CN116243207A - SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation - Google Patents

SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation Download PDF

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CN116243207A
CN116243207A CN202310026254.XA CN202310026254A CN116243207A CN 116243207 A CN116243207 A CN 116243207A CN 202310026254 A CN202310026254 A CN 202310026254A CN 116243207 A CN116243207 A CN 116243207A
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current
phase
short
value
jumping
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蔡骏
王雨铮
严颖
余彬
连静
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Nanjing University of Information Science and Technology
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Nanjing University of Information Science and Technology
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
    • H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/26—Testing of individual semiconductor devices
    • G01R31/2607—Circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
    • H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
    • H02H7/0854—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load responsive to rate of change of current, couple or speed, e.g. anti-kickback protection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/08—Reluctance motors

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electric Motors In General (AREA)

Abstract

The invention discloses a dynamic diagnosis method for short-circuit faults of an SRM switching tube by adopting current translation. The method for diagnosing the short-circuit fault of the switching tube adopts a mode of translating an actual current waveform by one electric period, takes the current waveform of the last electric period as a reference current waveform corresponding to the current electric period, further compares the reference current with the current of the current electric period to obtain a corresponding current difference value, and accurately judges the short-circuit fault of the switching tube of the asymmetric half-bridge power converter by combining a symbol of a measured value of a current sensor and a rotor position angle. The SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation can meet fault diagnosis during steady-state and dynamic operation of the motor. The switching tube short-circuit fault diagnosis scheme is suitable for switching reluctance motors with various phase numbers. The method has important application prospect in the application occasions with extremely high requirements on the reliability of motors, such as aero-starter generators, electric automobile motors and the like.

Description

SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation
Technical Field
The invention belongs to the technical field of switch reluctance motor control, and particularly relates to a dynamic diagnosis method for short-circuit faults of an SRM switch tube by adopting current translation.
Background
The power converter is an electronic device which is integrated with the control of the connection sequence of each phase winding and a power supply, the feedback loop for providing winding energy storage and the energy supply for the motor. If the switching tube of the power converter has short-circuit fault during normal operation of the motor, the operation state of the motor is deteriorated, and the normal operation of the motor is seriously affected. The short circuit of the switching tube can cause high current to be generated, and the motor and related equipment are seriously threatened. It is therefore important how to diagnose the short-circuit fault of the switching tube rapidly and accurately.
The conventional short-circuit fault diagnosis method mostly involves using an additional current sensor for fault diagnosis, and using the additional current sensor for detection certainly increases the detection cost and the complexity of operation. Therefore, the design does not need to use an additional current sensor to carry out a fault rapid diagnosis technology, is beneficial to further improving the reliability of the switched reluctance motor system, and has important practical value particularly for application scenes such as precision servo, electric vehicles, aerospace and the like which have very high requirements on the reliability of the switched reluctance motor.
Disclosure of Invention
The invention aims to: the invention aims to provide a dynamic diagnosis method for short-circuit faults of an SRM switching tube by adopting current translation, which is simple to operate, easy to realize and high in reliability, and an extra current sensor is not needed in the diagnosis scheme.
When the system is in steady state operation, the phase current waveform of the last electrical cycle is shifted by one electrical cycle by using a current shifting method, the phase current waveform is used as a reference current waveform to be compared with the current waveform of the current electrical cycle, the difference between the two is calculated in real time, and the amplitude of the difference is used as a fault judgment basis to rapidly diagnose the short-circuit fault of the switching tube in the current electrical cycle. When the system is in dynamic operation, diagnosing whether a chopper short circuit fault occurs or not in a conduction interval by setting a current threshold value; and judging and positioning the short-circuit fault switching tube in the non-conduction interval through the magnitude and the positive and negative of the measured value of the current sensor corresponding to the rotor position angles of 22.5 degrees and 25 degrees. The dynamic diagnosis of the short-circuit fault of the switching tube of the driving system is realized by switching the diagnosis modes under different system running states.
