WO2010053444A1 - Moteur linéaire à double bobine avec compensation de crantage et de force d’attraction - Google Patents

Moteur linéaire à double bobine avec compensation de crantage et de force d’attraction Download PDF

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Publication number
WO2010053444A1
WO2010053444A1 PCT/SG2008/000427 SG2008000427W WO2010053444A1 WO 2010053444 A1 WO2010053444 A1 WO 2010053444A1 SG 2008000427 W SG2008000427 W SG 2008000427W WO 2010053444 A1 WO2010053444 A1 WO 2010053444A1
Authority
WO
WIPO (PCT)
Prior art keywords
linear motor
coil
magnet track
track assembly
force
Prior art date
Application number
PCT/SG2008/000427
Other languages
English (en)
Inventor
Howe Yuen Lim
Chai Meng Goh
Yong Peng Leow
Original Assignee
Howe Yuen Lim
Chai Meng Goh
Yong Peng Leow
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Howe Yuen Lim, Chai Meng Goh, Yong Peng Leow filed Critical Howe Yuen Lim
Priority to PCT/SG2008/000427 priority Critical patent/WO2010053444A1/fr
Priority to KR1020117012477A priority patent/KR20110082183A/ko
Publication of WO2010053444A1 publication Critical patent/WO2010053444A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
    • H02K41/02—Linear motors; Sectional motors
    • H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
    • H02K41/031—Synchronous motors; Motors moving step by step; Reluctance motors of the permanent magnet type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
    • H02K41/02—Linear motors; Sectional motors
    • H02K41/03—Synchronous motors; Motors moving step by step; Reluctance motors
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K16/00—Machines with more than one rotor or stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K2213/00—Specific aspects, not otherwise provided for and not covered by codes H02K2201/00 - H02K2211/00
    • H02K2213/03—Machines characterised by numerical values, ranges, mathematical expressions or similar information
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K29/00—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices
    • H02K29/03—Motors or generators having non-mechanical commutating devices, e.g. discharge tubes or semiconductor devices with a magnetic circuit specially adapted for avoiding torque ripples or self-starting problems

