JP3278032B2 - Rotor pole polarity detection method for permanent magnet synchronous motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection method for detecting the polarity of a rotor magnetic pole of a permanent magnet synchronous motor.

[0002]

2. Description of the Related Art A permanent magnet synchronous motor needs to detect an absolute position of a field pole in order to generate a maximum torque. As a method for detecting the position of the field pole, there is a method using a resolver. This is a synchro or similar device in which the rotor is driven mechanically to produce an electrical output corresponding to the sine or cosine of the rotor angle. In this method, a separate coil-shaped sensor is provided coaxially with the rotor, and the output voltage is changed according to the position of the rotor. The position of the rotor can be known from the voltage value. In addition, since the positioning is performed in advance, if the rotor position is known, the polarity of the rotor magnetic pole can be naturally known.
There is also a method of detecting the position of a magnetic pole by combining Hall elements. In this method, the Hall elements are used in a number equal to the number of phases of the armature windings of the permanent magnet synchronous motor, and are fixed to the motor while maintaining a fixed relationship with the armature windings. A signal disk that rotates integrally with the field pole is provided on the rotor shaft, and a signal is given when the signal disk passes through the Hall element, and this is a position signal of the magnetic pole. As a sensorless position detection method, there is a method that utilizes the saliency of the rotor. When the rotor has saliency, the reactance of each phase differs depending on the position of the rotor. Therefore, the reactance can be detected to detect the magnetic pole position of the rotor. In addition, there is a method in which the instantaneous values of the voltage and current of each phase are converted into three-phase to two-phase, and the deviation angle between the d-axis and the q-axis is determined to detect the magnetic pole position of the rotor.

[0003]

Since the conventional permanent magnet type synchronous motor is provided with a magnetic pole position sensor such as a Hall element, the size of the motor becomes large and a cable from the sensor is required. In addition, there are various problems such as the cost of the sensor and the time and effort required for mounting and positioning during manufacture. In order to solve these situations, it is necessary to promote sensorless operation. However, even if the magnetic pole position can be detected, it is not possible to determine the polarity of the magnetic pole, that is, the N pole or the S pole. There was a problem that it could not be decided.

An object of the present invention is to provide a rotor magnetic pole polarity detection method capable of detecting the position and polarity of the magnetic pole of a permanent magnet synchronous motor without using a detection sensor.

[0005]

SUMMARY OF THE INVENTION In a permanent magnet synchronous motor having a permanent magnet on a rotor surface, a three-phase stator winding is formed by magnetizing a magnetic flux density of a stator core near an inflection point on a magnetization characteristic. Applying a positive and negative pulse voltage between one phase winding of the wire and the other short-circuited two phases, and a response current of both the transients after the application of the pulse voltage applied phase. A step of detecting the magnitude, and a step of determining whether the portion of the permanent magnet of the rotor facing the pulse voltage application winding is at the center of the magnetic pole or between the poles based on the presence or absence of the detected response current difference, When the position of the permanent magnet of the rotor facing the pulse voltage application winding is the center of the magnetic pole, a step of determining whether the detected response current is in the direction of increasing or decreasing the magnetic flux density of the stator core, The magnetic pole opposite to the phase to which the pulse voltage was applied is the N pole By comprising the step of determining whether the S-pole, to achieve the above object.

Further, the magnetic flux density of the rotor core is magnetized in the vicinity of the inflection point on the magnetizing characteristic, so that one of the three-phase stator windings is connected to the other two short-circuited phases. A step of applying a positive or negative direction pulse voltage, a step of detecting the magnitude of both response currents during a transient after application of the phase to which the pulse voltage is applied, and a step of applying a pulse voltage based on the presence or absence of a difference between the detected response currents. A step of determining whether the permanent magnet portion of the rotor facing the applied winding is at the center of the magnetic pole or between the poles, and when the permanent magnet portion of the rotor facing the pulse voltage applying winding is at the center of the magnetic pole Determining whether the detected response current is in the direction of increasing or demagnetizing the magnetic flux density of the stator core; and, based on the determination result, whether the magnetic pole facing the phase to which the pulse voltage has been applied is an N pole or an S pole. Is determined.

