JP2014185900A - Motor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration for detecting a rotor rotation position of a motor more properly, while preventing increase in physical size and cost of a device.SOLUTION: A motor and a resolver are configured so that a pole number ratio between the number of poles of a motor and the number of poles of a resolver is set so as not to periodically change an error of a resolver angle φ from an R/D converter due to a leakage flux from the motor. The resolver angle φ from the R/D converter 40 can be easily and properly corrected, to properly calculate an electric angle θe or the like of the motor 22.

Description

  The present invention relates to a motor device.

  Conventionally, this type of motor device includes a motor stator provided inside the motor case and having a motor coil, a rotor provided on the motor case via a bearing and attached to a rotating shaft, and an inner side of the motor case. A resolver stator provided with a resolver coil and a resolver rotor provided on a rotating shaft and corresponding to the resolver stator has been proposed, and a shield cover is provided so as to cover the resolver coil (for example, a patent) Reference 1). In this apparatus, by adopting such a configuration, the influence of the leakage magnetic flux generated between the motor coil and the rotor on the resolver coil is prevented.

JP-A-9-65617

  In the motor device described above, since the shield cover is provided in the space between the motor having the motor stator and the rotor and the resolver having the resolver stator and the resolver rotor, the physique of the device is increased and the cost is increased. There was a problem.

  The main purpose of the motor device of the present invention is to propose a configuration that can more appropriately detect the rotational position of the rotor of the motor while suppressing an increase in the size of the device and an increase in cost.

  The motor device of the present invention employs the following means in order to achieve the main object described above.

The motor device of the present invention is
A motor device comprising a motor and a resolver that detects a rotational position of a rotor of the motor,
The pole number ratio, which is the ratio of the number of poles of the rotor of the motor and the number of poles of the rotor of the resolver, is configured such that the detection error of the resolver does not vary due to leakage magnetic flux from the motor.
It is characterized by that.

  In the motor device according to the present invention, the pole number ratio, which is the ratio of the number of poles of the rotor of the motor and the number of poles of the resolver rotor, is such that the detection error of the resolver does not fluctuate due to leakage magnetic flux from the motor. Configure with resolver. Thereby, the rotational position of the rotor of the motor can be detected more appropriately without providing a shield cover or the like between the motor and the resolver.

  In the motor apparatus of the present invention, the pole number ratio may be 4: 1.

It is a block diagram which shows the outline of a structure of the drive device 20 as one Example of this invention. FIG. 3 is a configuration diagram showing an outline of the configuration of a motor 22. FIG. 3 is a configuration diagram showing an outline of a configuration of a resolver 32. FIG. 6 is an explanatory diagram schematically showing the relationship between the mechanical angle θm of the motor 22 and the resolver angle φ from the R / D converter 40, the electrical angle θe of the motor 22 and the error included in the resolver angle φ in the example and the comparative example. is there.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a drive device 20 as one embodiment of the present invention, FIG. 2 is a configuration diagram showing an outline of the configuration of a motor 22, and FIG. It is a block diagram which shows the outline of a structure.

  The driving device 20 of the embodiment is mounted on an electric vehicle, a hybrid vehicle, or the like, and as shown in FIG. 1, a motor 22 that is housed in a case 21 and outputs driving power, and an inverter for driving the motor 22 31, a resolver 32 that is housed in the case 21 and detects the rotational position of the rotor 24 of the motor 22, and a resolver digital converter (hereinafter referred to as an R / D converter) 40 that digitally converts an output signal from the resolver 32. And an electronic control unit 50 that receives a signal from the R / D converter 40 and calculates an electrical angle θe of the rotor 24 of the motor 22 and performs switching control of a switching element of the inverter 31. Here, the motor device includes the motor 22, the resolver 32, the R / D converter 40, and the electronic control unit 50.

  As shown in FIGS. 1 and 2, the motor 22 includes a rotor 24 attached to the rotary shaft 23, and a well-known three unit including a stator 27 that is disposed on the outer peripheral side of the rotor 24 and is fixed to the case 21. It is configured as a phase AC motor. The rotor 24 includes a rotor core 25 formed by laminating a plurality of rotor members formed by punching a non-oriented electrical steel sheet, and a plurality of (eight in the embodiment) slots embedded in the rotor core 25 (eight in the embodiment). 8) permanent magnets 26 in the embodiment. The stator 27 includes a stator core 28 formed by stacking a plurality of stator members formed by punching a non-oriented electrical steel sheet, and a coil 29 wound around a plurality of teeth of the stator core 28.