The technical scheme is as follows: the invention relates to a dynamic diagnosis method for short-circuit faults of SRM switching tubes by adopting current translation, which adopts an asymmetric half-bridge power converter of a switched reluctance motor, wherein when the switching-on interval of each phase of the switched reluctance motor is over, an upper switching tube of each phase bridge arm corresponding to the power converter is used as a chopper tube, and a lower switching tube is used as a conducting tube. Combining the current waveform translation of the phases, respectively taking each phase as a target phase, and executing the following steps to realize the rapid diagnosis of the short-circuit fault of the switching tube of the target phase;
step A: according to the position signal obtained by the position sensor, calculating the actual rotation speed of the switch reluctance motor driving system through the position signal, judging which state the switch reluctance motor driving system is in, if the difference delta between the preset reference rotation speed and the actual rotation speed is preset n Less than a preset rotation speed threshold n th B, judging that the switched reluctance motor driving system is in a steady state operation state, and jumping to the step B, otherwise, judging that the switched reluctance motor driving system is in a dynamic operation state and jumping to the step J;
and (B) step (B): c, entering a steady-state diagnosis process, measuring a target phase through a current sensor to obtain a current sensor measurement value, and jumping to the step C;
step C: d, obtaining an actual phase current value of the target phase through absolute value processing of the measured value of the current sensor, and jumping to the step D;
step D: shifting the current signal of the previous electric period by one electric period through calculating the electric period so as to realize the shift of the current signal of the target phase, taking the current waveform shifted by one electric period as the current reference waveform of the target phase corresponding to the current electric period, further obtaining the reference current value corresponding to the current electric period, and jumping to the step E;
step E: calculating the difference delta between the actual current value of the target phase and the reference current value corresponding to the current electric period, if the absolute value of the difference delta is larger than the preset threshold i th1 Step F, jumping to the step F; if the absolute value of the difference delta is smaller than or equal to the preset threshold i th1 Step I is skipped to;
step F: obtaining a current position angle of the target phase through a position sensor, if the current position angle is more than or equal to 0 degrees and less than or equal to 17 degrees, judging that the detection phase is in a conducting area at the moment, and jumping to the step G; if the current position angle is larger than 17 degrees and smaller than 45 degrees, judging that the detection phase is in a non-conduction interval at the moment, and jumping to the step H;
step G: when the target phase is detected to be in the conducting area, the absolute value of the difference delta between the actual phase current value and the reference current value corresponding to the current electrical period is detected to be larger than the preset threshold value i th1 And (3) diagnosing that the phase chopper tube is short-circuited, and jumping to the step (I) after the diagnosis is finished;
step H: when the target phase is detected to be in the non-conductive region, if the absolute value of the difference delta between the current value of the detected actual phase and the reference current value corresponding to the current electrical period is greater than the preset threshold i th1 And current sensor measurement i csa If the sign is positive, diagnosing that the detection phase chopper is short-circuited; if the absolute value of the difference delta between the actual phase current value and the reference current value corresponding to the current electric period is detected to be larger than the preset threshold value i th1 And current sensor measurement i csa If the sign is negative, diagnosing that the phase conducting tube is short-circuited, ending the diagnosis, and jumping to the step I;
step I: entering the next diagnosis period, and jumping to the step A;
step J: entering a dynamic diagnosis flow, and jumping to the step K;
step K: obtaining a current position angle through a position sensor, judging that the detection phase is in a conducting area at the moment if the current position angle is more than or equal to 0 degrees and less than or equal to 17 degrees, and jumping to the step M; if the current position angle is larger than 17 degrees and smaller than 45 degrees, judging that the detection phase is in a non-conduction interval at the moment, and jumping to the step L;
step M: setting a current threshold i th2 If the current i is measured in the conduction interval csa The absolute value of (a) exceeds the current threshold i th2 If the short-circuit fault of the chopper tube occurs, the system finishes diagnosis and jumps to the step P; if the current is smaller than the current threshold i in the conduction interval th2 And (3) diagnosing that the detected phase has no short-circuit fault, ending the diagnosis by the system, and jumping to the step (P);
step L: respectively obtaining current values of a position angle of 22.5 degrees and a position angle of 25 degrees through a rotor position signal of a target phase and a current signal of the target phase, and jumping to the step N;
step N: comparing the current values corresponding to the two position angles respectively, if the absolute value of the current value corresponding to the position angle 22.5 degrees or 25 degrees is found to be larger than the preset current threshold i th3 Judging that the short circuit fault of the switching tube occurs at the moment, and jumping to the step O;
step O: the current sensor measurement i of the target phase at this time csa If the current value is less than 0, diagnosing the system as a conduction pipe short-circuit fault, ending the diagnosis, and jumping to the step P; the current sensor measurement i at this time csa If the current value is more than 0, diagnosing the short-circuit fault of the chopper tube by the system, ending the diagnosis by the system, and jumping to the step P; the current sensor measurement i at this time csa When equal to 0, then the diagnostic flow remains in step O operation until the current sensor measurement i csa The sign shows positive and negative;
step P: and (3) finishing the dynamic diagnosis flow, entering the next diagnosis period, and jumping to the step A.
Further, the current sensor is connected as follows: the switch tube S 1 After the other end wire of the current sensor CS1 passes throughConnected to one end of the A-phase winding, and thereafter connected to the diode D 2 The cathode wire passes through the current sensor CS1 reversely and is connected to the same end of the A-phase winding, the switch tube S 3 Is connected with one end of the B-phase winding after passing through the current sensor CS2, and is connected with the diode D 4 The cathode wire passes through the current sensor CS2 reversely and is connected to the same end of the B-phase winding, the switch tube S 5 Is connected with one end of the C-phase winding after passing through the current sensor CS3 in the forward direction, and is connected with the diode D 6 The cathode wire passes back through the current sensor CS3 and is connected to the same end of the C-phase winding.