[0007] When the magnetic flux density of the stator core or the rotor core due to the magnetic flux generated from the permanent magnet does not reach the vicinity of the inflection point on the magnetization characteristics, the stator winding is DC-excited to excite the stator core or the stator core. After the magnetic flux density of the rotor core reaches the inflection point on the magnetization characteristic, a pulse voltage is superimposed in the positive and negative directions, and it is determined whether the magnetic pole corresponding to the phase to which the pulse voltage is applied is the N pole or the S pole. This is suitable for detecting the polarity of the rotor magnetic pole.

[0008]

According to the present invention, the inductance of a stator winding different in the magnetic pole polarity of a rotor is detected by a current corresponding to a change in magnetic flux density of a core caused by a voltage applied to the winding, and the phase of the stator winding is detected. This is to determine the polarity of the magnetic pole of the corresponding permanent magnet. That is, in the diagram showing the relationship between the magnetic property and the magnetic flux density of the stator core or the rotor core shown in FIG. 12, the magnetic flux density B of the iron core is set to be near the inflection point O on the magnetic property of FIG. , different changes in the magnetic flux when a current flows in a direction to demagnetize a when current flows in the direction of Zo磁magnetic flux in the stator windings, large flux change amount for demagnetization direction of current change H ₂ , the amount of magnetic flux change with respect to Zo磁direction of current change H ₁ is reduced. Since the inductance is proportional to the amount of change in magnetic flux, the inductance of the stator winding corresponding to the iron core in the direction of demagnetization is smaller than in the direction of demagnetization. This difference in inductance, as shown in Figure characteristics showing current change after the application of a voltage in the iron core of FIG. 13, the above-mentioned magnetic properties than Zo磁direction current of the core by applying a voltages V ₁ to the core from the stator winding Flows as A ₁ , and the demagnetizing current flows as A ₂ . Therefore, Zo磁direction current when applying a pulse voltage V _p as shown in FIG. 14 is changed as in A _p1, demagnetization direction current comes out as a difference in the rise of the changed current as the A _p2.

FIG. 15 is a sectional view of a permanent magnet type synchronous motor. In FIG. 15, a cylindrical permanent magnet 2 is mounted on an outer diameter side of a rotor core 1 which is a rotor shaft, and is magnetized in a radial direction to constitute a rotor. A stator core 3 which is an armature core is arranged on the outer diameter side of the rotor, and a stator winding U-phase winding (positive direction) 4 and a U-phase Winding (negative direction) 5, V-phase winding (positive direction)
6, V-phase winding (negative direction) 7, W-phase winding (positive direction) 8, W
A phase winding (negative direction) 9 is wound. In such a permanent magnet type synchronous motor, when the magnetic flux density of the stator core 3 or the rotor core 1 is magnetized in the vicinity of the inflection point on the magnetization characteristics, the winding phase is positive and negative as described above. During the transient of applying a pulse voltage in the direction, when the current flows in the direction of increasing the magnetic flux density of the iron core, the amount of change in magnetic flux is small and the response current is large, and when the current flows in the direction of demagnetization, the amount of change in magnetic flux is large. The response current is small. Therefore, when the magnetic flux generated by the current of the applied winding phase and the magnetic flux generated by the permanent magnet 2 pass through the stator core 3 or the rotor core 1 in the same direction, the magnetic flux is increased, and the magnetic flux generated by the applied phase current becomes permanent. When the magnetic flux from the magnet 2 passes in the opposite direction, demagnetization occurs. In this way, the polarity of the permanent magnet magnetic pole facing the pulse voltage application phase of the stator winding can be determined from the magnitude of both response currents.

When the magnetic flux density of the stator core 3 or the rotor core 1 does not reach the inflection point on the magnetization characteristics due to the magnetic flux generated from the permanent magnet, the stator winding is DC-excited and the stator is excited. By reaching the magnetic flux density of the iron core 3 or the rotor iron core 1 near the inflection point on the magnetization characteristic, the polarity of the rotor magnetic pole can be determined in the same manner as described above.

