CN104579086B - A kind of permagnetic synchronous motor failure judgment method based on zero sequence inductance - Google Patents

Abstract

A method for judging a fault of a permanent magnet synchronous motor based on a zero-sequence inductance relates to a method for judging a motor fault. At present, when the zero-sequence inductance is needed, the calculation is often derived from the physical model of the motor. The implementation method is relatively complicated, the calculation amount is large, and the data calculation and processing capabilities of the permanent magnet synchronous motor controller are required. In this technical solution, the calculation of the zero-sequence inductance starts directly from the existing three-phase permanent magnet synchronous motor winding flux linkage, obtains the flux linkage of the three-phase winding from the coordinate transformation of dqo to abc, and obtains the zero sequence through the phase flux linkage expression Sequence inductance, and then obtain the permanent magnet synchronous motor phase self-inductance and mutual inductance expression to find out the self-inductance and mutual inductance, compare with the normal self-inductance and mutual inductance in the permanent magnet synchronous motor controller, and determine which phase winding fault. By using the parameter variables in the vector control of the permanent magnet synchronous motor, the calculation amount of the controller data is greatly reduced, and if there is a fault in the permanent magnet synchronous motor winding, it can be responded in time.

Description

A Fault Judgment Method for Permanent Magnet Synchronous Motor Based on Zero Sequence Inductance

technical field

The invention relates to a motor fault judgment method, in particular to a permanent magnet synchronous motor fault judgment method based on zero-sequence inductance.

Background technique

With the rapid progress of power electronics technology and the continuous in-depth development of permanent magnet synchronous motor vector control technology, permanent magnet synchronous motors are widely used in industrial control and other fields. When the permanent magnet synchronous motor is in the state of overload operation and improper load matching, especially at start-up, the stator current of the permanent magnet synchronous motor will increase and cause heat generation, and the winding current imbalance will easily occur when the time is too long; when the inner bore of the stator enters the dust When there are problems such as debris, moisture, rotor and stator winding friction, it is easy to cause inter-turn short circuit and three-phase unbalance. The intrinsic relationship between the three-phase currents of the motor, that is, the sum of the three-phase currents is equal to zero will no longer hold true. The only way at this time is to add zero-sequence components on the basis of the dq variable for transformation. This method is very similar to the induction motor model, and the permanent magnet synchronous motor only needs to consider the stator winding.

At present, when the zero-sequence inductance is needed, the calculation is often derived from the physical model of the motor. The implementation method is relatively complicated, the calculation amount is large, and the data calculation and processing capabilities of the permanent magnet synchronous motor controller are required.

Contents of the invention

The technical problem to be solved and the technical task proposed by the present invention are to perfect and improve the existing technical solutions, and to provide a permanent magnet synchronous motor fault judgment method based on zero-sequence inductance for the purpose. For this reason, the present invention takes the following technical solutions.

A method for judging faults of permanent magnet synchronous motors based on zero-sequence inductance is characterized in that it comprises the following steps:

1) Calculate the zero-sequence current i _o value; extract the parameters in the vector control operation of the permanent magnet synchronous motor: q-axis flux linkage d-axis flux linkage Permanent magnet synchronous motor controller AD detects a-phase current i _as , b-phase current i _bs and c-phase current i _cs ; calculate zero-sequence current i _o :

i _o ＝1/3(i _as +i _bs +i _cs )

2) Calculate the steady state stator quadrature axis current in the dqo coordinate system and straight axis According to the parameter value obtained in step 1), by the following formula

Calculated with value; where θ _r is the rotor angle, which is obtained directly by extracting the parameter value of the rotor angle in the vector control operation of the permanent magnet synchronous motor;

3) Calculate the quadrature-axis inductance L _q and the direct-axis inductance L _d ; according to the flux linkage under the dqo coordinate system with expression:

Calculate the quadrature axis inductance L _q and the direct axis inductance L _d ; where ψ _af is the armature flux linkage generated by the permanent magnet and is the fixed parameter value of the motor;

4) Calculate the zero-sequence inductance L _o value of the permanent magnet synchronous motor under the current state; according to the expression of a-phase flux linkage:

Calculate the L _o value of the permanent magnet synchronous motor in the current state;