Further, in step A, the rotation speed threshold value n th And taking 120% times of the fluctuation value of the rotating speed of the motor in normal steady-state operation.
Further, the step D of performing the translation of the phase current includes the following steps:
step A, measuring the rotor position angle of a detection phase through a position sensor, differentiating the rotor position angle to obtain angular velocity, and converting the angular velocity into a rotating speed n through the quantity relation between the angular velocity and the rotating speed;
in the step B, the following numerical relation exists between the electric period T and the rotating speed n, and the relation is as follows:
Figure BDA0004044712900000041
since the motor used is a 12/8 switched reluctance motor, N r 8;
and step C, translating the current measurement value signal backwards for one electric period in real time according to the calculated rotating speed, and then, carrying out difference between the real-time current value obtained through the current sensor and a reference current value corresponding to the current electric period to obtain a current error value delta.
Further, in step G, it is detected that the absolute value of the difference Δ between the actual phase current value and the reference current value corresponding to the current electrical cycle is greater than a preset thresholdi th1 When the switching tube normally operates, the current error calculated by the current translation method is between (-0.2,0.2), and a threshold value i is set th1 0.4.
Further, in step M, the current threshold i th2 130% times of the current chopping limit value when the motor operates is taken.
Further, in step N, the current threshold i th3 The current value 4A of the position angle 22.5 degrees is taken when the motor is in normal operation.
When the system is in steady state operation, the phase current waveform of the last electrical cycle is shifted by one electrical cycle by a current shifting method. And then comparing the translated current waveform with the current waveform of the current electric period as a reference current waveform, calculating the difference value between the reference current waveform and the current waveform in real time, and rapidly diagnosing the short-circuit fault of the switching tube in the current electric period by taking the amplitude value of the difference value as a fault judgment basis.
When the system is in dynamic operation, diagnosing whether a chopper short circuit fault occurs or not in a conduction interval by setting a current threshold value; and judging and positioning the short-circuit fault switching tube in the non-conduction interval through the magnitude and the positive and negative of the measured value of the current sensor corresponding to the rotor position angles of 22.5 degrees and 25 degrees.
The beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages:
(1) The SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation can meet fault diagnosis during steady-state and dynamic operation of the motor. The switching tube short-circuit fault diagnosis scheme is suitable for switching reluctance motors with various phase numbers. The method has important application prospect in the application occasions with extremely high requirements on the reliability of motors, such as aero-starter generators, electric automobile motors and the like.
(2) The diagnosis scheme does not need an additional current sensor, is simple to operate, easy to realize and high in reliability; the short-circuit fault of the switching tube can be diagnosed rapidly while the current detection is not affected. The controller can still obtain the actual phase current value through the current sensor.
Drawings
FIG. 1 is a schematic diagram of a current sensor connection;
FIG. 2 is a schematic diagram of a translation current waveform;
FIG. 3 is a general logic flow diagram for short circuit fault diagnosis;
FIG. 4 is a flow chart of short circuit fault diagnostic logic during steady state operation;
FIG. 5 is a flow chart of a dynamic runtime short circuit fault diagnostic logic.
Detailed Description
The technical scheme of the invention is further described below with reference to the accompanying drawings.
The invention designs a dynamic diagnosis method for short-circuit faults of an SRM switching tube by adopting current translation, when a system is in steady-state operation, a current translation method is utilized to translate a phase current waveform of a previous electrical period by one electrical period, the phase current waveform is used as a reference current waveform to be compared with a current waveform of the current electrical period, a difference value between the two is calculated in real time, and the amplitude value of the difference value is used as a fault judgment basis to rapidly diagnose the short-circuit faults of the switching tube which occur in the current electrical period. When the system is in dynamic operation, diagnosing whether a chopper short circuit fault occurs or not in a conduction interval by setting a current threshold value; and judging and positioning the short-circuit fault switching tube in the non-conduction interval through the magnitude and the positive and negative of the measured value of the current sensor corresponding to the rotor position angles of 22.5 degrees and 25 degrees. The dynamic diagnosis of the short-circuit fault of the switching tube of the driving system is realized by switching the diagnosis modes under different system running states. The motor adopts a voltage pulse width modulation chopping single tube control strategy, simultaneously fixes the on-off angle and the current chopping limit, and sets an upper switching tube S on the A phase 1 Is a chopper tube, a lower switch tube S 2 Is a conduit; switch tube S is arranged on B phase 3 Is a chopper tube, a lower switch tube S 4 Is a conduit; switch tube S is arranged on C phase 5 Is a chopper tube, a lower switch tube S 6 Is a conduit.
