JPH10126993A - Switching device of winding for motor in machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching device of winding for motor in machine tool in which constant output control can be carried out over a wide range through a winding structure where the number of lead wires of a permanent magnet synchronous motor is decreased. SOLUTION: Each phase of the stator winding of a motor for machine tool comprises a plurality of windings which are switched through contactors between high speed rotation and low speed rotation. Each phase of the stator winding comprises a first winding wa having a large number of turns and a second winding wb having a small number of turns. The second windings wb of respective phases are connected in star at the end-of-winding while the first windings wa of respective phases are connected with power supply of respective phases at the start-of-winding of first winding wa of respective phases. Contactors C1, C2 are interposed between the start-of-winding of second windings wb, the end-of-winding of first windings wa and the power supply of respective phases in order to connect the first and second windings wa, wb in series, to connect first windings wa in star with the power supply of respective phases or to connect the second windings wb in star with the power supply of respective phases selectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a winding switching device for a machine tool motor for driving a main shaft of a machine tool.

[0002]

2. Description of the Related Art In recent years, various types of machine tool motors for driving a main shaft of a machine tool have been proposed in which a main shaft is directly driven without a speed change mechanism. Output constant control is required over a wide speed range up to a low speed. In particular, if the spindle has an indexing function, a large torque at low speed and high-precision servo performance are also required. In order to realize this, in a drive device using an AC motor as a machine tool motor, winding switching control for obtaining two different output characteristics at low speed and at high speed is performed.

[0003] Japanese Patent Application Laid-Open No. 4-105587 discloses FIG.
The example of the winding switching method shown in FIG. FIG.
Is an example in which U-, V-, and W-phase stator windings to which three-phase power supplies R, S, T are to be applied are respectively connected to two windings C _1U ,
By setting C _2U , C _1V , C _2V , C _1W , C _2W and turning on or off any of the groups of the multi-phase contactors M _1U , M _1V , M _1W and M _2U , M _2V , M _2W At low speeds, two windings are connected in series to increase the number of interlinkage magnetic fluxes so that a large torque can be output. At high speeds, the connection of the contactor is changed to a single winding to reduce the interlinkage fluxes and enable high-speed rotation. Is controlled. In addition, Japanese Patent Application Laid-Open No. 4-244771 discloses an example as shown in FIG. This is an example of a machine tool main shaft drive system by switching the windings of a synchronous motor. Each of the three phases is made up of three serial windings. The tap of three windings is switched so as to reduce the number of windings of the winding.

[0004]

However, the contactor insertion method disclosed in Japanese Patent Laid-Open No. 4-105587 requires twelve lead wires, complicated connection work, and leads of armature windings. At the time of wire processing, there is a problem that the coil end portion on the connection side becomes large and the axial dimension of the motor becomes long. In addition, Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 4-105587 discloses an example of tapping of a series connection of three coils.
Although the number of lead wires can be reduced to nine as compared with the example shown in the publication, the number of contactor contacts is required to switch and control the three windings, and the winding work of the armature windings is also required. Was also complicated. Further, Japanese Patent Application Laid-Open No.
In the conventional example described in Japanese Patent No. 4771, at the time of the maximum rotation speed, when an uncontrolled state occurs due to some trouble, the conventional example has a tap out configuration, so that a large voltage is applied to each terminal by the magnetic flux of the magnet. Induced, there was a problem with the reliability and safety of the winding insulation. For this reason, in the above-described conventional example, the number of lead wires is increased in order to perform the three modes of the essential functions of the spindle motor (1) indexing function, (2) low-speed heavy cutting function, and (3) high-speed finishing function. However, the number of contactors of the contactor increases, the control algorithm becomes complicated, and the reliability and safety of insulation are lacking. The problem to be solved by the present invention is to provide a machine tool motor winding switching device capable of performing a wide range of constant output control with a winding configuration with a reduced number of lead wires of a permanent magnet synchronous motor.

[0005]

