JP2007189818A - Current control method of synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it is necessary to make an inverter in multi-phases when creating magnetic flux that corresponds to each rotor, and when the number of the phases is increased corresponding to the rotors, the number of switch elements is increased, thus causing the complication of control. <P>SOLUTION: This current control method of a synchronous motor is applied to an inverter having three phases or four phases that drives the synchronous motor constituted of a plurality of the rotors (R1, R2) each having different pole algorithms, or one rotor (24) having a magnetic flux generation member that sums magnetic fluxes corresponding to a plurality of the different pole algorithms and generates them, and one stator (St1, 21). The method sums a plurality of current fields that correspond to pole algorithms for constituting the plurality of rotors, or to pole algorithms for constituting the one rotor, and controls the inverter so that a composite current by which the plurality of rotors or the one rotor can be rotated is imparted to the stator. By this constitution, since the current is imparted to the rotor so as to be rotatable by summing the plurality of current fields that correspond to the pole algorithms for constituting the rotor, the number of the phases of the inverter can be reduced compared with a conventional synchronous motor having two rotors and one stator, and a motor drive system can be reduced in size as a whole. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a current control method for a synchronous motor.

  In recent years, electric motors that are widely used in automobiles have been severely demanded for miniaturization and efficiency for automobile applications. Currently, many automobiles equipped with electric motors for traveling are hybrid automobiles that run by combining engine output and motor output, and many have two motors for generator use and electric motor use. Japanese Patent No. 3480301 (refer to Patent Document 1) has been proposed as a means for realizing miniaturization and high efficiency of such a motor for a hybrid vehicle.

According to this invention, it is possible to rotate two rotors independently by supplying power to one stator, and it is possible to generate torque for two motors with one motor physique. In addition, the average value of the current applied to the stator in accordance with both rotors is lower than the average value when the current is simply applied to the two motors, and there is an effect that the loss due to the current is reduced.
Japanese Patent No. 3480301 (Japanese Patent Laid-Open No. 11-275827, paragraph 0010, FIG. 1)

  However, in order to generate magnetic fluxes corresponding to the respective rotors, it is necessary to make the inverter multiphase. For example, if there are three phases for one rotor, a total of six-phase inverters are required. When the number of phases is increased according to the rotor in this way, there arises a problem that the number of switch elements increases and the control becomes complicated.

The present invention addresses such a problem, and reduces the number of phases for a rotor with a plurality of magnets having different numbers of pole pairs or a single rotor in which magnet magnetic fluxes corresponding to different numbers of pole pairs are combined. Thus, a current control method for generating current magnetic fields corresponding to a plurality of pole pairs in one stator is provided.
In order to solve the above-described problems, the synchronous motor current control method according to the first aspect of the present invention provides:
A plurality of rotors each having a different number of pole pairs (each having a pair of magnets corresponding to a different number of pole pairs) or magnet magnetic fluxes corresponding to a plurality of different pole pairs (for example, on the air gap surface on the rotor side) ) Three-phase or four-phase driving a synchronous motor composed of one rotor having a magnetic flux generating member to be generated in combination and a plurality of magnet pairs corresponding to the number of pole pairs. A method for controlling the current of a synchronous motor for the inverter of
A combined current that can add a plurality of current magnetic fields corresponding to the number of pole pairs constituting the plurality of rotors or the number of pole pairs that constitute the one rotor, and the plurality or one rotor can rotate. Controlling the inverter to feed the stator,
Including steps.

Moreover, the current control method of the synchronous motor according to the second invention is as follows:
For each number of pole pairs constituting the plurality of rotors (that is, for each set of magnets constituting each number of pole pairs), or for each number of pole pairs constituting the one rotor (that is, for each set of magnets constituting each number of pole pairs) ), A voltage command value calculation step for obtaining a voltage command value to be applied to a stator coil constituting the stator based on a current command value (for an inverter obtained from an upper circuit or the like);
Extraction step of extracting current components corresponding to the respective number of pole pairs (corresponding to a set of magnets) of the rotor from the coil current (more specifically, current waveform) of the stator (obtained using a current sensor or the like) When,
A step of supplying the current component for each number of pole pairs extracted by the extraction step to the voltage command value calculation step as a feedback element (that is, using the extracted current component as a feedback element, for example, the current extracted by the extraction step) The component is compared with the current command value for each number of pole pairs of the rotor to obtain the difference, and the voltage command value is obtained based on this difference).
It is characterized by including.

