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

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

A Dynamic Diagnosis Method for SRM Switching Tube Short Circuit Fault Using Current Translation

technical field

The invention belongs to the technical field of switched reluctance motor control, and in particular relates to a dynamic diagnosis method for a short-circuit fault of an SRM switch tube using current translation.

Background technique

The power converter is an electronic device that controls the order of switching on the windings of each phase and the power supply, provides a feedback loop for winding energy storage, and supplies energy to the motor. If a short-circuit fault occurs in the switch tube of the power converter when the motor is running normally, it will lead to deterioration of the running state of the motor and seriously affect the normal operation of the motor. Due to the short circuit of the switch tube, a large current may be generated, which poses a serious threat to the motor and its related equipment. Therefore, how to quickly and accurately diagnose the short-circuit fault of the switching tube is very important.

Most of the traditional short-circuit fault diagnosis methods involve the use of additional current sensors for fault diagnosis, and the use of additional current sensors for detection will undoubtedly increase the detection cost and increase the complexity of the operation. Therefore, the design of a technology that does not need to use additional current sensors for rapid fault diagnosis will help to further improve the reliability of the switched reluctance motor system, especially for precision servos, electric vehicles, aerospace, etc., which have very high reliability requirements for switched reluctance motors The application scenarios have important practical value.

Contents of the invention

Purpose of the invention: The purpose of the present invention is to provide a dynamic diagnosis method for short-circuit faults of SRM switching tubes using current translation. This diagnosis scheme does not require additional current sensors, and is simple to operate, easy to implement, and high in reliability.

When the system is in steady state operation, use the current translation method to shift the phase current waveform of the previous electrical cycle by one electrical cycle, and use it as a reference current waveform to compare with the current waveform of this electrical cycle, and calculate the difference between the two in real time and use the magnitude of the difference as the basis for fault judgment to quickly diagnose the short-circuit fault of the switching tube that occurred in this electrical cycle. When the system is in dynamic operation, it is possible to diagnose whether a chopper tube short-circuit fault occurs by setting the current threshold in the conduction interval; in the non-conduction interval, the value of the current sensor corresponding to the rotor position angle of 22.5° and 25° is measured. And its positive and negative to judge and locate the short-circuit fault switch tube. The dynamic diagnosis of the short-circuit fault of the switching tube of the drive system is realized by switching the diagnosis mode under different system operating states.

Technical solution: A dynamic diagnosis method for SRM switching tube short-circuit fault using current translation in the present invention, using an asymmetrical half-bridge power converter of a switched reluctance motor, during the conduction interval of each phase of the switched reluctance motor The upper switch tube of each phase bridge arm corresponding to the device is used as a chopper tube, and the lower switch tube is used as a conduction tube. Combined with the current waveform translation of the phases, each phase is taken as the target phase, and the following steps are performed to realize the rapid diagnosis of the short-circuit fault of the switch tube of the target phase;

Step A: Obtain the position signal according to the position sensor and calculate the actual speed of the switched reluctance motor drive system through the position signal, and judge the state of the switched reluctance motor drive system. If the difference between the preset reference speed and the actual speed Δ _n is less than If the speed threshold n _th is preset, it is judged that the switched reluctance motor drive system is in a steady-state operation state, and jump to step B; otherwise, it is judged that the switched reluctance motor drive system is in a dynamic running state and jump to step J;

Step B: Enter the steady-state diagnosis process, measure the target phase through the current sensor to obtain the measured value of the current sensor, and jump to step C;

Step C: After performing absolute value processing on the measured value of the current sensor to obtain the actual phase current value of the target phase, jump to step D;

Step D: Translating the current signal of the previous electrical cycle by one electrical cycle by calculating the electrical cycle to realize the translation of the target phase current signal and taking the current waveform shifted by one electrical cycle as the target phase current reference waveform corresponding to the current electrical cycle, Then obtain the reference current value corresponding to the current electrical cycle, and jump to step E;

Step E: Calculate the difference Δ between the actual current value of the target phase and the reference current value corresponding to the current electrical cycle, if the absolute value of the difference Δ is greater than the preset threshold i _th1 , then jump to step F; if the difference Δ is If the absolute value is less than or equal to the preset threshold i _th1 , jump to step I;

Step F: Obtain the current position angle of the target phase through the position sensor. If the current position angle is greater than or equal to 0° and less than or equal to 17°, it is judged that the detection phase is in the conduction area at this time, and jump to step G; if the current position angle If it is greater than 17° and less than 45°, it is judged that the detection phase is in the non-conduction interval at this time, and jumps to step H;