5) Calculate the self-inductance L _aa and mutual inductance L _ab and L _ac values of the permanent magnet synchronous motor; according to the self-inductance and mutual inductance expressions of phase a of the permanent magnet synchronous motor:

L _aa ＝2/3{L _o /2+(L _q +L _d )/2+((L _q -L _d )/2)cos2θ _r }

＝L _o /3+(L _q +L _d )/3+((L _q -L _d )/3) cos2θ _r

L _ab ＝-2/3{-L _o /2+(L _q +L _d )/4+((L _q -L _d )/2)}cos2(θ _r +30°)}

＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos2(θ _r +30°)}

L _ac ＝-2/3{-L _o /2+(L _q +L _d )/4+{(L _q -L _d )/2)}cos2(θ _r +150°)}

＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos2(θ _r +150°)}

Calculate the self-inductance and mutual inductance L _aa , _Lab and L _ac values of the permanent magnet synchronous motor;

6) Phase a winding fault judgment; compare the calculated self-inductance value L _aa of phase a with the self-inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the self-inductance value obtained by the identification of the permanent magnet synchronous motor control parameter, If the difference between the two exceeds the set value, it will report a phase winding failure;

7) Fault judgment of the _b -phase winding; compare the calculated mutual inductance value Lab a with the mutual inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the mutual inductance value obtained from the identification of the permanent magnet synchronous motor control parameter, if both When the difference exceeds the set value, it will report a b-phase winding fault;

8) C-phase winding fault judgment; compare the calculated a mutual inductance value _Lab with the initial input of the permanent magnet synchronous motor parameter mutual inductance value of the controller vector control or the mutual inductance value obtained from the permanent magnet synchronous motor control parameter identification, if the two When the difference exceeds the set value, it will report a c-phase winding fault.

In this technical solution, the calculation of the zero-sequence inductance starts directly from the existing three-phase permanent magnet synchronous motor winding flux linkage, obtains the flux linkage of the three-phase winding from the coordinate transformation of dqo to abc, and calculates the zero sequence through the phase flux linkage expression Sequence inductance, and then obtain the permanent magnet synchronous motor phase self-inductance and mutual inductance expression to find out the self-inductance and mutual inductance, compare with the normal self-inductance and mutual inductance in the permanent magnet synchronous motor controller, and determine which phase winding fault. By using the parameter variables in the vector control of the permanent magnet synchronous motor, the calculation amount of the controller data is greatly reduced, and if there is a fault in the permanent magnet synchronous motor winding, it can be responded in time.

As a further improvement and supplement to the above technical solutions, the present invention also includes the following additional technical features.

In step 2) calculate the steady state stator quadrature axis current in the dqo coordinate system and straight axis , assuming that the number of turns of each phase of the three-phase winding is T ₁ , and the magnitude of the current is equal, then according to the principle of equal magnetomotive force, the number of turns of each of the two windings is 3T ₁ /2. By decomposing the three-phase magnetomotive force along the d-axis and q-axis directions, the two-phase d-axis and q-axis magnetomotive forces are obtained.

It also includes the sudden change judgment of the zero-sequence inductance L _o . When the difference between the zero-sequence inductance L _o obtained by the current calculation and the previous zero-sequence inductance L _o ' exceeds the set value, it is determined that the motor is faulty and the motor is shut down for processing.

Beneficial effects: the technical scheme directly uses the parameter variables in the vector control of the permanent magnet synchronous motor, greatly reduces the calculation amount of controller data, and can respond in time if there is a fault in the permanent magnet synchronous motor winding. Avoid repeated calculations, effectively increase the calculation speed, and reduce the requirements for hardware. For the fault identification of permanent magnet synchronous motors in vector control, it is simple, practical and effective, and can realize timely and accurate online fault judgment under any circumstances.

Description of drawings

Fig. 1 is the flow chart of the present invention.

detailed description

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

In the conversion from the three-phase coordinate system of the motor to the two-phase coordinate system, the equivalence between the two-phase system and the three-phase system is based on the criterion that the two-phase system and the three-phase system produce equal magnetomotive force and equal current amplitude.

