WO2008026642A1

WO2008026642A1 - Power supply device for permanent magnet field type linear motor and pwm inverter for permanent magnet field type motor

Info

Publication number: WO2008026642A1
Application number: PCT/JP2007/066777
Authority: WO
Inventors: Kazuo Shoda; Yuki Nomura; Yoshifumi Nagato
Original assignee: Thk Co., Ltd.
Priority date: 2006-08-30
Filing date: 2007-08-29
Publication date: 2008-03-06
Also published as: KR101384063B1; CN101501982B; JPWO2008026642A1; JP5315053B2; CN101501982A; KR20090043602A

Abstract

Provided is a power supply device for a permanent magnet field type linear motor capable of controlling power supply to coils of the respective phases of the linear motor so as to reduce irregularities in thrust generated in the coils of the respective phases and reduce the speed ripple. The power supply device (11) for a permanent magnet field type linear motor supplies power to an armature (5) of the permanent magnet field type linear motor generating a magnetic flux by a field permanent magnet (4). The power supply device (11) includes: power supply means (13) which supplies a multi-phase AC current to multi-phase coils of the armature (5) of the linear motor (2); and current adjusting means (19) which reduces the current supplied to a coil of at least one phase (for example, W-phase) not located at both ends of the work direction of the linear motor (2) as compared to the current supplied to the remaining two phases (for example, U-phase and V-phase) located at the both ends of the work direction. Thus, it is possible to make the thrusts generated in the coils of the respective phases to be identical, which in turn reduces the speed ripple.

Description

Specification

Power supply device for permanent magnet field type linear motor and PWM inverter for permanent magnet field type motor

Technical field

The present invention relates to a permanent magnet field linear motor power supply device that supplies electric power to an armature of a permanent magnet field linear motor that generates magnetic flux with a field permanent magnet, and a field permanent magnet. The present invention relates to a PWM inverter for a permanent magnet field motor that supplies electric power to an armature of a permanent magnet field motor that generates magnetic flux.

Background art

[0002] A linear motor is obtained by extending a stator side and a mover side of a rotary motor in a straight line, and directly converts electric energy to a linear thrust. Linear motors are classified into DC motors, AC motors, stepping motors, brushless DC motors, etc., as well as rotary motors. DC motors and brushless DC motors are roughly classified into two types: permanent magnet field types that use permanent magnets, and permanent magnets that do not use permanent magnets!

[0003] A permanent magnet field type linear motor generates a magnetic flux by a field permanent magnet and causes an AC current to flow through the armature, thereby generating a thrust in the field permanent magnet or the armature (for example, a patent Reference 1). In a permanent magnet field type linear motor, as shown in FIG. 9, a multi-phase (generally three-phase) coil is wound around the comb teeth 1. The coil is a set of three phases U, W, and V. Since three sets of three coils are provided, the total number of coils is an integer multiple of three. The number of teeth of comb tooth 1 is an integral multiple of 3 equal to the total number of coils. The plurality of coils and comb teeth are arranged side by side in the operating direction of the armature or permanent magnet.

[0004] Patent Document 1: JP 2003-70226 A (see page 1)

Disclosure of the invention

Problems to be solved by the invention

[0005] Since there are always U-phase teeth and V-phase teeth on both sides of the W-phase teeth, for example, the magnetic flux φ generated by the W-phase coil is the adjacent teeth of the U-phase and V-phase teeth. W

1 1 The magnetic flux φ generated by the two-phase coil can pass through the teeth of both adjacent teeth u-phase and V-phase. The However, since only the phase teeth are adjacent to the phase teeth located at the ends of the comb teeth, the magnetic flux φ generated by the U-phase coil passes through the W-phase teeth, but is indicated by a broken line in the figure. It is difficult for the magnetic flux to pass through the area. V-phase teeth located at the other end of the comb teeth

The same can be said for 2. In other words, the U and V phase coinoles located at both ends of the comb teeth have higher magnetic resistance than the w phase coil. For this reason, when a current of the same magnitude is applied to the coinole of each phase (U, W, V phases respectively), the thrust acting on the U, V phase coil is smaller than the thrust acting on the W phase coil. As a result, speed ripple occurs.