Step G: When it is detected that the target phase is in the conduction region, and 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 detected to be greater than the preset threshold value i _th1 , it is diagnosed as detecting the phase chopper tube Short circuit, end of diagnosis, jump to step I;

Step H: When it is detected that the target phase is in the non-conduction region, if 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 the preset threshold value i _th1 and the measured value of the current sensor is i _csa If the sign is positive, it is diagnosed as detecting a short circuit of the phase chopper tube; if 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 detected to be greater than the preset threshold i _th1 and the current sensor measurement value i _csa If the sign is negative, then the diagnosis is a short circuit of the conduction tube of the detection phase, and the diagnosis is completed, and then jump to step I;

Step I: enter the next diagnostic cycle, and jump to step A;

Step J: enter the dynamic diagnosis process and jump to step K;

Step K: Obtain the current position angle through the position sensor. If the current position angle is greater than or equal to 0° and less than or equal to 17°, it is judged that the detection phase is in the conduction area at this time, and jump to step M; if the current position angle is greater than 17° and If it is less than 45°, it is judged that the detection phase is in the non-conduction interval at this time, and jumps to step L;

Step M: Set the current threshold i _th2 , if the absolute value of the measured current i _csa in the conduction interval exceeds the current threshold i _th2 , it is diagnosed as a chopper tube short-circuit fault, the system ends the diagnosis, and jumps to step P; if If the current in the conduction interval is less than the current threshold i _th2 , it is diagnosed that no short-circuit fault has occurred in the detection phase, the system ends the diagnosis, and jumps to step P;

Step L: obtain the current values at position angles of 22.5° and 25° respectively through the rotor position signal of the target phase and the current signal of the target phase, and jump to step N;

Step N: Compare the current values corresponding to the two position angles respectively, and if the absolute value of the current value corresponding to the position angle 22.5° or 25° is found to be greater than the preset current threshold value i _th3 , it is judged that a short circuit of the switching tube occurs at this time Fault, jump to step O;

Step O: When the measured value i _csa of the current sensor of the target phase is less than 0, the system diagnoses a short-circuit fault in the conduction tube, the system ends the diagnosis, and jumps to step P; when the measured value i _csa of the current sensor at this time is greater than When 0, the system diagnoses the chopper tube short-circuit fault, the system ends the diagnosis, and jumps to step P; when the measured value of the current sensor i _csa is equal to 0, the diagnosis process keeps running in step O until the measured value of the current sensor i _{The csa} symbol appears positive and negative;

Step P: The dynamic diagnosis process ends, enters the next diagnosis cycle, and skips to step A.

Further, the connection method of the current sensor is as follows: the wire at the other end of the switch tube _S1 passes through the current sensor CS1 forward and is connected to one end of the A-phase winding, and then connected to the cathode of the diode _D2 The lead wire of the switch tube S3 passes through the current sensor CS1 in reverse and is connected to the same end of the A-phase winding, and the other end lead of the switch tube _S3 forwardly passes through the current sensor CS2 and connects with the B-phase winding One end is connected, and then the wire connected to the cathode of the diode _D4 passes through the current sensor CS2 in reverse and is connected to the same end of the B-phase winding, and the other end wire of the switch tube _S5 passes forward The current sensor CS3 is then connected to one end of the C-phase winding, and then the wire connected to the cathode of the diode _D6 passes through the current sensor CS3 in reverse and is connected to the same end of the C-phase winding.

Further, in step A, the speed threshold n _th is 120% times the value of the speed fluctuation when the motor is in normal steady state operation.

Further, in step D, the steps for realizing the translation of the phase current are as follows:

Step A, measure the rotor position angle of the detection phase through the position sensor, then differentiate the rotor position angle to obtain the angular velocity, and then convert the angular velocity into a rotational speed n through the quantitative relationship between the angular velocity and the rotational speed;

Step B, since there is the following numerical relationship between the electrical cycle T and the rotational speed n, the relationship is as follows:

Since the motor used is a 12/8 switched reluctance motor, N _r is 8;

Step C, according to the calculated rotation speed, the current measurement value signal is shifted backward for one electrical cycle in real time, and then the real-time current value obtained by the current sensor is compared with the reference current value corresponding to the current electrical cycle to obtain the current error value Δ.

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 the preset threshold value i _th1 , and the current error calculated by the current translation method is between Between (-0.2,0.2), set the threshold i _th1 to 0.4.

Further, in step M, the current threshold i _th2 is 130% times the current chopping limit value when the motor is running.