As shown in Figure 1, the present invention comprises the following steps:

Step 1): Calculate the zero-sequence current i _o value; assuming that there is a zero-sequence inductance L _o , then there is a zero-sequence flux linkage Ψ _o ; the parameters that can be extracted during the vector control operation of the permanent magnet synchronous motor are q-axis flux linkage d-axis flux linkage The permanent magnet synchronous motor controller AD detects the a-phase current i _as , b-phase current i _bs and c-phase current i _cs ; thus the zero-sequence current i _o can be expressed as follows

i _o ＝1/3(i _as +i _bs +i _cs ) (Formula 18)

Step 2): Assuming that the number of turns of each phase of the three-phase winding is T ₁ , and the amplitude of the current is equal, then according to the principle of equal magnetomotive force, the number of turns of each of the two windings should be 3T ₁ /2 . By decomposing the three-phase magnetomotive force along the d-axis and q-axis directions, the two-phase d-axis and q-axis magnetomotive forces can be obtained. Common terms on both sides of the equation, such as the number of turns of the winding, will be eliminated to obtain the current equation. Then the relationship between dqo and the current i _as , i _bs , i _cs in the abc coordinate system can be written as

It can be calculated from this formula with value;

In the formula with are the steady-state stator quadrature axis and direct axis currents in the dqo coordinate system.

Step 3): According to the flux linkage under the dqo coordinate system with Expression, can calculate L _d and L _q value;

The flux linkage expression of the permanent magnet synchronous motor in the dqo coordinate system is

ψ _o ＝L _o i _o (Formula 22)

Step 4): Magnetic linkage in the dqo coordinate system and ψ _o can be transformed from dqo to abc three-phase coordinate system, and the motor phase flux linkage ψ _as can be obtained, and its expressed value is as follows

Put the dqo coordinates under the magnet link and ψ _o are substituted into the phase flux linkage expression, i _o is represented by phase current i _as , i _bs and i _cs , and the expression of phase a flux linkage can be obtained, from which the L _o value of the permanent magnet synchronous motor in the current state can be calculated;

Step 5): In the abc three-phase coordinate system, the a-phase flux linkage ψ _as can be expressed by self-inductance flux linkage and mutual inductance flux linkage, and then can be written as the expression of corresponding inductance and current as follows

ψ _as ＝L _aa i _as +L _ab i _bs +L _ac i _cs +Ψ _af sinθ _r (Formula 25)

By comparing Equation 24 and Equation 25, the expression of self-inductance and mutual inductance of phase a of permanent magnet synchronous motor can be obtained as

L _aa ＝2/3{L _o /2+(L _q +L _d )/2+((L _q -L _d )/2)cos2θ _r }

＝L _o /3+(L _q +L _d )/3+((L _q -L _d )/3)cos2θ _r (Formula 26)

L _ab ＝-2/3{-L _o /2+(L _q +L _d )/4+((L _q -L _d )/2)}cos2(θ _r +30°)}

＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos2(θ _r +30°)} (Formula 27)

L _ac ＝-2/3{-L _o /2+(L _q +L _d )/4+{(L _q -L _d )/2)}cos2(θ _r +150°)}

＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos2(θ _r +150°)} (Formula 28)

The self-inductance and mutual inductance L _aa , _{Lab ab} and L _ac values of the permanent magnet synchronous motor are calculated from the above relational formula.

Step 6) Compare the calculated self-inductance value L _aa of phase a with the self-inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the self-inductance value obtained by the identification of the permanent magnet synchronous motor control parameter. If they are not equal, report A-phase winding failure;

Step 7) Compare the calculated a mutual inductance value _Lab with the mutual inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the mutual inductance value obtained by the identification of the permanent magnet synchronous motor control parameter. If they are not equal, report the phase b winding Fault;

Step 8) Compare the calculated mutual inductance value L _ac with the mutual inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the mutual inductance value obtained by the identification of the permanent magnet synchronous motor control parameter. If they are not equal, report the c-phase winding Fault.

A permanent magnet synchronous motor fault judgment method based on zero-sequence inductance shown in the above figure 1 is a specific embodiment of the present invention, which has already reflected the substantive characteristics and progress of the present invention, and can be used according to actual needs in the present invention. Under the inspiration of the present invention, the equivalent modification of its shape, structure and other aspects are all within the scope of protection of this scheme.