[0011]

FIG. 1 is a diagram showing magnets and magnetic flux due to current when a magnetic pole of a permanent magnet is directly below a U-phase in a permanent magnet type synchronous motor. FIG. 1 (A) is a diagram showing a case where an N-pole is directly below. (B) is a diagram showing a case where the S pole is directly below. FIG. 1 has the same configuration as that of FIG. 15 in which the stator winding is a short section and concentrated winding, and the same parts as those of FIG. 15 are denoted by the same reference numerals and description thereof will be omitted. In FIG. 1, the stator core 3 is configured such that the magnetic flux density of the stator core 3 reaches near the inflection point on the magnetization characteristic by the magnetic flux generated from the permanent magnet 2.
In this case, when a magnetic pole exists immediately below the U phase stator core, the V and W phase windings are short-circuited, and a pulse voltage is applied between the U and VW phases. At this time, when the U-, V-, and W-phase currents flow as shown in FIG. 1 , the magnetic flux 10 generated by the magnet flows in the direction of the solid arrow, and the magnetic flux 11 generated by the current flows in the direction of the broken arrow. As a result, when the magnetic pole immediately below the U-phase is the N-pole, the current is in the direction of increase in magnetism, and when the magnetic pole immediately below the U-phase is the S-pole, the current is in the direction of demagnetization. For this reason, if the detected value of the stator winding current is large, the magnetic pole immediately below the U phase is the N pole, and if the detected current value of the stator winding response current is small, the magnetic pole immediately below the U phase is the S pole. You can see that.

FIG. 2 is a diagram showing the magnetic flux generated by the permanent magnet when the gap between the permanent magnets is immediately below the U-phase. In this case, the magnetic flux from the permanent magnet 2 hardly passes through the stator core, so that it is far from the inflection point of the magnetization characteristic, and the inductance of the stator winding does not change due to the increase or decrease of the magnetization. Even if a pulse voltage is applied, no difference in the magnitude of the current appears. In such a case, the phase to be detected may be the V phase or the W phase. That is,
In FIG. 2, since the magnets immediately below the V-phase windings 6, 7 and the W-phase windings 8, 9 are located at the center of the magnetic poles, V-WU
By applying a pulse voltage between the two or between W and UV, the polarity of the magnet can be determined as described above.

[0013] In the embodiment described above, that the magnetic flux density of the stator core 3 is made of a configuration that is set to be located in the vicinity of the inflection point on the magnetic properties by magnetic flux generated from the permanent magnet 2
Is a determination method in, it is possible to determine similarly permanent magnet type synchronous motor having the configuration in which the rotor core 1 is magnetized to be the inflection point on the magnetizable. That is, when a magnetic pole exists immediately below the U-phase stator core shown in FIGS. 1A and 1B, the magnetic flux 11 and the permanent magnet 2 caused by the current flowing when a pulse voltage is applied between the U-VW phases. The magnetic flux 10 crosses and passes through the rotor core 1. Therefore, by setting the rotor core 1 so as to be near the inflection point on the magnetization characteristics as described above , the magnetic pole immediately below the U phase as shown in FIG. When a pulse voltage is applied between U and VW, the response current of the U-phase stator windings 4 and 5 is in the direction of demagnetization, and the current in the case of the S pole is in the direction of demagnetization as shown in FIG. Accordingly, it is possible to determine the magnetic pole polarity of the permanent magnet provided on the rotor surface. Further, by providing the magnetic flux region near the magnetization characteristic inflection point on the rotor core in the DC magnetic field, the increase in iron loss is suppressed as compared with the case where the magnetic field is provided on the stator core in the AC magnetic field on the armature side. Motor configuration.

