JPH0642792B2 - Brushless motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to a controller for a brushless motor having a large output torque.

[Conventional technology]

Generally, the performance of a servomotor can be evaluated by the torque / inertia ratio, and the torque is proportional to the amount of magnetic flux when the electrical winding relationship is the same. Therefore, the increase in the amount of magnetic flux greatly affects the performance improvement. Further, although a ferrite magnet is generally used for a servo motor due to price restrictions, the residual magnetic flux density of the ferrite magnet is low, so that the motor performance is limited.

The prior art relating to the control of the permanent magnet servomotor is described in, for example, Japanese Patent Application Laid-Open No. 60-62894.

FIG. 6 shows the entire internal structure of the brushless motor. In FIG. 6, the stator 1 houses a stator core 4 and a stator winding 5 inside a housing 3. Rotor 2
Is equipped with a yoke 7, a permanent magnet 8, a position detector PS, and an encoder E on the shaft 6, and is rotatably held by the stator 1 by an end bracket 10 and a bearing 9.

FIG. 7 is an explanatory view of the overall structure of the rotor 2 incorporated in the conventional brushless motor. The figure shows a two-pole example,
The permanent magnet 8 is magnetized as shown and is fixed to the yoke 7 with an adhesive or the like.

FIG. 8 is a control circuit diagram of a conventional brushless motor, FIG. 9 is an operation characteristic diagram of the control circuit shown in FIG. 8, and FIG. 10 is an explanatory diagram of normal operation of the rotor 2 shown in FIG. .

In FIG. 8, electric power is supplied from the DC power supply 11 to the stator winding 5 via the control device 12. Describing the control operation of the motor, the ASR (speed controller) calculates the speed command ws, the speed error w _e from the actual speed w _f obtained through the FV converter from the encoder E, which in P
A torque command, that is, a current command I _S is output by I control (proportional integration control) or the like. On the other hand, in the sine / cosine generating circuit, a pulse from the position detector PS (for example, a Hall element and a magnet, etc.) that detects the position of the rotor 2 and the encoder E, that is, rotor position information. From FIG. 9 (a), via the prewritten ROM,
The sine and cosine signals shown in (b) are output, and each phase is A
It has a CR (current control) system. Current commands for each phase I _SA , I _SB ,
I _SC ((c), (d), (e) in FIG. 5) is 2 phase-3
It is the product of the output signal of the phase conversion and the current command IS signal. The current command, the induced voltage E _U of each phase winding, E _V, E
Position of the position detector PS and R so that it is in phase with _W
Adjust the OM address.

In FIG. 10, which is an explanatory view of the normal rotation operation of the rotor 2 shown in FIG. 7, the combined current of each phase always occupies a position perpendicular to the magnetic flux I _f of the permanent magnet 8 and, in the case of a constant speed, is absolute. There is no change in the value, there is no commutator, and it is possible to obtain the same characteristics as the DC machine (small torque pulsation).

In FIG. 11 which is an operation characteristic diagram of FIG. 10, assuming that the magnetic flux distribution of the permanent magnet 8 is a sine wave, BM
Is represented by (θ), and the combined current i (θ) of the three-phase current is
By the control described above, the magnetic flux BM (θ) is in phase with the magnetic flux BM (θ), and the distribution is always sinusoidal. Torque T in this case
Is expressed as follows, and this value is always constant.

T = K ・ ∫ ^2π ₀ ▼ BM (θ) ・ i (θ) ・ dθ
(1) The magnetomotive force due to the armature reaction is the magnetic flux BM of the permanent magnet 8.
It is 90 degrees out of phase with (θ) and appears as AT (θ), which causes the magnetic flux BAT (θ) due to the armature reaction.
Occurs. Current i (θ) and armature reaction magnetic flux BAT
The torque T _at due to (θ) is expressed as follows.

T _at = k ・ ▲ ∫ ^2π ₀ ▼ BAT (θ) ・ i (θ) ・ dθ
(2) In the equation (2), BAT (θ) and i (θ) are
Since it has a phase difference of 90 degrees, it becomes zero. Therefore, since the magnetic flux due to the armature reaction is not used and the magnetic flux density of the permanent magnet 8 is low, the characteristic as the servo motor is low.