A current control method for a synchronous motor according to a third invention is
When the inverter is a three-phase inverter and the number of pole pairs constituting the plurality of rotors or one rotor has an integer multiple pole pair ratio other than a multiple of 3, for a small number of pole pairs Applying the composite current to the three-phase inverter including a sine wave shifted by 120 ° in electrical angle and a sine wave shifted by 120 ° in electrical angle × pole pair ratio for a large number of pole pairs.
Including steps.

A current control method for a synchronous motor according to a fourth invention is
When the inverter is a four-phase inverter and the number of pole pairs constituting the plurality of rotors or one rotor has a pole pair ratio that is a multiple of 3, the electrical angle is 90 for a small number of pole pairs. Applying the composite current to the four-phase inverter so as to include a sine wave with a shift of ° and a sine wave with an electrical angle of 90 ° × pole pair ratio for a large number of pole pairs.
Including steps.

Moreover, the current control method of the synchronous motor according to the fifth invention is:
The plurality of rotors is a single rotor mechanically connected;
It is characterized by that.

  As described above, the solution of the present invention has been described as a method. However, the present invention can be realized as a device, a program, and a storage medium storing the program substantially corresponding to these, and the scope of the present invention. It should be understood that these are also included.

  According to the first aspect of the present invention, since a plurality of current magnetic fields corresponding to the number of pole pairs constituting the rotor are added and the current is supplied so as to be able to rotate, the inverter is compared with the conventional 2-rotor, 1-stator synchronous motor. Therefore, it is possible to reduce the size of the entire motor drive system.

  According to the second invention, the current control method includes means for obtaining a voltage command value to be applied to the stator coil based on the current command value for each number of pole pairs of the rotor, and each of the rotors from the coil current waveform of the stator. There are means for extracting the component corresponding to each pole pair and means for comparing the component extracted thereby and the current command value for each rotor pole pair. Since the inverter is controlled by the combined signal, the rotating magnetic flux corresponding to each pole pair can be generated effectively.

  Further, according to the third invention, when the rotor has a pole pair ratio that is an integer multiple other than a multiple of 3, for a small number of pole pairs, a sine wave shifted by 120 ° in electrical angle, for a large number of pole pairs In this case, a sine wave with an electrical angle of 120 ° × pole-to-log ratio ratio is generated and applied to the three-phase inverter, so that a rotating magnetic field can be generated by adding a plurality of current magnetic fields corresponding to this rotor by an inverter with a small number of phases. Can do.

  According to the fourth invention, when the rotor has a pole pair ratio that is a multiple of 3, a sine wave shifted by 90 ° in electrical angle for a small number of pole pairs, and an electrical angle for a large number of pole pairs. Since a sine wave with a 90 ° × pole pair ratio deviation is generated and applied to the four-phase inverter, a rotating magnetic field can be generated by adding a plurality of current magnetic fields corresponding to this rotor by an inverter having a small number of phases.

  According to a fifth aspect of the invention, the plurality of rotors are mechanically connected rotors, and the current control method is used for the rotors. For example, a single shaft such as a wheel-in motor is used. In a good application, it is possible to drive a motor with an inverter having a small number of phases while taking advantage of the characteristics of a two-rotor and one-stator motor that can generate torque for two motors with one motor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
First Embodiment FIG. 1 shows a specific example of a rotor having a pole-to-number ratio other than a multiple of 3 and a corresponding stator. First, the rotor of FIG. 1 will be described. Eight magnets are arranged on the outer rotor R2 so as to have the number of pole pairs of four pole pairs. On the other hand, four magnets are arranged in the inner rotor R1 so as to have the number of pole pairs of two pole pairs. In addition, the code | symbol N in a figure represents the N pole magnet which N pole opposes to the stator side, and the code | symbol S represents the S pole magnet which S pole opposes to the stator side. Each rotor is rotatably supported by a motor housing (not shown) via a bearing or the like.

  Next, the stator will be described. The stator (stator) St1 has six teeth, and windings are wound around the six teeth in a concentrated manner. Two windings arranged every three windings form one set, and are connected in series or in parallel to form a winding set. There are three winding sets, and one of the winding sets is connected to one of the other winding sets. U, V, and W in the figure represent U-phase, V-phase, and W-phase windings, respectively. The other end of each winding set constituting the motor M is connected to the three-phase inverter shown in FIG. As shown in FIG. 2, this inverter is composed of a switching element SW1-6 and a diode D1-6, and is connected to a power supply Vdc and a smoothing capacitor C1.

  Next, a current control method will be described. FIG. 3 shows a control block diagram. As shown in FIG. 3, since the rotor has two pole pairs and four pole pairs as described above, the d1 current command for the d-axis current corresponding to the two-pole pair and the q1 current command for the q-axis current A d2 current command related to the d-axis current corresponding to the 4-pole pair and a q2 current command related to the q-axis current are generated and input to the control block.