[0006] Various methods have been proposed in the past in order to reduce the speed ripple generated in the linear motor. For example, in Patent Document 1, by devising the magnetization direction and arrangement of the permanent magnets on the stator side, the magnetic flux density distribution by the permanent magnet array is made a sine wave, and the counter electromotive force induced in the coil is made closer to a sine wave. A method is disclosed. However, there is no technology in the prior art that reduces the thrust unevenness by focusing on the magnetic resistance of each phase coil of the linear motor and controlling the supply current supplied to each phase coil.

[0007] Therefore, according to the present invention, by controlling the current supplied to the coils of each phase of the linear motor, it is possible to reduce the unevenness of the thrust generated in the coils of each phase, and thus reduce the speed ripple. An object of the present invention is to provide a permanent magnet field type linear motor power supply device and a permanent magnet field type motor PWM inverter.

Means for solving the problem

[0008] Hereinafter, the present invention will be described.

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a permanent magnet field linear motor power supply that supplies power to an armature of a permanent magnet field linear motor that generates magnetic flux with a field permanent magnet. A power supply means for supplying a multiphase alternating current to a multiphase coil of an armature of a linear motor, and at least one phase (for example, W phase) not located at both ends in the operating direction of the linear motor. A permanent magnet field linear motor comprising: current adjusting means for reducing the current supplied to the coil to be less than the current supplied to the remaining two phases (for example, U phase and V phase) located at both ends of the operating direction. Power supply device.

[0009] The invention according to claim 2 is a power supply device for a permanent magnet field linear motor that supplies power to an armature of a permanent magnet field linear motor that generates a magnetic flux with a field permanent magnet. Therefore, the U, V, W phase force of the armature of the linear motor, a power supply circuit that supplies a three-phase alternating current to the three-phase coil, and one phase that is not located at both ends of the linear motor operating direction ( For example, the current supplied to the one phase coil is connected to the other two phases (for example, the U phase and the V phase) located at both ends of the operation direction. And a power supply device for a permanent magnet field type linear motor.

[0010] The invention of claim 3 is a PWM inverter for a permanent magnet field type motor for supplying electric power to an armature of a permanent magnet field type motor that generates a magnetic flux with a field permanent magnet. The arm composed of the upper and lower switching elements operating in the form of three-phase coils for the three-phase coil composed of the U, V, and W phases of the armature and in parallel between the DC power supplies, An arm composed of two upper and lower switching elements that operate in pairs is further provided in parallel between the DC power supplies for the lead wire drawn from the neutral point (N) of the star-connected three-phase coil. And a PWM inverter for a permanent magnet field type motor that controls on and off of the switching element for the three-phase coil and the switching element for the lead wire by a control circuit.

[0011] The invention according to claim 4 is the PWM inverter for the permanent magnet field type motor according to claim 3, wherein the permanent magnet field type motor is a linear motor, and the permanent magnet field type When a three-phase alternating current is supplied to a three-phase coil consisting of U, V, and W phases of the armature of the linear motor, the PWM inverter for motor uses one phase that is not located at both ends of the linear motor operating direction (for example, It is characterized in that the current supplied to the coil of the W phase is made lower than the current supplied to the remaining two phases (for example, the U phase and the V phase) located at both ends of the operating direction.

The invention's effect

[0012] According to the invention described in claim 1, the current adjusting means places the current supplied to the coils of at least one phase (for example, W phase) not located at both ends in the operating direction at both ends in the operating direction. This reduces the current supplied to the remaining two phases (for example, U phase and V phase), so that the thrust generated in the coils of each phase can be made uniform. Therefore, the force S is used to reduce the speed ripple. [0013] According to the invention of claim 2, the current supplied to the coil of at least one phase (for example, W phase) that is not located at both ends in the operation direction is supplied to the remaining resistors located at both ends in the operation direction. Since the current supplied to two phases (for example, U phase and V phase) is reduced, the thrust generated in the coils of each phase can be made uniform. Therefore, the speed ripple can be reduced.

[0014] According to the invention of claim 3, the current supplied to the three-phase coil of the armature of the motor can be controlled for each phase.