Further, in step N, the current threshold value i _th3 takes the current value of 4A at a position angle of 22.5° when the motor is in normal operation.

When the system is in steady state operation, the phase current waveform of the previous electrical cycle is shifted by one electrical cycle through the current translation method. Then compare the shifted current waveform as the reference current waveform with the current waveform of this electrical cycle, calculate the difference between the two in real time, and use the magnitude of the difference as the basis for fault judgment. Periodic switch tube short-circuit faults are quickly diagnosed.

When the system is in dynamic operation, it is possible to diagnose whether a chopper tube short-circuit fault occurs by setting the current threshold in the conduction interval; in the non-conduction interval, the value of the current sensor corresponding to the rotor position angle of 22.5° and 25° is measured. And its positive and negative to judge and locate the short-circuit fault switch tube.

Beneficial effect: compared with the prior art, the present invention has the following significant advantages:

(1) A method for dynamic diagnosis of SRM switching tube short-circuit fault using current translation in the present invention can meet the fault diagnosis of the motor in steady state and dynamic operation. The switch tube short-circuit fault diagnosis scheme is applicable to switched reluctance motors with various phase numbers. It has an important application prospect in applications such as aviation starter generators and electric vehicle motors that require extremely high reliability of motors.

(2) The diagnosis scheme of the present invention does not require an additional current sensor, is simple to operate, is easy to implement, and has high reliability; without affecting current detection, it can quickly diagnose the short-circuit fault of the switching tube. The controller can still obtain the actual phase current value through the current sensor.

Description of drawings

Figure 1 is a schematic diagram of the current sensor connection;

Fig. 2 is a schematic diagram of translation current waveform;

Fig. 3 is the overall logic flowchart of short-circuit fault diagnosis;

Fig. 4 is a logic flowchart of short-circuit fault diagnosis during steady-state operation;

Fig. 5 is a logic flowchart of short-circuit fault diagnosis during dynamic operation.

Detailed ways

The technical solution of the present invention will be further described below in conjunction with the accompanying drawings.

The present invention designs a dynamic diagnosis method for short-circuit faults of SRM switching tubes using current translation. When the system is in steady state operation, the phase current waveform of the previous electrical cycle is translated by one electrical cycle by using the current translation method, and it is used as a reference The current waveform is compared with the current waveform of this electrical cycle, and the difference between the two is calculated in real time, and the magnitude of the difference is used as the basis for fault judgment to quickly diagnose the short-circuit fault of the switching tube that occurred in this electrical cycle . When the system is in dynamic operation, it is possible to diagnose whether a chopper tube short-circuit fault occurs by setting the current threshold in the conduction interval; in the non-conduction interval, the value of the current sensor corresponding to the rotor position angle of 22.5° and 25° is measured. And its positive and negative to judge and locate the short-circuit fault switch tube. The dynamic diagnosis of the short-circuit fault of the switching tube of the drive system is realized by switching the diagnosis mode under different system operating states. The motor adopts the control strategy of voltage pulse width modulation chopping single tube, and at the same time, the on-off angle and the current chopping limit are fixed. In phase A, the upper switching tube S ₁ is set as the chopper tube, and the lower switching tube S ₂ is the conduction tube; In phase C, the upper switching tube _S3 is used as a chopper tube, and the lower switching tube _S4 is used as a conducting tube; in phase C, the upper switching tube _S5 is used as a chopper tube, and the lower switching tube _S6 is used as a conducting tube.

As shown in Figure 1, this figure is a schematic diagram of the current sensor connection. The connection mode of each current sensor is as follows: the other end wire of the switch tube _S1 forwardly passes through the current sensor CS1 and is connected to one end of the A-phase winding, and then the wire connected to the cathode of the diode _D2 Reversely pass through the current sensor CS1 and connect to the same end of the A-phase winding. The wire at the other end of the switching tube _S3 forwardly passes through the current sensor CS2 and is connected to one end of the B-phase winding, and then the wire connected to the cathode of the diode _D4 passes through the current sensor in reverse CS2 and connected to the same end of the B-phase winding. The wire at the other end of the switching tube _S5 forward passes through the current sensor CS3 and is connected to one end of the C-phase winding, and then the wire connected to the cathode of the diode _D6 passes through the current sensor in reverse CS3 and connected to the same end of the C-phase winding.