Claims (3)

1. a permanent magnet synchronous motor fault determination method based on zero-sequence inductance, is characterized in that comprising the following steps: 1) Calculate the zero-sequence current i _o value; extract the parameters in the vector control operation of the permanent magnet synchronous motor: q-axis flux linkage d-axis flux linkage Permanent magnet synchronous motor controller AD detects a-phase current i _as , b-phase current i _bs and c-phase current i _cs ; calculate zero-sequence current i _o : i _o ＝1/3(i _as +i _bs +i _cs ) 2) Calculate the steady state stator quadrature axis current in the dqo coordinate system and straight axis According to the parameter value obtained in step 1), by the following formula Calculated with value; where θ _r is the rotor angle, which is obtained directly by extracting the parameter value of the rotor angle in the vector control operation of the permanent magnet synchronous motor; 3) Calculate the quadrature-axis inductance L _q and the direct-axis inductance L _d ; according to the flux linkage under the dqo coordinate system with expression: Calculate the quadrature axis inductance L _q and the direct axis inductance L _d ; where ψ _af is the armature flux linkage generated by the permanent magnet and is the fixed parameter value of the motor; 4) Calculate the zero-sequence inductance L _o value of the permanent magnet synchronous motor under the current state; according to the expression of a-phase flux linkage: Calculate the L _o value of the permanent magnet synchronous motor in the current state; 5) Calculate the self-inductance L _aa and mutual inductance L _ab and L _ac values of the permanent magnet synchronous motor; according to the self-inductance and mutual inductance expressions of phase a of the permanent magnet synchronous motor: L _aa ＝2/3{L _o /2+(L _q +L _d )/2+((L _q -L _d )/2)cos 2θ _r } ＝L _o /3+(L _q +L _d )/3+((L _q -L _d )/3) cos 2θ _r L _ab ＝-2/3{-L _o /2+(L _q +L _d )/4+((L _q -L _d )/2)}cos 2(θ _r +30°)} ＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos 2(θ _r +30°)} L _ac ＝-2/3{-L _o /2+(L _q +L _d )/4+{(L _q -L _d )/2)}cos 2(θ _r +150°)} ＝-{-L _o /3+(L _q +L _d )/6+((L _q -L _d )/3)cos 2(θ _r +150°)} Calculate the self-inductance and mutual inductance L _aa , _Lab and L _ac values of the permanent magnet synchronous motor; 6) Phase a winding fault judgment; compare the calculated self-inductance value L _aa of phase a with the self-inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the self-inductance value obtained by the identification of the permanent magnet synchronous motor control parameter, If the difference between the two exceeds the set value, it will report a phase winding fault; 7) Fault judgment of the _b -phase winding; compare the calculated mutual inductance value Lab a with the mutual inductance value of the permanent magnet synchronous motor parameter initially input by the controller vector control or the mutual inductance value obtained from the identification of the permanent magnet synchronous motor control parameter, if both When the difference exceeds the set value, it will report a b-phase winding fault; 8) C-phase winding fault judgment; compare the calculated a mutual inductance value L _ac with the initial input of the permanent magnet synchronous motor parameter mutual inductance value of the controller vector control or the mutual inductance value obtained from the permanent magnet synchronous motor control parameter identification, if the two When the difference exceeds the set value, it will report a c-phase winding fault. 2. a kind of permanent magnet synchronous motor fault determination method based on zero-sequence inductance according to claim 1, is characterized in that: in step 2) calculates steady state stator quadrature axis current under dqo coordinate system and straight axis , assuming that the number of turns of each phase of the three-phase winding is T ₁ , and the magnitude of the current is equal, then according to the principle of equal magnetomotive force, the number of turns of each phase of the two-phase winding is 3T ₁ /2, by The three-phase magnetomotive force is decomposed along the d-axis and q-axis directions to obtain the magnetomotive force of the two-phase d-axis and q-axis. 3. A kind of permanent magnet synchronous motor fault judgment method based on zero-sequence inductance according to claim 1, it is characterized in that: also comprise zero-sequence inductance L _O sudden change judgment, when current calculation obtains zero-sequence inductance L _o and before When the difference of the zero-sequence inductance L _o ' exceeds the set value, it is determined that the motor is faulty, and the motor is stopped to wait for processing.