  Next, a current command for outputting magnet torque will be described. First, the current command for a two-pole pair will be described. The difference between the d1 current command corresponding to the torque produced by the two-pole pair and a feedback signal described later is input to the control block of FIG. The current command is converted into a voltage command to be applied to the coil by the current controller 1 in FIG. 3, and the d-phase and q-axis components are converted into rotating coordinates with a frequency of two pole pairs by the 2-phase / 3-phase coordinate converter 2. Then, after converting from 2 phase to 3 phase, it is added to the voltage command on the 4 pole pair side and input to the inverter 9. The rotation signal is a signal obtained from the position sensor 11 attached to the inner two-pole pair rotor. The inverter 9 has a function of generating a PWM signal (not shown), and applies a voltage corresponding to the voltage command to each winding of the motor 10.

  The feedback signal is obtained by obtaining the motor current with the current sensor AM, converting the current from the three-phase to the two-phase with the three-phase / two-phase coordinate converter 3, and further rotating the d-axis from the rotation coordinates with the frequency of two pole pairs. Convert back to q-axis. This signal is input to the current controller 1 as a feedback element after the waveform component of the quadrupole pair is removed by the low-pass filter 4. The difference between the feedback signal and the current command obtained by the above processing is input to the current controller 1. Since the control block including the current controller 1, the two-phase / three-phase coordinate converter 2, the three-phase / two-phase coordinate converter 3, and the low-pass filter 4 is a block for the two-pole pair, the control for the two-pole pair is performed. It will be referred to as block B1. Similarly, a voltage command is similarly generated for the current command of the 4-pole pair, and the control block B2 for the 4-pole pair is also the current controller 5, the 2-phase / 3-phase coordinate converter 6, the 3-phase / 2-phase coordinate converter. 7 and a low-pass filter 8. However, as the rotation signal, a signal obtained from the position sensor 12 attached to the outer 4-pole pair rotor is used.

  Here, since only the magnet torque is considered, it is assumed that the q-axis is 0. However, when the reluctance torque is controlled, the q-axis command is similarly generated. Further, in this embodiment, a three-phase inverter is used, and this cannot be applied when the pole-to-number ratio is a multiple of 3. This case will be described in the second embodiment.

  In summary, in the conventional synchronous motor having two rotors, an inverter having a number of phases corresponding to each rotor, for example, three phases + three phases and a total of six phases is required. If it is made to flow, a three-phase inverter is sufficient, and the number of inverter phases may be small. That is, according to the present invention, the characteristic of the synchronous motor of 2 rotors + 1 stator, that is, the torque of two motors is generated by one motor body, and the average value of the current applied to the stator in accordance with both rotors is simply 2 A combined rotating magnetic field corresponding to a plurality of rotors can be generated with an inverter having a small number of phases while taking advantage of the fact that the loss due to current is lower than the average value when current is supplied to one motor.

Second Embodiment FIG. 4 shows a specific example of a rotor having a pole-to-number ratio of 3 and a corresponding stator. First, the rotor of FIG. 4 will be described. Eight magnets are arranged on the outer rotor R3 so as to form a set of four-pole pairs of magnets. On the other hand, 24 magnets are arranged in the inner rotor R4 so as to form a 12-pole pair magnet set. That is, one set of magnets is arranged for each. Each rotor is arranged inside the stator St2, and in this case, the two rotors are mechanically coupled. The combined magnetic flux of both sets of magnets is distributed on the surface (on the stator side) of the combined rotor.

  By the way, the three-phase inverter as shown in FIG. 2 cannot produce a waveform having a frequency three times that of the basic waveform. Therefore, a four-phase inverter shown in FIG. 5 is used for a rotor having a triple pole-to-number ratio as shown in FIG. This inverter is provided with switching elements SW7 and 8 and diodes D7 and 8 corresponding to the increased one phase. The control block is as shown in FIG. 6. The d1 current command for the d-axis current corresponding to the 4-pole pair and the q1 current command for the q-axis current, the d2 current command for the d-axis current of the 12-pole pair, and the q2 for the q-axis current. The current command is converted into a voltage command, synthesized in four phases, and then combined, and this command is input to the inverter 9 (INV). That is, the voltage command generated by the control block B3 for 4 pole pairs and the control block B4 for 12 pole pairs is configured and supplied to the inverter. In this case, since the two rotors are integrated, only one position sensor 11 is required.