Definitions

  • the present invention relates to a permanent magnet synchronous linear motor with compensated cogging force and attraction force, thereby giving superior performance and efficiency.
  • ironless linear motor also called coreless linear motor
  • iron core linear motor the ironless linear motor
  • Ironless linear motor derives its name from the fact that it does not contain iron core or iron laminations in the coil.
  • the coil comprises only copper wire formed or molded into a desired shape.
  • Iron core motors uses iron laminations to form a core where the copper wires are wound.
  • the iron core helps to focus the magnetic flux onto the copper wire.
  • Iron core linear motor provides much higher force than an ironless linear motor. It also uses less magnet material in the design compared to ironless motors, thereby making it more cost effective.
  • a cogging force is present in iron core linear motors.
  • This force is formed by the magnetic interaction of the magnets and the teeth of the iron core. It is a well known phenomenon in permanent magnet iron core motors.
  • This cogging force is sometimes called parasitic force or reluctant force.
  • This force is directed along the axis of motion of the linear motor and is present even when no electric current is passed through the motor coils. It disturbs the proper operation of the linear motor by interfering with the desired force from the motor, thereby also disturbing the required motion.
  • Fig 1 illustrates the cogging force, Fc acting on an iron core linear motor. The direction of the force can be positive or negative, depending on the relative position of the coil and the magnet track.
  • the gap between the teeth and the magnets is typically between 0.8 to 1.0 mm.
  • This force and its direction are illustrated by Fa, as shown in Fig 1.
  • the attraction force is about 1 ,450 N, or equivalent to 145 Kg of force.
  • the attraction force is 23,000 N, or equivalent to 2,300 Kg of force. This attraction force is highly undesirable because very large bearing guide rails and runner blocks need to be installed to hold the coil against the magnet track.
  • auxiliary teeth at the ends of the iron core linear motor. This is illustrated in Fig 2, where 5a and 5b are the auxiliary teeth.
  • U.S. Patent No. 5,910,691 describes such a design where two auxiliary teeth (5a, 5b) are added to an iron core linear motor.
  • the auxiliary teeth (5a, 5b) are designed with a slanted angle. With a certain optimized angle, the cogging force can be reduced to a minimum, even though it cannot be eliminated completely.
  • U.S. Patent No. 4,912,746 uses auxiliary teeth (5a, 5b) in the shape of a triangular wedge to reduce cogging force.
  • 6,831 ,379 B2 also describes a linear motor with a 8 pole and 9 slot design, and 2 auxiliary teeth (5a, 5b) are also added to the ends of the linear motor coil.
  • 2 auxiliary teeth (5a, 5b) are also added to the ends of the linear motor coil.
  • U.S. Patent No. 6,476,524 B1 describes another method whereby at least 2 or 3 linear motor coils are arranged in series. Each individual motor coil is made up of 8 poles and 9 slots. By varying the gap or space between the individual coils to a fraction of the magnetic pitch, it has been shown that the net cogging force can be completely eliminated by superimposing the cogging force caused by the individual coils.
  • the minimum coil length of the linear motor is the length of at least 2 linear motor coils, or the equivalent of 16 poles. This makes the linear motor coil very long and not suitable for applications where the moving carriage has space or length limitation. Moreover, this method does not solve the problem caused by the attraction force between the linear motor coil and the magnet track.
  • PCT/NL2005/000029 describes a modular linear motor comprising a number of magnets of alternating polarity placed successively in a plane; at least two successively placed coil modules which modules comprise a stack of parallel plates form, each provided with at least three parallel fingers, and electric coils arranged around the fingers, where the at least two modules are arranged at a distance from each other.
  • This prior art document describes the "cogging effect" of linear motors is hereby reduced when the lamination stacks of the different coil modules are thus not in contact but have a certain distance between them.
  • this prior art document failed to describe the "certain distance” nor suggest neutralizing the "cogging effect”.
  • the cogging force produced by the linear motor as it moves through one cycle has a period of 60 electrical degrees or an equivalent of the distance of 1 /3 of the magnetic pitch.
  • the cogging force Fd produced by the top linear motor coil is counterbalanced or compensated by the cogging force Fc2 produced by the bottom linear motor coil.
  • the net attraction force as seen by the load on which the two linear motors are thus arranged, is effectively zero. In other words, the opposing cogging forces are mutually cancelled
  • a first object of the invention is a dual coil linear motor having
  • each one or more linear motor coils in the first set is diametrically opposed and corresponds to each one or more linear motor coils of the second set, and each linear motor coil in the first set and each corresponding linear motor coil in the second set are offset by a distance of 1 /3 the magnetic pitch, Pm such that the dual coil linear motor produces net zero cogging force and attraction force.
  • a second object of the invention is a dual coil linear motor having
  • first linear motor coil assembled from the same reference position, to form a first magnet track assembly
  • second linear motor coil assembled from the same reference position, to form a second magnet track assembly
  • first magnet track assembly and the second magnet track assembly are diametrically opposite each other and are offset from each other by the distance of 1/3 the magnetic pitch, Pm such that the dual coil linear motor produces net zero cogging force and attraction force.
  • the dual core linear motor having a first magnet track assembly, and a second magnet track assembly are mounted on a mounting plate.
  • the mounting plate is an aluminum plate.