As shown in fig. 1, this figure is a schematic diagram of the current sensor connection. The connection mode of each current sensor is as follows: the switch tube S 1 Is connected with one end of the A phase winding after passing through the current sensor CS1 in the forward direction, and isThen by connecting the diode D 2 The cathode wire passes back through the current sensor CS1 and is connected to the same end of the a-phase winding. The switch tube S 3 Is connected with one end of the B-phase winding after passing through the current sensor CS2, and is connected with the diode D 4 The cathode wire passes back through the current sensor CS2 and is connected to the same end of the B-phase winding. The switch tube S 5 Is connected with one end of the C-phase winding after passing through the current sensor CS3 in the forward direction, and is connected with the diode D 6 The cathode wire passes back through the current sensor CS3 and is connected to the same end of the C-phase winding.
1. The power converter switching tube short-circuit fault type comprises the following fault types: a-phase chopper tube S 1 Short circuit occurs in the conduction region, and the A-phase chopper tube S 1 Short circuit occurs in non-conductive region, and A phase conductive tube S 2 Short circuit occurs and B phase chopper tube S 3 Short circuit occurs in the conduction region, and B-phase chopper tube S 3 Short circuit occurs in non-conductive area and B phase conduction pipe S 4 Short circuit occurs and C phase chopper tube S 5 Short circuit occurs in the conduction region and C-phase chopper tube S 5 Short circuit occurs in non-conductive area and C phase conduction pipe S 6 A short circuit occurs.
For the above nine switching tube short-circuit faults, because each phase of the asymmetric half-bridge power converter is independent, the switching tube short-circuit fault dynamic diagnosis scheme of the reference current translation reconstruction is described by taking the switching tube short-circuit fault of the A phase as an example. First, the change condition of the A phase current of the switching tube under the normal working condition is analyzed.
In the case of normal operation of the switching tube, when the phase is in the conducting region, if the chopper tube S 1 Drive signal P s1 =1 and conducting tube S 2 Drive signal P s2 When=1, the current rises rapidly, and the current sensor measures i as the current flows through the current sensor from the positive direction csa The sign is positive; if P s1 =0 and P s2 When=1, the phase current decreases, and the measured value i thereof is measured by the current sensor flowing in the negative direction csa The sign is negative; when the phase is off, P S1 、P S2 Always put 0,S 1 、S 2 And (5) switching off. Current through freewheeling diode D 2 、D 1 The loop drops rapidly and the phase demagnetizes rapidly, the measured value i of the current sensor due to the current flowing in the negative direction csa The sign is negative. The current translation method is adopted to translate the phase current of the previous electric period to the current electric period for comparison, and the current of the current electric period is not obviously changed compared with the current of the previous electric period because no short-circuit fault of a switching tube occurs, so that the current error can be stabilized in a range, the error value fluctuates up and down at a zero value, and the general error is stabilized between (-0.2,0.2). The current error and sensor measurement sign change are shown in table 1.
Table 1 phase current change under normal operation of switching tube
Figure BDA0004044712900000061
Specifically, as shown in table 1, the presence of a value of 0 is indicated. P (P) s1 Is a chopper tube S 1 PWM driving signal, P s2 Is a conducting pipe S 2 I real I is the actual phase winding current value csa For the current sensor measurement, i ref For the translational phase winding current values.
If chopper tube S 1 Short-circuiting in the conduction region if P s1 =1 and P s2 When=1, the current rises rapidly, and the current flows from the positive direction through the current sensor, and the measured value i csa The sign is positive; if P s1 =0 and P s2 When=1, but due to S 1 Short circuit, this phase still in the positive excitation phase, the current error increases, exceeding the preset threshold. If chopper tube S 1 Short-circuiting in non-conductive region, when P s1 =0 and P s2 When=0, due to S 1 Short circuit leading to S 1 Open, S 2 Turn off, current through S 1 、D 1 The circuit freewheels, at which time the measured value i csa The sign is positive. The continuous current slowly decreases, resulting in actual current and translational currentThe difference between them increases gradually. The current error and sensor measurement sign change are shown in table 2.
TABLE 2 phase Current Change conditions before and after the chopper tube was shorted
Figure BDA0004044712900000071
If the conduction pipe S 2 The short circuit is generated in the conducting area, and the conducting pipe is always kept in an open state in the conducting area, so that the short circuit fault current does not change obviously in the conducting area. If the conduction pipe S 2 Short-circuiting in non-conductive region, when P s1 =0 and P s2 When=0, due to S 2 Short circuit leading to S 1 Turn off, S 2 On, current passes through S 2 、D 2 The circuit freewheels, at which time the measured value i csa The sign is negative. The difference between the actual current and the translation current gradually increases due to the slow decrease of the follow-up current. The current error and sensor measurement sign change are shown in table 3.