FIG. 12 is a diagram for explaining a normal rotation operation of a rotor incorporated in an improved brushless motor according to a conventional proposal. The stator structure of the brushless motor incorporating the rotor shown in FIG. The outer periphery of 2 is composed of a permanent magnet 8 and a magnetic material 13 having a magnetic permeability higher than that of the permanent magnet 8, and the magnetic material 13 can also be manufactured integrally with the yoke 7.

Therefore, in contrast to the brushless motor in which the rotor indicated by reference numeral 2 in FIG. 12 is incorporated, the high-permeability magnetic material (hereinafter, referred to as auxiliary salient pole) 13 and the armature are used according to FIGS. 8 and 9. The control is performed so that the reaction magnetizing action is applied (specifically, as shown in FIG. 12, the composite current i of the winding current is advanced by θ with respect to the center of the auxiliary salient pole 13). Control) and, as is clear from FIG. 13 which is an operation characteristic diagram of FIG. 12, the permanent magnet magnetic flux BM expressed by the equation (1).
The torque between (θ) and the winding current i (θ) decreases because the cross-sectional area of the permanent magnet 8 is smaller than that in the case of FIG. However, the torque of the armature reaction magnetic flux BAT (θ) and the winding current i (θ) expressed by the equation (2) is generated, and the torque is increased as a result. The principle of torque generation due to armature reaction is as follows. That is,
A magnetic flux is generated in the same direction as the permanent magnet in the auxiliary magnetic pole arranged on the side where the magnetic demagnetization of the armature reaction works, and the magnetic permeability of the auxiliary magnetic pole is large, while it is arranged on the side where the demagnetization works. In addition, since the magnetic permeability of a permanent magnet is small, the decrease in the magnetic flux of the permanent magnet can be suppressed, and therefore the field magnetic flux amount (permanent magnet magnetic flux amount and auxiliary magnetic flux amount Sum of) can be increased.

On the other hand, the operation system when the rotor shown by reference numeral 2 in FIG. 12 is reversed will be described. FIG. 14 is an operation explanatory view thereof, and FIG. 15 is an operation characteristic diagram of FIG. That is, as shown in FIG. 14, when the rotor 2 is reversed,
The demagnetizing force of the armature reaction is applied to the auxiliary salient poles 13, and the magnetic flux in the direction opposite to the permanent magnet 8 increases. That is, the auxiliary salient pole 13
The magnetic flux of becomes the brake torque, and the torque is reduced in comparison with the case where the rotor 2 is composed of only the permanent magnet 8.

[Problems to be Solved by the Invention] As described above, the conventional brushless motor and the improved bushingless motor according to the conventional proposal have the rotor 2
No consideration has been given to the combined magnetomotive force of the winding current with respect to the change between forward rotation and reverse rotation, between the forward rotation instruction and reverse rotation instruction, or between the positive and negative currents, and it can only be used for a one-way rotation motor. I couldn't do it.

The present invention has been made in consideration of the above points,
It is an object of the present invention to provide a novel brushless motor which can obtain a high output torque regardless of whether the rotor is forward / reverse, forward / reverse command, or positive / negative of current.

[Means for solving problems]

The purpose is to provide a stator having multi-phase stator windings, a rotor having auxiliary salient poles made of a high-permeability magnetic material on the outer periphery and having polarities at equal intervals, and a position of the rotor. And a controller for supplying a current to the multi-phase stator windings corresponding to the signals from the plurality of position detectors. Between the reverse rotation and the reverse rotation, between the forward rotation instruction and the reverse rotation instruction, or between the positive and negative of the current, the combined magnetomotive force of the winding current is generated at a position different from that before the change and the opposite phase (180 degrees) with respect to the rotor. This is accomplished by including a controller that supplies current to the polyphase stator windings.

