Measure the initial position of rotor method of permagnetic synchronous motor
Technical field
The present invention relates to a kind of permagnetic synchronous motor, relate in particular to the initial position of rotor method of measuring this motor.
Background technology
Can the accuracy that the permagnetic synchronous motor initial position of rotor is judged is directly connected to motor start smoothly, and with the problem of breakdown torque starting.
The initial position of rotor method of existing measurement permagnetic synchronous motor is the step of applying the constant voltage space vector for the armature winding by adopting, in motor gas-gap, form equivalent magnetic linkage circle, detect armature supply corresponding under each vector effect then, the phase current equivalent transformation is become current component under the dq coordinate system, compare the size of d shaft current under each voltage vector effect, the angle at the voltage vector place of maximum current correspondence is the initial position angle of rotor.In the method, do not rotate, need make adjustment, promptly take the vector applying method of " positive is anti-" the order that applies of space vector of voltage in order when applying space vector of voltage, not make motor." one positive one is anti-" promptly after having applied some vectors, next applies the anti-vector of this vector.
As seen from Figure 1: in an electric cycle, distribute 12 space vector of voltage, each vector angle at interval is 30 ° of electrical degrees; 12 voltage vectors have identical modulation degree.Each voltage vector applies a switch periods, needs to close six some switch periods of switching tube between any two voltage vectors.
Concrete applying method is as follows: after vector 1 has applied, close six some switch periods of switching tube, apply vector 2 then, close the same switch periods of six switching tubes and front afterwards; Then, apply vector 3, then close six some cycles of switching tube, continue to apply vector 4, like this and the like, apply up to 12 vectors and to finish., need to detect the phase current magnitude of motor two-phase, and carry out equivalent transformation between action period at each voltage vector.After 12 voltage vectors apply and finish, compare the axial current amplitude size of d under each self-corresponding dq coordinate system, the rotor-position of the vector place angle of the correspondence of current amplitude maximum for tentatively obtaining.
Figure 2 shows that the voltage vector when rotor-position is proceeded accurately to judge applies principle schematic.The rotor-position that obtains with top step judgement is that the θ angle is the example explanation.This step applies the regular as follows of voltage vector: first voltage vector angle that applies is (θ-15) electrical degree, next, close six some switch periods of switching tube, need to apply vector 2 afterwards, this vector is the anti-vector of vector 1, and promptly its angle differs 180 ° of electrical degrees with (θ-15); The angle of vector 3 is θ, and vector 4 is the anti-vector of vector 3, and the angle of vector 5 is (θ+15), and vector 6 is the anti-vector of vector 5.Apply successively according to order from vector 1~vector 6, each vector applies a switch periods, at each vector between action period, detect electric machine phase current and carry out equivalent transformation, be transformed to the current value under the dq coordinate system, and relatively in the axial current value size of d, to be the precision that obtains be the rotor position angle of 15 ° of electrical degrees to the angle of the vector correspondence at maximum electric current place in six current values.
According to accurate determination methods as above, under the situation of current sampling circuit and software condition permission, voltage vector further can be segmented, thereby obtain the more rotor position angle of pinpoint accuracy.
But, this method is applied to actual time, sometimes also such problem can occur: actual angle is the θ angle, and judge that by above-mentioned method perhaps the result who obtains is θ+180 ° or θ-180 °, even may be other angles, even more accurate hardware circuit is arranged like this and,, also has the problem that evaluated error is big even estimation is failed because radix θ is wrong than the complex software algorithm.
Summary of the invention
The technical issues that need to address of the present invention have provided a kind of initial position of rotor method of measuring permagnetic synchronous motor, are intended to solve above-mentioned defective.
In order to solve the problems of the technologies described above, the present invention realizes by following steps:
The present invention includes the step that applies the constant voltage space vector to the armature winding;
Also comprise applying identical width voltage pulse, be used to the step of judging that the initial rotor magnetic pole points to armature winding:
Apply first potential pulse, A goes up the brachium pontis conducting mutually, and B descends the brachium pontis conducting mutually with C, and three's conducting width equates that conduction period A phase current is the purpose electric current, promptly will detect A phase current peak value;
Apply second potential pulse, A descends the brachium pontis conducting mutually, and B goes up the brachium pontis conducting mutually with C, and three's conducting width equates and be also equal with the width of first pulse that conduction period A phase current is the purpose electric current, but this moment, electric current was a negative value;
Apply the 3rd potential pulse, B goes up the brachium pontis conducting mutually, and A descends the brachium pontis conducting mutually with C, and three's conducting width equates that conduction period B phase current is the purpose electric current, promptly will detect B phase current peak value;
Apply the 4th potential pulse, B descends the brachium pontis conducting mutually, and A goes up the brachium pontis conducting mutually with C, and three's conducting width equates and be also equal with the width of first pulse that conduction period B phase current is the purpose electric current, but this moment, electric current was a negative value;
Apply the 5th potential pulse, C goes up the brachium pontis conducting mutually, and A descends the brachium pontis conducting mutually with B, and three's conducting width equates that conduction period C phase current is the purpose electric current, promptly will detect C phase current peak value;
Apply the 6th potential pulse, C descends the brachium pontis conducting mutually, and A goes up the brachium pontis conducting mutually with B, and three's conducting width equates and be also equal with the width of first pulse that conduction period C phase current is the purpose electric current, but this moment, electric current was a negative value;
Detect and calculate purpose electric current separately;
The current changing rate on three phase windings relatively, that axis mutually of rotor magnetic pole axis and current changing rate maximum from recently, and the sense of current of direction and variation is consistent.