TABLE 3 phase current change conditions before and after a short circuit of the conducting tube
Figure BDA0004044712900000072
As shown in fig. 2, which is a schematic diagram of the translational current waveform. In the figure, i a Is the winding current of phase A, i a Equal to the absolute value of the current sensor measurement i csa ，P s2 Is a phase A lower switching tube S 2 Drive signal of θ on Is the position opening angle theta off Is the position off angle, i, assuming that the current is the k time of the electrical cycle k real A phase A winding current i at k time of current electric period k a ，i ref Phase a winding current i at time k for the previous electrical cycle k-1, which is the translation current value a . Since the current translation method is to calculate the required translation time according to the real-time rotation speed under the assumption that the rotation speed of the front and rear electric periods is constant, the rotation speed may be changed in the actual processIn this way, the rotational speeds corresponding to the two adjacent electric cycles are not completely identical. Thus, the current signal of the previous electrical cycle is caused to lead or lag the present current signal when the translation is caused. For this purpose, fault diagnosis can be performed by using the absolute value of the current difference between the two adjacent electrical cycles before and after as the fault feature of the switching tube short-circuit fault.
As shown in fig. 3, the figure is a general logic flow diagram for short circuit fault diagnosis. The running state of the system is judged according to the real-time rotating speed, and the difference delta between the preset reference rotating speed and the real-time rotating speed is preset n Greater than the rotation speed threshold n th And judging that the system is in a dynamic running state, otherwise, judging that the system is in a steady running state. The judgment of the conduction section and the non-conduction section is selected according to the setting of the on/off angle. When the rotor position angle θ of the motor is at (θ on ,θ off ) And judging the system as a conduction interval. Otherwise, the non-conduction interval is formed. When the system is in steady-state operation, the phase current waveform of the last electric period is shifted for one electric period, the phase current waveform is used as a reference current waveform to be compared with the current waveform of the current electric period, the difference value between the phase current waveform and the current electric period is calculated in real time, and the amplitude value of the difference value is used as a fault judgment basis to rapidly diagnose the short-circuit fault of the switching tube which occurs in the current electric period; when the system is in dynamic operation, diagnosing whether a chopper short circuit fault occurs in a conduction interval by setting a current threshold value; and judging and positioning the short-circuit fault switching tube in a non-conduction interval through the magnitude and the positive and negative of the measured value of the current sensor corresponding to the rotor position angles of 22.5 degrees and 25 degrees.
As shown in FIG. 4, this figure is a logic flow diagram for diagnosing a short circuit fault during steady state operation of the system. When the driving system runs stably, the phase current waveform of the last electric period is shifted for one electric period, the phase current waveform is used as a reference current waveform to be compared with the current waveform of the current electric period, the difference value between the phase current waveform and the current waveform is calculated in real time, and the amplitude value of the difference value is used as a fault judgment basis to rapidly diagnose the short-circuit fault of the switching tube in the current electric period. Taking phase a as an example, the following steps are performed in real time:
and step A, performing voltage pulse width modulation chopping tube control on the motor, fixing a switching-on/off angle and a current chopping limit, and obtaining a current signal through a current sensor.
And step A-1, detecting a current signal of a motor A phase by a current sensor, and collecting an A phase current value.
And step A-2, conducting the phase A winding at 0-17 degrees, and controlling the voltage pulse width modulation chopping tube by the controller. The embodiments are as follows:
in the conduction interval of the phase, a pwm signal with a certain duty ratio is obtained as a driving signal of the chopper tube according to the rotating speed ring. The position logic signal, the current chopping signal and the pwm signal are logically and-ed to obtain a final chopper control signal, and then the final chopper control signal is sent to the chopper tube, and the position logic signal is sent to the conducting tube. When P s1 =1 and P s2 When=1, the current rises rapidly, and since the current flows through the current sensor from the positive direction, the measured value sign thereof is positive; if P s1 =0 and P s2 When=1, the phase current decreases, and the measured value sign is negative since the current flows through the current sensor from the negative direction; in addition, in the conduction region, the conduction pipe S 2 Always remain on.
Step B, judging the state of the system according to the real-time rotating speed, and presetting a difference delta between the reference rotating speed and the real-time rotating speed n Less than the rotation speed threshold n th (rotation speed threshold n) th C, taking 120% of the fluctuation value of the rotating speed when the motor normally and stably operates, judging that the system is in a steady state operation state, and jumping to the step C;
and step C, translating the current signal of the previous current period and calculating a current difference value.
Step C-1, calculating translation time according to the position signal, translating the current signal, and translating for one electric period T, wherein the calculation formula is as follows:
Figure BDA0004044712900000091
and C-2, performing difference between an actual current value obtained by the current sensor and a reference current value shifted by one electric period (a reference current value corresponding to the current electric period), and obtaining a current error value delta. The expression is as follows:
Δ＝i real -i ref (2)
wherein i is real I is the actual current value ref Is the reference current value.
Step D, judging the current position interval, and jumping to the step E when theta is more than or equal to 0 degree and less than or equal to 17 degrees; otherwise, jumping to the step G.
