to U_b,aveAnd U_b,PNDetermining whether an open-circuit fault occurs in a b-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the B-phase circuit_b,ave> 0 and U_b,PN＞V_thThen, the first IGBT S of the b phase in the T-type three-level inverter is determined_b1An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave> 0 and U_b,PN＜V_thJudging the second insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b2An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave< 0 and U_b,PN＞V_thJudging the third insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b3An open-circuit fault occurs, and fault diagnosis is finished; if U is_b,ave< 0 and U_b,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the b phase in the T-type three-level inverter_b4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_ccb、U_b,ave、U_b,PN、U_b,pos、U_b,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_b,posRepresents U'_ccbPositive peak value of, U_b,negRepresents U'_ccbNegative peak value of, V_thFor a set voltage threshold, V_thIn volts, in this example, V_th2.5 volts.

Step seven: calculating c-phase residual voltage of the T-type three-level inverter and recording the c-phase residual voltage as U_ccc，U_ccc＝U_refc-U”_cn(ii) a Then judges U_cccIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that the c-phase circuit of the T-type three-level inverter fails, and then executing the step eight; if not, judging that the c-phase circuit of the T-type three-level inverter has no fault, and then executing the step nine; wherein, U_cccThe unit of (a) is volt, the sampling period is set to be T 'and the number of sampling points is Num in the process of acquiring the sampling voltage value, and T' is taken in the embodiment20 ms, get Num 1000.

U_c,PN＝||U_c,pos|-|U_c,negL; then according to U_c,aveAnd U_c,PNDetermining whether an open-circuit fault occurs in a c-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the C-phase circuit_c,ave> 0 and U_c,PN＞V_thThen, the first IGBT S of the c phase in the T-type three-level inverter is determined_c1An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave> 0 and U_c,PN＜V_thJudging the second insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c2An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＞V_thJudging the third insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c3An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_ccc、U_c,ave、U_c,PN、U_c,pos、U_c,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_c,posRepresents U'_cccPositive peak value of, U_c,negRepresents U'_cccNegative peak value of, V_thFor a set voltage threshold, V_thIn volts, in this example, V_th2.5 volts.

Claims

1. A T-type three-level inverter fault diagnosis method based on phase voltage residual errors is characterized by comprising the following steps:

the method comprises the following steps: building a T-type three-level inverter, wherein the T-type three-level inverter can work normally or is a T-type three-level inverter added with an open-circuit fault; the added open-circuit fault is one of 12 open-circuit faults, and the 1 st to 12 th open-circuit faults correspond to the first insulated gate bipolar transistor S of the a-phase_a1A second insulated gate bipolar transistor S of phase a_a2A third insulated gate bipolar transistor S of a phase_a3And a phase fourth insulated gate bipolar transistor S_a4B phase first insulated gate bipolar transistor S_b1B phase second insulated gate bipolar transistor S_b2B phase third insulated gate bipolar transistor S_b3B phase fourth insulated gate bipolar transistor S_b4C-phase first insulated gate bipolar transistor S_c1C-phase second insulated gate bipolar transistor S_c2C-phase third insulated gate bipolar transistor S_c3C-phase fourth insulated gate bipolar transistor S_c4An open circuit failure of any one of the transistors;

step two: obtaining a-phase voltage, b-phase voltage and c-phase voltage of the T-type three-level inverter, and correspondingly marking the voltage as U_an、U_bnAnd U_cn(ii) a Then to U_anThe voltage after the high-frequency noise removal was recorded as "U'_an(ii) a Likewise, for U_bnThe voltage after the high-frequency noise removal was recorded as "U'_bn(ii) a To U_cnThe voltage after the high-frequency noise removal was recorded as "U'_cn(ii) a Then using a phase reference voltage U_refaFor reference, to U'_anPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_an(ii) a Similarly, reference voltage U is referred to as phase b_refbFor reference, to U'_bnPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_bn(ii) a With reference voltage U of phase c_refcFor reference, to U'_cnPerforming amplification or reduction treatment, and recording the amplified or reduced voltage as U "_cn(ii) a Wherein, U_an、U_bn、U_cn、U'_an、U'_bn、U'_cn、U”_an、U”_bn、U”_cn、U_refa、U_refb、U_refcAll units of (a) are volts;