[0015] According to the invention described in claim 4, the thrust generated in the coils of each phase can be made uniform. Therefore, the speed lip glue can be reduced.

Brief Description of Drawings

[0016] [FIG. 1] A sectional view along the direction of operation of a permanent magnet field linear motor.

FIG. 2 is a configuration diagram of a power supply device for a permanent magnet field linear motor according to an embodiment of the present invention.

[Fig.3] Diagram showing how to wire the linear motor coil

[Fig.4] A graph of measured voltage (back electromotive force) generated in each phase coil

FIG. 5A is a graph showing an example in which a three-phase alternating current having the same amplitude is supplied to each phase coil.

FIG. 5B is a graph showing an example in which the amplitude of the current supplied to the W-phase coil is reduced below the amplitude of the current supplied to the U-phase and V-phase.

FIG. 6 is a block diagram showing a PWM inverter for a permanent magnet field motor in an embodiment of the present invention.

[Fig. 7] Schematic showing the current flowing in the three-phase coil

[FIG. 8A] —Schematic showing the current flowing in the three-phase coil in the stage processing.

[FIG. 8B] Schematic showing the current flowing in the three-phase coil in the second stage process

[Fig.9] Diagram showing comb teeth of linear motor

Explanation of symbols

[0017] 2 · · · Permanent magnet field linear motor

3 ··· Stator

4 ... Permanent magnet 5. Armature

10 ... Koinole

11 ··· Power supply device for permanent magnet field type linear motor

13 ... Inverter main circuit (Power supply means)

19 .. Resistance (Power adjustment means)

N ... medium raw

20 ... PWM inverter for permanent magnet field type motor (power adjustment means)

21 ... DC power supply

22 ... 'Inverter main circuit (power supply means)

28 ... Control circuit

23, 24, 25 ... Three-phase coinole arm

23a, 23b, 24a, 24b, 25a, 25b… switching element for three-phase coil 26… arm for neutral point

26a, 26b… Switching element for neutral point

27 ... Leader

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a cross-sectional view along the operating direction of a permanent magnet field type linear motor whose armature side is movable as an example of the permanent magnet field type linear motor 2. On the stator 3 side, N-pole and S-pole permanent magnets 4 are alternately arranged at a constant pitch in the armature operating direction. On the armature 5 side, a three-phase coil 10 having U, V, and W phase forces is provided. The armature 5 includes a comb tooth 9 fixed to the top plate 7 with a bolt 8 or the like, and a coil 10 wound around the tooth 9a of the comb tooth 9. The coil 10 is a set of three phases U, W, and V. Since three sets of three coils 10 are provided, the total number of coils 10 is an integer multiple of three. The number of teeth 9a as an iron core is an integral multiple of 3 equal to the total number of coils 10. Coils 10 are arranged side by side in the operating direction of the U, W, V, ..., U, W, V phase and armature. Both ends of the armature 5 in the operating direction are a U-phase coil 10 and a V-phase coil 10. When a three-phase alternating current is passed through the three-phase coil 10, a moving field that moves linearly is generated, and the armature 5 moves linearly with respect to the stator 3. In addition, The coil 10 may be a coreless coil without an iron core. The linear motor may be a so-called rod-type linear motor in which a coil is wound in an annular shape around a rod.

FIG. 2 shows a permanent magnet field type linear motor power supply device 11 according to an embodiment of the present invention. The power supply device 11 of this embodiment is composed of a voltage-type PWM inverter (PWM: Pulse Width Modulation) that converts a DC voltage into an AC voltage, and the armature 5 of the linear motor 2 has a three-phase AC. Supply current.

The permanent magnet field linear motor power supply device 11 includes a DC power source 12, an inverter main circuit 13, and a control circuit 14. The inverter main circuit 13 consists of three phases (U phase, W phase, V phase) arm 15, 16, 17 force. Each of the arms 15, 16, and 17 is also configured with switching elements 15a, 15b, 16a, 16b, 17a, and 17b that move in pairs. Each of the switching elements 15a to 17b is composed of a parallel connection of a transistor and a flywheel diode. The flywheel diode is used to feed back the reverse current to the transistor. The on / off of the switching elements 15a to 17b is determined by the on / off signal of the transistor. By turning on and off the switching element, it is possible to output a three-phase AC voltage equivalently by changing the width of the output voltage without changing the magnitude of the DC voltage. As the switching elements 15a to 17b, MOSFETs (Metal Oxide Semi-conductors or Piezoelectric Defects) A "IGBTs (Insulated Bipolar Mode Transistors) can be used.