1. Power converter switching tube short-circuit fault types, the fault types include: A-phase chopper tube S ₁ short-circuits in the conduction area, A-phase chopper tube S ₁ short-circuits in the non-conduction area, A-phase conduction tube S ₂ is short-circuited, B-phase chopper tube S ₃ is short-circuited in the conduction area, B-phase chopper tube S ₃ is short-circuited in the non-conduction area, B-phase conduction tube S ₄ is short-circuited, C-phase chopper tube S ₅ is short-circuited A short circuit occurs in the conduction area, a short circuit occurs in the C-phase chopper tube _S5 in a non-conduction area, and a short circuit occurs in the C-phase conduction tube _S6 .

In view of the above nine kinds of short-circuit faults of switching tubes, since each phase of the asymmetrical half-bridge power converter is independent, taking the short-circuit fault of switching tubes in phase A as an example, the dynamic diagnosis scheme for short-circuiting faults of switching tubes based on translational reconstruction of reference current is explained . First, analyze the variation of the A-phase current when the switch tube is in normal operation.

In the case of normal operation of the switching tube, when the phase is in the conduction region, if the chopper tube S ₁ driving signal P _s1 =1 and the conduction tube S ₂ driving signal P _s2 =1, the current rises rapidly. If the current sensor flows through the current sensor in the positive direction, the sign of the measured value i _csa of the current sensor is positive; if P _s1 = 0 and P _s2 = 1, the current of this phase drops, because the current flows through the current sensor from the negative direction, the measured value i _csa The sign is negative; when the correlation is off, P _S1 and P _S2 are always set to 0, and S ₁ and S ₂ are off. The current drops rapidly through the freewheeling diode D ₂ and D ₁ circuit, and the phase demagnetizes rapidly. Since the current flows through the current sensor from the negative direction, the sign of the measured value i _csa is negative. Using the current translation method, the phase current of the previous electrical cycle is shifted to the current electrical cycle for comparison. Since there is no short-circuit fault of the switching tube, the current of this electrical cycle does not change significantly compared with the previous electrical cycle, so the current error will be stable. In a range, the error value fluctuates around zero, and the general error is stable between (-0.2,0.2). The current error and the sign change of the sensor measurement value are shown in Table 1.

Table 1 The change of phase current under the normal operation of the switch tube

Specifically, as shown in Table 1, * indicates that there is a case where the value is 0. P _s1 is the PWM driving signal of the chopper tube S ₁ , P _s2 is the driving signal of the conduction tube S ₂ , i _real is the actual phase winding current value, _icsa is the measured value of the current sensor, and i _ref is the translational phase winding current value .

If the chopper tube S ₁ is short-circuited in the conduction area, if P _s1 = 1 and P _s2 = 1, the current rises rapidly, since the current flows through the current sensor from the positive direction, the sign of the measured value i _csa is positive; if P _s1 =0 and P _s2 =1, but because S ₁ is short-circuited, the phase is still in the positive voltage excitation phase, and the current error increases, exceeding the preset threshold. If the chopper tube S ₁ is short-circuited in the non-conducting area, when P _s1 = 0 and P _s2 = 0, due to the short circuit of S _{1, S 1 is} turned on, S ₂ is turned off, and the current continues to flow through the loops of S ₁ and D ₁ , at this time the sign of the measured value i _csa is positive. As the freewheeling current decreases slowly, the difference between the actual current and the translational current gradually increases. The current error and the sign change of the sensor measurement value are shown in Table 2.

Table 2 Changes of phase current before and after short circuit of chopper tube

If the conduction transistor _S2 is short-circuited in the conduction region, since the conduction transistor remains on in the conduction region, the short-circuit fault current will not change significantly in this section. If the conduction tube S ₂ is short-circuited in the non-conduction area, when P _s1 = 0 and P _s2 = 0, due to the short circuit of S 2, S ₁ is turned off, _{S 2 is} turned on, and the current continues to flow through the loops of S ₂ and D ₂ , the sign of the measured value i _csa is negative. As the freewheeling current decreases slowly, the difference between the actual current and the translational current gradually increases. The current error and the sign change of the sensor measurement value are shown in Table 3.

Table 3 Changes of phase current before and after the conduction tube short circuit

As shown in FIG. 2 , the figure is a schematic diagram of a translational current waveform. In this figure, i _a is the winding current of phase A, i _a is equal to the measured value _icsa of the current sensor after taking the absolute value, P _s2 is the driving signal of the switch tube S ₂ in phase A, θ _on is the position opening angle, θ _off is the position turn-off angle, assuming that the current is the k moment of the electric cycle k, then i _real is the A-phase winding current i _a at the k moment of the current electric cycle k, and i _ref is the translation current value, that is, the previous electric cycle k- A-phase winding current _ia at time k of 1. Since the current translation method calculates the translation time required based on the real-time rotational speed when the rotational speeds of the two electrical cycles before and after are assumed to be constant, however, the rotational speed may change in the actual process, and the corresponding rotational speeds of the two adjacent electrical periods are not the same. totally agree. Therefore, the current signal of the previous electrical cycle leads or lags behind the current current signal when the translation is caused. For this reason, the fault diagnosis can be carried out by using the absolute value of the current difference between two adjacent electrical cycles before and after as the fault feature of the short-circuit fault of the switching tube.