In order to solve the above problems, a winding switching device for a machine tool motor according to the present invention comprises a plurality of windings for each phase of a stator winding of the machine tool motor. The contactors are arranged such that the number of windings of each phase winding is reduced during high speed rotation of the spindle control, and the number of windings of each phase is increased during low speed rotation of the spindle index control. In the winding switching device for a machine tool motor, the winding of each phase of the stator winding is constituted by a first winding having a large number of windings and a second winding having a small number of windings, Second of each phase
The windings are connected in a star connection by connecting the end of the winding, the starting of the first winding of each phase is connected to the power supply of each phase, and the starting of the second winding of each phase is The first winding and the second winding are connected in series between the end of the first winding and the power supply of each phase, or the first winding is star-connected to the power supply of each phase. Or a contactor for selectively switching between the power supply of each phase and the star connection of the second winding. In the three modes of indexing the spindle, high-speed finishing, and low-speed heavy cutting, the indexing function is only the first winding, high-speed finishing is only the second winding, and low-speed heavy cutting is the first and second windings. Switch to using the lines in series. When the ratio between the base rotation speed and the maximum rotation speed of the machine tool motor is 1: m, the ratio of the number of turns of the first winding to the second winding is approximately ((√m) -1). : 1 is desirable. As motor machine tool to be used, and interior permanent magnet inside a rotor core, the motor of the d-axis direction inductance L _d and q axis inductance L _q relationship L _d
<It can be used a permanent magnet synchronous machine forms a motor having saliency comprising the L _q.

[0006]

FIG. 1 shows an embodiment of the present invention. In the figure, the one-phase winding divided into two is divided into a coil w _a having a large number of turns and a coil w _b having _a small number of turns. 1) In a low-speed rotation region, w _a + w _b (series connection) 2) High-speed rotation as current flows through the w _a case if the area of w _b 3) spindle indexing control, performing winding switching control using the contactor C _1, C _2.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. The motor used here is a permanent magnet synchronous machine type motor having a permanent magnet as shown in FIG. 3 in a rotor, and a permanent magnet 4a is provided in a magnet insertion hole 2 in a rotor core 1 and a d-axis inductance of the motor is provided. The present invention is applied to an inner-magnet type motor (IPMM) having saliency in which the relationship between L _d and q-axis direction inductance L _q is L _d <L _q . This I
The PMM has substantially the same characteristics as a constant output characteristic that an induction motor can output, and has the advantage that there is no loss of a rotor (secondary side) that is disliked as a machine tool, but has a large inductance, and particularly has a winding function in an indexing function mode. when the line connected to the low-speed heavy cutting mode the same (w _a + w _b), inductance becomes particularly large, in the control of the indexing function mode, in which significantly reduces the frequency characteristic of the current loop, velocity loop. The present invention is to perform winding switching for such an IPMM.

FIG. 1 shows a connection relationship between a winding and a contactor according to the present invention. Dividing the phase of AC armature winding of a three-phase electric motor used in the second winding w _b less busy winding number first winding w _a and the number of windings, a first winding w _a the number of turns of the second winding w _b, n _1: the ratio of _{n 2 (n 1 ≧ n 2} ). Winding start of the first winding w _a, put a read both the end windings, corresponding pin _{[U 1, X 1] [} V 1, Y 1]
And [W _1, Z _1], the second coil w _b is 3 a winding end
A phase star connection is made, and the winding start is lead out, and its terminals are X ₂ , Y ₂ , Z ₂ . As a result, a total of 9
Book leads will be issued. And the lead end U
Between ₁ -U _2, X ₁ -U ₂ between a contactor C ₁ are each
Contacts, put b contacts C _1, also connected in the same manner the other two phases. Moreover, putting a contact of the contactor C ₂ between the winding starting lead terminal of the second winding w _b of the respective phases, U ₂ -V ₂
During take winding switching method respectively between W ₂ -U ₂ put b contacts of the contactor C _2. The characteristic of the spindle is a constant output characteristic as shown in FIG. 2, and the speed from 0 to the winding switching speed N _cont is called a low speed, and the winding speed from the winding switching speed N _cont to the maximum rotation speed N _top is called a high speed. The control and the sequence of these three switching modes are performed as shown in Table 1.

[0009]

[Table 1]