The control circuit 14 outputs a PWM signal for controlling on / off of the transistor.

As a method for generating a PWM signal, for example, a triangular wave comparison method is used in which a three-phase sine wave voltage command is compared with a triangular wave (carrier) that is a carrier wave to obtain a voltage of a pulse train. When the transistor is turned on and off by the PWM signal using the triangular wave comparison method, the inverter main circuit 13 outputs a voltage in a Nores series approximated to a three-phase AC voltage. When a three-phase AC voltage is output from the inverter main circuit 13, a three-phase AC current is supplied to the three-phase coil of the linear motor. Two transistor powers connected in series in each phase.If they are turned on at the same time for a short time, a short-circuit of the DC voltage will be caused and the transistor will be destroyed. There is a short-circuit prevention time. FIG. 3 shows a method for connecting coils of a linear motor. There are two types of connection methods: delta connection (delta connection) that connects coils in a ring, Y connection (star) that combines U, V, and W of three coils together, and force S. Figure 3 shows a commonly used star connection.

[0023] The voltage output from the inverter main circuit 13 is a line voltage between WV, WU, and UV.

When a voltage is applied between the WV lines, a current flows through the W phase coil and the V phase coil simultaneously. When a voltage is applied between the W U lines, a current flows through the W phase coil and the U phase coil simultaneously. Therefore, no matter how softly the voltage output from the inverter is controlled, it is not possible to reduce the current supplied to the W-phase coil while keeping the magnitude of the current supplied to the V-phase coil unchanged. In addition, the current supplied to the U-phase coil cannot be reduced while the magnitude of the current supplied to the U-phase coil remains unchanged. For this reason, in this embodiment, the resistor 19 is connected in parallel with the W-phase coil in order to reduce the current supplied to the W-phase harder than the current supplied to the U-phase and V-phase coils. The resistor 19 may be provided in the power supply device or may be provided in the linear motor.

[0024] When a resistor 19 is connected in parallel to the W-phase coil and a line voltage is applied across WV, the current flows between the resistor 19 side and the W-phase coil side as indicated by the arrow (1) in the figure. Branch off. The current flowing in the resistor 19 side and the current flowing in the V-phase coil side merge at the neutral point N and then flow into the V-phase coil. As indicated by the white arrow (2) in the figure, even when a directional force flows from the V-phase coil to the W-phase coil, the current flowing through the V-phase coil is neutral. N branches into a current flowing in the W-phase coil side and a current flowing in the resistor 19 side. Thereafter, they are joined and returned to the inverter main circuit 13. Similarly, when a line voltage is applied between WUs, the current flowing in the W-phase coil branches into a current flowing in the resistor 19 side and a current flowing in the W-phase coil side. By connecting the resistor 19 in parallel to the W-phase coil in this way, it is possible to reduce the current flowing through the W-phase coil without affecting the current flowing through the U-phase and V-phase coils.

[0025] Fig. 4 shows the voltage generated in the coils of each phase when the armature is moved at a constant speed.

The graph which measured (back electromotive force) is shown. When measuring this generated voltage, no current is supplied to the armature, and the resistor 19 is not connected in parallel to the W-phase coil.

Yes [0026] Since the W-phase coil is not located at both ends of the linear motor in the operating direction, it has a lower magnetic resistance than the other U-phase and V-phase. For this reason, as shown in FIG. 4, the amplitude force of the generated voltage at both ends of the W-phase coil is larger than the amplitude of the generated voltage generated in the U-phase and V-phase coils. In other words, the counter electromotive force constant of the W phase coil is larger than the counter electromotive force constant of the U phase and V phase coils. In the case of a DC motor, the counter electromotive force constant is equal to the torque constant. Therefore, when a three-phase AC current with the same amplitude is passed through a three-phase coil, the torque generated by the W-phase coil is caused by the U-phase and V-phase coils. It becomes larger than the generated torque. As a result, the speed becomes constant and speed ripple occurs.