As shown in Figure 3, this figure is the overall logic flow chart of short-circuit fault diagnosis. The operating state of the system is judged based on the real-time rotational speed. If the difference Δ _n between the preset reference rotational speed and the real-time rotational speed is greater than the rotational speed threshold n _th , it is judged that the system is in a dynamic operating state; otherwise, it is judged that the system is operating in a steady state. In addition, the judgment of the conduction interval and the non-conduction interval is selected according to the setting of the on-off angle. When the rotor position angle θ of the motor is in (θ _on , θ _off ), the system judges that it is in the conduction interval. On the contrary, it is a non-conduction interval. When the system is in steady-state operation, by shifting the phase current waveform of the previous electrical cycle by one electrical cycle as a reference current waveform and comparing it with the current waveform of this electrical cycle, the difference between the two is calculated in real time and the The amplitude of the difference is used as the basis for fault judgment to quickly diagnose the short-circuit fault of the switch tube that occurred in this electrical cycle; when the system is in dynamic operation, it is diagnosed whether a chopper tube occurs by setting the current threshold in the conduction interval. Short-circuit fault: in the non-conduction interval, judge and locate the short-circuit fault switch tube by the size and positive or negative of the measured value of the current sensor corresponding to the rotor position angle of 22.5° and 25°.

As shown in Figure 4, this figure is a logic flow chart of short-circuit fault diagnosis when the system is running in a steady state. When the drive system is running in a steady state, by shifting the phase current waveform of the previous electrical cycle by one electrical cycle as a reference current waveform and comparing it with the current waveform of this electrical cycle, the difference between the two is calculated in real time and the The magnitude of the difference is used as the basis for fault judgment to quickly diagnose the short-circuit fault of the switching tube that occurred in this electrical cycle. Taking phase A as an example, perform the following steps in real time:

In step A, the voltage pulse width modulation chopper control is performed on the motor, the on-off angle and the current chopping limit are fixed, and the current signal is obtained through the current sensor.

Step A-1: Detect the current signal of phase A of the motor through the current sensor, and collect the current value of phase A.

In step A-2, the phase A winding is turned on at 0°-17°, and the controller performs voltage pulse width modulation and single-tube control. The implementation is as follows:

In the conduction interval of this phase, a PWM signal with a certain duty ratio is obtained according to the speed loop as the driving signal of the chopper tube. The position logic signal, the current chopping signal, and the pwm signal are logically combined to obtain the final control signal of the chopper tube, and then the signal is sent to the chopper tube, and the position logic signal is sent to the conduction tube. When P _s1 =1 and P _s2 =1, the current rises rapidly, and since the current flows through the current sensor from the positive direction, the sign of the measured value is positive; if P _s1 =0 and P _s2 =1, the phase current decreases, Since the current flows through the current sensor from the negative direction, the sign of its measured value is negative; in addition, in this conduction region, the conduction tube S ₂ is always in conduction.

Step B, judging what state the system is in according to the real-time rotational speed, the difference _Δn between the preset reference rotational speed and the real-time rotational speed is less than the rotational speed threshold n _th (the rotational speed threshold n _th is 120% times the rotational speed fluctuation value when the motor is in normal and stable operation) , it is judged that the system is in a steady state, and jump to step C;

Step C, shifting the current signal of the previous current cycle and calculating the current difference.

Step C-1, calculate the shift time according to the position signal and shift the current signal, and shift one electric cycle T, the calculation formula is as follows:

Step C-2, taking the difference between the actual current value obtained by the current sensor and the reference current value shifted by one electrical cycle (corresponding to the reference current value of the current electrical cycle), to obtain the current error value Δ. The expression is as follows:

Δ=i _real -i _ref (2)

Among them, i _real is the actual current value, and i _ref is the reference current value.

Step D, judging the current position interval, when θ is greater than or equal to 0° and less than or equal to 17°, go to step E; otherwise, go to step G.