  The inverter is provided with means for generating a PWM signal (not shown), and applies a voltage corresponding to the voltage command to each winding of the motor. The details of the control block are the same as in the first embodiment except that there is one position sensor. In the case of four phases, each phase is shifted by π / 2. If the d-axis component is an A-phase current, the q-axis is the B phase, the -d axis is the C phase, and the -q phase is the D phase. It becomes. Therefore, connect the inverter and each phase winding, for example, phase A and phase C to the same arm so that the phase winding is in the opposite direction, and phase B and phase D to the same arm Can be connected in the opposite direction. In that case, each coil set (A phase-C phase and B phase-D phase) is connected to the full bridge circuit.

  Although an example in which two rotors are mechanically coupled has been described above, a structure in which magnets are bonded inside and outside with a one-piece rotor as shown in FIG. 7 may be used. As shown in FIG. 7, the single rotor Rt may be configured by bonding an outer rotor R5 configured with a 4-pole pair and an inner rotor R6 configured with a 12-pole pair. For convenience of drawing and explanation, there is a gap between R5 and R6, but this gap disappears after the rotor is actually bonded.

  Although the motor of FIG. 7 has a configuration in which the canceling portion of the magnet is not removed, the present invention can be applied to a configuration in which the canceling portion is removed. FIG. 8 shows a cross-sectional view of the rotor configuration with the offset portion removed. Reference numeral 21 denotes a stator, which is composed of 18 divided cores 22, and windings 23 are intensively wound around the 18 divided cores 22. Three windings are arranged as a set (6 sets in total), and are connected in series or in parallel, and one of them is connected to one of the other phases as a neutral point. The other is inside an inverter (not shown) and is connected to the P side and N side of the power supply line via a switching element. This inverter is configured to control six phases. Although this stator is described with a divided core, the same operation can be performed with a non-divided core, or the present invention can be applied to a slotless motor. Further, the winding is not limited to concentrated winding, and can be applied to distributed winding.

  Reference numeral 24 denotes a rotor (rotor). In this embodiment, the rotor 24 includes three N-pole magnets N1 to N3 and six S-pole magnets S1 to S6. It functions as two sets of magnets having two types of pole pairs of six pole pairs. The two sets of magnets in this case are conceptual, and the members are not clearly separated. For one current constituting the composite current supplied to the stator winding, Means that there is one set of magnets that behave as a set of pole pairs, and that there is one set of magnets that behaves as a set of 6 pole pairs for the other current that makes up the composite current The magnets S1 to S6 and N1 to N3 simultaneously function as both sets of magnets. This will be described in detail with reference to FIG. For convenience of drawing and explanation, the rotor magnets are illustrated and described as N and S poles, but it is noted that the operation and effect of the invention are the same even if the configuration and arrangement of the NS poles are reversed. I want. Further, the N-pole and S-pole magnets are magnets in which the magnetization direction is in the radial direction (opposite direction) so that the direction of the magnetic field lines is in the radial direction, and the N pole is on the outer side (stator side). The poles are arranged on the outside (stator side). In this embodiment, a magnet is used in which the magnetizing direction is arranged in the radial direction. However, the arrangement is not limited to this, and there is no problem as long as the magnetic lines of force are directed substantially in the radial direction. For example, a V-shaped magnet arrangement is used. It may be.

  FIG. 9 is an explanatory diagram of the rotor generation of FIG. 8. FIG. 9A is a rotor of a motor having a two-rotor structure, in which the inner rotor is a three-pole pair and the outer rotor is a six-pole pair. The magnet is provided. FIG. 9B shows that this magnet is arranged in two layers on the surface layer of the inner rotor. Some phase adjustment is performed at the time of arrangement. Referring to FIG. 9B, the rotor 24A has two kinds of magnets having different magnetization directions in contact with each other at several positions. As is well known, when magnets having different magnetization directions are bonded together, the magnets are equivalent to those without magnets if the magnetic forces of the magnets are the same.

  Therefore, FIG. 9C is a diagram in which the magnets are excluded from the portion where the magnets having different magnetizations as viewed in the radial direction are bonded together, and the rotor 24 has N-pole magnets N1 to N3 and S-pole magnets. S1 to S6 are included. As a result, the rotor 24 that generates the composite magnetic flux CF of the three-pole pair and the six-pole pair as shown by a curved line is completed. This rotor is basically the same as that shown in FIG. 9B, in which the inner rotor and the outer rotor are integrated without removing the portion of the magnet that is in contact with the magnet of different polarity. It should be noted that the effect of miniaturization and current reduction is obtained, and the same composite magnetic flux CF (not shown in FIG. 9B) is generated as in FIG. 9C. That is, the rotor 24A is a rotor having a configuration in which the first rotor of the inner rotor and the second rotor of the outer rotor are integrated. Of course, the configuration of FIG. 9C from which unnecessary magnets are removed is more effective in improving torque by reducing the inertia of the magnets deleted, reducing the weight of the motor, and reducing the cost of the deleted magnets. . It should be noted that the present invention can be applied to a configuration after removing such a canceling portion of the magnet, or a configuration without removing it.