And E, calculating the difference value between the actual current and the reference current in real time, and diagnosing the short-circuit fault of the switching tube in the conduction interval in real time. The method comprises the following steps:
step E-1, setting a threshold value i slightly larger than the normal value of the current error th1 . In general practice, the current error calculated by the current translation method is between (-0.2,0.2) when the switching tube is in normal operation, so that a diagnostic threshold i is required to be set th1 . Taking the diagnostic threshold i th1 Is 0.4 (is a normal value of 2 times), and jumps to step E-2.
Step E-2, if the absolute value of the current error exceeds the preset threshold i in the conduction interval th1 At this time, it is diagnosed as a chopper tube S 1 F, jumping to the step F after short-circuit fault; if the absolute value of the current error in the conduction interval is smaller than the preset threshold i th1 Then diagnosing as switch tube S 1 、S 2 And (5) normally working, and jumping to the step F.
Step F, finishing the diagnosis, entering the next diagnosis immediately if the phase is still in the conducting area, and cycling the steps to step E; if the phase enters the non-conductive region, it jumps to the non-conductive region diagnosis step G.
And G, calculating a current difference value in real time in a non-conduction area, detecting a detection value of a sensor, and diagnosing the short-circuit fault of the switching tube in real time. The method comprises the following steps of:
step G-1, setting a threshold i slightly larger than the normal value of the current error th1 . In general practice, the current error calculated by the current translation method is between (-0.2,0.2) when the switching tube is in normal operation, so that a diagnostic threshold i is required to be set th1 . Taking the diagnostic threshold i th1 Is 0.4 (is a normal value of 2 times), and the process jumps to step G-1.
Step G-2, if the absolute value of the current error exceeds the preset threshold i in the non-conduction interval th1 And at this point the current sensor measurement i csa The sign is positive, and at this time, the chopper tube S is diagnosed 1 The short circuit fault is jumped to the step H; if the absolute value of the current error exceeds a preset threshold i in the non-conduction interval th1 And at this point the current sensor measurement i csa The sign is negative, and the conduction pipe S is diagnosed at the moment 2 The short circuit fault is jumped to the step H; if the absolute value of the current error in the conduction interval is smaller than the preset threshold i th1 Then diagnosing as switch tube S 1 、S 2 And (3) normally working, and jumping to the step (H).
And step H, ending the diagnosis. If the phase is still in the non-conducting area, then entering the next diagnosis, and cycling the steps to step G; if the phase enters the conduction region, the phase jumps to the conduction region diagnosis step E.
As shown in FIG. 5, this figure is a flow chart of the short circuit fault diagnostic logic during dynamic operation of the system. When the system is in dynamic operation, diagnosing whether a chopper short circuit fault occurs or not in a conduction interval by setting a current threshold value; and judging and positioning the short-circuit fault switching tube in a non-conduction interval through the magnitude and the positive and negative of the measured value of the current sensor corresponding to the rotor position angles of 22.5 degrees and 25 degrees. Taking phase a as an example, the following steps are performed in real time:
and step A, performing voltage pulse width modulation chopping tube control on the motor, fixing a switching-on/off angle and a current chopping limit, and obtaining a current signal through a current sensor.
And step A-1, detecting a current signal of a motor A phase by a current sensor, and collecting an A phase current value.
And step A-2, conducting the phase A winding at 0-17 degrees, and controlling the voltage pulse width modulation chopping tube by the controller. The embodiments are as follows:
in the conduction interval of the phase, a pwm signal with a certain duty ratio is obtained as a driving signal of the chopper tube according to the rotating speed ring. Logic AND is performed on the position logic signal, the current chopping signal and the pwm signalAnd obtaining a final chopper control signal, then sending the signal into a chopper tube, and sending a position logic signal to a conducting tube. When P s1 =1 and P s2 When=1, the current rises rapidly, and since the current flows through the current sensor from the positive direction, the measured value sign thereof is positive; if P s1 =0 and P s2 When=1, the phase current decreases, and the measured value sign is negative since the current flows through the current sensor from the negative direction; in addition, in the conduction region, the conduction pipe S 2 Always remain on.