When the constant output range (N _base : N _top ) is 1:12 or less, the ratio between the first winding w _a and the second winding w _b is expressed as n ₁ : n ₂ = It is designed 2: 1. This will be described below. When the turns ratio of the first winding to the second winding, that is, the constant output ratio is about 1: m, the constant output is about 1: √m for the low-speed winding and about 1: √m for the high-speed winding. Characteristics. IPM to be driven
M is different from a general induction motor, and generates an induced voltage due to magnet magnetic flux when rotating. When the inverter drives, an emergency power failure occurs, and if the motor enters the uncontrolled state, this induced voltage will be generated at the motor terminal, and its value will be the maximum value at the maximum rotation speed of each winding below. Become. When the base rotation speed is N _base , 1) the maximum rotation speed in the low-speed winding: N _Lmax = (√m) · N
_base 2) maximum speed of the fast _winding: N _Hmax = m · N _base, and when a 200V inverter, the maximum permissible value becomes 280V (r.m.s).. That is, 1) Induced voltage at the maximum rotation speed in the low-speed winding: E _Lmax =
(√m) · N _base × K _eL (K _eL : induced voltage constant in low-speed winding) 2) Induced voltage at maximum rotation speed in high-speed winding: E _Hmax =
m · N _base × K _eH (K _eH : induced voltage constant in high-speed winding). Are the _{E Lmax = E Hmax = 280V (} r.m.s), satisfy this condition, (a low speed winding turns W _L) :( fast winding turns W _H) = m: 1, and the thus, (First winding w _a ): (second winding w _b ) = ((√m) −
1): 1. When the numerical values are actually applied, when the constant output ratio is 1:12 (m = 12), (first winding w _a ) :( second winding w _b ) = 2.5: 1. , Rounding down the decimal point, (first winding w _a ) :( second winding w _b ) = 2: 1. The reason for rounding off the decimal point is that when rounded down, when the low speed winding is connected, E _Lmax > 280 V, and the inverter may be broken. In general, (first winding w _a ) :( second winding w _b ) =
n: 1, where n <((√m) −1), so that there is a margin for safety when the low-speed winding is connected. By the above means,
IPMM, a permanent magnet synchronous motor with the characteristic that the rotor does not generate heat, reduces the number of lead wires, enables a wide range of constant output control in the S-axis operation mode (low speed, high speed), and is a necessary and sufficient condition for spindle indexing control. The response frequency characteristics of the velocity loop can be increased.

[0011]

As described above, according to the present invention, it is possible to control a wide range of constant output with a winding configuration in which the number of lead wires of a permanent magnet synchronous motor is reduced, and the number of coils is two. Since it is configured, winding workability is also improved. Furthermore, insulation reliability and safety in use can be ensured. In addition, by reducing the number of lead wires and contactor contacts, low-speed heavy cutting, high-speed finishing, and further, when controlling spindle indexing with the IPMM spindle motor, which is the most important issue of the present invention,
Tamakisen w _a only by switching control of the contactor as star connection, can be the inductance of the motor to about a half or less as compared with the conventional mode switching control in the motor current The response frequency characteristic of the loop can be improved twice or more, and the speed loop can be improved accordingly.
As a result, the control performance for disturbance torque is improved, and there is an effect that the accuracy of machining using the spindle indexing function is improved.

[Brief description of the drawings]

FIG. 1 is a winding and contactor connection diagram illustrating the present invention.

FIG. 2 is a constant output characteristic diagram of a spindle motor.

FIG. 3 is a front sectional view of a rotor of the inner magnet type motor.

FIG. 4 is a connection diagram of a conventional winding and a contactor.

FIG. 5 is a connection diagram of a conventional winding and a contactor.

[Explanation of symbols]

 1 rotor core, 2 magnet insertion hole, 4a permanent magnet

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Yamamoto 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Inside Yaskawa Electric Co., Ltd. (72) Kojiro Sawamura 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu City, Fukuoka Prefecture Yaskawa Electric Co., Ltd. (72) Inventor Akira Kumagai 2-1, Kurosaki Castle Stone, Yawata Nishi-ku, Kitakyushu-shi, Fukuoka Prefecture

Claims (3)

[Claims] 1. A stator winding of a machine tool motor comprises a plurality of windings each having a plurality of windings. When a spindle is controlled at a high rotation speed, a low-speed rotation is performed so that the number of windings of each phase is reduced. In the spindle indexing control, in a winding switching device for a machine tool motor that switches the windings by a contactor so that the number of windings of the windings of each phase is increased, the windings of each phase of the stator windings are wound. It is composed of a first winding having a large number of turns and a second winding having a small number of turns. The second windings of the respective phases are connected at the end of the winding to form a star connection. The first winding is connected to the power supply of each phase, and the first winding is connected between the starting of the second winding of each phase and the ending of the first winding. The wire and the second winding are connected in series, the first winding is star-connected to the power supply of each phase, or the second winding is connected to the power supply of each phase. Winding switching apparatus for a motor for a machine tool, characterized in that it has established a contactor that performs one of selective switching to over connections. 2. When the ratio between the base rotation speed and the maximum rotation speed of the machine tool motor is 1: m, the ratio of the number of turns of the first winding to the second winding is n: 1 ( Where n <(√m)
2. The winding switching device for a machine tool motor according to claim 1, wherein the setting is set to -1). As 3. A motor machine tool to be used, and interior permanent magnet inside a rotor core, d axis inductance of the motor L _d and q-axis inductance L relationship _q is L _d
<Winding switching apparatus for a motor for a machine tool according to claim 1 or 2, wherein the using a permanent magnet synchronous machine forms a motor having saliency comprising the L _q.