In step E, the difference between the actual current and the reference current is calculated in real time, and the short circuit fault of the switching tube in the conduction interval is diagnosed in real time. Follow the steps below:

Step E-1, setting a threshold i _th1 slightly larger than the normal value of the current error. In general practice, the current error calculated by the current translation method is between (-0.2,0.2) when the switch tube is running normally, so the diagnostic threshold i _th1 needs to be set. Take the diagnostic threshold i _th1 as 0.4 (twice the normal value), and skip to step E-2.

Step E-2, if the absolute value of the current error in the conduction interval exceeds the preset threshold i _th1 , it is diagnosed as a short-circuit fault of the chopper tube S ₁ at this time, and jump to step F; if the absolute value of the current error in the conduction interval is If it is less than the preset threshold i _th1 , it is diagnosed that the switching tubes S ₁ and S ₂ are working normally, and jump to step F.

Step F, this diagnosis is over, if the phase is still in the conduction area, then enter the next diagnosis, repeat the above steps and jump to step E; if the phase enters the non-conduction area, jump to the non-conduction area diagnosis step g.

Step G, calculating the current difference in real time in the non-conducting area and detecting the sensor detection value, and performing real-time diagnosis on the short-circuit fault of the switching tube. Calculate as follows:

Step G-1, setting a threshold i _th1 slightly larger than the normal value of the current error. In general practice, the current error calculated by the current translation method is between (-0.2,0.2) when the switch tube is running normally, so the diagnostic threshold i _th1 needs to be set. Take the diagnostic threshold i _th1 as 0.4 (twice the normal value), and skip to step G-1.

Step G-2, if the absolute value of the current error in the non-conducting interval exceeds the preset threshold i _th1 and the sign of the measured value i _csa of the current sensor is positive at this time, it is diagnosed as a short-circuit fault of the chopper tube S ₁ at this time, and jumps to Step H; if the absolute value of the current error in the non-conducting interval exceeds the preset threshold i _th1 and the sign of the measured value i _csa of the current sensor is negative at this time, it is diagnosed as a short-circuit fault of the conduction tube _S2 at this time, and jumps to step H ; If the absolute value of the current error in the conduction interval is less than the preset threshold i _th1 , it is diagnosed that the switching tubes S ₁ and S ₂ are working normally, and jump to step H.

In step H, this diagnosis ends. If the phase is still in the non-conduction region, it will enter the next diagnosis immediately, repeat the above steps and jump to step G; if the phase enters the conduction region, it will jump to step E of the conduction region diagnosis.

As shown in Figure 5, this figure is a logic flow chart of short-circuit fault diagnosis when the system is running dynamically. When the system is in dynamic operation, it is possible to diagnose whether a chopper tube short-circuit fault occurs by setting the current threshold in the conduction interval; in the non-conduction interval, the value measured by the current sensor corresponding to the rotor position angle of 22.5° and 25° And its positive and negative to judge and locate the short-circuit fault switch tube. Taking phase A as an example, perform the following steps in real time:

In step A, the voltage pulse width modulation chopper control is performed on the motor, the on-off angle and the current chopping limit are fixed, and the current signal is obtained through the current sensor.

Step A-1: Detect the current signal of phase A of the motor through the current sensor, and collect the current value of phase A.

In step A-2, the phase A winding is turned on at 0°-17°, and the controller performs voltage pulse width modulation and single-tube control. The implementation is as follows:

In the conduction interval of this phase, a PWM signal with a certain duty ratio is obtained according to the speed loop as the driving signal of the chopper tube. The position logic signal, the current chopping signal, and the pwm signal are logically combined to obtain the final control signal of the chopper tube, and then the signal is sent to the chopper tube, and the position logic signal is sent to the conduction tube. When P _s1 =1 and P _s2 =1, the current rises rapidly, and since the current flows through the current sensor from the positive direction, the sign of the measured value is positive; if P _s1 =0 and P _s2 =1, the phase current decreases, Since the current flows through the current sensor from the negative direction, the sign of its measured value is negative; in addition, in this conduction region, the conduction tube S ₂ is always in conduction.

Step B, judging what state the system is in according to the real-time rotational speed, the difference _Δn between the preset reference rotational speed and the real-time rotational speed is greater than the rotational speed threshold _nth (the rotational speed threshold _nth is taken as 120% times the rotational speed fluctuation value when the motor is in normal steady-state operation ), it is judged that the system is in a dynamic running state, and jumps to step C;

Step C, enter the dynamic diagnosis process and jump to step D;

Step D: Obtain the current position angle through the position sensor. If the current position angle is greater than or equal to 0° and less than or equal to 17°, it is judged that the detection phase is in the conduction area at this time, and jump to step E; if the current position angle is greater than 17° and less than 45°, it is judged that the detection phase is in the non-conduction interval at this time, and jumps to step F;