  • the dual coil linear motor has a plurality of ducts in the mounting plate for water to pass through to cool the dual coil linear motor.
  • Fig 1 shows a conventional linear motor.
  • Fig 2 shows another type conventional linear motor.
  • Fig 3 shows the cogging force produced by the linear motor when it moves through one electrical cycle.
  • Fig 4 shows a configuration where 2 linear motor coils are assembled opposite and facing each other.
  • Fig 5 shows the cogging force for a configuration of Fig. 4
  • Fig 6 is a cross section of the preferred embodiment.
  • Fig 7 shows the magnetic circuits of the linear motors.
  • Fig 8 shows another embodiment of this invention.
  • Fig 9 shows the use of mounting plates to join the 2 linear motors and to strengthen the mounting of the 2 linear motor coils
  • Fig 10 shows a complete module using this configuration proposed in Fig. 9
  • Fig 11 shows another embodiment where the linear motor coil mounting plate is designed with water channels to allow water cooling of the linear motor.
  • a conventional dual coil linear motor using a 8 pole, 6 slot design is shown.
  • the linear motor coil (1 a, 1 b) is formed by stacks of iron laminations and the copper coil (2) are formed around the slots of the linear motor coil (1 a, 1 b).
  • Permanent magnets (3) are assembled on a back iron (4).
  • the magnetic pitch, Pm is the distance between one magnet (3) and another. 2 magnets (3) will form one complete electrical cycle, or 360 electrical degrees.
  • the cogging force produced by the dual coil linear motor when it moves through one electrical cycle is shown in Fig 3, where 6 repetitive cycles are observed over one complete electrical cycle of 360 electrical degrees. This means that each of those repetitive cycles has a period of 60 electrical degrees, or an equivalent of the distance of 1/3 of the magnetic pitch.
  • Fig 4 shows a configuration where 2 linear motor coils (1 a, 1 b) are assembled opposite, facing each other.
  • the 2 magnet track assemblies (6a, 6b) are intentionally offset from each other with a distance of 1/3 magnetic pitch.
  • the cogging force Fd produced by the top linear motor coil (1 a) is counterbalanced or compensated by the cogging force Fc2 produced by the bottom linear motor coil (1 b).
  • the 2 linear motor coils (1 a, 1 b) can be mechanically connected by a mounting plate (8) where the load is to be mounted.
  • the linear motor coil (1 a, 1 b) can also be electrically connected together, either in parallel or in series. This means that the 2 linear motor coils (1a, 1 b) can be seen effectively as a single linear motor coil and be driven by one single servo amplifier, with the same current passing to or through the linear motor coil (1 a, 1 b), depending on whether a series or parallel connection is used.
  • Fig 7 shows the magnetic circuits of the linear motors (11 a, 11 b). Since the aluminum track mounting plate (7) is non magnetic, and both linear motors (11 a, 11 b) are separated by this piece, the magnetic circuit of the top motor (9a) and the magnetic circuit of the bottom motor (9b) are separate. There is no interference between the 2 magnetic circuits.
  • Fig 8 shows another embodiment of this invention whereby instead of offsetting the magnetic track assemblies (6a, 6b), the linear motor coil assemblies (10) are offset by the same distance, which is 1/3 of the magnetic pitch or 60 electrical degrees. The effect of this configuration is the same as that described in Fig 4.
  • end plates (15) are used to join the 2 linear motor coils (1 a, 1 b), as shown in Fig 9.
  • These end plates (15) also made of aluminum are very stiff in the lateral direction and helps to maintain the air gap between the linear motor coil (1 a, 1 b) and the magnet track assembly (6a, 6b).
  • FIG 10 A complete module using this configuration is shown in Fig 10, where the linear motor coil assembly (10) is mounted in the center of the module on carriage plate (12), with 2 guide rails (13) on each side on the linear motor assembly (10).
  • the carriage plate (12) is actually joined to the top of the mounting plate (8).
  • the size of the guide rails (13) can be significantly reduced compared to the conventional dual coil linear motors, due to the net zero attraction force acting on the guide rails (13).
  • the guide rails (13) are just used to support the load and guide the linear motors (1 1 a, 1 1 b) in the direction of motion.
  • Such a design can be used in applications such as PCB drilling machines and machine tools.
  • Fig 11 shows another embodiment where the linear motor coil mounting plate (8) is designed with water channels to allow water cooling of the linear motors (11a, 11 b).
  • copper coils (2) can typically operate up to 130 degrees, cooling is necessary for applications where it is not desirable to have heat being transferred to the load.
  • water cooling tubes (14) are typically installed within the linear motor coils (1 a, 1 b) to provide cooling. This method makes the manufacturing process very expensive and tedious, as care needs to be taken to properly isolate the cooling fluid from the copper coil (2) where electric currents are passed. Any leakage will cause shorting and failure of the linear motor coil (1 a, 1 b).
  • This method also takes up useful space on the linear motor coil (1 a, 1 b), replacing some of the copper coils (2) in the limited space available between the slots of the linear motor coil (1 ,1 b).
  • our design by machining the mounting plate (8) to incorporate cooling channels, manufacturing costs is significantly reduced, and more space is available for the windings of the copper coil (2), thereby making the dual coil linear motor more efficient. Any replacement of linear motor coil (1 a, 1 b) or worn out parts is also possible with this modular design.
  • the cogging forces interferes with the proper operation of the linear motor (11a, 1 1 b) by reducing the desired force output from the motor. In so doing, the cogging forces reduces the efficiency of the linear motors (11 a, 1 1 b). By effectively cancelling the cogging forces, the linear motor (11a, 11 b) becomes more efficient and uses less energy in the process. Savings in energy costs as well as higher productivity will accrue to this invention.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Electromagnetism (AREA)
  • Power Engineering (AREA)
  • Linear Motors (AREA)