[0027] To eliminate the speed ripple, as shown in FIG. 5A, instead of supplying the same amplitude current to the three-phase coil, it is supplied to the W-phase coil as shown in FIG. 5B. It is only necessary to reduce the current (ie, reduce the amplitude) compared to the current supplied to the U-phase and V-phase coils. According to the coil connection method shown in Fig. 3, the resistor 19 is connected in parallel to the W-phase coil. Therefore, the current supplied to the W-phase coil is more than the current supplied to the U-phase and V-phase coils. Can also reduce power S. For this reason, it is possible to eliminate the variation in thrust generated by the coils of each phase, and to reduce the speed ripple. The size of the resistor 19 is determined in consideration of variations in the back electromotive force constant of each phase coil and the inductance of each phase coil.

[0028] When a resistor is connected in parallel to the W-phase coil, the motor connection may be a Δ connection, or the motor may be driven by a unipolar drive using three semiconductor elements. Further, the motor may be a four-phase motor connected with a three-phase motor.

FIG. 6 shows a PWM inverter 20 (PWM: Pulse Width Modulation) for a permanent magnet field motor in an embodiment of the present invention. The PWM inverter 20 converts a DC voltage into an AC voltage and supplies a three-phase AC current to the armature of the linear motor.

The PWM inverter 20 includes a DC power source 21, an inverter main circuit 22, and a control circuit 28. The inverter main circuit 22 has two upper and lower switching elements 23a, 23b, 24a, 24b, 25a, and 25b that operate in pairs. For three-phase coils consisting of phases, three phases are provided in parallel between DC power supplies 21. More In addition, the inverter main circuit 22 of this embodiment includes the upper and lower switching elements 26a and 26b acting as a pair, and the arm 26 consisting of the neutral point of the star-connected three-phase coil. Provided in parallel between the DC power supplies 21 for the lead wire 27 drawn from N. That is, the arm 26 composed of the upper and lower switching elements 26a, 26b is connected in parallel to the DC power source 21, while the lead wire 27 is drawn from the neutral point N, and the upper switching element 26a and the lower switching element Connect lead wire 27 drawn from neutral point N to 26b.

[0031] Each arm 23 to 26 is composed of switching elements 23a to 26b that operate in pairs in the vertical direction. Each switching element 23a to 26b is configured by a parallel connection of a transistor and a flywheel diode. The flywheel diode is used to feed back the reverse current to the transistor. The on / off state of the switching element is determined by the on / off signal of the transistor. By turning on and off the switching element, it is possible to output a three-phase AC voltage equivalently by changing the width of the output voltage without changing the magnitude of the DC voltage. As the switching element, a MOSFET (Metal Oxide Semi-conductor or Piezoelectric Effect Transistor) A "IGBT (Insulated Bipolar Mode Transistor) can be used.

[0032] In the conventional PWM inverter 11 (see Fig. 2) in which the arm for the three-phase coil is provided without providing the arm for the neutral point, the switching element of the arm for the three-phase coil is turned on. By turning it off, a three-phase AC voltage is output. However, as described above, since the voltage output from the inverter main circuit 13 is a line voltage between WV, WU, and UV, for example, at the point (1) in FIG. A line voltage (for example, 280V) is applied between the WV lines, and a line voltage (for example, 280V) is applied between the WV lines. At this time, as shown in FIG. 7, a current I flows through the W-phase coil and the U-phase coil, and a current I flows through the W-phase coil and the V-phase coil. Therefore, supply to U phase and V phase

2

It is not possible to reduce only the current supplied to the W-phase coil without changing the current that is supplied.

[0033] In order to solve this problem, in the PWM inverter 20 of this embodiment, an arm 26 is provided for the lead-out line drawn from the neutral point N. For example, at the point (1) in FIG. Thus, the processing when the switching element is on is divided into two stages. Specifically, as shown in FIG. 8A, in the first stage processing, current I flows from the W-phase coil to the lead wire 27.