Next, the results of the simulation are shown in FIGS. FIG. 3 is a diagram showing an analysis shape of the permanent magnet synchronous motor. In FIG. 3, a permanent magnet 2 is attached to the outer diameter of the rotor core 1 and magnetized as shown in FIG. 3 to form a rotor. The magnetic flux density of the stator core 3 is magnetized by the magnetic flux generated by the permanent magnet 2. It is set to be near the characteristic inflection point. A stator core 3 is arranged outside the rotor, and a U-phase winding (positive direction) 4, a U-phase winding (negative direction) 5, a V-phase winding (positive direction) 6, and a V-phase winding Line (negative direction)
7, a W-phase winding (positive direction) 8, and a W-phase winding (negative direction) 9 are wound. FIG. 4 is a diagram showing the magnetic flux generated by the magnet when the pole of the permanent magnet is located immediately below the U-phase in FIG. FIG.
Is a diagram showing a voltage waveform applied to the permanent magnet synchronous motor of FIG. 3, in which the horizontal axis represents time (seconds) and the vertical axis represents voltage (V). Figure 6 is a diagram showing a U-phase response current upon application by changing the voltage direction in FIG. 5 between U-VW, A _U1 is Zo磁direction current,
A _U2 indicates a demagnetization direction current. FIG. 7 is a diagram showing the U-phase response current for 1.2 ms in FIG. 6, where A _U1 is the current in the magnetizing direction,
A _U2 indicates a demagnetization direction current. The final difference between the current in the increasing direction and the current in the demagnetizing direction in FIG. 7 corresponds to the difference between the rising currents at a pulse voltage of 1.2 ms width.

FIG. 8 is a diagram showing the magnetic flux generated by the magnet when the gap between the poles of the permanent magnet type synchronous motor is directly below the U-phase. 8, the same parts as those in FIG. 7 are denoted by the same reference numerals. At this time, since magnetic poles having different polarities exist under the V phase and the W phase in the same positional relationship, the voltage shown in FIG.
FIG. 9 shows the calculated response currents of the V and W phases applied between VW. In FIG. 9, A _W indicates a W-phase current, and A _V indicates a V-phase current. In this case, the V-phase current is in the demagnetization direction, and the W-phase current is in the magnetization direction. FIG. 10 is a diagram showing the V-phase and W-phase response currents up to 1.2 ms in FIG. The difference in the final current value after 1.2 ms in FIG. 10 corresponds to the difference in the rising current when the voltage width is 1.2 seconds. Therefore, if it is determined in advance whether the direction of voltage application is between U-VW, V-WU, or W-UV, the magnitude of the response current of each phase can be used to determine whether the magnetization is demagnetization or demagnetization. It can be determined whether it is a pole.

When the magnetic flux density of the stator core 3 or the rotor core 1 is not near the inflection point on the magnetization characteristic due to the magnetic flux from the permanent magnet 2, the stator winding is DC-excited and the stator core is excited. 3 or the magnetic flux density of the rotor core 1 is set near the inflection point. Then, the positive and negative pulse voltages are superimposed and applied to the stator winding. FIG. 11 shows the state when the above-described DC excitation and pulse voltage were applied to the stator winding.
It is a figure which shows a voltage and a current waveform. After applying the pulse voltage,
As described above, the magnetic pole polarity of the rotor can be determined from the magnetization characteristics of the stator core 3 or the rotor core 1 and the response current. In this embodiment, the configuration of the short section and concentrated winding is described, but the same applies to other armature shapes such as full section and distributed winding.

[0017]

According to the present invention, the stator core or the rotor core of the permanent magnet type synchronous motor is designed so that the magnetic flux density is near the inflection point on the magnetization characteristic, or the stator winding is formed. DC excitation to apply a pulse voltage in both positive and negative directions to the stator winding so that the magnetic flux density of the stator core or rotor core is near the inflection point of the magnetization characteristics. The position and polarity of the permanent magnet facing the pulse voltage application phase of the stator winding by detecting whether the magnetic flux of the stator winding Can be determined, so that the rationalization of the detection measurement is achieved without requiring a special sensor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a magnet and a magnetic flux by an electric current when a magnetic pole is directly below a U-phase in a permanent magnet type synchronous motor;
(A) is a diagram showing a case where the N pole is directly below, and (B) is a diagram showing a case where the S pole is directly below.

FIG. 2 is a diagram illustrating magnets and magnetic fluxes due to current when a gap is directly below a U-phase in a permanent magnet synchronous motor.

FIG. 3 is a diagram showing an analysis shape of a permanent magnet type synchronous motor.

FIG. 4 is a diagram illustrating a magnetic flux generated by a magnet when a magnetic pole of a permanent magnet is located immediately below a U-phase in FIG. 3;

5 is a diagram showing a voltage waveform applied to the permanent magnet type synchronous motor of FIG.