  As shown in FIGS. 1 and 3, the resolver 32 includes a rotor 34 attached to the rotating shaft 23 of the motor 22, and a stator 35 that is disposed on the outer peripheral side of the rotor 34 and is fixed to the case 21. . The rotor 34 is formed in an elliptical shape (a shape having two convex portions with respect to a circular shape) by a magnetic material, and rotates integrally with the rotating shaft 23 of the motor 22. The stator 35 is formed in a hollow cylindrical shape by a magnetic material, and is electrically shifted by 90 degrees (phase difference is 90 degrees) from an oscillation circuit (not shown) to which an alternating current having a constant frequency is applied as an excitation signal. The two output coils 37 and 38 arranged are incorporated. The output signals of the two output coils 37 and 38 are signals generated in accordance with the change in the gap between the rotor 34 and the stator 35 caused by the rotation of the elliptical rotor 34, and are respectively sinusoidal when the peak values are complemented. , A signal having a cosine wave shape (hereinafter also referred to as a SIN signal and a COS signal, respectively).

  As shown in FIG. 1, the R / D converter 40 receives an output signal (SIN signal, COS signal) from the resolver 32, calculates a resolver angle φ based on the SIN signal and the COS signal, and performs an electronic control unit. Output to 50.

  Although not shown, the electronic control unit 50 is configured as a microprocessor centered on a CPU, and includes a ROM for storing a processing program, a RAM for temporarily storing data, and an input / output port in addition to the CPU. The electronic control unit 50 is input with a resolver angle φ from the R / D converter 40, a phase current flowing in each phase of the motor 22 from a current sensor (not shown), and the like through the input port. The switching control signal to the switching element of the inverter 31 is output via the output port. The electronic control unit 50 determines the electrical angle θe as the rotational position of the rotor of the motor 22, the mechanical angle θm, the rotational angular velocity ωm, based on the value obtained by correcting the resolver angle φ from the R / D converter 40. The rotational speed Nm is calculated. The relationship among resolver angle φ, electrical angle θe, and mechanical angle θm is expressed by the following equation (1) according to the number of poles Pr of resolver 32 and the number of poles Pm of motor 22. In the embodiment, as described above, the number of poles Pm of the motor 22 is set to a value of 8 and the number of poles Pr of the resolver 32 is set to a value of 2 (the ratio of both is set to a value of 4: a value of 1). It becomes the relationship of Formula (2).

φ / Pr = θe / (Pm / 2) = θm (1)
φ / 2 = θe / 4 = θm (2)

  Here, the reason why the number of poles Pm of the motor 22 is set to 8 and the number of poles Pr of the resolver 32 is set to 2 (the ratio between them is set to value 4: value 1) will be described. As shown in the following equation (3), the change frequency Fce of the error of the resolver angle φ from the R / D converter 40 caused by the leakage flux of the motor 22 is determined by the experiment and analysis so far, It was found that the difference between the frequency Flf of the signal and the frequency Fr of the resolver angle φ from the R / D converter 40 is equal to the difference (the absolute value of the value obtained by subtracting one from the other). Here, as shown in Expression (4), the frequency Flf of the leakage magnetic flux of the motor 22 is substantially equal to the frequency Fe of the electrical angle θe of the motor 22. Further, as shown in Expression (5), the frequency Fe of the electrical angle θe of the motor 22 is equal to a value obtained by multiplying the frequency Fm of the mechanical angle θm of the motor 22 by half of the number of poles Pm of the motor 22. Furthermore, as shown in Expression (6), the frequency Fr of the resolver angle φ from the R / D converter 40 is equal to a value obtained by multiplying the frequency Fm of the mechanical angle θm of the motor 22 by the number of poles Pr of the resolver 32. Therefore, when formulas (3) to (6) are summarized, as shown in formula (7), the change frequency Fce of the error of the resolver angle φ from the R / D converter 40 caused by the leakage flux of the motor 22 is The absolute value of the product of the half of the frequency Fm of the mechanical angle θm of the motor 22 and the value obtained by subtracting four times the number of poles Pr of the resolver 32 from the number of poles Pm of the motor 22. From this equation (7), it is understood that the value in the parentheses on the right side should be 0 in order to set the frequency Flf of the leakage magnetic flux of the motor 22 to 0. Therefore, in the embodiment, the ratio between the number of poles Pm of the motor 22 and the number of poles Pr of the resolver 32 is set to value 4: value 1. As a result, the frequency component of the leakage magnetic flux of the motor 22 can be obtained with a value of 0, so the electronic control unit 50 cancels the offset error (steady error) with respect to the resolver angle φ from the R / D converter 40. The electrical angle θe of the motor 22 and the like may be calculated using the corrected resolver angle φ and the relationship “φ / Pr = θe / (Pm / 2)”. Note that the offset error may be determined in advance by experiments or analysis. As a result, the electrical angle θe of the motor 22 can be calculated more appropriately.