  In FIG. 9C, the area from which unnecessary magnets are removed is a space, and air occupies the area. The area occupied by the air functions to prevent magnetic flux from passing therethrough. That is, it is necessary to place a member other than a material that easily allows magnetic flux, such as iron, in this region from which the magnet has been removed, but space (air) is usually sufficient. Of course, a member that is difficult to pass magnetic flux other than air may be provided in the region.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each member, each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of members, means, steps, etc. can be combined or divided into one. Is possible.

It is sectional drawing of a rotor with a pole pair number ratio of 2 times. It is a three-phase inverter circuit diagram. FIG. 5 is a current control block diagram corresponding to a rotor having a pole pair number ratio of 2 times. It is sectional drawing of a rotor with a pole pair number ratio of 3 times. It is a four-phase inverter circuit diagram. It is a current control block diagram corresponding to a rotor having a pole pair number ratio of 3 times. It is sectional drawing of the integral structure rotor which has the pole pair number ratio of 3 times which bonded the inner and outer magnet. It is sectional drawing which shows the rotor structure which removed the cancellation part. It is rotor production | generation explanatory drawing of FIG.

Explanation of symbols

R1 Inner rotor R2 Outer rotor St1 Stator motor M
C1 Smoothing capacitor D1-8 Diode SW1-8 Switching element Vdc Power source 1, 5 Current controller 2, 6 2-phase / 3-phase coordinate converter 3, 7 3-phase / 2-phase coordinate converter 4, 8 Low-pass filter 9 Inverter 10 Motors 11, 12 Position sensor AM Current sensor B1 2-pole pair control block B2 4-pole pair control block B3 4-pole pair control block B4 12-pole pair control block R3 Outer rotor R4 Inner rotor St2 Stator R5 Outer rotor R6 Inside Rotor Rt Rotor 21 Stator 22 Core 23 Winding 24 Rotor 24A Rotor CF Composite magnetic flux N1-N3 Magnet S1-S6 Magnet

Claims (5)

A synchronous motor including a plurality of rotors each having a different number of pole pairs, or one rotor having a magnetic flux generating member that generates a magnetic flux corresponding to a plurality of different pole pairs and a stator. A synchronous motor current control method for a three-phase or four-phase inverter to be driven,
A combined current that can add a plurality of current magnetic fields corresponding to the number of pole pairs constituting the plurality of rotors or the number of pole pairs that constitute the one rotor, and the plurality or one rotor can rotate. Controlling the inverter to feed the stator,
A current control method for a synchronous motor. In the synchronous motor current control method according to claim 1,
Voltage command value calculation for obtaining a voltage command value to be applied to a stator coil constituting the stator based on a current command value for each pole pair constituting the plurality of rotors or for each pole pair constituting the one rotor. Steps,
An extraction step of extracting current components corresponding to the number of pole pairs of the rotor from the coil current of the stator;
Providing the voltage command value calculation step with a current component for each pole pair extracted in the extraction step as a feedback element;
A method for controlling the current of a synchronous motor, comprising: In the synchronous motor current control method according to claim 1 or 2,
When the inverter is a three-phase inverter and the number of pole pairs constituting the plurality of rotors or one rotor has an integer multiple pole pair ratio other than a multiple of 3, for a small number of pole pairs Applying the composite current to the three-phase inverter including a sine wave shifted by 120 ° in electrical angle and a sine wave shifted by 120 ° in electrical angle × pole pair ratio for a large number of pole pairs.
A current control method for a synchronous motor. In the synchronous motor current control method according to claim 1 or 2,
When the inverter is a four-phase inverter and the number of pole pairs constituting the plurality of rotors or one rotor has a pole pair ratio that is a multiple of 3, the electrical angle is 90 for a small number of pole pairs. Applying the composite current to the four-phase inverter so as to include a sine wave with a shift of ° and a sine wave with an electrical angle of 90 ° × pole pair ratio for a large number of pole pairs.
A current control method for a synchronous motor. In the current control method of the synchronous motor according to any one of claims 1 to 4,
The plurality of rotors is a single rotor mechanically connected;
A current control method for a synchronous motor.

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