Step B, judging the state of the system according to the real-time rotating speed, and presetting a difference delta between the reference rotating speed and the real-time rotating speed n Greater than the rotation speed threshold n th (rotation speed threshold n) th C, taking 120% of the fluctuation value of the rotating speed of the motor in normal steady-state operation, judging that the system is in a dynamic operation state, and jumping to the step C;
step C, entering a dynamic diagnosis process, and jumping to the step D;
step D, obtaining a current position angle through a position sensor, judging that the detection phase is in a conducting area at the moment if the current position angle is more than or equal to 0 degrees and less than or equal to 17 degrees, and jumping to the step E; if the current position angle is larger than 17 degrees and smaller than 45 degrees, judging that the detection phase is in a non-conduction interval at the moment, and jumping to the step F;
step E, setting a current threshold i th2 (current threshold i) th2 Taking 130% times of the chopper limit value of the current when the motor operates), if the current i is measured in a conduction interval csa If the absolute value (i.e., winding current) exceeds the threshold, a short circuit fault of the chopper is diagnosed. The system finishes diagnosis and jumps to the step I; if the current is smaller than the threshold value in the on-period, it is diagnosed that the detected phase has no short-circuit fault. The system finishes diagnosis and jumps to the step I;
f, respectively obtaining current values of a position angle of 22.5 degrees and a position angle of 25 degrees through the rotor position signal and the current signal of the phase A, and jumping to the step G;
step G, respectively comparing the current values corresponding to the two position angles, if the absolute value of the current value corresponding to the position angle of 22.5 degrees or 25 degrees of the phase A is found to be larger than the preset current thresholdValue i th3 (current threshold i) th3 Taking the current value of the position angle 22.5 degrees when the motor is in normal operation: 4A) Judging that the short circuit fault of the switching tube occurs at the moment, and jumping to the step H;
step H, when the current sensor measurement i is at that time csa If the value is less than 0, diagnosing the system as a conduction pipe short-circuit fault, ending the diagnosis, and jumping to the step I; the current sensor measurement i at this time csa When the current value is more than 0, diagnosing the short-circuit fault of the chopper tube by the system, ending the diagnosis by the system, and jumping to the step I;
and step I, finishing the dynamic diagnosis flow, and entering the next diagnosis period.

Claims (7)

1. A dynamic diagnosis method for short-circuit faults of SRM switching tubes by adopting current translation is characterized in that an asymmetric half-bridge power converter of a switched reluctance motor is adopted, when the switching-on interval of each phase of the switched reluctance motor is adopted, an upper switching tube and a lower switching tube of a bridge arm of each phase corresponding to the power converter are used as chopper tubes, a lower switching tube are used as conducting tubes, the current waveform translation of the phase is combined, each phase is used as a target phase, and the following steps are executed to realize the rapid diagnosis of the short-circuit faults of the switching tubes of the target phase;
step A: according to the position signal obtained by the position sensor, calculating the actual rotation speed of the switch reluctance motor driving system through the position signal, judging which state the switch reluctance motor driving system is in, if the difference delta between the preset reference rotation speed and the actual rotation speed is preset n Less than a preset rotation speed threshold n th B, judging that the switched reluctance motor driving system is in a steady state operation state, and jumping to the step B, otherwise, judging that the switched reluctance motor driving system is in a dynamic operation state and jumping to the step J;
and (B) step (B): c, entering a steady-state diagnosis process, measuring a target phase through a current sensor to obtain a current sensor measurement value, and jumping to the step C;
step C: d, obtaining an actual phase current value of the target phase through absolute value processing of the measured value of the current sensor, and jumping to the step D;
step D: shifting the current signal of the previous electric period by one electric period through calculating the electric period so as to realize the shift of the current signal of the target phase, taking the current waveform shifted by one electric period as the current reference waveform of the target phase corresponding to the current electric period, further obtaining the reference current value corresponding to the current electric period, and jumping to the step E;
step E: calculating the difference delta between the actual current value of the target phase and the reference current value corresponding to the current electric period, if the absolute value of the difference delta is larger than the preset threshold i th1 Step F, jumping to the step F; if the absolute value of the difference delta is smaller than or equal to the preset threshold i th1 Step I is skipped to;
step F: obtaining a current position angle of the target phase through a position sensor, if the current position angle is more than or equal to 0 degrees and less than or equal to 17 degrees, judging that the detection phase is in a conducting area at the moment, and jumping to the step G; if the current position angle is larger than 17 degrees and smaller than 45 degrees, judging that the detection phase is in a non-conduction interval at the moment, and jumping to the step H;
step G: when the target phase is detected to be in the conducting area, the absolute value of the difference delta between the actual phase current value and the reference current value corresponding to the current electrical period is detected to be larger than the preset threshold value i th1 And (3) diagnosing that the phase chopper tube is short-circuited, and jumping to the step (I) after the diagnosis is finished;