Fce = | Flf-2 ・ Fr | (3)
Flf ≒ Fe (4)
Fe = Fm ・ Pm / 2 (5)
Fr = Fm ・ Pr (6)
Fce = | Fm / 2 ・ (Pm-4 ・ Pr) | (7)

  FIG. 4 schematically shows the relationship between the mechanical angle θm of the motor 22, the resolver angle φ from the R / D converter 40, the electrical angle θe of the motor 22, and the error included in the resolver angle φ in the example and the comparative example. It is explanatory drawing shown. In the figure, solid lines indicate examples, and alternate long and short dash lines indicate comparative examples. Here, as a comparative example, the number of poles of the motor 22 is assumed to be 8 and the number of poles of the resolver 32 is assumed to be 4 (the ratio between the two is assumed to be value 2: value 1). In the comparative example, as indicated by the alternate long and short dash line in the figure, the error included in the resolver angle φ from the R / D converter 40 varies in the same cycle as the resolver angle φ from the R / D converter 40. Thus, if the error included in the resolver angle φ varies periodically, the variation appears in the electrical angle θe, which may cause torque variation and power variation of the motor 22. On the other hand, in the embodiment, the error included in the resolver angle φ from the R / D converter 40 does not vary but only the offset component. Thereby, correction with respect to the resolver angle φ from the R / D converter 40 can be performed more easily and appropriately, and the electrical angle θe of the rotor of the motor 22 and the like can be calculated more appropriately. That is, by not providing a shield cover or the like between the motor and the resolver, it is possible to more appropriately calculate the electrical angle θe of the rotor of the motor 22 while suppressing an increase in the size of the apparatus and an increase in cost. The error included in the resolver angle φ from the R / D converter 40 does not fluctuate, and the electric angle θe of the rotor of the motor 22 can be calculated more appropriately, so that the motor based on the detection error of the electric angle θe can be calculated. 22 torque fluctuations and power fluctuations can be suppressed.

  According to the motor device of the embodiment described above, the number of poles Pm of the motor 22 is set to a value of 8 and the number of poles Pr of the resolver 32 is set to a value of 2 (the ratio of both is set to a value of 4: a value of 1). The resolver angle φ from the R / D converter 40 can be suppressed from including periodically changing errors. As a result, it is possible to easily and appropriately correct the resolver angle φ from the R / D converter 40 based on the output signal from the resolver 32 without providing a shield cover or the like between the motor 22 and the resolver 32. The electrical angle θe of the rotor 24 of the motor 22 can be calculated more appropriately.

  In the motor device of the embodiment, the number of poles Pm of the motor 22 is set to 8 and the number of poles Pr of the resolver 32 is set to 2, but the number of poles Pm of the motor 22 and the number of poles Pr of the resolver 32 are The pole number ratio only needs to be a ratio in which the error of the resolver angle φ from the R / D converter 40 does not periodically change due to the leakage magnetic flux from the motor 22, and therefore the pole number Pm of the motor 22 and the pole number Pr of the resolver 32. For example, a combination of value 16 and value 4, or a combination of value 12 and value 3 may be used.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor 22 having the rotor 24 and the stator 27 corresponds to a “motor”, and the resolver 32 having the rotor 34 and the stator 35 corresponds to a “resolver”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention is applicable to the motor device manufacturing industry.

  20 drive unit, 21 case, 22 motor, 23 rotating shaft, 24 rotor, 25 rotor core, 26 permanent magnet, 27 stator, 28 stator core, 29 coil, 31 inverter, 32 resolver, 34 rotor, 35 stator, 36 excitation coil, 37 , 38 output coil, 40 R / D converter, 50 electronic control unit.

Claims (2)

A motor device comprising a motor and a resolver that detects a rotational position of a rotor of the motor,
The pole number ratio, which is the ratio of the number of poles of the rotor of the motor and the number of poles of the rotor of the resolver, is configured such that the detection error of the resolver does not vary due to leakage magnetic flux from the motor.
Motor device. The motor device according to claim 1,
The pole number ratio is configured to be 4: 1.
Motor device.