FIG. 6 is a diagram showing a U-phase response current when the voltage of FIG. 5 is applied in a different direction between U and VW.

FIG. 7 is a diagram showing a U-phase response current for 1.2 ms in FIG. 6;

FIG. 8 is a diagram illustrating a magnetic flux generated by a magnet when a gap between the poles of the permanent magnet type synchronous motor is immediately below a U-phase.

FIG. 9 is a diagram showing V and W phase response currents when the voltage of FIG. 5 is applied between U and VW.

FIG. 10 is a diagram showing V-phase and W-phase response currents up to 1.2 ms in FIG. 9;

FIG. 11 is a diagram showing voltage and current waveforms when DC excitation and pulse voltage are applied to a stator winding.

FIG. 12 is a diagram showing a relationship between a magnetization characteristic of an iron core and a magnetic flux density.

FIG. 13 is a diagram showing a change in current after voltage is applied to the iron core.

FIG. 14 is a diagram showing a current when a pulse voltage is applied to an iron core.

FIG. 15 is a longitudinal sectional view of a permanent magnet type synchronous motor.

[Explanation of symbols]

 Reference Signs List 1 rotor core 2 permanent magnet 3 stator core 4 U-phase winding (positive direction) 5 U-phase winding (negative direction) 6 V-phase winding (positive direction) 7 V-phase winding (negative direction) 8 W-phase Winding (positive direction) 9 W-phase winding (negative direction) 10 Magnetic flux by magnet 11 Magnetic flux by current

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02P 6/16 H02K 21/16 H02P 5/28 H02P 7/36

Claims (3)

(57) [Claims] In a permanent magnet type synchronous motor having a permanent magnet on a rotor surface, a magnetic flux density of a stator core is magnetized near an inflection point on magnetization characteristics, and one of three-phase stator windings is provided.
Applying positive and negative pulse voltages between the phase windings and the other two short-circuited phases, and detecting the magnitude of both the response current during the transient after the application of the pulse voltage applied phase Determining whether the portion of the permanent magnet of the rotor facing the pulse voltage application winding is at the center of the magnetic pole or between the poles based on the presence or absence of the difference between the detected response currents. When the position of the permanent magnet of the rotor facing the line is the center of the magnetic pole, a step of determining whether the detected response current is in the direction of increasing or decreasing the magnetic flux density of the stator core, and from the determination result, Discriminating whether a magnetic pole facing a phase to which a voltage is applied is an N pole or an S pole. A method of detecting the polarity of a rotor magnetic pole of a permanent magnet type synchronous motor, comprising: 2. A permanent magnet synchronous motor having a permanent magnet on a rotor surface, wherein a magnetic flux density of a rotor core is magnetized near an inflection point on a magnetization characteristic, and one of three-phase stator windings is provided.
Applying positive and negative pulse voltages between the phase windings and the other two short-circuited phases, and detecting the magnitude of both the response current during the transient after the application of the pulse voltage applied phase Determining whether the portion of the permanent magnet of the rotor facing the pulse voltage application winding is at the center of the magnetic pole or between the poles based on the presence or absence of the difference between the detected response currents. A step of determining whether the detected response current is the direction of increase or demagnetization of the magnetic flux density of the stator core when the permanent magnet portion of the rotor facing the wire is at the center of the magnetic pole; Discriminating whether a magnetic pole facing a phase to which a voltage is applied is an N pole or an S pole. A method of detecting the polarity of a rotor magnetic pole of a permanent magnet type synchronous motor, comprising: 3. The method for determining the polarity of a rotor magnetic pole of a permanent magnet synchronous motor according to claim 1 or 2, wherein the magnetic flux density of the stator core or the rotor iron core due to the magnetic flux generated from the permanent magnet is reduced in terms of magnetization characteristics. When it does not reach near the inflection point, the DC voltage is applied to the stator winding to allow the magnetic flux density of the stator core or rotor core to reach the inflection point on the magnetization characteristics, and then the pulse voltage in the positive and negative directions And determining whether the magnetic pole corresponding to the phase to which the pulse voltage is applied is an N pole or an S pole.