Step E, set the current threshold i _th2 (the current threshold i _th2 is 130% times the current chopping limit value when the motor is running), if the absolute value of the measured current i _csa (ie winding current) in the conduction interval exceeds the threshold, then Diagnosed as a chopper tube short circuit fault. The system ends the diagnosis and jumps to step I; if the current is less than the threshold in the conduction interval, it is diagnosed that no short-circuit fault has occurred in the detection phase. The system ends the diagnosis and jumps to step I;

Step F, obtain the current values at position angles of 22.5° and 25° respectively through the rotor position signal and current signal of phase A, and jump to step G;

Step G, compare the current values corresponding to these two position angles respectively, if it is found that the absolute value of the current value corresponding to the position angle of phase A of 22.5° or 25° is greater than the preset current threshold i _th3 (the current threshold i _th3 is taken as the motor is normal The current value at a position angle of 22.5° during operation: 4A), then it is judged that a short-circuit fault of the switching tube occurs at this time, and jumps to step H;

Step H, when the current sensor measured value i _csa is less than 0 at this time, the system diagnoses the conduction tube short circuit fault, the system ends the diagnosis, and jumps to step I; when the current sensor measured value i _csa is greater than 0 at this time, The system diagnosis is a short-circuit fault of the chopper tube, the system ends the diagnosis, and jumps to step I;

In step I, the dynamic diagnosis process ends and enters into the next diagnosis cycle.

Claims (7)