Abstract

La présente invention concerne un moteur linéaire à double bobine comprenant un premier ensemble d’une ou de plusieurs bobine(s) de moteur linéaire (1a) assemblée(s) depuis la même position de référence, pour former un premier ensemble de chemin magnétique (6a), un second ensemble d’une ou de plusieurs bobines de moteur linéaire (1b) assemblée(s) depuis la même position de référence, pour former un second ensemble de chemin magnétique (6b). Chacune ou des bobine(s) de moteur linéaire dans le premier ensemble (1a) est diamétralement opposée et correspond à chacune ou des bobines de moteur linéaire du second ensemble (1b) et sont décalées par une distance de 1/3 du pas magnétique, Pm. En variante, les ensembles de chemin magnétique (6a, 6b) formés sont décalés l’un de l’autre par une distance de 1/3 du pas magnétique, Pm. Selon les deux modes de réalisation, le moteur linéaire à double bobine produit une force de crantage nette nulle et une force d’attraction.
PCT/SG2008/000427 2008-11-07 2008-11-07 Moteur linéaire à double bobine avec compensation de crantage et de force d’attraction WO2010053444A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
PCT/SG2008/000427 WO2010053444A1 (fr) 2008-11-07 2008-11-07 Moteur linéaire à double bobine avec compensation de crantage et de force d’attraction
KR1020117012477A KR20110082183A (ko) 2008-11-07 2008-11-07 보상된 코깅력 및 인력을 갖는 이중 코일 선형 모터

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/SG2008/000427 WO2010053444A1 (fr) 2008-11-07 2008-11-07 Moteur linéaire à double bobine avec compensation de crantage et de force d’attraction

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Publication Number Publication Date
WO2010053444A1 true WO2010053444A1 (fr) 2010-05-14

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WO (1) WO2010053444A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104767352A (zh) * 2014-01-08 2015-07-08 株式会社安川电机 直线电机及直线电机的制造方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102350608B1 (ko) 2021-05-26 2022-01-12 주식회사 대곤코퍼레이션 기생력을 상쇄시키는 코어리스 리니어 모터 시스템

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1042496A (ja) * 1996-07-19 1998-02-13 Yamaha Motor Co Ltd リニアモータ
US6300691B1 (en) * 1999-08-13 2001-10-09 Mirae Corporation Linear motor with an improved cooling structure
US6445092B1 (en) * 2000-06-07 2002-09-03 Sandia Corporation Dual-circuit segmented rail phased induction motor
US20060012252A1 (en) * 2004-07-16 2006-01-19 Shin-Etsu Chemical Co., Ltd. Linear motor for use in machine tool

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1042496A (ja) * 1996-07-19 1998-02-13 Yamaha Motor Co Ltd リニアモータ
US6300691B1 (en) * 1999-08-13 2001-10-09 Mirae Corporation Linear motor with an improved cooling structure
US6445092B1 (en) * 2000-06-07 2002-09-03 Sandia Corporation Dual-circuit segmented rail phased induction motor
US20060012252A1 (en) * 2004-07-16 2006-01-19 Shin-Etsu Chemical Co., Ltd. Linear motor for use in machine tool

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104767352A (zh) * 2014-01-08 2015-07-08 株式会社安川电机 直线电机及直线电机的制造方法

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