Compared with prior art, the invention has the beneficial effects as follows: can definite angle fix in certain scope, thereby improve accuracy and the reliability that initial position of rotor is judged initial rotor.
Description of drawings
Fig. 1 is the sequential schematic that applies space vector of voltage in the initial position of rotor method of existing measurement permagnetic synchronous motor;
When Fig. 2 was the initial position of rotor method rotor initial position judgement of existing measurement permagnetic synchronous motor, segmentation angle, the voltage vector of accurately judging applied sequential schematic;
Embodiment
Below in conjunction with accompanying drawing and embodiment the present invention is described in further detail:
The present invention realizes by following steps:
The present invention includes the step that applies the constant voltage space vector to the armature winding;
Also comprise applying identical width voltage pulse, be used to the step of judging that the initial rotor magnetic pole points to armature winding:
Apply first potential pulse, A goes up the brachium pontis conducting mutually, and B descends the brachium pontis conducting mutually with C, and three's conducting width equates that conduction period A phase current is the purpose electric current, promptly will detect A phase current peak value;
Apply second potential pulse, A descends the brachium pontis conducting mutually, and B goes up the brachium pontis conducting mutually with C, and three's conducting width equates and be also equal with the width of first pulse that conduction period A phase current is the purpose electric current, but this moment, electric current was a negative value;
Apply the 3rd potential pulse, B goes up the brachium pontis conducting mutually, and A descends the brachium pontis conducting mutually with C, and three's conducting width equates that conduction period B phase current is the purpose electric current, promptly will detect B phase current peak value;
Apply the 4th potential pulse, B descends the brachium pontis conducting mutually, and A goes up the brachium pontis conducting mutually with C, and three's conducting width equates and be also equal with the width of first pulse that conduction period B phase current is the purpose electric current, but this moment, electric current was a negative value;
Apply the 5th potential pulse, C goes up the brachium pontis conducting mutually, and A descends the brachium pontis conducting mutually with B, and three's conducting width equates that conduction period C phase current is the purpose electric current, promptly will detect C phase current peak value;
Apply the 6th potential pulse, C descends the brachium pontis conducting mutually, and A goes up the brachium pontis conducting mutually with B, and three's conducting width equates and be also equal with the width of first pulse that conduction period C phase current is the purpose electric current, but this moment, electric current was a negative value;
Detect and calculate purpose electric current separately;
The current changing rate on three phase windings relatively, that axis mutually of rotor magnetic pole axis and current changing rate maximum from recently, and the sense of current of direction and variation is consistent.
With first pulse is example explanation, suppose in the three-phase current, and the rate of change of A phase current is maximum and be negative value, then can judge rotor magnetic pole axis and A phase winding axis from must be recently, and magnetic pole is oriented to the negative direction of A phase winding axis.In conjunction with Fig. 1 as can be known, the angle that A phase winding axis negative direction zone comprises should be between-150 °~210 °, if be example with 12 vectors, then comprised vector 11, vector 2, vector 4.Therefore, if the exact position of the rotor that obtains between this zone, illustrates that the judgement angle of rotor-position is correct, if not, then explanation gets the wrong sow by the ear.
Table 1 is the rule that identical width voltage pulse applies:
The potential pulse order |
Rule S (ABC) |
The purpose electric current |
The region comprises space vector of voltage |
1 |
100 |
i
A+ |
A+:12,1,3 |
2 |
011 |
i
A |
A-:11,2,4 |
3 |
010 |
i
B+ |
B+:7,9,11 |
4 |
101 |
-i
B- |
B-:8,10,12 |
5 |
001 |
i
C+=-(i
A+i
B)
|
C+:4,6,8 |
6 |
110 |
i
C-=-(i
A+i
B)
|
C-:3,5,7 |
The present invention relies on to armature winding and applies identical width voltage pulse successively, measure the positive current and the negative current of every phase winding, by relatively its current changing rate and the positive and negative concrete sensing of judging rotor magnetic pole, improve reliability and the accuracy judged, reduce the possibility of judging failure.