1. A method for dynamic diagnosis of SRM switching tube short-circuit faults using current translation, characterized in that, the asymmetrical half-bridge power converter of the switched reluctance motor is used, and when the conduction interval of each phase of the switched reluctance motor, the power conversion The upper switching tube of each phase bridge arm corresponding to the device is used as the chopper tube, and the lower switching tube is used as the conduction tube. Combined with the phase current waveform translation, each phase is used as the target phase, and the following steps are performed to realize the short circuit of the target phase switching tube. Rapid diagnosis of faults; Step A: Obtain the position signal according to the position sensor and calculate the actual speed of the switched reluctance motor drive system through the position signal, and judge the state of the switched reluctance motor drive system. If the difference between the preset reference speed and the actual speed _{Δn is} less than If the speed threshold n _th is preset, it is judged that the switched reluctance motor drive system is in a steady-state operation state, and jump to step B; otherwise, it is judged that the switched reluctance motor drive system is in a dynamic running state and jump to step J; Step B: Enter the steady-state diagnosis process, measure the target phase through the current sensor to obtain the measured value of the current sensor, and jump to step C; Step C: After performing absolute value processing on the measured value of the current sensor to obtain the actual phase current value of the target phase, jump to step D; Step D: Translating the current signal of the previous electrical cycle by one electrical cycle by calculating the electrical cycle to realize the translation of the target phase current signal and taking the current waveform shifted by one electrical cycle as the target phase current reference waveform corresponding to the current electrical cycle, Then obtain the reference current value corresponding to the current electrical cycle, and jump to step E; Step E: Calculate the difference Δ between the actual current value of the target phase and the reference current value corresponding to the current electrical cycle, if the absolute value of the difference Δ is greater than the preset threshold i _th1 , then jump to step F; if the difference Δ is If the absolute value is less than or equal to the preset threshold i _th1 , jump to step I; Step F: Obtain the current position angle of the target phase through the position sensor. If the current position angle is greater than or equal to 0° and less than or equal to 17°, it is judged that the detection phase is in the conduction area at this time, and jump to step G; if the current position angle If it is greater than 17° and less than 45°, it is judged that the detection phase is in the non-conduction interval at this time, and jumps to step H; Step G: When it is detected that the target phase is in the conduction region, and 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 detected to be greater than the preset threshold value i _th1 , it is diagnosed as detecting the phase chopper tube Short circuit, end of diagnosis, jump to step I; Step H: When it is detected that the target phase is in the non-conduction region, if 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 the preset threshold value i _th1 and the measured value of the current sensor is i _csa If the sign is positive, it is diagnosed as detecting a short circuit of the phase chopper tube; if 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 detected to be greater than the preset threshold i _th1 and the current sensor measurement value i _csa If the sign is negative, then the diagnosis is a short circuit of the conduction tube of the detection phase, and the diagnosis is completed, and then jump to step I; Step I: enter the next diagnostic cycle, and jump to step A; Step J: enter the dynamic diagnosis process and jump to step K; Step K: Obtain the current position angle through the position sensor. If the current position angle is greater than or equal to 0° and less than or equal to 17°, it is judged that the detection phase is in the conduction area at this time, and jump to step M; if the current position angle is greater than 17° and If it is less than 45°, it is judged that the detection phase is in the non-conduction interval at this time, and jumps to step L; Step M: Set the current threshold i _th2 , if the absolute value of the measured current i _csa in the conduction interval exceeds the current threshold i _th2 , it is diagnosed as a chopper tube short-circuit fault, the system ends the diagnosis, and jumps to step P; if If the current in the conduction interval is less than the current threshold i _th2 , it is diagnosed that no short-circuit fault has occurred in the detection phase, the system ends the diagnosis, and jumps to step P; Step L: obtain the current values at position angles of 22.5° and 25° respectively through the rotor position signal of the target phase and the current signal of the target phase, and jump to step N; Step N: Compare the current values corresponding to the two position angles respectively, and if the absolute value of the current value corresponding to the position angle 22.5° or 25° is found to be greater than the preset current threshold value i _th3 , it is judged that a short circuit of the switching tube occurs at this time Fault, jump to step O; Step O: When the measured value i _csa of the current sensor of the target phase is less than 0, the system diagnoses a short-circuit fault in the conduction tube, the system ends the diagnosis, and jumps to step P; when the measured value i _csa of the current sensor at this time is greater than When 0, the system diagnoses the chopper tube short-circuit fault, the system ends the diagnosis, and jumps to step P; when the measured value of the current sensor i _csa is equal to 0, the diagnosis process keeps running in step O until the measured value of the current sensor i _{The csa} symbol appears positive and negative; Step P: The dynamic diagnosis process ends, enters the next diagnosis cycle, and skips to step A. 2. A kind of SRM switching tube short-circuit fault dynamic diagnosis method that adopts current translation according to claim 1, is characterized in that, the connection mode of current sensor is as follows: the other end wire of described switching tube S ₁ passes through described The current sensor CS1 is connected to one end of the A-phase winding, and then the wire connected to the cathode of the diode _D2 passes through the current sensor CS1 in reverse and is connected to the same end of the A-phase winding. The wire at the other end of the tube _S3 is forwardly passed through the current sensor CS2 and then connected to one end of the B-phase winding, and then the wire connected to the cathode of the diode _D4 passes through the current sensor CS2 in reverse and is connected to To the same end of the B-phase winding, the other end of the switch tube _S5 is forwardly passed through the current sensor CS3 and connected to one end of the C-phase winding, and then connected to the cathode of the diode _D6 The wires of the current sensor CS3 pass through the current sensor CS3 in reverse and are connected to the same end of the C-phase winding. 3. a kind of SRM switching tube short-circuit fault dynamic diagnosis method that adopts current translation according to claim 1, is characterized in that, in the step A, the speed threshold value n _gets 120% times of the speed fluctuation value when the motor is in normal steady state operation. 4. according to claim 1, a kind of SRM switching tube short-circuit fault dynamic diagnosis method that adopts current translation, it is characterized in that, in the step D, realize its step of the translation of phase current as follows: Step A, measure the rotor position angle of the detection phase through the position sensor, then differentiate the rotor position angle to obtain the angular velocity, and then convert the angular velocity into a rotational speed n through the quantitative relationship between the angular velocity and the rotational speed; Step B, since there is the following numerical relationship between the electrical cycle T and the rotational speed n, the relationship is as follows:

Since the motor used is a 12/8 switched reluctance motor, N _r is 8; Step C, according to the calculated rotation speed, the current measurement value signal is shifted backward for one electrical cycle in real time, and then the real-time current value obtained by the current sensor is compared with the reference current value corresponding to the current electrical cycle to obtain the current error value Δ. 5. A kind of SRM switching tube short-circuit fault dynamic diagnosis method using current translation according to claim 1, characterized in that, in step G, the difference Δ between the actual phase current value and the reference current value corresponding to the current electrical cycle is detected The absolute value of is greater than the preset threshold i _th1 , and the current error calculated by the current translation method is between (-0.2,0.2) when the switch tube operates normally, and the threshold i _th1 is set to 0.4. 6. a kind of SRM switching tube short-circuit fault dynamic diagnosis method that adopts current translation according to claim 1, is characterized in that, in step M, current threshold value i _th2 gets 130% times of current chopping limit value when motor is running. 7. a kind of SRM switching tube short-circuit fault dynamic diagnosis method that adopts current translation according to claim 1, is characterized in that, in step N, current threshold value i _th3 gets the electric current numerical value 4A of position angle 22.5 ° when motor is running normally.

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