U_a,PN＝||U_a,pos|-|U_a,negL; then according to U_a,aveAnd U_a,PNDetermining whether an open-circuit fault occurs in an a-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the A-phase circuit_a,ave> 0 and U_a,PN＞V_thThen, the first phase of a phase in the T-type three-level inverter is determinedInsulated gate bipolar transistor S_a1An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave> 0 and U_a,PN＜V_thJudging the second insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a2An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＞V_thJudging the third insulated gate bipolar transistor S of the phase a in the T-type three-level inverter_a3An open-circuit fault occurs, and fault diagnosis is finished; if U is_a,ave< 0 and U_a,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the a phase in the T-type three-level inverter_a4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_cca、U_a,ave、U_a,PN、U_a,pos、U_a,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_a,posRepresents U'_ccaPositive peak value of, U_a,negRepresents U'_ccaNegative peak value of, V_thFor a set voltage threshold, V_thIn volts;

step six: will U_ccbTaking the sampling time of the 1 st sampling voltage value which is greater than +2 volts or less than-2 volts as the starting time; then from U_ccbVoltage of one time period starting from the initial extraction time is recorded as U'_ccb(ii) a Then calculate U'_ccbAverage value of and U'_ccbPositive and negative peak difference of (2), pairShould be noted as U_b,aveAnd U_b,PN，

step seven: calculating c-phase residual voltage of the T-type three-level inverter and recording the c-phase residual voltage as U_ccc，U_ccc＝U_refc-U”_cn(ii) a Then judges U_cccIf the sampling voltage value is larger than +2 volts or smaller than-2 volts, judging that the c-phase circuit of the T-type three-level inverter fails, and then executing the step eight; if not, the c-phase circuit of the T-type three-level inverter is judged not to be availableIf the fault occurs, executing the step nine; wherein, U_cccThe unit of the sampling point is volt, and the sampling period is set to be T' and the number of the sampling points is Num in the process of acquiring the sampling voltage value;

U_c,PN＝||U_c,pos|-|U_c,negL; then according to U_c,aveAnd U_c,PNDetermining whether an open-circuit fault occurs in a c-phase circuit of the T-type three-level inverter if the open-circuit fault occurs in the C-phase circuit_c,ave> 0 and U_c,PN＞V_thThen, the first IGBT S of the c phase in the T-type three-level inverter is determined_c1An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave> 0 and U_c,PN＜V_thJudging the second insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c2An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＞V_thJudging the third insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c3An open-circuit fault occurs, and fault diagnosis is finished; if U is_c,ave< 0 and U_c,PN＜V_thJudging the fourth insulated gate bipolar transistor S of the c phase in the T-type three-level inverter_c4An open-circuit fault occurs, and fault diagnosis is finished; wherein T ' represents a time period, and is the same as T ', U '_ccc、U_c,ave、U_c,PN、U_c,pos、U_c,negThe unit of (a) is volt, t is a time integral variable, the symbol "|" is an absolute value symbol, U_c,posRepresents U'_cccPositive peak value of, U_c,negRepresents U'_cccIs negativePeak value, V_thFor a set voltage threshold, V_thIn volts;

2. The method for diagnosing the fault of the T-type three-level inverter based on the phase voltage residual errors according to claim 1, wherein in the second step, the filtering method is a low-pass filtering method.

3. The method for diagnosing the fault of the T-type three-level inverter based on the phase voltage residuals according to claim 1 or 2, wherein in the step two, the scaling up or scaling down process is determined by: under the condition that the T-type three-level inverter normally works, a-phase voltage, b-phase voltage and c-phase voltage under the normal work are obtained and are correspondingly marked as U_normal-an、U_normal-bnAnd U_normal-cn(ii) a Then put U_normal-anPeak value and U of_refaIs U 'as the ratio of the peak value of'_anScale up or down the process, will U_normal-bnPeak value and U of_refbIs U 'as the ratio of the peak value of'_bnScale up or down the process, will U_normal-cnPeak value and U of_refcIs U 'as the ratio of the peak value of'_cnScale up or down of the process; wherein, U_normal-an、U_normal-bnAnd U_normal-cnAll units of (a) are volts.