[Action]

Therefore, according to the present invention, as the control device, the combined magnetomotive force of the winding current with respect to the change between the forward rotation and the reverse rotation of the rotor, the forward rotation command and the reverse rotation command, or the change between the positive and negative of the current is applied to the rotor. On the other hand, by providing the control device for supplying the current to the multi-phase stator winding so that it occurs at a position different from that before the change and in the opposite phase, even when the rotor reverses, the reverse command and the current are negative. As in the case where the normal rotation of the rotor, the normal rotation command, and the current are positive, the maximum torque can be obtained.

〔Example〕

The present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a diagram for explaining a reverse rotation operation of a brushless motor (rotor 2) used for carrying out the invention, and FIG. 2 is FIG. FIG. 4 is a motion characteristic diagram of the rotor 2 in the present invention,
The operation principle when the forward rotation command or the current is positive is the same as the operation principle of FIGS. 8 to 13 described above.

On the other hand, when the rotor 2 is in the reverse rotation, the reverse rotation command or the current is negative, as shown in FIG. 1, the combination of the winding currents when the rotor 2 is in the forward rotation, the normal rotation command or the current is positive Unlike the position of i ₂ (in this position, the motor output torque is reduced, as shown in FIG. 14), which is in the opposite phase to the position of the value i ₁ , the auxiliary salient pole 13 is advanced by θ. The current is supplied to the multi-phase stator windings so that a combined magnetomotive force of the winding currents is generated at position A.

Further, according to the present invention, which supplies the current as described above, the north pole of the permanent magnet 8 is different from the auxiliary salient pole 13A having the same polarity when the rotor rotates in the normal direction, the normal rotation command or the current is positive. , The auxiliary salient pole 13B has the same polarity,
This is exactly the same as the case where the forward rotation, forward rotation command or current of the rotor 2 shown in FIG. 3 is positive, and the combination of the magnetic flux amount by the permanent magnet 8 and the magnetic flux amount by the auxiliary salient pole 13 and the winding current A large output torque can be obtained during the synthesis.

FIG. 3 is a control circuit diagram of a two-phase motor used for implementing the present invention, and FIG. 4 is a detailed view of a rotor indicated by reference numeral 2 in FIG.

The control of the two-phase motor shown in FIG.
At R, the speed error we is calculated from the speed command ws and the actual speed wf obtained from the encoder E through FV conversion. On the other hand, a two-phase sine wave signal is obtained from the position detector PS via the permanent magnets, Hall elements H _A , H _B, etc. according to the position of the rotor 2. In addition, the two phases are
It has a CR system (ACRA, ACRB) and controls each phase. Here, the input signal of the ACR system is represented as the product of the Hall element output and the speed error wf. Even with this, when the forward rotation, forward rotation command or current of the rotor is positive, FIG. As shown in FIG. 12, the winding current i ₁ and
The positional relationship of the rotor 2 including the permanent magnet 8 and the auxiliary salient pole 13 can be obtained, and a large torque can be obtained.

On the other hand, when the reverse rotation of the rotor 2, the reverse rotation command or the current is negative, the signals H _A , H of the position detector PS shown in FIG.
_B and a controller 12 for supplying current to the two-phase stator windings
Different correspondence with A and 12B. That is, the signal H _A of the position detector PS is associated with ACRB and the control device 12B, and the signal H _B of the position detector PS is associated with ACRA and the control device 12A. In this case, when the reverse rotation of the rotor 2, the reverse rotation command, or the current becomes negative, the composite i ₂ of the winding currents becomes almost the same value as in FIG. 1, as shown in FIG.
A large torque can be obtained according to the principle described above.

The present invention can also be applied to a three-phase motor.