step H: when the target phase is detected to be in the non-conductive region, if the absolute value of the difference delta between the current value of the detected actual phase and the reference current value corresponding to the current electrical period is greater than the preset threshold i th1 And current sensor measurement i csa If the sign is positive, diagnosing that the detection phase chopper is short-circuited; if the absolute value of the difference delta between the actual phase current value and the reference current value corresponding to the current electric period is detected to be larger than the preset threshold value i th1 And current sensor measurement i csa If the sign is negative, diagnosing that the phase conducting tube is short-circuited, ending the diagnosis, and jumping to the step I;
step I: entering the next diagnosis period, and jumping to the step A;
step J: entering a dynamic diagnosis flow, and jumping to the step K;
step K: obtaining a current position angle through a position sensor, judging that the detection phase is in a conducting area at the moment if the current position angle is more than or equal to 0 degrees and less than or equal to 17 degrees, and jumping to the step M; if the current position angle is larger than 17 degrees and smaller than 45 degrees, judging that the detection phase is in a non-conduction interval at the moment, and jumping to the step L;
step M: setting a current threshold i th2 If the current i is measured in the conduction interval csa The absolute value of (a) exceeds the current threshold i th2 If the short-circuit fault of the chopper tube occurs, the system finishes diagnosis and jumps to the step P; if the current is smaller than the current threshold i in the conduction interval th2 And (3) diagnosing that the detected phase has no short-circuit fault, ending the diagnosis by the system, and jumping to the step (P);
step L: respectively obtaining current values of a position angle of 22.5 degrees and a position angle of 25 degrees through a rotor position signal of a target phase and a current signal of the target phase, and jumping to the step N;
step N: comparing the current values corresponding to the two position angles respectively, if the absolute value of the current value corresponding to the position angle 22.5 degrees or 25 degrees is found to be larger than the preset current threshold i th3 Judging that the short circuit fault of the switching tube occurs at the moment, and jumping to the step O;
step O: the current sensor measurement i of the target phase at this time csa If the current value is less than 0, diagnosing the system as a conduction pipe short-circuit fault, ending the diagnosis, and jumping to the step P; the current sensor measurement i at this time csa If the current value is more than 0, diagnosing the short-circuit fault of the chopper tube by the system, ending the diagnosis by the system, and jumping to the step P; the current sensor measurement i at this time csa When equal to 0, then the diagnostic flow remains in step O operation until the current sensor measurement i csa The sign shows positive and negative;
step P: and (3) finishing the dynamic diagnosis flow, entering the next diagnosis period, and jumping to the step A.
2. The method for dynamically diagnosing a short-circuit fault of an SRM switching tube by adopting current translation according to claim 1, wherein the current sensor is connected as follows: the switch tube S 1 Is connected with one end of the A-phase winding after passing through the current sensor CS1 in the forward direction, and is then connected with the other end of the A-phase windingBy connecting said diode D 2 The cathode wire passes through the current sensor CS1 reversely and is connected to the same end of the A-phase winding, the switch tube S 3 Is connected with one end of the B-phase winding after passing through the current sensor CS2, and is connected with the diode D 4 The cathode wire passes through the current sensor CS2 reversely and is connected to the same end of the B-phase winding, the switch tube S 5 Is connected with one end of the C-phase winding after passing through the current sensor CS3 in the forward direction, and is connected with the diode D 6 The cathode wire passes back through the current sensor CS3 and is connected to the same end of the C-phase winding.
3. The method for dynamic diagnosis of short-circuit fault of SRM switching tube by current translation according to claim 1, wherein in step A, the rotation speed threshold value n th And taking 120% times of the fluctuation value of the rotating speed of the motor in normal steady-state operation.
4. The method for dynamically diagnosing a short-circuit fault of an SRM switching tube by means of current translation according to claim 1, wherein the step D of translating the phase current is implemented as follows:
step A, measuring the rotor position angle of a detection phase through a position sensor, differentiating the rotor position angle to obtain angular velocity, and converting the angular velocity into a rotating speed n through the quantity relation between the angular velocity and the rotating speed;
in the step B, the following numerical relation exists between the electric period T and the rotating speed n, and the relation is as follows:
Figure FDA0004044712890000031
since the motor used is a 12/8 switched reluctance motor, N r 8;
and step C, translating the current measurement value signal backwards for one electric period in real time according to the calculated rotating speed, and then, carrying out difference between the real-time current value obtained through the current sensor and a reference current value corresponding to the current electric period to obtain a current error value delta.
5. The method for dynamic diagnosis of a short-circuit fault of an SRM switching tube by means of current translation according to claim 1, wherein in step G, it is detected that the absolute value of the difference DeltaA between the actual phase current value and the reference current value corresponding to the current electrical period is greater than a preset threshold i th1 When the switching tube normally operates, the current error calculated by the current translation method is between (-0.2,0.2), and a threshold value i is set th1 0.4.
6. The method for dynamic diagnosis of short-circuit fault of SRM switching tube by current translation according to claim 1, wherein in step M, the current threshold i is th2 130% times of the current chopping limit value when the motor operates is taken.
7. The method for dynamic diagnosis of short-circuit fault of SRM switching tube by current translation according to claim 1, wherein in step N, the current threshold i is th3 The current value 4A of the position angle 22.5 degrees is taken when the motor is in normal operation.
CN202310026254.XA 2023-01-09 2023-01-09 SRM switching tube short-circuit fault dynamic diagnosis method adopting current translation Pending CN116243207A (en)

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