3 so that no current flows through the U-phase and V-phase coils. On the other hand, as shown in FIG. 8B, in the second stage processing, current I flows from the lead wire 27 to the U-phase coil.

Four

At the same time, current I flows from lead wire 27 to the V-phase coil, and current flows to the W-phase coil.

Five

Do not let it. Table 1 shows the two-step switching mode of the PWM inverter 20.

[0034] [Table 1]

[0035] Then, by adjusting the processing time of each of the first and second stages, the magnitude of the current flowing in the U phase and the V phase is left unchanged, and only the magnitude of the current flowing in the W phase is reduced. be able to. Since the current flowing through the W-phase coil can be reduced, variations in the thrust generated by the coils of each phase can be eliminated, and consequently the speed ripple can be reduced. The PWM signal for turning on and off the switching element is created by the control circuit d * o

In addition to this, control by a conventional triangular wave comparison method that obtains a voltage of a pulse train by comparing a three-phase sine wave voltage command and a triangular wave (carrier) as a carrier wave, and a current to a W-phase coil. By combining the control in the second switching mode in which the current flows only to the U-phase and V-phase coils without flowing, the current flowing to the W-phase coil can be reduced.

[0037] By providing the arm 26 for the neutral point N, it is possible to increase the current flowing in the W-phase coil as well as reducing the current flowing in the W-phase coil. Furthermore, even when current flows from U → V, U → w, v → u, v → w, the current flowing in the U-phase coil and V-phase coil is controlled by providing a two-step switching mode. It becomes possible to do. Therefore, it is possible to control the current flowing through the coils of each phase. This specification is based on Japanese Patent Application No. 2006-234412 filed on August 30, 2006. All this content is included here.

Claims

The scope of the claims

[1] A power supply device for a permanent magnet field linear motor that supplies power to an armature of a permanent magnet field linear motor that generates magnetic flux with a field permanent magnet,

Power supply means for supplying a multiphase alternating current to the multiphase coil of the armature of the linear motor, and at least one phase (for example, W phase) not located at both ends of the linear motor in the operating direction.

Current adjusting means for reducing the current supplied to the coil of (2) below the current supplied to the remaining two phases (for example, the U phase and the V phase) located at both ends of the operating direction. Power supply device for magnetic linear motor.

[2] A power supply device for a permanent magnet field linear motor that supplies power to an armature of a permanent magnet field linear motor that generates magnetic flux with a field permanent magnet,

A power supply circuit for supplying a three-phase alternating current to a three-phase coil composed of U, V, and W phases of a linear motor armature;

The current supplied to the coil of one phase that is connected in parallel to one phase (for example, W phase) coil that is not located at both ends in the operation direction of the linear motor is supplied to the remaining two coils that are located at both ends in the operation direction. A permanent magnet field-type linear motor power supply device comprising a resistance that is reduced more than the current supplied to two phases (for example, U phase and V phase).

[3] A PWM inverter for a permanent magnet field motor that supplies electric power to the armature of a permanent magnet field motor that generates magnetic flux with a field permanent magnet,

Arms composed of upper and lower switching elements that operate in pairs are provided in parallel for three-phase coils for the three-phase coil composed of the U, V, and W phases of the armature and between the DC power supplies. ,

Arms consisting of two upper and lower switching elements that operate in pairs are further provided in parallel between the DC power supplies for the lead wire drawn from the neutral point of the three-phase coil connected in a single line.

A permanent magnet field motor PWM inverter that controls on and off of the switching element for the three-phase coil and the switching element for the lead wire by a control circuit. The permanent magnet field type motor is a linear motor,

The PWM inverter for the permanent magnet field type motor is positioned at both ends of the linear motor in the operation direction when supplying a three-phase alternating current to a three-phase coil composed of U, V, and W phases of the armature of the linear motor. The current supplied to the coil of one phase (for example, W phase) not to be reduced is less than the current supplied to the remaining two phases (for example, U phase and V phase) located at both ends of the operating direction. 4. A PWM inverter for a permanent magnet field motor according to claim 3.