FIG. 5 shows a modified example of the rotor used for carrying out the present invention, and the rotor 2 shown in FIG. 5 does not have the permanent magnet 8 previously shown. Thus, in FIG. 5, unlike the case where the permanent magnet 8 is provided, the positions of operable winding currents are two in each of the normal rotation and the normal rotation of the rotor 2 as shown in the figure. This is because the auxiliary salient poles 13 can correspond to the N and S poles of the winding magnetomotive force due to the absence of the permanent magnets 8, and the signal from the position detector PS shown in FIG. H _A , H _B and 2-phase stator winding 5
By changing the correspondence with the control devices 12A and 12B that supply current to A and 5B, the forward and reverse rotations of the rotor 2 can be performed.
Corresponding to the forward rotation command, reverse rotation command, and change between positive and negative current,
Maximum torque can always be obtained.

By the way, in the above-mentioned embodiment, the case where the present invention is applied to the rotary type motor drive has been illustrated, but instead of this, the present invention is applied to the linear motor drive, and further, it has the magnetic pole teeth. It can also be applied to pulse motor drive.

Further, the method of switching the correspondence between the control device for supplying current to the multi-phase stator winding and the plurality of position detectors is useful when it is desired to change the rotation speed of the motor. This is because the phase of the winding current composite value with respect to the rotor changes, which causes the output torque to change.

〔The invention's effect〕

The present invention is as described above, and as is clear from the description of the illustrated embodiment, according to the present invention, a high output torque can be obtained regardless of whether the rotor is forward / reverse, forward / reverse command, or positive / negative of current. It is possible to provide an unprecedented new brushless motor that can be used.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a reverse rotation operation of a brushless motor (rotor) used for practicing the present invention, FIG. 2 is an operation characteristic diagram of FIG. 1, and FIG. 3 is used for practicing the present invention. Phase motor control circuit diagram, FIG. 4 is a detailed view of the rotor shown by reference numeral 2 in FIG. 3, FIG. 5 is a diagram showing a modified example of the rotor used for carrying out the present invention, and FIG. An upper half longitudinal sectional view showing the entire internal structure of the brushless motor, FIG. 7 is an explanatory view of the overall structure of a rotor incorporated in a conventional brassless motor, and FIG. 8 is a control circuit of the conventional brassless motor. FIG. 9, FIG. 9 is an operating characteristic diagram of the control circuit shown in FIG. 8, FIG. 10 is an explanatory diagram of normal operation of the rotor shown in FIG. 7, and FIG. 11 is an operating characteristic diagram of FIG. FIG. 12 is a diagram for explaining a normal rotation operation of a rotor incorporated in an improved brushless motor according to a conventional proposal, and FIG. 13 is a diagram of FIG. Work characteristic diagram, Fig. 14 reverse operation explanatory view of a rotor shown in FIG. 12, FIG. 15 is an operation characteristic diagram of Figure 14. 1 ... Stator, 2 ... Rotor, 4 ... Stator core, 5 ... Stator winding, 7 ... Yoke, 8 ... Permanent magnet, 11 ... DC power supply, 1
2 (12A and 12B) ... Control device, 13 (13A and 13B) ... High permeability magnetic material, E ... Encoder, PS
… Position detector.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshimi Agawagawa 4026 Kujimachi, Hitachi City, Ibaraki Prefecture Hitachi Research Laboratory Ltd. (72) Seiichi Narushima 1410 Inada, Katsuta City, Ibaraki Hitachi Tokai Co., Ltd. in the factory

Claims (2)

[Claims] 1. A stator provided with multi-phase stator windings, a rotor having a high permeability magnetic material on its outer periphery and having polarities at equal intervals, and a plurality of rotors for detecting the position of the rotor. And a controller for supplying current to the multi-phase stator windings in response to signals from the plurality of position detectors, and as the controller, between normal rotation and reverse rotation of the rotor, The combined magnetomotive force of the winding current for changes between the forward rotation command and the reverse rotation command or between the positive and negative currents is
A brushless motor comprising a control device that supplies current to the multi-phase stator winding so that it is generated at a position different from the phase before the change (180 degrees) with respect to the rotor. 2. The invention according to claim 1, as a control device for supplying a current to a polyphase stator winding, wherein the correspondence between the control device and a plurality of position detectors is A brushless motor equipped with a control device that makes the forward / reverse rotation of the child, the forward / reverse rotation command, or the positive / negative of the current different.